synthesis and characterization of low loss dielectric...

Research ArticleSynthesis and Characterization of Low LossDielectric Ceramics Prepared from Composite ofTitanate Nanosheets with Barium Ions

AleksandraWypych-Puszkarz1 Izabela Bobowska1

AngelikaWrzesinska1 Agnieszka Opasinska1 Waldemar Maniukiewicz2

Piotr Wojciechowski1 and Jacek Ulanski1

1Department of Molecular Physics Faculty of Chemistry Lodz University of Technology Zeromskiego 116 90-924 Lodz Poland2Institute of General and Ecological Chemistry Faculty of Chemistry Lodz University of TechnologyZeromskiego 116 90-924 Lodz Poland

Correspondence should be addressed to Aleksandra Wypych-Puszkarz aleksandrawypychplodzpl

Received 28 February 2017 Revised 23 April 2017 Accepted 14 May 2017 Published 14 June 2017

Academic Editor Claude Estournes

Copyright copy 2017 Aleksandra Wypych-Puszkarz et al This is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited

We report a strategy for preparing barium titanate precursor being the composite of titanate nanosheets (TN)with barium ions (Ba-TN) which subjected to step sintering allows obtaining TiO2 rich barium titanate ceramics of stoichiometry BaTi4O9 or Ba2Ti9O20These compounds are important in modern electronics due to their required dielectric properties and grainsrsquo size that can bepreserved in nanometric range The morphology studies structural characterization and dielectric investigations were performedsimultaneously in each step of Ba-TN calcinations in order to properly characterize type of obtained ceramic its grainsrsquomorphologyand dielectric properties The Ba-TN precursor can be sintered at given temperatures so that its dielectric permittivity can betuned between 25 and 42 with controlled temperature coefficients that change from negative 32 ppm∘C for Ba-TN sintered at900∘C up to positive 37 ppm∘C after calcination at 1300∘C XRD analysis and Raman investigations performed for the Ba-TNin the temperature range of 900 divide 1250∘C showed that below 1100∘C we obtained as a main phase BaTi4O9 whereas the highercalcinations temperature transformed Ba-TN into Ba2Ti9O20 Taking into account trend of device miniaturization and nanoscopicsize requirements temperatures of 900∘C and 1100∘C seem to be an optimal condition for Ba-TN precursor calcinations thatguarantee the satisfactory value of dielectric permittivity (120576 = 26 and 32) and ceramic grains with a mean size of sim180 nm andsim550 nm respectively

1 Introduction

Barium titanate ceramic materials have long history inelectrotechnical applicationsThese dielectric oxide ceramicsserve asmicrowave resonators and they aremain componentsof many devices like cellular phones global positioningsystem and environmental monitoring systems on satellites[1] The main aim of research in this area is to develop newmaterials or improve properties of already known systems(ie reducing dielectric loss and increasing dielectric permit-tivity) Recent revolutionary changes in wireless communica-tion were achieved by reducing size and cost of components

made from improved microwave ceramics Wide variety ofpolytitanates has been synthesized and characterized up tonow Among them particularly a BaO-TiO2 system with Tirich region is interesting because it exhibits eligible electricalproperties like good electrical permittivity and low dielectricloss at radio frequencies BaTi4O9 BaTi5O11 and Ba2Ti9O20are prominent low loss dielectric compounds in this groupBaTi4O9 as dielectric ceramic was for the first time reportedby Masse et al [2] at early 1970 and had a huge contri-bution to a breakthrough in dielectric resonators ceramictechnology Conventional method for the preparation ofBaTi4O9 is the solid state ceramic route by ball milling of

HindawiJournal of NanomaterialsVolume 2017 Article ID 1351085 9 pageshttpsdoiorg10115520171351085

2 Journal of Nanomaterials

stoichiometric amounts of BaCO3 and TiO2 for about 24hours [3 4] and sintering at about 1100∘C It is then againball milled pelletized and sintered at about 1350∘C to achievedensification of the ceramic body Wet chemical methodssuch as oxalate [5] and citrate route [6] as well as modifiedPechini method [7] were also applied for BaTi4O9 powderspreparation Cernea et al [5] obtained BaTi4O9 from oxalatesand documented its stable dielectric properties dielectricpermittivity 120576=38 quality factor119876 = 3800divide4000 at 6divide7GHzand temperature coefficient 120591119891 = 11 ppm∘C Pure BaTi4O9suffers from relatively high values of temperature coefficientso it is not very suitable as dielectric resonator Hence thedielectric properties of BaTi4O9 phase are often modifiedby using different additives [8] BaTi5O11 synthesis was forthe first time described by Tillmanns but it was not purephase but mixed with rutile [9] Single-phase BaTi5O11 wasprepared by wet chemical methods like citrate route [10] orsol-gel [11] This phase is stable under heating up to 1200∘Cthen it decomposes into TiO2 Ba2Ti9O20 andor BaTi4O9BaTi5O11 phase has higher dielectric constant and qualityfactor compared to BaTi4O9 however the values of 120591119891 are alsohigher Fukui et al prepared BaTi5O11 by sol-gel method afterheating at 1120∘C for 48 hours Obtained samples exhibiteddielectric permittivity equal to 42 119876 times 119891 gt 60000GHzand 120591119891 = 39 ppm∘C [12] Ba2Ti9O20 can be conventionallysynthesized by mixing BaCO3 and TiO2 in appropriatestoichiometry and calcined at about 1200∘C again milledpelletized and sintered at about 1400∘C for 3 hours [13]Ba2Ti9O20 obtained by solid state synthesis usually coexistswith BaTi4O9 phase as it is thermodynamically stable in thevicinity of the desired composition However pure phasesynthesis was achieved by wet chemistry methods Lu et al[11] described synthesis based on mixing methanol solutionof bariumhydroxidewith titania sol obtained fromhydrolysisof titanium alkoxide Obtained xerogel was stepwise heatedup to 1100∘C giving BaTi5O11 phase while prolonged heatingat 1200∘C gave pure Ba2Ti9O20 Fang et al [14] preparedBa2Ti9O20 in reaction of BaTi4O9 with TiO2 and sinteringat 1390∘C Obtained sample showed grain size of about 2-3micrometers and high sintered density of 99The dielectricpermittivity was equal to 39 quality factor was 42000GHzand the temperature coefficient reached 5 ppm∘C BaTi4O9and Ba2Ti9O20 have similar values of dielectric permittivityand quality factors BaTi4O9 has temperature coefficient closeto zero and is always positive while reported values of 120591119891 forBa2Ti9O20 are close to zero as well as being negative in somereports [10]

The method of mixing of two low loss ceramic mate-rials with positive and negative temperature coefficient hasbecome well known [15] This kind of approach is veryconvenient for preparation of new materials with desiredproperties by simple selection of proper components How-ever very often it is difficult to obtain material with expectedintermediate properties because it is impossible to retainindividual character of components during sintering processThus development of new precursors of barium titanatesand study of their temperature transformation and dielectricproperties are still very attractive

The aim of this work was to develop a method forTiO2 rich barium titanates synthesis by employing titanatenanosheets (TN) They have an orthorhombic layered struc-ture that is composed of corrugated host layers of edge-shared octahedra and interlayer (tetramethyl)ammoniumions (TMA+) compensating for the negative charge whicharises from substitution of lower valence metal ions orvacancies of Ti [16] These TMA+ ions are exchangeablewith a variety of inorganic and organic ions and in thisway the TN is an ideal candidate for host-guest chemistryas well as ion exchange [17] The ion exchangeability alsoprovided the opportunity to prepare precursor of ceram-ics For example potassium hexatitanate (K2Ti6O13) wasprepared by ion exchange followed by heat treatment at600∘C [18] Taking this into consideration in this work weapplied TN in ion exchange process to immobilize bariumions from solution The obtained by this way compositeunder a thermal treatment in moderate temperature in airtransformed to BaTi4O9 BaTi5O11 and Ba2Ti9O20 phaseswith desired dielectric properties

2 Experimental Section

All reagents were used as received without further purification

Synthesis 250ml aqueous solution of barium acetate mono-hydrate (545 g 20mol purchased from Polish ChemicalReagents POCH Gliwice Poland) was mixed with 250mlaqueous colloidal solution of titanate nanosheets TN (25 g R =06) The details of preparation and characterization of TNhave been reported elsewhere [19] After mixing solutionsion exchange reaction between (tetramethyl)ammonium ionsfrom TN and barium cations from barium acetate in aqueousenvironment led to precipitation of the powder The mixturewas heated for 10 h at room temperature under stirring andnext without stirring for 10 h at 90∘C After the reactionthe precipitate was separated by centrifugation washed withwater until pH 7 and dried under vacuum The total yield ofdried organic-inorganic powder was 23 g and it is labeled asBa-TN or precursor of barium titanate The Ba-TN powderafter reaction was subjected to calcination at 500∘C for 1hour and pressed to get a pellet under pressure of 436MPafor 10min Based on thermogravimetric measurement (datanot shown) temperature of 500∘C was chosen as an optimalone that allows a decomposition of the organic part of theprecursor and the evaporation of volatile products from thesample The higher temperatures allow for thermal diffusionof the reagents throughout the volume to facilitate thereaction that produces barium titanate ceramic The pelletwas sintered at 900∘C for 4 hours and then subsequently at950∘C 1000∘C 1050∘C 1100∘C 1150∘C 1200∘C 1250∘C and1300∘C for 2 h in each temperature The time of sinteringwas chosen according to research of Pfaff who found thatat temperature higher than 900∘C a densification parameterof BaTi4O9 is constant after two hours of heat treatment[20] During the applied step sintering procedure the meanparticle diameter was investigated and pelletsrsquo green densitycalculated simultaneously with its phase transformation anddielectric properties studies

Journal of Nanomaterials 3

3 Characterization

Raman investigations were performed using a FourierTransform Raman spectrometer (Bruker) All spectra wererecorded in the macrochamber light scattering mode theRaman spectra were obtained at 20∘Cusing theNdYAG laserwavelength 120582 = 1064 nm

Room temperature powder X-ray diffraction patternswere collected using a PANalytical XrsquoPert Pro MPD diffrac-tometer in the BraggndashBrentano reflection geometry CopperCuK120572 radiation was used from a sealed tube Data werecollected in the 2120579 range 5ndash90∘ with a step of 00167∘ andan exposure per step of 20 s The samples were spun duringdata collection to minimize preferred orientation effects Forphase analysis the PANalytical High Score Plus softwarepackage was used combined with the International Centrefor DiffractionDatarsquos (JCPDS) powder diffraction file (PDF-2ver 2009) database of standard reference materials

Particle sizes of Ba-TN obtained in different step of calci-nation were estimated from SEM images that were collectedusing a Hitachi S3400N scanning electron microscope withaccelerating voltage of 25000V

The dielectric properties of synthesized sample wereinvestigated using a Novocontrol GmbH Concept 40 broad-band dielectric spectrometer equipped with Quatro Cryosys-tem in the frequency range of 10minus1 divide 106Hz and in thetemperature range of minus140∘C divide 200∘C (in steps of 10∘C) Theobtained complex dielectric function (120576lowast) was measured by

120576lowast = 1205761015840 minus 11989412057610158401015840 (1)

where 1205761015840 and 12057610158401015840 are the real and imaginary parts respectivelyBefore electric measurement each pellet was additionally

dried at 90∘C under reduced pressure in order to exclude theinfluence of the humidity To provide good contact betweenthe sample and external electrodes during electrical investi-gations 150 nm thick gold electrodes were deposited on bothsites of the pellet The densities of the samples sintered atdifferent temperatures were evaluated based on the externaldimensions and mass of the pellets The relative density ofpellets was estimated through comparison with theoreticalcrystallographic density of the major crystallographic phasedefined from Raman and XRD investigations

4 Results and Discussion

Raman spectra of the samples before and after the ionexchange are shown in Figure 1 For TN in Figure 1(a)the spectrum is essentially the same as the data reportedfor titanate nanosheets intercalated by TMA+ ions [21]According to the literature [21 22] Raman bands observedat 275 cmminus1 384 cmminus1 448 cmminus1 662 cmminus1 883 cmminus1 and899 cmminus1 can be attributed to the Ti-O lattice vibrations in theTiO6 octahedral host layers and the strong peaks at 756 cm

minus1

and 954 cmminus1 were related to (tetramethyl)ammonium ions(TMA+) These two peaks just disappear after the exchangereaction-replacement (Figure 1(b)) of TMA+ ions in TN bybarium ions The Raman vibration assigned to Ti-O stillexists which is a convenient proof that 2D structure of TN

Inte

nsity

(au

)

(b)

(a)

280 cmminus1

384 cmminus1

448 cmminus1

675 cmminus1 810 cmminus1

890 cmminus1

275 cmminus1

384 cmminus1

448 cmminus1

662 cmminus1

756 cmminus1

883 cmminus1899 cmminus1

954 cmminus1

200 600400 1000800Wavenumber (cmminus1)

Figure 1 Raman spectra of dried (a) titanate nanosheets TN and(b) precipitate Ba-TN

267

591

478

447

359

117

(e)(d)(c)

(b)

Inte

nsity

(a)

860650626

429

286

262230

188

134

144lowast

415lowast

537lowast

558lowast

750lowast

200 300 400 500 600 700 800 900 1000100

Raman shift (cmminus1)

Figure 2 Raman spectra collected at room temperature for Ba-TNafter sintering at (a) 900∘C (b) 950∘C (c) 1000∘C (d) 1050∘C and(e) 1100∘C Raman bands characteristic for BaTi5O11 are labeled bystars

was preserved However peaks at 600ndash1000 cmminus1 spectralregion shift to lower frequencies which could be affected by apresence of Ba2+ ions in the interlayer of TN [23] Obtainedpowder of Ba-TN could be considered as a precursor ofBaTi4O9 since after the thermal treatment at 900∘C for 4 h itgave the characteristic Raman spectrum for this compound(Figure 2(a)) One can observe bands located at 117 cmminus1134 cmminus1 188 cmminus1 230 cmminus1 262 cmminus1 267 cmminus1 286 cmminus1359 cmminus1 429 cmminus1 447 cmminus1 478 cmminus1 591 cmminus1 626 cmminus1650 cmminus1 and 860 cmminus1 that are characteristic for BaTi4O9[24] according to work of Rossel et al Further sintering attemperature range between 950∘C and 1100∘C during 2 hat each temperature gave the Raman spectra of the sameintensity and identical Raman bands as observed for Ba-TNsintered at 900∘C (see Figure 2(bndashe)) These results allowfor conclusion that there was not any phase transformation


536

61542

6

308

224

(c)

(b)

Inte

nsity

(a)

259

21016

815

0122

340 39

435

9

508

770 80

5 845

567

694

465

130lowast

184lowast

287lowast

650lowast

200 300 400 500 600 700 800 900 1000100


Figure 3 Raman spectra collected at room temperature for Ba-TNafter sintering at (a) 1150∘C (b) 1200∘C and (c) 1250∘CRamanbandsassigned to BaTi4O9 are marked by stars

during the applied thermal treatment in the temperaturerange between 900∘C and 1100∘C Moreover sharpness ofRaman peaks denotes well crystallized structure that wasindependently revealed by X-ray diffraction studies Detailedanalysis of the recorded Raman spectra allowed observingbands of lower intensity which are located at 144 cmminus1415 cmminus1 537 cmminus1 558 cmminus1 and 750 cmminus1They aremarkedby stars (in Figure 2) and their occurrence indicates thepresence of barium titanate of stoichiometry BaTi5O11

Figure 3 shows Raman spectra for Ba-TN precursorsintered for 2 h at (a) 1150∘C (b) 1200∘C and (c) 1250∘C onwhich one can observe a significant change of the spectra ascompared to Raman spectrum of precursor sintered up to1100∘C In Figure 3(andashc) there are Raman bands characteristicfor BaTi4O9 phase that almost totally disappearedwith excep-tion of the bands located at 130 cmminus1 184 cmminus1 287 cmminus1and 650 cmminus1 For the precursor sintered at the temperaturesof 1150∘C and higher there are detected Raman bandslocated at 122 cmminus1 150 cmminus1 168 cmminus1 210 cmminus1 224 cmminus1259 cmminus1 308 cmminus1 340 cmminus1 359 cmminus1 394 cmminus1 426 cmminus1465 cmminus1 508 cmminus1 536 cmminus1 567 cmminus1 615 cmminus1 694 cmminus1770 cmminus1 805 cmminus1 and 845 cmminus1 that can be assigned tobarium titanate of stoichiometry Ba2Ti9O20 Raman spectrashown in Figure 3(andashc) have a very good agreement withwork of Javadpour and Eror [25] who detected by Ramanspectroscopy Ba2Ti9O20 phase after long treatment at 1200∘Cas well as with work of Xu et al [26]

The XRD diffraction patterns of the Ba-TN samplesafter sintering at 900∘Cndash1250∘C are shown in Figure 4 TheXRD analysis revealed that below 1100∘C we observed asa main phase orthorhombic BaTi4O9 (JCPDS number 34-0070) and the presence of BaTi5O11 (JCPDS number 35-0805) as secondary phase The increase of the calcinationtemperature above 1100∘C caused the phase transition andcrystallization of Ba2Ti9O20 (JCPDS number 40-0405) butthe peaks attributed to BaTi4O9 were still visibleThese results

Table 1 Phase composition [ ww] of Ba-TN sintered at differenttemperatures estimated from XRD patterns

Phase Temp900∘C 1100∘C 1150∘C 1200∘C 1250∘C

BaTi4O9 66 42 8 6 6BaTi5O11 34 45 mdash mdash mdashBa2Ti9O20 mdash 13 92 94 94

(f)

(e)

(d)

(c)

(b)In

tens

ity (a

u)

(a)

xxxxxxxxx

x

xxxx

30 40 50 6020

2휃 (∘)

Figure 4 XRD patterns of Ba-TN after sintering at (a) 900∘C (b)950∘C (c) 1100∘C (d) 1150∘C (e) 1200∘C and (f) 1250∘C (X BaTi4O9x BaTi5O11 e Ba2Ti9O20)

are in good agreement with Raman spectra where phasetransformation of BaTi4O9 into Ba2Ti9O20 was also observedfor Ba-TN sintered at temperature higher than 1100∘C Thequantitative phases composition of the studied samples wasestimated on the basis of XRD spectra using the referenceintensity ratio (RIR) method [27] and the obtained data aregathered in Table 1 The RIR method involves comparing theintensity of one or more peaks of a phase with the intensity ofa peak of a standard (usually the corundum 113 reflection) ina 50 50 mixture by weight For the processing of diffractiondata the PANalytical High Score Plus software package wasused

It was found that in the effect of sintering at 900∘C theBaTi4O9 phase constituted 66 ww and BaTi5O11 34 wwof the sample An increase of the temperature to 1100∘Cinduced certain changes in phase composition A proportionof BaTi4O9 to BaTi5O11 phases slightly changed into ratio4245 ww and a new phase showed up ndash Ba2Ti9O20with the content of 11 ww The rise of the temperatureof only 50∘C resulted in very significant changes in phasecomposition BaTi5O11 phase disappeared completely andnew phase that is Ba2Ti9O20 with a content of 92 ww andBaTi4O9 with a content of 8 ww was observed Furtherincrease of sintering temperature up to 1200∘C and 1250∘Cdid not influence significantly the phase composition TheBa2Ti9O20BaTi4O9 weight ratio was estimated at 946 wwfor higher sintering temperatures The observed changes


2 휇m

(a)

2 휇m

(b)

2 휇m

(c)

2 휇m

(d)

5 휇m

(e)

5 휇m

(f)

Figure 5 SEM images of Ba-TN subjected to step sintering at (a) 500∘C (b) 950∘C (c) 1050∘C (d) 1100∘C (magnification 10k) (e) 1150∘Cand (f) 1200∘C (magnification 25k) collected with accelerating voltage 25 kV

are in good agreement with observation made by Ramanspectroscopy However the scattering intensities of BaTi5O11andBa2Ti9O20 phases aremarkedly lower thanBaTi4O9ThusBa2Ti9O20 phase was not observed by Raman spectroscopyafter the sample sintering at the temperature of 1100∘C butonly after treatment at the temperature of 1150∘C where thedomination of this phase was reached

Figure 5 illustrates SEM images of Ba-TN powder sub-jected to calcination at 500∘C for 1 hour and sintering for 2 hat the temperature range from 950∘C to 1200∘C Mean sizeof grains and standard deviation evaluated on the basis ofSEM images analysis are presented in Figure 6 in relationto sintering temperature The grain size of Ba-TN precursorannealed at 500∘C and 950∘C kept constant value below200 nm

After the sintering at the temperature of 1050∘C theparticles were still characterized by narrow size distributionand sphere-like grains morphology however mean sizeincreased to ca 400 nm and size distribution significantlywidened A shift of sintering temperature to 1100∘C inducedevident changes in morphology partial coarsening of grainsoccurred At the temperature of 1150∘C and higher thesphere-like morphology of grains disappeared and irregularagglomerates and large grains were mainly observed Themean size of grains increases up to about 10 120583m and 16120583mfor the temperatures 1150∘C and 1200∘C respectively In thecase of Ba-TN sintered at 1200∘C irregular agglomerates ofrounded shape transformed into sharp angular grains Amarked change in grainsrsquo size and morphology observed atthe temperature above 1100∘C coincides with the structural


Table 2 Pellets filling percentage and dielectric properties of the Ba-TN precursor sintered at different temperatures

Sintering temperatureof Ba-TN precursor [∘C]

Relativedensity []

Dielectric constant (120576)(at 1MHz)

tan(120575)(at 1MHz)

Quality factor(119876) at 1MHz

Temperature coefficient(c)ppm∘C

900 64a 257 42 lowast 10minus4 2300 minus321100 78a 324 87 lowast 10minus5 11500 minus181200 85b 351 77 lowast 10minus5 13000 71250 88b 376 75 lowast 10minus5 13300 331300 98b 420 15 lowast 10minus5 66600 37aValue calculated in regard to theoretical density of BaTi4O9

bvalue calculated in regard to theoretical density of Ba2Ti9O20cvalue calculated in a temperature

range from minus130∘C to 100∘C

500 600 700 800 900 1000 1100 1200 1300400

Sintering temperature (∘C)

00

05

10

15

20

25

30

Gra

in si

ze (휇

m)

Figure 6 Grain size dependence as a function of calcinationtemperature

transformation observed by Raman spectroscopy and XRDanalysis

The dielectric parameters of the sintered precursor arestrictly dependent on densification behavior that is shrink-age of formed discs upon heating From this reason therelative density and percentage of pelletsrsquo filling were investi-gated as a function of applied step sintering It is well knownthat higher temperature of sintering rises these parametershowever in Figures 7(a) and 7(b) one can find some regimesthat are distinguished by different behavior below and abovetemperature of 1050∘C Below this temperature the increaseof relative density and percentage of pelletsrsquo filling is slowwhereas above 1050∘C these parameters rise substantiallyThis caused a rapid pelletrsquos contraction that can be connectedwith an acceleration of diffusion in solid state and initiation ofneck formation between crystallites above this temperaturethat is in agreement with grainsrsquo morphology changes at1100∘C revealed by SEM investigations Above this temper-ature there is a phase transformation of main (BaTi4O9) andsecondary (BaTi5O11) phases into Ba2Ti9O20 and concomi-tant further increase of pelletsrsquo relative density The percent-age of pelletsrsquo filling was calculated taking into account thetheoretic density values of BaTi4O9 and Ba2Ti9O20 that areequal 452 gcm3 (PearsonrsquosCrystalData ICDD04-007-2688)

and 458 gcm3 (crystallographic data reference code 00-035-0051) respectively Finally after sintering at 1250∘C calculatedrelative pelletrsquos density was 401 gcm3 that corresponds tomore than 85 of Ba2Ti9O20 crystallographic density

To characterize the dielectric properties of sintered atdifferent temperatures Ba-TN pellets we applied broadbanddielectric spectroscopy which allowed us to determine thefollowing physical properties that are important for ceramicapplications dielectric permittivity (120576) quality factor (119876)defined as 1tan (120575) and temperature coefficient of resonantfrequency (120591120576) Figure 8 shows three-dimensional graphscomprising the temperature-frequency representations ofdielectric permittivity for Ba-TN sintered at 900∘C (Fig-ure 8(a)) and 1200∘C (Figure 8(b)) respectively The graphsclearly show that in very broad temperature and frequencyranges there is a lack of any relaxation process in thematerialThe increase in these variables at low frequencies and athigh temperatures is connected with interfacial polarizationor electrode polarization contribution that might be presentunder these conditions These graphs are exemplary also forBa-TN precursor sintered in other temperatures

In Figure 9 the temperature dependence of dielectricpermittivity of Ba-TN subjected to sintering at differenttemperatures is shown All samples in MHz frequencies arecharacterized by very stable flat response over broad rangeof temperatures (more than 230∘C) One can observe anincrease of 120576 with sintering temperature that is connected towell known relationship between density of the sample andits dielectric properties according to which higher densityresults in a higher dielectric permittivity and lower porositywhich improves also quality factor value 119876 The relativedensity of ceramic pellets studied by us was varying from64 to 96 (Table 2) It means that measured ceramicswere partially porous and can be considered as capacitorcomposed of ceramic and air Phase composition ofmeasuredsample (calculated from XRD data gathered in Table 1) isanother factor influencing dielectric permittivity In the caseof BaTi4O9 and Ba2Ti9O20 the maximum literature valuesof 120576 were equal to 39 [5] and 52 [28] respectively The Ba-TN subjected to step sintering in a range of temperaturesfrom 900∘C to 1300∘C can be considered as a mixture oftetra- and nonatitanates thus they are expected to possessintermediate dielectric properties It can be concluded thatBa-TN precursor can be sintered at given temperatures sothat its dielectric permittivity can be tuned between 25 and


Main phase BaTi4O9 Ba2Ti9O20

900 950 1000 1050 1100 1150 1200 1250 1300850

Temperature (∘C)

28

30

32

34

36

38

40

Relat

ive d

ensit

y (g

cm

3)

(a)

Main phase

900 950 1000 1050 1100 1150 1200 1250 1300850

Temperature (∘C)

60

65

70

75

80

85

90

Filli

ng (

)

BaTi4O9 Ba2Ti9O20

(b)

Figure 7 Dependence of pelletrsquos relative density (a) and percentage of pelletrsquos filling (b) on the Ba-TN sintering temperature

Temperature (∘C)

Perm

ittiv

ity

Frequency (Hz) 107105

103101

10minus1

2001000minus100minus200

103

102

101

(a)Temperature (∘C)

Perm

ittiv

ity


103101

10minus1


103

102

101

(b)

Figure 8 Temperature-frequency representation of dielectric permittivity Ba-TN sintered at (a) 900∘C and (b) 1200∘C

42 Detected values of tan(120575) measured at 20∘C for frequency1MHz were also very interesting and vary from 42 lowast 10minus4(for Ba-TN sintered at 900∘C) to 15 lowast 10minus5 (for Ba-TNsintered at 1300∘C) The lower value of loss tangent detectedfor samples sintered at higher temperatures can be connectedto higher density of measured pellets It can be noticed that119876 values arise with higher sintering temperature reachinga maximum value of 66600 for sample sintered at 1300∘Cwhich exhibits the highest density equal to 442 gcm3 that is98 of Ba2Ti9O20 theoretical density This can be associatedwith a change of porosity that is higher density of pelletsafter treatment at higher temperature and it is in agreement

with a statement according to which the porosity decreasesthe quality factor due to the presence ofmoisture in the pores

From the representations given in Figure 5 the tem-perature coefficient (120591120576) was calculated as a function oftemperature from minus130∘C to 100∘C according to (2)

1205911205761003816100381610038161003816100∘Cminus130∘C =

1120576(minus130∘C) (

Δ120576Δ119879) ppm

∘C (2)

It was observed that temperature coefficients changed fromnegative for Ba-TN sintered up to 1100∘C with BaTi4O9 asa main phase to positive for Ba-TN sintered in a range of


1300∘C

1250∘C

1200∘C

1100∘C

900∘C

50 1000minus50minus150 minus100

Temperature (∘C)

222426283032343638404244

Die

lect

ric p

erm

ittiv

ity

Figure 9 The temperature dependence of dielectric permittivitymeasured at 115MHz of Ba-TN sintered at different temperaturesRed lines correspond to linear fits for calculation of temperaturecoefficients

temperatures 1150divide1300∘Cwith a main phase of Ba2Ti9O20This can be connected with phase transformation of BaTi4O9into Ba2Ti9O20 and low value of temperature coefficient forbarium nonatitanate that was found equal to about 6 ppm∘C[28] It should be emphasized that the dielectric properties ofthe investigated ceramics depend considerably on sinteringtemperature and their microstructures According to thisthe temperature coefficient for Ba2Ti9O20 may vary betweenminus6 and 38 ppm∘C [10 29] Presented herein are dielectricresults which are in agreement with results of Kumar etal who obtained BaTi4O9 and Ba2Ti9O20 ceramics by thewet chemical gel-carbonate method and found comparabledielectric permittivity but therewas no exact data concerningtemperature coefficient values [28]

Obtained within this work are materials which areregarded as three important low loss dielectric ceramicsBaTi4O9 and Ba2Ti9O20 are regarded as stable forms whereasBaTi5O11 is a metastable one The observed by us trans-formation is in agreement with phase diagram of BaTiO3-TiO2 system [30] where BaTi4O9 is located in the immediatevicinity of Ba2Ti9O20 and both phases appear to be inequilibrium below 1420∘C for compositions between 80 and818mol TiO2 in BaTiO3-TiO2

5 Conclusion

Ba-TN precursor obtained from reaction of titanatenanosheets with barium ions was found as an interestingmethod to obtain barium titanates that exhibit elevatedvalues of dielectric permittivity and low loss tangent in MHzfrequencies The dielectric properties of this composite canbe tailored by suitably adjusting the sintering temperaturesAccording to this barium titanates of stoichiometry BaTi4O9being the predominant phase and BaTi5O11 as minor phasebelow 1150∘C are present whereas Ba2Ti9O20 is formed athigher temperatures of sintering The dielectric properties ofthese ceramics depend considerably on sintering temperature

and theirmicrostructures From this reason structural studiesaswell as grainmorphology and dielectric investigationswerecarried out simultaneously in each step of Ba-TN sintering Itwas found that up to temperature of 1050∘C barium titanateexhibits fine ceramics grain size At higher temperaturegrain morphology radically changes simultaneously withcrystallographic phase composition change revealed by XRDand Raman studies

Conflicts of Interest

The authors declare that they have no conflicts of interest

Acknowledgments

This work was financially supported by National ScienceCenter (Poland) grant awarded by Decision no DEC-201103DST506074 Izabela Bobowska Agnieszka Opasin-ska and Jacek Ulanski acknowledge financial support byFoundation for Polish Science Grant Master 92013

References

[1] M T Sebastian in Dielectric materials for wireless communica-tion Elsevier BV Great Britain 1st edition 2008

[2] D J Masse R A Pucel D W Readey E A Maguire and C PHartwig ldquoANewLow-LossHigh-KTemperature-CompensatedDielectric forMicrowave Applicationsrdquo Proceedings of the IEEEvol 59 no 11 pp 1628-1629 1971

[3] S G Mhaisalkar W E Lee and D W Readey ldquoProcessing andCharacterization of BaTi4O9rdquo Journal of the American CeramicSociety vol 72 no 11 pp 2154ndash2158 1989

[4] S G Mhaisalkar D W Readey and S A Akbar ldquoMicrowaveDielectric Properties of Doped BaTi4O9rdquo Journal of the Ameri-can Ceramic Society vol 74 no 8 pp 1894ndash1898 1991

[5] M Cernea E Chirtop D Neacsu I Pasuk and S IordanesculdquoPreparation of BaTi4O9 fromoxalatesrdquo Journal of theAmericanCeramic Society vol 85 no 2 pp 499ndash503 2002

[6] J Choy Y Han J Sohn and M Itoh ldquoMicrowave Charac-teristics of BaO-TiO2 Ceramics Prepared via a Citrate RouterdquoJournal of the American Ceramic Society vol 78 no 5 pp 1169ndash1172 1995

[7] F Li L-QWeng G-Y Xu S-H Song and J Yu ldquoSynthesis andcharacterization of microwave dielectric BaTi 4O9 ceramics viaEDTA-citrate gel processrdquo Materials Letters vol 59 no 23 pp2973ndash2976 2005

[8] K Fukuda R Kitoh and I Awai ldquoMicrowave characteristicsof mixed phases of BaTi4O9-BaPr2Ti4O12 ceramicsrdquo Journal ofMaterials Science vol 30 no 5 pp 1209ndash1216 1995

[9] E Tillmanns ldquoDie Kristallstruktur von BaTi5O11rdquoActa Crystal-lographica Section B vol 25 p 1444 1969

[10] J-H Choy Y-S Han J-T Kim and Y-H Kim ldquoCitrate routeto ultra-fine barium polytitanates with microwave dielectricpropertiesrdquo Journal of Materials Chemistry vol 5 no 1 pp 57ndash63 1995

[11] H Lu L E Burkhart and G L Schrader ldquoSol-Gel Process forthe Preparation of Ba2Ti9O20 and BaTi5O11rdquo Journal of theAmerican Ceramic Society vol 74 no 5 pp 968ndash972 1991


[12] T Fukui C Sakurai and M Okuyama ldquoEffects of heating rateon sintering of alkoxide-derived BaTi5O11 powderrdquo Journal ofMaterials Research vol 7 no 1 pp 192ndash196 1992

[13] S-F Wang Y-F Hsu T-H Ueng C-C Chiang J P Chu andC-Y Huang ldquoEffects of additives on the microstructure anddielectric properties of Ba2Ti9O20microwave ceramicrdquo Journalof Materials Research vol 18 no 5 pp 1179ndash1187 2003

[14] T-T Fang J-T Shiue and S-C Liou ldquoFormation mechanismand sintering behavior of Ba2Ti9O20rdquo Journal of the EuropeanCeramic Society vol 22 no 1 pp 79ndash85 2002

[15] K P Surendran PMohanan andMT Sebastian ldquoTailoring themicrowave dielectric properties of GdTiNb1-xTaxO6 and Sm1-x YxTiTaO6 ceramicsrdquo Journal of the European Ceramic Societyvol 23 no 14 pp 2489ndash2495 2003

[16] T Sasaki F Kooli M Iida et al ldquoA mixed alkali metal titanatewith the lepidocrocite-like layered structure Preparation crys-tal structure protonic form and acid-base intercalation proper-tiesrdquo Chemistry of Materials vol 10 no 12 pp 4123ndash4128 1998

[17] W A England J E Birkett J B Goodenough and P J Wise-man ldquoIon exchange in the Csx[Ti2-x2Mgx2]O4 structurerdquoJournal of Solid State Chemistry vol 49 no 3 pp 300ndash308 1983

[18] E Chiellini J Sunamoto CMigliaresi RM Ottenbrite andDCohn Biomedical Polymers and Polymer Therapeutics KluwerAcademic Publishers Boston 2002

[19] I Bobowska A Opasinska A Wypych and P WojciechowskildquoSynthesis and dielectric investigations of ZnTiO3 obtained by asoft chemistry routerdquoMaterials Chemistry and Physics vol 134no 1 pp 87ndash92 2012

[20] G Pfaff ldquoSynthesis and characterization of BaTi4O9rdquo Journal ofMaterials Science Letters vol 10 no 3 pp 129ndash131 1991

[21] T Ohya A Nakayama T Ban Y Ohya and Y TakahashildquoSynthesis and characterization of halogen-free transparentaqueous colloidal titanate solutions from titanium alkoxiderdquoChemistry of Materials vol 14 no 7 pp 3082ndash3089 2002

[22] T Gao H Fjellvag and P Norby Journal of Physical ChemistryB vol 112 p 9400 2008

[23] N Li L Zhang Y Chen M Fang J Zhang and H WangldquoHighly efficient irreversible and selective ion exchange prop-erty of layered titanate nanostructuresrdquo Advanced FunctionalMaterials vol 22 no 4 pp 835ndash841 2012

[24] M Rossel H-R Hoche H S Leipner et al ldquoRaman micro-scopic investigations of BaTiO3 precursors with core-shellstructurerdquo Analytical and Bioanalytical Chemistry vol 380 no1 pp 157ndash162 2004

[25] J Javadpour and N G Eror ldquoRaman Spectroscopy of HigherTitanate Phases in the BaTiO3-TiO2 Systemrdquo Journal of theAmerican Ceramic Society vol 71 no 4 pp 206ndash213 1988

[26] Y Xu X Yuan G Huang and H Long ldquoPolymeric precursorsynthesis of Ba2Ti9O20rdquo Materials Chemistry and Physics vol90 no 2-3 pp 333ndash338 2005

[27] F H Chung Journal of Applied Crystallography vol 7 p 5191974

[28] S Kumar V S Raju andT RN Kutty ldquoPreparation of BaTi4O9and Ba2Ti9O20 ceramics by the wet chemical gel-carbonatemethod and their dielectric propertiesrdquo Materials Science andEngineering B Solid-State Materials for Advanced Technologyvol 142 no 2-3 pp 78ndash85 2007

[29] C-L Huang M-H Weng C-T Lion and C-C Wu ldquoLowtemperature sintering andmicrowave dielectric properties of Ba2Ti 9O 20 ceramics using glass additionsrdquo Materials ResearchBulletin vol 35 no 14-15 pp 2445ndash2456 2000

[30] K W Kirby and B A Wechsler ldquoPhase relations in the BariumTitanatemdashTitanium Oxide Systemrdquo Journal of the AmericanCeramic Society vol 74 no 8 pp 1841ndash1847 1991

Submit your manuscripts athttpswwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of



CeramicsJournal of


CompositesJournal of

NanoparticlesJournal of



International Journal of

Biomaterials


NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014


CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research



MetallurgyJournal of


BioMed Research International

MaterialsJournal of



stoichiometric amounts of BaCO3 and TiO2 for about 24hours [3 4] and sintering at about 1100∘C It is then againball milled pelletized and sintered at about 1350∘C to achievedensification of the ceramic body Wet chemical methodssuch as oxalate [5] and citrate route [6] as well as modifiedPechini method [7] were also applied for BaTi4O9 powderspreparation Cernea et al [5] obtained BaTi4O9 from oxalatesand documented its stable dielectric properties dielectricpermittivity 120576=38 quality factor119876 = 3800divide4000 at 6divide7GHzand temperature coefficient 120591119891 = 11 ppm∘C Pure BaTi4O9suffers from relatively high values of temperature coefficientso it is not very suitable as dielectric resonator Hence thedielectric properties of BaTi4O9 phase are often modifiedby using different additives [8] BaTi5O11 synthesis was forthe first time described by Tillmanns but it was not purephase but mixed with rutile [9] Single-phase BaTi5O11 wasprepared by wet chemical methods like citrate route [10] orsol-gel [11] This phase is stable under heating up to 1200∘Cthen it decomposes into TiO2 Ba2Ti9O20 andor BaTi4O9BaTi5O11 phase has higher dielectric constant and qualityfactor compared to BaTi4O9 however the values of 120591119891 are alsohigher Fukui et al prepared BaTi5O11 by sol-gel method afterheating at 1120∘C for 48 hours Obtained samples exhibiteddielectric permittivity equal to 42 119876 times 119891 gt 60000GHzand 120591119891 = 39 ppm∘C [12] Ba2Ti9O20 can be conventionallysynthesized by mixing BaCO3 and TiO2 in appropriatestoichiometry and calcined at about 1200∘C again milledpelletized and sintered at about 1400∘C for 3 hours [13]Ba2Ti9O20 obtained by solid state synthesis usually coexistswith BaTi4O9 phase as it is thermodynamically stable in thevicinity of the desired composition However pure phasesynthesis was achieved by wet chemistry methods Lu et al[11] described synthesis based on mixing methanol solutionof bariumhydroxidewith titania sol obtained fromhydrolysisof titanium alkoxide Obtained xerogel was stepwise heatedup to 1100∘C giving BaTi5O11 phase while prolonged heatingat 1200∘C gave pure Ba2Ti9O20 Fang et al [14] preparedBa2Ti9O20 in reaction of BaTi4O9 with TiO2 and sinteringat 1390∘C Obtained sample showed grain size of about 2-3micrometers and high sintered density of 99The dielectricpermittivity was equal to 39 quality factor was 42000GHzand the temperature coefficient reached 5 ppm∘C BaTi4O9and Ba2Ti9O20 have similar values of dielectric permittivityand quality factors BaTi4O9 has temperature coefficient closeto zero and is always positive while reported values of 120591119891 forBa2Ti9O20 are close to zero as well as being negative in somereports [10]

The method of mixing of two low loss ceramic mate-rials with positive and negative temperature coefficient hasbecome well known [15] This kind of approach is veryconvenient for preparation of new materials with desiredproperties by simple selection of proper components How-ever very often it is difficult to obtain material with expectedintermediate properties because it is impossible to retainindividual character of components during sintering processThus development of new precursors of barium titanatesand study of their temperature transformation and dielectricproperties are still very attractive

The aim of this work was to develop a method forTiO2 rich barium titanates synthesis by employing titanatenanosheets (TN) They have an orthorhombic layered struc-ture that is composed of corrugated host layers of edge-shared octahedra and interlayer (tetramethyl)ammoniumions (TMA+) compensating for the negative charge whicharises from substitution of lower valence metal ions orvacancies of Ti [16] These TMA+ ions are exchangeablewith a variety of inorganic and organic ions and in thisway the TN is an ideal candidate for host-guest chemistryas well as ion exchange [17] The ion exchangeability alsoprovided the opportunity to prepare precursor of ceram-ics For example potassium hexatitanate (K2Ti6O13) wasprepared by ion exchange followed by heat treatment at600∘C [18] Taking this into consideration in this work weapplied TN in ion exchange process to immobilize bariumions from solution The obtained by this way compositeunder a thermal treatment in moderate temperature in airtransformed to BaTi4O9 BaTi5O11 and Ba2Ti9O20 phaseswith desired dielectric properties

2 Experimental Section

All reagents were used as received without further purification

Synthesis 250ml aqueous solution of barium acetate mono-hydrate (545 g 20mol purchased from Polish ChemicalReagents POCH Gliwice Poland) was mixed with 250mlaqueous colloidal solution of titanate nanosheets TN (25 g R =06) The details of preparation and characterization of TNhave been reported elsewhere [19] After mixing solutionsion exchange reaction between (tetramethyl)ammonium ionsfrom TN and barium cations from barium acetate in aqueousenvironment led to precipitation of the powder The mixturewas heated for 10 h at room temperature under stirring andnext without stirring for 10 h at 90∘C After the reactionthe precipitate was separated by centrifugation washed withwater until pH 7 and dried under vacuum The total yield ofdried organic-inorganic powder was 23 g and it is labeled asBa-TN or precursor of barium titanate The Ba-TN powderafter reaction was subjected to calcination at 500∘C for 1hour and pressed to get a pellet under pressure of 436MPafor 10min Based on thermogravimetric measurement (datanot shown) temperature of 500∘C was chosen as an optimalone that allows a decomposition of the organic part of theprecursor and the evaporation of volatile products from thesample The higher temperatures allow for thermal diffusionof the reagents throughout the volume to facilitate thereaction that produces barium titanate ceramic The pelletwas sintered at 900∘C for 4 hours and then subsequently at950∘C 1000∘C 1050∘C 1100∘C 1150∘C 1200∘C 1250∘C and1300∘C for 2 h in each temperature The time of sinteringwas chosen according to research of Pfaff who found thatat temperature higher than 900∘C a densification parameterof BaTi4O9 is constant after two hours of heat treatment[20] During the applied step sintering procedure the meanparticle diameter was investigated and pelletsrsquo green densitycalculated simultaneously with its phase transformation anddielectric properties studies


3 Characterization





120576lowast = 1205761015840 minus 11989412057610158401015840 (1)





minus1


Inte

nsity

(au

)

(b)

(a)

280 cmminus1

384 cmminus1

448 cmminus1


890 cmminus1

275 cmminus1

384 cmminus1

448 cmminus1

662 cmminus1

756 cmminus1


954 cmminus1



267

591

478

447

359

117

(e)(d)(c)

(b)

Inte

nsity

(a)

860650626

429

286

262230

188

134

144lowast

415lowast

537lowast

558lowast

750lowast

200 300 400 500 600 700 800 900 1000100





536

61542

6

308

224

(c)

(b)

Inte

nsity

(a)

259

21016

815

0122

340 39

435

9

508

770 80

5 845

567

694

465

130lowast

184lowast

287lowast

650lowast

200 300 400 500 600 700 800 900 1000100







Phase Temp900∘C 1100∘C 1150∘C 1200∘C 1250∘C


(f)

(e)

(d)

(c)

(b)In

tens

ity (a

u)

(a)

xxxxxxxxx

x

xxxx

30 40 50 6020

2휃 (∘)





2 휇m

(a)

2 휇m

(b)

2 휇m

(c)

2 휇m

(d)

5 휇m

(e)

5 휇m

(f)








Relativedensity []








500 600 700 800 900 1000 1100 1200 1300400


00

05

10

15

20

25

30

Gra

in si

ze (휇

m)









900 950 1000 1050 1100 1150 1200 1250 1300850

Temperature (∘C)

28

30

32

34

36

38

40

Relat

ive d

ensit

y (g

cm

3)

(a)

Main phase

900 950 1000 1050 1100 1150 1200 1250 1300850

Temperature (∘C)

60

65

70

75

80

85

90

Filli

ng (

)

BaTi4O9 Ba2Ti9O20

(b)


Temperature (∘C)

Perm

ittiv

ity


103101

10minus1


103

102

101


Perm

ittiv

ity


103101

10minus1


103

102

101

(b)





1205911205761003816100381610038161003816100∘Cminus130∘C =

1120576(minus130∘C) (

Δ120576Δ119879) ppm

∘C (2)



1300∘C

1250∘C

1200∘C

1100∘C

900∘C


Temperature (∘C)

222426283032343638404244

Die

lect

ric p

erm

ittiv

ity




5 Conclusion





Acknowledgments


References







































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of



3 Characterization





120576lowast = 1205761015840 minus 11989412057610158401015840 (1)





minus1


Inte

nsity

(au

)

(b)

(a)

280 cmminus1

384 cmminus1

448 cmminus1


890 cmminus1

275 cmminus1

384 cmminus1

448 cmminus1

662 cmminus1

756 cmminus1


954 cmminus1



267

591

478

447

359

117

(e)(d)(c)

(b)

Inte

nsity

(a)

860650626

429

286

262230

188

134

144lowast

415lowast

537lowast

558lowast

750lowast

200 300 400 500 600 700 800 900 1000100





536

61542

6

308

224

(c)

(b)

Inte

nsity

(a)

259

21016

815

0122

340 39

435

9

508

770 80

5 845

567

694

465

130lowast

184lowast

287lowast

650lowast

200 300 400 500 600 700 800 900 1000100







Phase Temp900∘C 1100∘C 1150∘C 1200∘C 1250∘C


(f)

(e)

(d)

(c)

(b)In

tens

ity (a

u)

(a)

xxxxxxxxx

x

xxxx

30 40 50 6020

2휃 (∘)





2 휇m

(a)

2 휇m

(b)

2 휇m

(c)

2 휇m

(d)

5 휇m

(e)

5 휇m

(f)








Relativedensity []








500 600 700 800 900 1000 1100 1200 1300400


00

05

10

15

20

25

30

Gra

in si

ze (휇

m)









900 950 1000 1050 1100 1150 1200 1250 1300850

Temperature (∘C)

28

30

32

34

36

38

40

Relat

ive d

ensit

y (g

cm

3)

(a)

Main phase

900 950 1000 1050 1100 1150 1200 1250 1300850

Temperature (∘C)

60

65

70

75

80

85

90

Filli

ng (

)

BaTi4O9 Ba2Ti9O20

(b)


Temperature (∘C)

Perm

ittiv

ity


103101

10minus1


103

102

101


Perm

ittiv

ity


103101

10minus1


103

102

101

(b)





1205911205761003816100381610038161003816100∘Cminus130∘C =

1120576(minus130∘C) (

Δ120576Δ119879) ppm

∘C (2)



1300∘C

1250∘C

1200∘C

1100∘C

900∘C


Temperature (∘C)

222426283032343638404244

Die

lect

ric p

erm

ittiv

ity




5 Conclusion





Acknowledgments


References







































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of



536

61542

6

308

224

(c)

(b)

Inte

nsity

(a)

259

21016

815

0122

340 39

435

9

508

770 80

5 845

567

694

465

130lowast

184lowast

287lowast

650lowast

200 300 400 500 600 700 800 900 1000100







Phase Temp900∘C 1100∘C 1150∘C 1200∘C 1250∘C


(f)

(e)

(d)

(c)

(b)In

tens

ity (a

u)

(a)

xxxxxxxxx

x

xxxx

30 40 50 6020

2휃 (∘)





2 휇m

(a)

2 휇m

(b)

2 휇m

(c)

2 휇m

(d)

5 휇m

(e)

5 휇m

(f)








Relativedensity []








500 600 700 800 900 1000 1100 1200 1300400


00

05

10

15

20

25

30

Gra

in si

ze (휇

m)









900 950 1000 1050 1100 1150 1200 1250 1300850

Temperature (∘C)

28

30

32

34

36

38

40

Relat

ive d

ensit

y (g

cm

3)

(a)

Main phase

900 950 1000 1050 1100 1150 1200 1250 1300850

Temperature (∘C)

60

65

70

75

80

85

90

Filli

ng (

)

BaTi4O9 Ba2Ti9O20

(b)


Temperature (∘C)

Perm

ittiv

ity


103101

10minus1


103

102

101


Perm

ittiv

ity


103101

10minus1


103

102

101

(b)





1205911205761003816100381610038161003816100∘Cminus130∘C =

1120576(minus130∘C) (

Δ120576Δ119879) ppm

∘C (2)



1300∘C

1250∘C

1200∘C

1100∘C

900∘C


Temperature (∘C)

222426283032343638404244

Die

lect

ric p

erm

ittiv

ity




5 Conclusion





Acknowledgments


References







































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of



2 휇m

(a)

2 휇m

(b)

2 휇m

(c)

2 휇m

(d)

5 휇m

(e)

5 휇m

(f)








Relativedensity []








500 600 700 800 900 1000 1100 1200 1300400


00

05

10

15

20

25

30

Gra

in si

ze (휇

m)









900 950 1000 1050 1100 1150 1200 1250 1300850

Temperature (∘C)

28

30

32

34

36

38

40

Relat

ive d

ensit

y (g

cm

3)

(a)

Main phase

900 950 1000 1050 1100 1150 1200 1250 1300850

Temperature (∘C)

60

65

70

75

80

85

90

Filli

ng (

)

BaTi4O9 Ba2Ti9O20

(b)


Temperature (∘C)

Perm

ittiv

ity


103101

10minus1


103

102

101


Perm

ittiv

ity


103101

10minus1


103

102

101

(b)





1205911205761003816100381610038161003816100∘Cminus130∘C =

1120576(minus130∘C) (

Δ120576Δ119879) ppm

∘C (2)



1300∘C

1250∘C

1200∘C

1100∘C

900∘C


Temperature (∘C)

222426283032343638404244

Die

lect

ric p

erm

ittiv

ity




5 Conclusion





Acknowledgments


References







































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of





Relativedensity []








500 600 700 800 900 1000 1100 1200 1300400


00

05

10

15

20

25

30

Gra

in si

ze (휇

m)









900 950 1000 1050 1100 1150 1200 1250 1300850

Temperature (∘C)

28

30

32

34

36

38

40

Relat

ive d

ensit

y (g

cm

3)

(a)

Main phase

900 950 1000 1050 1100 1150 1200 1250 1300850

Temperature (∘C)

60

65

70

75

80

85

90

Filli

ng (

)

BaTi4O9 Ba2Ti9O20

(b)


Temperature (∘C)

Perm

ittiv

ity


103101

10minus1


103

102

101


Perm

ittiv

ity


103101

10minus1


103

102

101

(b)





1205911205761003816100381610038161003816100∘Cminus130∘C =

1120576(minus130∘C) (

Δ120576Δ119879) ppm

∘C (2)



1300∘C

1250∘C

1200∘C

1100∘C

900∘C


Temperature (∘C)

222426283032343638404244

Die

lect

ric p

erm

ittiv

ity




5 Conclusion





Acknowledgments


References







































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of




900 950 1000 1050 1100 1150 1200 1250 1300850

Temperature (∘C)

28

30

32

34

36

38

40

Relat

ive d

ensit

y (g

cm

3)

(a)

Main phase

900 950 1000 1050 1100 1150 1200 1250 1300850

Temperature (∘C)

60

65

70

75

80

85

90

Filli

ng (

)

BaTi4O9 Ba2Ti9O20

(b)


Temperature (∘C)

Perm

ittiv

ity


103101

10minus1


103

102

101


Perm

ittiv

ity


103101

10minus1


103

102

101

(b)





1205911205761003816100381610038161003816100∘Cminus130∘C =

1120576(minus130∘C) (

Δ120576Δ119879) ppm

∘C (2)



1300∘C

1250∘C

1200∘C

1100∘C

900∘C


Temperature (∘C)

222426283032343638404244

Die

lect

ric p

erm

ittiv

ity




5 Conclusion





Acknowledgments


References







































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of



1300∘C

1250∘C

1200∘C

1100∘C

900∘C


Temperature (∘C)

222426283032343638404244

Die

lect

ric p

erm

ittiv

ity




5 Conclusion





Acknowledgments


References







































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of





























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


synthesis and characterization of low loss dielectric...

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