ゼオライトの配列ナノ空間を利用した新物質系
ゼオライト・・・多くの種類，種々の組成
ゲスト物質・・・多くの種類（吸蔵，イオン交換）
ゼオライトとゲスト物質の多様な組み合わせ
μＳＲとナノ構造物質の物性研究
野末泰夫
大阪大学大学院理学研究科物理学専攻
KnClusters in Zeolite A
ゼオライト結晶の配列ナノ空間
類縁物質（配列ナノ空間を利用する新物質系）
Si
Ba
!"
!"
!"
!"
!"
!"
!"
!"
!"
!"
X
!"
Zeolite A (LTA Structure)
Zeolite X (FAU Structure)
Sodalite (SOD Structure)
8 46
シリコンクラスレート化合物
Ba Si
!"
!"
!"
!"
K C
3 60
1
Field
e+
µ+
sample
HL
A(t) =
Front Counter
NF
N F (t) " #N B (t)
N F ( t) + #N B (t)
理研-RAL ミュオンポート
H ( r,t ) = Hmat ( r,t ) + Hext
µ+
Back Counter
NB
中性子
Interaction with dipole field H
Fermi contact interaction with
magnetic moment of electrons
H
S
e+
ISIS 大強度陽子パルスビーム
Interactions of muon spin
e+
µ+
2
ラザフォード・アップルトン研究所 (RAL)
Muon Spin Rotation/Relaxation of µ+
(µSR = Muon Spin Rotation/Relaxation/Resonance)
S
filled skutterudite MT4X12
M = Pr, Nd,..., T = Fe, Os, Ru, X = P, As, Sb
ユビキタス元素戦略（元素にはない新し性質が現れる）
RCNP研究会 「ミューオン科学と加速器研究」
２００８年１０月２０日(月)ー２１日(火) 大阪大学核物理研究センター
e+
T
M
electron spins and
Hmat ( r,t ) from
nuclear spins of materials
Hext = 0
ZF-µSR
Hext ! beam
LF-µSR
H
ext ! beam
TF-µSR
Parameters of materials
Temperature T
理研-RAL ミュオンポート
Muonium states
3
4
MuSR study on K-clusters in Zeolite
Mylar sheet
Sample powder
Main Collaborators
T. Nakano (Osaka University)
I. Watanabe (Muon Science Laboratory, RIKEN)
F. L. Pratt (ISIS Facility, Rutherford Appleton Laboratory)
unit: K12Al12Si12O48 (K-type zeolite A)
Zeolite A
Ti
aluminosilicate
(structure typec code LTA)
Al12Si12O48 : framework (negatively charged)
K＋ : exchangeable cations
µ+
Experiment: RIKEN-RAL Muon
Science Laboratory
Ti cell and setting of
sample powder
Al
O
unit
4 mm
5Å
Handling in pure He gas
11 Å
Guest K atoms
Si
4s
K+
Quantum states of s-electrons
confined in a cluster
(super atom)
4s
1d(10)
~1.5 eV
1p(6)
~1.2 eV
1s(2)
12.3 Å
!-cage
(supercage)
11 Å
Spherical-well potential model
"-cage
5
Zeolite (α cage)
Al
O
6
n=0
1d
1p
1s
Si
K+
1
2
3
4
5
6
7
8
9
Km+m Km+m K +m
m
Km+m K +m
Km+m K +m
m
m
Km+m K +m
+ 2K + 3K
m
Km+m
+ 4K + 5K + 6K
+ 7K + 8K
+ 9K
スーパーアトム(クラスター)に閉じ込められた電子
+K
Static potential for electron
殻模型
12.3 Å
配列したクラスター
（クラスター間の相互作用）
11 Å
7
8
Potassium clusters in zeolite A
s-electron ferromagnetism (ferromagnetism by nonmagnetic elements)
3.0
T < TC
K/K-LTA [#101-04]
n ~ 4.3
0.8
2K
1.0
T > TC
M2 (G 2 )
2.0
0.6
5K
6K
7K
8K
1.0
0.4
Temperature (K)
0.8
9K
10K
0.2
TC
0.0
0.0
0
2
4
6
8
Temperature (K)
10
12
14
0
2 104
3 104
5 105
K/K-LTA [#101-04]
n = 4.3, T = 2 K
0.8
soft ferromagnetism
3
0.4
0.0
-0.4
-0.8
5 104
surface plasmon
K/K-LTA(1)
RT
P
1p -> 1d
$
$
#
Curie Temperature
0.6
0
1s -> 1p
$
Weiss Temperature
electron concentration
per cluster
7.3
$
–10
–20
6 104
0.4
6.6
$
6.0
5.4
$
4.7
K/K-LTA(1)
–30
$
4.1
0.2
3.2
$
antiferromagnetic
–40
K/K-LTA [#101-05]
n ~ 4.5, H = 10,000 Oe
4 105
1/! (cm /emu)
1.2
4 104
H/M (Oe/G)
1.6
M (G)
1 104
1p
1s
5
Reflectance
K/K-LTA [#101-04]
n ~ 4.3, H = 100 Oe
1.2
M (G)
K-clusters in zeolite A
• canted antiferromagnetism by electrons in 1p-like state
• Mott 10insulator
Arrott plot
1.4
2.4
0
1
2
3
4
5
6
7
8
Electron Concentration per Cluster n
"
1.0
canted antiferromagnetism
3 105
1.5
!
0.8
0
1.5
2.0
2.5
3.0
Photon Energy (eV)
1d(10)
2 105
ferromgnetic
1p(6)
M
1 105
-1.2
1s(2)
0
-1.6
-1000
-500
0
H (Oe)
500
TW 0 TC
1000
40
80
Temperature (K)
120
11 Å
9
ZF-µSR spectra are approximated by
RIKEN-RAL
GZ (t) = A0 exp(" #0 t) + A1 exp("#1 t) + A2 exp("# 2t)cos($t) + B
Muon stopping site 1 : 8-ring site
Muon stopping site 2 : Double 4-ring site
0.4
0.3
18
1
0
2
10
K/K-LTA(1)
n = 5.6
ZF-µSR
0.1
4.1 K
14
20
0.2
6.1 K
0
2
4
Temperature (K)
1.8 K
6
0
2
4
Time !! (µs)
6
8
!SR (Riken-RAL Muon Facility)
15
30 Oe
5 Oe
10
K/K-LTA (1)
n = 5.6
LF-µSR, 1.8 K
0
TC = 5 K
0.6
ZF
4
Time ( µs)
6
8
M
#
21
!0
!1
T
C
19
K/K-LTA(1)
n = 5.6
LF-µSR 1.8 K
0.2
0.0
2
8R-site
TC = 5 K
0.8
0.4
Fermi Contact interaction
with s-electrons of cluster
at 8R-site
!"
LF
10 Oe
ZF-µSR
n = 5.6
1.0
10
LF = 100 Oe
5
0
3.6 K
Depolarization Rate (1/ µs)
Asymmetry!! (%)
19.4 K
K/K-LTA(1)
n = 5.6
ZF-µSR
20
30
Initial asymmety (%)
22
RIKEN-RAL
LF-µSR
Asymmetry (%)
0.5
Internal magnetic field (Oe)
2
Frequency ! (MHz)
1
10
17
0
5
10
15
Temperature (K)
20
11
0
40
80
Longitudinal field (Oe)
H ( r,t ) = Hmat ( r,t ) + Hext
12
H mat ! 200 Oe
Laboratory for Muon Spin Spectroscopy
Paul Scherrer Institut, Switzerland
PSI-GPS
ZF-µSR
(PSI)
General Purpose Surface-Muon Instrument
(GPS)
LF-µSR
T. Nakano, J. Matsumoto, T.C. Duan, I. Watanabe, T. Suzuki, T. Kawamata, A. Amato, F.L. Pratt
and Y. Nozue, to be published in Physica B, 2008
13
14
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