Structual and Magnetic Properties of …Structual and Magnetic Properties of Nanocrystallized...
Transcript of Structual and Magnetic Properties of …Structual and Magnetic Properties of Nanocrystallized...
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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
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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
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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
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MetalMetal Strongly CorrelatedStrongly CorrelatedElectron System Electron System
Ex) Alkali Metal Ex) Transition metal oxides
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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
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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
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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
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30Å (30~80Å)
SiO2~5Å
102 ~
103 n
mStructure of MCMStructure of MCM--4141
Hexagonal NanomaterNanomater sized glass tube sized glass tube
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LaMnOLaMnO33Perovskite Structure
LaOMnO2LaOMnO2LaOMnO2LaO
LaMnO3Canted Antiferromagnet
( TN=141K)
T.Sato, 2003(Tohoku University)
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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
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Magnetic properties of LMOMagnetic properties of LMO//MCMMCM--4141
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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
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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
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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
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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
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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
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Magnetism of LMO/MCMMagnetism of LMO/MCM--4141
Three types of ferromagnetism
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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
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Electronic states of Electronic states of nanonano crystals in crystals in LMO/MCMLMO/MCM--4141
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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
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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??
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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