1. Pressure generation of toroidal anvil cell for physical property investigation under ultra-high pressure
2019/5/29
Shimizu Lab
Kara Yusuke

2. Introduction ・High Pressure ・Applied pressure ⇒ Change atomic distance
1 GPa : about 10,000 atm
center of the Earth : about 360 GPa
・Applied pressure ⇒ Change atomic distance
results: change electron state
structure type
metalization
superconductivity...etc.
・Predicted the pressure of hydrogen’s metallization and become superconductivity is about 500 GPa .
N. W. Ashcroft, Phs. Rev. Lett. 21, 1748 (1968)

3. Diamond anvil cell (DAC)
Sample
can generate high pressure (~300 GPa)
can measure electrical resistance
X-ray diffraction

4. Culet: a flat surface on the tip of a diamond anvil
Introduction
How to increase pressure
Make smaller culet size.
100 kg / 1 mm² = 10×1010 Pa = 10 GPa
100 kg / 0.1 mm2 = 10×1011 Pa = 100 GPa
100 kg / 0.01 mm2 = 10×1012 Pa = 1000 GPa
Culet: a flat surface on the tip of a diamond anvil
Lateral support prevent from
being broken diamond anvil.

5. Paper introduction
Toroidal diamond anvil cell for detailed measurements under extreme static pressure
Agnes Dewaele, Paul Loubeyre, Florent Occelli, Olivier Marie and Mohamed Mezouar
A. Dewaele et al.: Nature Commun., 9, 2913 (2018)

6. Purpose
Searched for a design of the diamond anvil that would enable to optimize the anvil strain so as to reach pressures up to the TPa range.
Calibrate equation of state above 400 GPa.

7. Anvil design and sample
Run
d 1 (μm)
d 2 (μm)
Sample 1 16 60 Au 2
Au+KCl 3
Al+Au 4 Al 5 25 75 Ar
30 𝛍𝐦
30 𝛍𝐦

8. Pressure measurement
In five runs, always succeeded in generating pressures over 300 GPa, especially run1 reached up to 603 GPa.
Run
d 1 (μm)
d 2 (μm)
Sample
P max (GPa) 1 16 60 Au
603 2
Au+KCl
443 3
Al+Au
317 4 Al
368 5 25 75 Ar
429

9. Anvil deformation
The anvil was designed with a dome shape, trying to compensate the deformation of the diamond tip, called cupping, under very high pressure.

10. Pressure dependence of volume of gold
Run1,2,3
Volume of gold measured up to 603 GPa is based on the (111) diffraction line position.

11. Methods X-ray diffraction measurement X ray wavelength 0.3738 Å
Pressure determination
All runs pressure at the center of the toroidal-DAC measured using the XRD signal of rhenium gasket.
Re EoS :Anzellini form
S. Anzellini et al .: J. Appl. Phys., 115, (2014)
X ray
DAC

12. Equation of state of Al and Ar
Volume of Al and Ar compared with the EoS obtained by a fit of lower pressure data points.

13. Summary
All runs succeeded in generating pressures over 300 GPa, especially run1 reached up to 603 GPa.
The data quality will enable researchers to solve some of the current pressure calibration issue above 400 GPa.

14. The toroidal anvil are made by FIB.
My work (Anvil design and processing)
20 μm
50 μm
70 μm
30 μm
3 μm
before processing
after processing
The toroidal anvil are made by FIB.
FIB: 集束イオンビーム

15. My work (Experimental method)
Sample : Ca
Gasket : Re
Insulating layer : c-BN, CaSO4
Electrode : Pt

16. My work (resistance measurement)
Success measurement electrical resistance by using toroidal diamond anvil.