A computer program PFRUBY has long been used in the Photon Factory, which determines the pressure from ruby fluorescence. The details of the program is described in this article, including the algorithm for fitting the peak top of the R1 line, the way how to find the initial values of the fitting parameters, and the accuracy of the fitting under different nonhydrostatic conditions.
This article addresses the computer control and data analysis system for “SPEED-1500”, a Kawai-type multi-anvil press installed on beamline BL04B1 at the SPring-8, which is for in situ x-ray diffraction and radiography experiments using synchrotron radiation. The system consists of several different computer applications, which are for pressure and temperature control, stage and goniometer control, and data-collection and its analysis. These programs have been used by many public users and are still improving.
In this article, a control program at the high-pressure beam lines in the SPring-8 and Photon Factory is described. This program is able to control not only the position of the many stages needed but also their 2-dimensional mapping. It efficiently and smoothly controls the positions of the 4 masking plates needed to produce a slit to shape the incident beam as well as a collimator, a main stage and a diamond anvil cell containing the sample. This program is very important to allow research within the limited machine time at the synchrotron facility.
Laser-heated diamond anvil cell is a powerful tool to generate ultra-high pressure and temperature. However, the temperature stability of laser-heated sample in a diamond anvil cell is correlated closely with stability of the absorption coefficient of the sample. A numeric control of laser power is occasionally effective to maintain a given temperature under the circumstances. In this paper, critical problems to realize a stable heating and principles of dynamic control of the sample temperature are discussed in detail. The software developed to enable temperature control using a personal computer has been shown with actual examples of the improved stability of the sample temperature.
Recent progress in the software PIP is briefly summarized. New algorithms of the divided histogram method and the super sampling method have greatly improved the accuracy for two-dimensional image to one-dimensional profile conversion. The accuracy of peak positions in the one-dimensional pattern has been increased by optimizing their fitting region. Many other issues such as running with a TrueColor mode and porting to other platforms are also introduced.
Pressure-induced phase transitions are one of the most interesting fields in high-pressure research. The X-ray powder diffraction method is useful to detect such phase transition, although it can not provide information about the diffraction direction. Therefore the process of indexing the X-ray powder diffraction pattern of the high-pressure phase is the most important, because even the crystal system of the phase can not be determined without this process. Both classic and modern indexing methods for X-ray powder diffraction patterns are reviewed in this article. Several successful results are also introduced, using a computer code called “DICVOL91” for the indexing method.
We have paid attention to the ground state of the high-temperature magnetic phase of YbInCu4 which exhibits a first-order valence transition at 42 K. The high-temperature phase, which shows Curie-Weiss paramagnetism of Yb3+, is stabilized down to zero temperature by the application of pressure and/or substitution of Y for Yb. We have measured magnetization of Yb0.8Y0.2InCu4 under high pressure in the low temperature ranges down to 0.6 K and could observe suppression of the valence transition and occurrence of ferromagnetism at the same time. The ferromagnetism is characterized by a low Curie temperature of 1.8 K and very small spontaneous magnetization of 0.067 μB/Yb.
Local structures around germanium in liquid germanate have been investigated by in-situ X-ray absorption measurements up to 9 GPa at 1000°C. Liquid germanate consisting of tetrahedrally coordinated germanium contracts with increasing pressure without significant changes in the local structure up to 2.5 GPa and then shows an abrupt fourfold-sixfold coordination change around 3 GPa. The coordination change is completed below 4 GPa and a high-density liquid consisting of octahedrally coordinated germanium is stable to 9 GPa. GeO6 octahedron in the high-density liquid is more compressible than that in solids, suggesting the possibility of a density inversion between liquid and solid at higher pressure. By considering the analogy of germanates to silicates, these results give some far-reaching implications for the evolution and dynamics of the Earth’s deep interior.