A miniature ceramic anvil high-pressure cell (mCAC) was designed for magnetic measurements at pressures up to 12.6 GPa in a commercial superconducting quantum interference (SQUID) magnetometer. The simplified mCAC without anvil alignment mechanism is easy-to-use for researchers who are not familiar with high-pressure technology. Here, we introduce basic performance as well as recent developments in the mCAC. Also, experimental data on a pressure-induced ferromagnetic phase in YbCu2Si2 are shown. The pressure-induced phase has a strong uniaxial Ising-type anisotropy.
We developed the AC-calorimeter for measuring the absolute value of specific heat up to 10 GPa. We used Bridgman anvil cell made of WC with the top of 3 mm in diameter. A hollow at the top prevents expansion of the sample space over the anvil top. As for the thermometer and the heater, two chip resistors were mounted on the fringe of the Cu-Be gasket in the shape of a frying pan. Thereby, the thermometer is free from pressure. In order to thermally isolate the gasket from the anvil, diamond powder of 0.25 μm was laid on the anvil top. Two jumps of specific heat at the superconducting transitions of Pb (3.3 mg) and In (5.0 mg) are observed under pressures up to 9 GPa as clearly as at ambient pressure.
In this article, a modified technique using diamond anvil cell (DAC) for four-probe resistivity measurement is introduced. The full detail of sample mounting technique in a DAC is described. We performed high-pressure transport measurements for a Mott insulator β′-ET2ICl2 up to 12 GPa. By comparing the result obtained by the cubic anvil cell measurement, we proved that a choice of small culet size, small samples, and encapsulating the sample provides high quality hydrostatic pressure in DAC.
In this article, a newly constructed measurement system for simultaneous measurements of dielectric constant, electrical polarization, and AC-calorimetry under high pressure using a diamond anvil cell is reviewed. The system is designed to measure pressure and magnetic-field profiles of magnetoelectric properties in multiferroics. As an example, we show the results of the pressure effect on magnetoelectric properties in one of the best studied multiferroics, TbMnO3.
Magnetic field as well as temperature and pressure plays an important role to determine the states of the matter. All these parameters are always required to expand the accessible ranges because it is effective and attractive to open a new stage on the research in the solid state physics. Recently we extend the strength of the pulsed magnetic field by using a pulsed magnet wound with newly developed high strength-high conductivity Cu-6 wt% Ag alloy wire. The structure of the magnet is also reexamined for introducing Cu-6 wt% Ag alloy. New wire and new design of magnet allow us to mark our new record.
In this article, we review recent advances in ultrasonic measurements under multi-extreme conditions such as high pressures, high magnetic fields and low temperatures. We have developed a clamped piston-cylinder high-pressure cell for the application of hydrostatic pressure and uniaxial one as well, and succeeded to perform the ultrasonic measurement under multi-extreme conditions, even in a pulsed magnetic field for the first time. We show the technical details, the current problems and some of recent results obtained in compounds with a ThCr2Si2-type crystal structure such as EuRh2Si2 and BaFe2As2.
We have developed a Bridgman-type pressure cell for pulsed high magnetic field up to 58 T and low temperature down to 1.5 K. We have tested the difference in increase of temperature in the sample space due to the eddy-current heating between a metallic gasket and plastic one. From the starting of the pulse to 58 T of the maximum pulse, the increase of the temperature of the sample space at base temperature 1.5 K was reduced from about 6-7 K with the metallic gasket to 1-2 K with the plastic one. Improving the design of the pressure cell with large windows around a pair of anvils, the increase of the temperature at 1.5 K was reduced to 0.1-0.2 K. Combination of a zirconia-anvil with thin channels for wires of electrode and pyrophyllite gasket is effective to get high pressure and to reduce the noise-level of the electrical resistivity measurement in the pulsed magnetic field. We have observed clear metamagnetic transition below and above the critical pressure Pc=1 GPa in an heavy fermion antiferromagnet CeRh2Si2.
We found the feasibility of sterilization by applying a pressure treatment of 200 MPa before heat treatment. The wet density of spores of Bacillus cereus was decreased by the pressure history when we applied a high-pressure treatment of 200 MPa, and the heat resistance of the spores was decreased. Afterwards when we applied a heat at a medium-temperature of about 100℃, the sterilization of spores was promoted. Furthermore, we found the turbidity of the spore suspensions greatly decreased after the pressure reduction step of the high-pressure treatment. The decrease of turbidity was also found to be highly correlated with the survival spore counts after the heat treatment. Therefore the turbidity was considered to be a sterilization indicator.