Contents

Introduction
Superconductivity of elements
Property of Beryllium

Experiment
Electrical resistance measurement
Powder X-ray diffraction
Result & Discussion
 Summary

Superconductivity of single elements
400 μK
T. Matsuoka, et al., J. Phys.:
Conf. Ser. 121, 052003 (2008).
My sample!
Ref. S. Okada. et al., J. Phys.
Soc. Jpn., 65, 1924 (1996)
In case of Lithium
Lithium have a very low Tc at
ambient pressure.
But the Tc reach to 20 K under
pressure with phase transition.
400 μK
Property of beryllium
Crystal structure : hcp
Melting point: 1551 K
toxic
Beryllium is
hard
reactive
Ref. D. A. Young, Phase Diagrams of the Elements
(University of California, 1991), P. 79.
Debye temperature: 1440 K
Debye Temp.
cf. diamond : 2230 K
Li
: 344 K
Ca : 230 K
Fe
: 470 K
In BCS theory…
Tc = 1.14 θD exp [ -1 / N(0) V ]
θD : Debye temperature
N(0): Density of electrons near the Fermi surface
V : Interaction between electron and lattice vibration
but
Tc of beryllium is 24.38 mK at ambient pressure
Experiment
For electrical resistance measurements
diamond
ruby
Be
Al2O3
Pt scotch tape
300 µm
SUS310S
ruby
Be
4.0 GPa
Sample setting
Sample: Be (99.9 %)
Cell: 30 mm (Cu-Be)
Diamond anvil: 300 mm
Insulating layer: Al2O3
Pressure medium: no
electrode
38 GPa
Result & Discussion
25.90
Electrical resistance measurement
Beryllium
26GPa
25.85
I observed small drop in the
electrical resistance around
1.0 K at 26 GPa
25.80
run2
R (m )
The reduction is up to
about 1 percent.
70
Beryllium
Cooling
R (m)
25.75
25.70
・ 38 GPa
69
0.1 mA
1 mA
10 mA
・ 48 GPa
25.65
68
run1
・ 43 GPa
0.1 mA
67
25.60
0
5
T (K)
10
0
1
2
T (K)
3
4
5
About Tc
4.0
Beryllium
3.5
3.0
2.0
1.5
1.0
24 mK
0.5
Beryllium
20
30
40
50
38 GPa
69
P (GPa)
I determine Tc like
right graph.
・
10
・
0
50 GPa
68
・
0.0
70
R (m )
Tc onset (K)
2.5
45 GPa
67
0
5
T (K)
10
For powder X-ray diffraction in SPring-8 beam line BL10XU
Sample setting
Sample: Beryllium (99.9 %)
Cell: gas driven type
Diamond anvil: 200 mm
Gasket: Re
Pressure medium: no
Pressure marker: Ruby and Au
Ruby
Au
Sample (40 μm)
diamond
Au & ruby
Be
200 µm
Gasket
X-ray diffraction
We can observed beryllium’s diffractions.
But there are some rhenium's peaks (G).
G
G
G
112
201
200
103
100
G
110
102
T = RT
101
103
200
112
201
110
G
102
G
101
002
G
100
Beryllium
40.9 GPa
 = 0.41411 (Å)
T = RT
002
Beryllium
9.7 GPa
 = 0.41411 (Å)
5
10
15
20
2(deg)
25
30
5
10
15
20
2 (deg)
25
30
4
16
3.5
15
3
a
c
2.5
2
V (Å3)
a, c (Å)
At room temperature
14
13
12
11
1.5
0
10
20
30
40
50
60
70
P (GPa)
10
0
10
20
30
40
50
60
70
P (GPa)
1.7
1.65
c/a
1.6
1.55
1.5
1.45
0
10
20
30
40
P (GPa)
50
60
70
1 Mbar = 100 GPa
Ref. G. V. Sin’ko, et al., Phys. Rev. B 71, 214108 (2005)
I cannot observe any phase transition.
Summary
4.0
3.5
Beryllium
・ Tc
・ Tc onset
Tc (K)
Tc onset (K)
3.0
2.5
2.0
1.5
1.0
0.5
0.0
20
25
30
35
40
P (GPa)
45
50
55

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参考資料2 file05の書き換