sl7 study of the real structure of the laser-cladded … · Ó krystalografická spoleènost 166...

Ó Krystalografická spoleènost

166 Struktura 2019 - Stu dent symposium Ma te ri als Struc ture, vol. 26, no. 3 (2019)

Ac cord ing to these re sults, the op ti mal high res o lu -tion dif frac tion limit was de ter mined as 1.80C res o lu tion.It does not look like a large dif fer ence in com par i son withthe pre vi ous choice (1.85 C). How ever, the res o lu tion shell 1.85–1.80 C con tains 9,929 unique re flec tions (8 % ofwhole dataset) which is not a neg li gi ble num ber, given thenum ber of re fined pa ram e ters (45,388).

1. P. A. Karplus & K. Diederichs, Sci ence 336, (2012),pp. 1030–1033.

2. W. Kabsch, Acta Cryst. D, 66, (2010), 125.

3. G. N. Murshudov, A. A. Vagin, E. J. Dodson, ActaCryst. D, 53, (1997), pp. 240–255.

4. M. Stranava et al., J. Biol. Chem., 292, (2017), pp.20921-20935.

This pub li ca tion was sup ported by pro jects CAAS(CZ.02.1.01/0.0/0.0/16_019/0000778) and CIISB4HEALTH (CZ.02.1.01/0.0/0.0/16_013/0001776) from theERDF fund and by the GA CTU in Prague (SGS19/189/OHK4/3T/14).

Session II

SL7

STUDY OF THE REAL STRUCTURE OF THE LASER-CLADDED STEEL

Karel Tro jan1, Václav Ocelík

2, Jiøí Èapek

1 and Nikolaj Ganev

1

1De part ment of Solid State En gi neer ing, Fac ulty of Nu clear Sci ences and Phys i cal En gi neer ing,CTU in Prague, Trojanova 13, 120 00 Prague 2, Czech Re pub lic

2De part ment of Ap plied Phys ics, Zernike In sti tute for Ad vanced Ma te ri als, Fac ulty of Sci ence and En gi neer -ing, Uni ver sity of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Neth er lands

AISI H13 hot work ing tool steel is one of the most com mon die ma te rial used in metal and cast ing in dus tries. Dies suf -fer dam age due to wear and thermo-dy namic stresses dur -ing their life time [1]. There fore, var i ous meth ods havebeen de vel oped for their re pair, which is cheaper than man -u fac tur ing new ones. A great ben e fit of la ser clad ding inthis field is a high pro duc tiv ity with min i mal in flu ence dueto a low heat in put on sur round ing ma te rial by ther malstresses [2]. There fore, the aim of the con tri bu tion is to de -scribe the ef fects of la ser pro cess ing on the microstructureof la ser cladded H13 tool steel us ing ori en ta tion im ag ingmi cros copy (OIM) based on elec tron back scat ter dif frac -tion (EBSD) and other tech niques.

La ser clad ding was car ried us ing an IPG 3 kW Yt:YAG fi bre la ser. The la ser power den sity of 114 J/mm2 was ap -plied to form a vol ume con sist ing of five over lap ping lay -ers, see Fig. 1. The martensitic struc ture was ob served on

the cross-sec tion of the clad us ing elec tron back scat ter ingdif frac tion, see in verse pole fig ures (IPF) of fer rit ic phasein Fig. 2. The orig i nal aus ten ite grains with a char ac ter is ticsize of 20–50 µm, which were formed dur ing the tran si tionof the melt into a solid phase and whose were sub se quentlytrans formed into martensitic or bainitic laths, are clearlyseen in the fig ure. It has to be noted that the EBSD tech -nique is not able di rectly dis tin guish fer rite and martensite.

Fur ther, the clads were sub jected to X-ray dif frac tionmea sure ment, ten sile test ing, wear re sis tance and hard nessmea sure ment for com pre hen sive uti li za tion eval u a tion oflaser cladding.

Mea sure ments were sup ported by the pro ject TH02010664 of the Tech nol ogy Agency of the Czech Re pub lic and byUni ver sity of Groningen. This work was sup ported by theGrant Agency of the Czech Tech ni cal Uni ver sity in Prague, grant No. SGS19/190/OHK4/3T/14.

Fig ure 1: Metallographic cross-sec tion of the clad AISI H13 tool steel with marked di rec tions and area which was ob servedus ing OIM.

1. G. Telasang, J. Majumdar, N. Wasekar, G. Padmanabham,I. Manna, Microstructure and Me chan i cal Prop er ties of La -ser Clad and Post-clad ding Tem pered AISI H13 Tool Steel. Metall. Ma ter. Trans. A. 46A (2015) 2309-2321.

2. M. Vedani, B. Previtali, G.M. Vimercati, A. Sanvito, G.Somaschini, Prob lems in la ser re pair-weld ing a sur -face-treated tool steel, Surf. Coat. Tech. 201 (2007)4518-4525.

SL8

THERMALLY INDUCED CHANGES IN MODULATED STRUCTURE OF 10MNi50Mn27Ga22Fe1 MARTENSITE

P. Veøtát1,2

, L. Straka2,3

, O. Pacherová2, M. Klicpera

3, A. Sozinov

4, O. Heczko

2

1Fac ulty of Nu clear Sci ences and Phys i cal En gi neer ing, Czech Tech ni cal Uni ver sity in Prague, Prague,11519, Czech Re pub lic

2In sti tute of Phys ics, Czech Acad emy of Sci ences, Prague, 18221, Czech Re pub lic3Fac ulty of Math e mat ics and Phys ics, Charles Uni ver sity, Prague 2, 12116, Czech Re pub lic

4Ma te rial Phys ics Lab o ra tory, LUT Uni ver sity, Lappeenranta, 53850, Fin land

[email protected]

The ob ser va tion of mag netic shape mem ory (MSM) ef fectin Heusler al loy Ni2MnGa by Kari Ullakko [1] stim u latedtre men dous sci en tific in ter est in this class of ma te ri als. The MSM al loys pos sess many prac ti cal ap pli ca tions in sen sors [2], ac tu a tors [3, 4], micropumps [5] and en ergy-con ver -sion de vices [6]. From the fun da men tal point of view, theMSM ef fect in cludes the mag net i cally in duced thermo -elastic martensitic trans for ma tion and mag net i cally in -duced struc tural re ori en ta tion of martensite, where theex tremely mo bile twin bound aries of martensite play andes sen tial role.

The struc ture of martensite of the Ni-Mn-Ga-based al -loys is of ten mod u lated, de pend ing on com po si tion andtem per a ture. Al though the mod u lated struc ture is de ci sivein the afore men tioned ex tremely mo bile twin bound aries of Ni-Mn-Ga al loys, the char ac ter of mod u la tion is still un derdis cus sion – es pe cially for the 10M mod u lated martensite,for which the high est twin bound ary mo bil ity is found. Fordif fer ent com po si tions, the “10M martensite” was re ported to have com men su rate or in com men su rate mod u la tion[7-10] or to be nanotwinned [11, 12]. Both in com men su -rate and nanotwinned struc ture can re sult in sim i lar ap par -ent changes in mod u la tion vec tor. Con sid er ing theincommensurality ap proach, it has been shown that themod u la tion vec tor changes grad u ally with tem per a ture [7,9].

Us ing neu tron and X-ray dif frac tion on sin gle crys tal of Ni50Mn27Ga22Fe1 al loy, we dis cov ered tran si tion be tweencom men su rate and in com men su rate mod u lated struc turewith chang ing tem per a ture (Fig. 1) and fol lowed its evo lu -tion in 10M martensite. We ob served that dop ing of theNi-Mn-Ga al loy with Fe leads to ac cen tu a tion of the mod u -la tion sat el lites and it also leads to shift ing of the tem per a -ture ranges of oc cur rence of dif fer ent martensites, which islikely fa vour able for the ap pli ca tions.

We found that the dis cov ered tran si tion ex hib its ther -mal hys ter esis around the room tem per a ture. Ow ing to thehys ter esis, sam ple can be pre pared in com men su rate or in -com men su rate state at the same tem per a ture us ing ap pro -pri ate heat ing/cool ing pro ce dure. Ob served tran si tion wascon firmed by re sis tiv ity mea sure ments and by scan ningelec tron mi cros copy. The in ves ti ga tion whether theincommensurality is proper or only ap par ent caused bynanotwinning is the subject of ongoing research.

1. K. Ullakko, J. K. Huang, C. Kantner, R. C. O’Handley, V.V. Kokorin, Ap plied Phys ics Let ters, 69, (1996), 1966.

2. J. M. Stephan, E. Pagounis, M. Laufenberg, O. Paul, P.Ruther, IEEE Sen sors Jour nal, 11, (2011), 2683.

3. R. C. O’Handley, K. Ullakko, High-strain, mag neticfield-controlled ac tu a tor ma te ri als, US patenUS5958154A,1997.


Ma te ri als Struc ture, vol. 26, no. 3 (2019) 167

Fig ure 2: IPF maps of fer rit ic phase for dif fer ent di rec tions in the se lected area, where N, T, and L de note the di rec tions.



4. J. Tellinen, I. Suorsa, A. Jääskeläinen, I. Aaltio, K.Ullakko, in Pro ceed ings of the 7th In ter na tional Con fer -ence on New Ac tu a tors, Ac tu a tor 2002, Bre men, Ger many,ed ited by H. Borgmann, 2002, pp. 566-569.

5. A. R. Smith, D. Fologea, P. Müllner, in Pro ceed ings of the18th In ter na tional Conference on New Ac tu a tors, Ac tu a tor2008, Bre men, Ger many, ed ited by H. Borgmann, 2018.

6. N. M. Bruno, C. Ciocanel, H. P. Feigenbaum, A. Waldauer, Smart Ma te ri als and Struc tures, 21, (2012), 094018.

7. L. Righi, F. Albertini, A. Paoluzi, S. Fabbrici, E. Villa, G.Calestani, S. Besseghini, Ma te ri als Sci ence Fo rum, 635,(2010), 33.

8. T. Fukuda, H. Kushida, M. Todai, T. Kakeshita, H. Mori,Scripta Materialia, 61, (2009), 473.

9. A. Çakir, M. Acet, L. Righi, F. Albertini, M. Farle, AIPAd vances, 5, (2015), 097222.

10. S. O. Mariager, T. Huber, G. Ingold, Acta Materialia, 66,(2014), 192.

11. S. Kaufman, U. K. Rößler, O. Heczko, M. Wuttig, J.Buschbeck, L. Schultz, S. Fähler, Phys i cal Re view Let ters,104, (2010), 1457029.

12. L. Straka, J. Drahokoupil, P. Veøtát, M. Zelený, J.Kopeèek, A. Sozinov, O. Heczko, Sci en tific Re ports, 8(2018), 11943.

This work was sup ported by the Grant Agency of the CzechTech ni cal Uni ver sity in Prague, grant No. SGS19/190/OHK4/3T/14.

Fig ure 1. Mea sured q-scans in the [110] di rec tion of the re cip ro cal space. At 298 K, the mea sure ment in di cates in -com men su rate 10M mod u lated martensite. Upon heat ing to 328 K, the struc ture trans forms to com men su rate 10M.Mod u la tion sat el lites be long ing to 400 and 620 re flec tions are marked red and blue. The slight split ting of the peaksis caused by the mosaicity of the crys tal and a/b twinning. Re flec tions from the sam ple holder are marked grey.



SL9

COMPARISON OF THE ROLLING TEXTURE OF PARTICULAR PHASES OFDUAL-PHASE STEEL WITH SINGLE-PHASE STEELS

J. Èapek, K. Tro jan, N. Ganev

De part ment of Solid State En gi neer ing, Fac ulty of Nu clear Sci ences and Phys i cal En gi neer ing, Czech Tech ni cal Uni ver sity in Prague

[email protected]

Du plex steels are dual-phase steels with 50/50 pro por tion

of fer rite (a-Fe) and aus ten ite (g-Fe) phases. Be cause of the com bi na tion of prop er ties of both the phases in dual-phasemicrostructure, du plex steels are dis tin guished by goodprop er ties in many en vi ron ments, where the stan dardaustenitic and fer rit ic steels are usu ally used [1]. Due tovery of ten pres ence of pre ferred ori en ta tion (tex ture) inthese ma te ri als, anal y sis and con se quent in ter pre ta tion ofthe tex ture is cru cial, es pe cially in ma te rial en gi neer ing.The im por tance of study the tex ture re sides in the ani so -tropy of most ma te rial prop er ties in duced by its pres ence.Be cause of dif fer ent me chan i cal prop er ties of fer rite andaus ten ite phases, their be hav iour dur ing de for ma tion, gen -er ally spo ken, is dif fer ent in dual-phase steel in com par i son with sin gle-phase steels [2].

The plate shape sam ples of size 19×120 mm2 and dif -fer ent thick nesses were made of AISI 420 (fer rit ic), AISI304 (austenitic) and AISI 318LN (du plex) type of stain lesssteels. The sam ples were cold-rolled with 0, 10, 20, 30, 40,and 50% re duc tion of thick ness, so the fi nal thick ness of all sam ples was 1.5 mm. Sam ples made of fer rit ic, austeniticand du plex steel were marked as F0–F50, A0–A50 andD0–D50, re spec tively.

The X’Pert PRO MPD diffractometer with co balt ra di a -tion was used to the RD-TD plane sam ples anal y ses byX-ray dif frac tion, where roll ing (RD), transversal (TD) and

nor mal (ND) di rec tions cre ate a co or di na tion sys tem of thesam ple. Tex ture anal y sis was per formed based on ori en ta -tion dis tri bu tion func tion (ODF) calculated from ex per i -men tal pole fig ures ob tained by anal y sis of threedif frac tion lines {110}/{220}, {200}, {211} of fer ritephase and {111}/{311}, {200}, {220} of aus ten ite phases.

The roll ing tex ture of fer rite may be de scribed by sev -

eral tex ture fibres [3], for ex am ple, the lim ited a1, e, and g,see Fig. 1. Fer rit ic steel ex hib its the typ i cal tex ture com po -nents: {001}n, {112}n, and {111}n. For austenitic steel,

the roll ing tex ture is usu ally com posed of a, t, and h tex -ture fibres. The typ i cal tex ture com po nents of these ma te ri -als are Brass, Goss, and Cop per [3]. Nev er the less, it isnec es sary to ex pect that dual-phase steel should have dif -fer ent be hav iour of the con stit u ent phases in com par i sonwith sin gle-phase steel. It has been found that ODFs of fer -rite phase of the du plex steel do not con sist of tex turefibres, but only of the par tic u lar tex ture com po nents. Foraus ten ite phase of the du plex steel, fewer tex ture com po -nents and fibres are gen er ated com pared to the austeniticsteel.

The pres ence of two phases re sults in a de crease ofstrain hard en ing speed. The rea son for that be hav iour is thepar ti tion of plas tic de for ma tion oc cur ring within both thephases, dur ing cold roll ing. The strain hard en ing of aus ten -ite is very high at low de for ma tions, but at about 15%

Sam ple F50 Sam ple D50 - a phase

Sam ple A50Sam ple D50 - g phase

Fig ure 1. Se lected ori en ta tion dis tri bu tion func tions in the j1 = 0° (left) and j1 = 45° (right) sec tions for a phases, and j2 = 0° (left) and

j2 = 45° (right) sec tions for g phases.



thick ness re duc tion it gets in creas ingly con cen trated within the fer rite phase, which has a larger num ber of ac tive slipsys tems and a con sid er ably higher stack ing-fault en ergy[4]. There fore, the typ i cal tex ture fibres of the phases in thedual-phase steel are not gen er ated but only strong sep a -rated tex ture com po nents are pre sented. How ever, the typ i -cal tex ture com po nent and fibres are generated in thesample with higher deformation.

1. R. Dakhlaoui, C. Braham, A. Baczmañski, Ma ter. Sci.

Eng.: A., 444, (2007), 6-17.

2. J. Ryœ, W. Ratuszek, M. Witkowska, Arch. Metall. Ma ter.,

51, (2006), 495-502.

3. H. J. Bunge, Tex ture Anal y sis in Ma te ri als Sci ence. Lon -don: Butterworth. 1982.

4. I. Alvarez-Armas, S. Degallaix-Moreuil, Du plex stain less

steels. John Wiley & Sons. 2013.


SL10

CRYSTAL STRUCTURE AND PROPERTIES OF SrTi1-xMnxO3 PEROVSKITES –FROM CALCULATIONS TO EXPERIMENTS

M. Lebeda1, J. Drahokoupil

2

1Fac ulty of Nu clear Sci ences and Phys i cal En gi neer ing, Czech Tech ni cal Uni ver sity in Prague, Prague,Czech Re pub lic

2In sti tute of Phys ics of the Czech Acad emy of Sci ences, Prague, Czech Re pub lic

[email protected]

The SrTi1-xMnxO3 ce ram ics were ex per i men tally stud iedby X-ray dif frac tion and res o nant ul tra sound spec tros copyand the re sults were com pared with the the o ret i cal cal cu la -tion from DFT. Firstly, it was con firmed that our sam pleswere crys tal lized as cu bic and the de pend ence of lat tice pa -ram e ter a on Mn con cen tra tion was de ter mined. The lin earde crease of a with in creas ing Mn can be seen in Fig. 1 - left. There fore, it can be ex pected that it fol lows Vegard’s law.Sub se quently the com par i son be tween those lat tice pa ram -e ters ob tained by X-ray dif frac tion mea sure ments and theval ues cal cu lated by DFT method in CASTEP mod ule ofMa te ri als Stu dio was per formed.

Sec ondly, the cal cu la tion of the free en ergy ofSrTi1-xMnxO3 as a func tion of the vol ume of the unit cellwas cal cu lated from the first-prin ci ples and the ob tainedde pend ence was fit ted by Birch-Murnaghan equa tion ofstate [1], which al lowed the es ti ma tion of the bulk modulusand equi lib rium vol ume of the unit cell. Fur ther more, thechange of the cal cu lated bulk modulus caused by the dif fer -

ent fit ted vol ume range was tested and the re sult ing de -pend ence is em pha sized for the pure SrTiO3 in Fig.1 –right, with the ex per i men tal value [2]. The cal cu lated dataare in very good agree ment with the cor re spond ing ex per i -ment: in all stud ied perovskites the rel a tive de vi a tions from the ex per i men tal val ues are in the case of the lat tice pa ram -e ter only up to two per cent and in the case of the bulkmodulus up to four per cent.

1. F. Birch. Fi nite elas tic strain of cu bic crys tals. Phys. Rev.71(11): 809, 1947.

2. R. O. Belt, G. Rupprecht. Elas tic con stants of stron tium ti -

tan ite. Phys. Rev. 129(1): 90, 1963.


Fig ure 1. Left: ex per i men tally ob served lin ear de crease of the lat tice pa ram e ter a with in creas ing Mn con cen tra tion at SrTi1-xMnxO3

cu bical perovskites (squares) and the lat tice pa ram e ters data from ab-in itio sim u la tions with GGA, resp. GGA+U func tional (tri an gles,resp. rhom buses). Right: de pend ence of the SrTiO3 bulk modulus on the dif fer ent fit ted per cent age range of the vol ume (lat tice pa ram e -ter) of the unit cell at Birch-Murnaghan equa tion of state. The straight line in di cates the ex per i men tal value [2].

SL11

STRUCTURAL ANALYSIS OF PEROVSKITE THIN FILMS AND MULTILAYERS

T. Èíž, M. Kiaba, O. Caha, A. Dubroka

De part ment of Con densed Mat ter Phys ics, Fac ulty of Sci ence, Masaryk Uni ver sity, Kotláøská 2, 61137 Brno, Czech Re pub lic

[email protected], caha@phys ics.muni.cz

Perovskite ox ides with chem i cal for mula ABO3 have manyunique ap pli ca tions in mod ern mat ter sci ence such as su -per con duc tiv ity, magnetoresistance or ferroelectricity.Com pounds stud ied in this re search are LaFeO3/SrTiO3

(LFO/STO). LFO is an in su la tor and in bulk form has nomac ro scopic magnetoelectric cou pling or con trol of mag -ne tism by elec tric field. In com bi na tion with semi con duct -ing STO is cre ated po lar-nonpolar in ter face which makes it pos si ble to achieve the above men tioned prop er ties [1, 2].

The aim of this re search is mea sur ing the thick ness ofthin lay ers, rough ness of in ter faces and den sity of thesecom pounds with method X-ray struc tural anal y sis, namelyx-ray re flec tivity and coplanar dif frac tion were used. Thesam ples were pre pared us ing pulsed la ser de po si tion(PLD) tech nique in ox y gen at mo sphere at high tem per a ture of ap prox i mately 700 oC and us ing com pound polycrys tal -line tar gets.

The layer thick ness t can be de ter mined from the an gu -lar po si tion of the daugh ter’s max i mum on the re flec tioncurve. These max ima are caused by the in ter fer ence ofwaves re flected from the up per and lower lay ers. The

rough ness of the in ter face s is largely in flu enced by the

slope of the re flec tion curve. The den sity r is de ter mined

by the crit i cal an gle qc [3].The goal of the ex per i ment is to mea sure the re flected

in ten sity of the X-ray beam in de pend ence on the re flec tion

an gle q and its com par i son with nu mer i cal sim u la tion. This sim u la tion al lows to ob tain all men tioned pa ram e ters ofsam ple. In Fig. 1 is re flec tion curve, where is easy to re cog -nise equi dis tant thick ness os cil la tions. We have de ter -mined the thick ness of the film as 11 nm and rough ness of0.6 nm.

An other part of this re search is ob ser va tion of re flectedX-ray ra di a tion from multilayers STO/LFO/STO. Here aredis cussed two dif fer ent ap proaches. First of them is con sid -er ing of each sin gle atomic plane in stack. These sam pleswere pre pared us ing pulsed la ser de po si tion (PLD) methodby first de pos it ing sev eral atomic planes of the same ma te -rial on top of each other, and sub se quently ap ply ing theatomic planes of the other com pound (com plex model inFig. 2). This pro cess was sub se quently re peated. The sec -ond ap proach ne glect this man u fac tur ing pro cess and con -sider only one layer of each ma te rial with ap pro pri aterep e ti tion. In Fig. 2 is superlattice with (3+3) x 4monolayers. The data were fit ted within the sec ond ap -proach with a model of 4 pe ri ods, each con sist ing of STOlayer with thick ness of 1.2 nm and LFO layer with thick -ness of 0.37 nm. The rough ness of in ter face co mes out as0.46 nm for STO layer and 0.03 for LFO layer. If we sumthe layer thick ness of the in di vid ual lay ers in the com plexmodel, we get sim i lar re sults.

A to tal of about 12 sam ples with dif fer ent thick nessesand num ber of pe ri ods were mea sured. All pa ram e terswere also de ter mined for all. Fi nally, we have used methodcalled re cip ro cal space mapping (RSM). This measurement has confirmed that all these samples are pseudomorphic.

1. LI, Lili, Guangbiao ZHANG, Jingyu LI, Dong CHEN,Zhenxiang CHENG a Yuanxu WANG. Elec tric field in -duced two-di men sional elec tron gas and mag ne tism inLaFeO3/SrTiO3 (0 0 1) heterostructures. Ap plied Sur faceSci ence [on line]. 2019, 2019(471), 185 - 195 [cit.2019-05-01]. ISSN 0169-4332. Dostupné z:http://www.sciencedirect.com/sci ence/ar ti -

cle/pii/S0169433218333063

2. NAKAMURA, Kentarou, Hisanori MASHIKO, KoheiYOSHIMATSU a Akira OHTOMO. Im pact of built-in po -ten tial across LaFeO3/SrTiO3 heterojunctions onphotocatalytic ac tiv ity. In: Ap plied Phys ics Let ters [on -



Fig ure 2. Re flec tion curve of superlattice STO/LFO/STO with(3+3) x 4 monolayers with two dif fer ent sim u la tions. In this caseoc curs ex tinc tion of max ima.

Fig ure 1. Ex am ple of mea sured re flec tivity curve fit ted by thesim u la tion. The thick ness can be de ter mined from the fre quencyof the os cil la tions. This sam ple is a sin gle layer of LaFeO3/SrTiO3

with thick ness of 11 nm.



line]. 2016, 108(21) [cit. 2019-05-01]. DOI:10.1063/1.4952736. ISSN 0003-6951. Dostupné z:

http://aip.scitation.org/doi/10.1063/1.4952736.

3. PIETSCH, Ullrich, Václav HOLÝ a Tilo BAUMBACH.High-Res o lu tion X-Ray Scat ter ing: From Thin Films toLat eral Nanostructures. Sec ond Edi tion. 2004. ISBN978-144-1923-073.

Ses sion III

SL12

THERMAL EVOLUTION AND MICROSTRUCTURE OF GAS AGGREGATION CLUSTER SOURCE PRODUCED METAL NANOPARTICLES

Tereza Kretková1, Lukáš Horák

1, Pavel Pleskunov

2, Jan Hanuš

2, Andrei Choukourov

2,

Miroslav Cieslar3, Mi lan Dopita

1

1De part ment of Con densed Mat ter Phys ics, Fac ulty of Math e mat ics and Phys ics, Charles Uni ver sity,Ke Karlovu 5, 121 16 Prague 2, Czech Re pub lic

2De part ment of Macromolecular Phys ics, Fac ulty of Math e mat ics and Phys ics, Charles Uni ver sity,V Holešovièkách 2, 180 00 Prague 8, Czech Re pub lic

3De part ment of Phys ics of Ma te ri als, Fac ulty of Math e mat ics and Phys ics, Charles Uni ver sity, Ke Karlovu 5,121 16 Prague 2, Czech Re pub lic

[email protected]

Nanoparticles be long to mod ern, pro gres sive ma te ri alswith wide ap pli ca tion po ten tial. Its in ter est ing prop er tiescome from the high sur face to vol ume ra tio and of ten dif ferfrom the prop er ties of bulk or coarse-grained ma te ri alswith the same chem i cal com po si tion. Nanoparticles cat a -lytic, mag netic, elec tric or op ti cal prop er ties are just ex am -ples. In this study we in ves ti gated ni o bium nanoparticlespre pared by mag ne tron sput ter ing in com bi na tion with gasag gre ga tion clus ter source op er ated in DC mode in ar gonat mo sphere.

Stud ied nanoparticles de pos ited on sil i con sub strateswere char ac ter ized by com bi na tion of X-ray scat ter ing anddif frac tion meth ods and trans mis sion and scan ning elec -tron microscopies with en ergy-dispersive X-ray spec tros -copy. These an a lyt i cal meth ods pro vide the in for ma tionabout the nanoparticles sizes, shapes, their dis tri bu tions,

chem i cal com po si tion and the real atomic struc ture. In or -der to de ter mine the ther mal evo lu tion of nanoparticlesmicrostructure, the in situ high tem per a ture XRD mea sure -

ment was done in am bi ent air at mo sphere up to 800 °C.Mea sured SAXS data for tem per a tures in range be tween

50° C – 800 °C are shown in Fig ure 1. Two main tran si tionare ob served and de scribed.

Thin ox y gen layer is pres ent on the sur face of as pre -pared ni o bium nanoparticles, which acts as a pro tec tionbar rier against fur ther cor ro sion. The thick ness of thisamor phous ox ide layer, as de ter mined by fit ting the SAXSpat terns, is about 0.9 nm. The nanoparticle core is formedby pure ni o bium bcc phase and its mean ra dius is 11 nm.With in creas ing tem per a ture, the growth of the ox ide shelllayer at the ex pense of the size of nanoparticle me tal lic core

oc curs. Slightly above 200 °C the nanoparticles are fully

Fig ure 1. The SAXS pat terns mea sured dur ing an neal ing of

nanoparticles from 50 °C to 750 °C, at am bi ent air at mo sphere.Fig ure 2. Tem per a ture de pend ence of nanoparticle sizes, two dif -fer ent mod els were used to fit the measured data: core@shell

model up to 200 °C, above 200 °C spheres model.

sl7 study of the real structure of the laser-cladded … · Ó krystalografická spoleènost 166...

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