StructualStructual and Magnetic Properties of and Magnetic Properties of NanocrystallizedNanocrystallized TrantitionTrantition--Metal Oxides.Metal Oxides.

Hiroshi Kira(2004.8.1～)

Tohoku Y. Murakami, H. Tamura, Y. AndoUniversity T. Takahashi、M. Onodera

K. TsudaK.Oyama

Shizuoka Y. YamazakiUniversity

Kyushu H. IdeguchiUniversity

本研究における階層融合本研究における階層融合

Moleculemolecular

orbital

Electric structureLattice

原子・分子と凝縮物質の融合領域原子・分子と凝縮物質の融合領域

本研究における階層融合本研究における階層融合

Moleculemolecular

orbital

Electric structureLattice

???Nano crystal

原子・分子と凝縮物質の融合領域原子・分子と凝縮物質の融合領域

MetalMetal Strongly CorrelatedStrongly CorrelatedElectron System Electron System

Ex) Alkali Metal Ex) Transition metal oxides

0

0.5

1

1.5

0 2 4 6 8 10

Mag

netiz

atio

n (e

mu/

cm3 )

Temperature (K)

K5.0

/K12-LTA

M-T 20G

Potassium clusters arranging in simple cubic structure

Tc～6K Ferromagnetic transition

KK5.05.0/K/K1212--LTALTASpherical well potential

Strongly CorrelatedStrongly CorrelatedElectron System Electron System

Charge

Spin Orbital

site 1 site 2

site 3site 4

NanoNano--crystallized crystallized Strongly CorrelatedStrongly CorrelatedElectron System Electron System

1～10nm

Clarify the electronic states of nano-crystallized matter

ProblemsProblems

・・ Synthesis of the nano-crystallized transitional metal oxide

・ Stability ・ Size-distribution・ Amounts

1～10nm→MCM-41

PurposePurpose

30Å (30～80Å)

SiO2～5Å

102 ～

103 n

mStructure of MCMStructure of MCM--4141

Hexagonal NanomaterNanomater sized glass tube sized glass tube

LaMnOLaMnO33Perovskite Structure

LaOMnO2LaOMnO2LaOMnO2LaO

LaMnO3Canted Antiferromagnet

（ TN=141K）

T.Sato, 2003(Tohoku University)

Preparation of LMO/MCMPreparation of LMO/MCM--4141

1. MCM-41+ La and Mn Nitrate solution

La and Mn nitrate is introduced into 1-d channel of MCM-41

Dried

2. Annealing (700℃, 20h, Oxygen atmosphere)La(NOLa(NO33))33 ＋＋ Mn(NOMn(NO33))22 →→ LaMnOLaMnO33 + 5NO+ 5NO22 + O+ O22

Pristine Annealed

Magnetic properties of LMOMagnetic properties of LMO//MCMMCM--4141

・

0

0.005

0.01

0.015

0.02

0.025

0 50 100 150 200 250 300

試料①試料②試料③単結晶※強度は任意倍

Magnetization [

µ B/ion]

Temperature [K]

LMO/MCM-41M-T at 1000G

・Tc = 270 K??LaMnO3+δ : Tc=130K – 160K

Tc270K150K75K

Three Types FM TransitionsThree Types FM TransitionsTcTc=75K,150K,270K=75K,150K,270K

0 20 40 60 80 100

LMO/MCM-41LMO Bulk

Intensity (Arb. Units)

2Theta (deg)

2004.11.05 PF BL-1ALMO/MCM-41 XRDRT λ=1.409Å

XX--Ray Powder Diffraction AND TEM ImageRay Powder Diffraction AND TEM Image

Energy

Energy

0 20 40 60 80 100

Intensity

2Theta (deg)

RT λ=1.409Å

117Å

(112),(200)

138Å

(202)

96Å

(201), (004)

62Å

(224)

81Å

(024),

(312), (

204)

・ LMO nano crystal ・ No bulk phase LMO→Observed FM transition corresponding to the nano crystal?

XX--Ray Powder Diffraction AND TEM ImageRay Powder Diffraction AND TEM Image

0

0.5

1

1.5

2

2.5

3

3.5

0

0.05

0.1

0.15

0.2

0.25

0.3

0 50 100 150 200 250 300

800℃ 780℃770℃ 760℃740℃700℃

Magnetization (emu/g)

Temperature (K)

2005.02.03-07 LMO/MCM-41(25v%) H=1kG,ZFC

Magnetization (μB/Mn)

酸素流中・20h処理温度依存性

0 10 20 30 40 50 60 70 80

Intensity (arb. units)

2Theta (deg)

2005.02.11 KEK PF BL-1ALMO/MCM-41 O2Flow 20h

λ=1.408Å

800℃

780℃

770℃

760℃

740℃

LMO Bulk

Optimization of the synthetic condition Optimization of the synthetic condition １１

Magnetization X-Ray Powder Diffraction

770℃で最も大きい磁化

Observed FM transition (Tc=280K)corresponding to the nano crystal

760℃以上ではLa2Si2O7

Optimization of the synthetic condition 2Optimization of the synthetic condition 2

0

1

2

3

4

0 10 20 30 40 50 60 70 80

I (×

105 Counts)

2Theta (deg)

2005.02.14 KEK PF BL-1BLMO/MCM-41

λ=1.408Å83Å

92Å

74Å

74Å

57Å

Annealed at 750℃

・ Peaks of LMO Nano Crystal

・Size of the nano crystal →60～100Å

Succeeded in Succeeded in ddevelopeveloppingping the the method of method of nanonano--crystallize the crystallize the

transition metal oxidestransition metal oxides

Magnetism of LMO/MCMMagnetism of LMO/MCM--4141

Three types of ferromagnetism

0

0.5

1

1.5

2

2.5

3

3.5

0

0.05

0.1

0.15

0.2

0.25

0.3

0 50 100 150 200 250 300

800℃ 780℃770℃ 760℃740℃700℃

Magnetization (emu/g)

Temperature (K)

2005.02.03-07 LMO/MCM-41(25v%) H=1kG,ZFC

Magnetization (μB/Mn)

酸素流中・20h処理温度依存性

0

0.005

0.01

0.015

0.02

0.025

0.03

0 50 100 150 200 250 300

Magnetization (μ

B/ion)

temperature(K)

LMO/MCM-41M-T at 1000G

270～280K

150K75K

Three types of LMO Three types of LMO nanonano crystalscrystals

Electronic states of Electronic states of nanonano crystals in crystals in LMO/MCMLMO/MCM--4141

Magnetism of LMO/MCMMagnetism of LMO/MCM--4141

--11

((LaOLaO))

(Mn(Mn3+3+OO22))

((LaOLaO)) +1+1

+1+1

Amounts of introduced hole

１．TC = 270 K

２．TN = 150 K

３．TN = 75 K

δ = 0.1 – 0.2hole dope

δ = 0.1 – 0.2carrier dope

δ = 0

～30Å10-15 Layers？？？？

Nano-crystallizedLaMnO3

Limited Size

Carrier dope

TiOTiO2 2 / MCM/ MCM--4141

0

1000

2000

3000

4000

5000

10 20 30 40 50 60 70

5%10%TiO2

I (co

unts

)

2Theta (deg)

TiO2/MCM-41TiO2 Cataryst

XX--ray powder diffractionray powder diffractionTiO2 nano clusters realized

works with UV light

Nanocrystal TiO2Visible light??

ConclusionConclusion

Succeeded in preparation of LaMnO3nano crystalsSucceeded in Succeeded in ddevelopeveloppingping the method of the method of nanonano--crystallize the crystallize the transition metal oxidestransition metal oxides

ResultsResults

high Tc of FM Transition in LaMnO3/MCM-41Size effects acts the effective charge transferTiO2/MCM-41 nano crystalsMnO2/MCM-41

Clarify the electronic states of nano-crystallized matterPurposePurpose

Structual and Magnetic Properties of Nanocrystallized Trantition-Metal Oxides.本研究における階層融合本研究における階層融合PurposeStructure of MCM-41LaMnO3Preparation of LMO/MCM-41