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In situ angle dispersive synchrotron X-ray diffraction and Raman scattering measurements under pressure are employed to study the structural evolution of Cu4Bi4S9 nanoribbons, which are fabricated by using a facile solvothermal method. Both experiments show that a structural phase transition occurs near 14.5 GPa, and there is a pressure-induced reversible amorphization at about 25.6 GPa. The electrical transport property of a single Cu4Bi4S9 nanoribbon under different pressures is also investigated. [ABSTRACT FROM AUTHOR]

The electrical transport properties and structures of Y2O3/ZrO2 solid solution have been studied under high pressure up to 23.2 GPa by means of in situ impedance spectroscopy and x-ray diffraction (XRD) measurements. In the impedance spectra, it can be found that the pressure-dependent resistance of Y2O3/ZrO2 presents two different change trends before and after 13.3 GPa, but the crystal symmetry still remains stable in the cubic structure revealed by the XRD measurement and Rietveld refinement. The pressure dependence of the lattice constant and unit cell volume shows that the Y2O3/ZrO2 solid solution undergoes an isostructural phase transition at 13.1 GPa, which is responsible for the abnormal change in resistance. By fitting the volume data with the Birch–Murnaghan equation of state, we found that the bulk modulus B0 of the Y2O3/ZrO2 solid solution increases by 131.9% from 125.2 GPa to 290.3 GPa due to the pressure-induced isostructural phase transition. [ABSTRACT FROM AUTHOR]

High-pressure phase transitions of cubic Y2O3 are investigated using in situ synchrotron x-ray diffraction in a diamond anvil cell up to 36.3 GPa. The pressure-induced phase transitions of cubic Y2O3, which display apparent inconsistencies in previous studies, are verified to be from a cubic phase to a monoclinic phase and further to a hexagonal phase at 11.7 and 21.6 GPa, respectively. The hexagonal Y2O3 displays noticeable anisotropic compressibility due to its layered structure and it is stable up to the highest pressure in the present study. A third-order Birch–Murnaghan fit based on the observed pressure-volume data yields zero pressure bulk moduli of 180(3), 196(7) and 177(7) GPa for cubic, monoclinic and hexagonal phases, respectively. [ABSTRACT FROM AUTHOR]

The structural phase transitions of bismuth under rapid compression has been investigated in a dynamic diamond anvil cell using time-resolved synchrotron x-ray diffraction. As the pressure increases, the transformations from phase I, to phase II, to phase III, and then to phase V have been observed under different compression rates at 300 K. Compared with static compression results, no new phase transition sequence appears under rapid compression at compression rate from 0.20 GPa/s to 183.8 GPa/s. However, during the process across the transition from phase III to phase V, the volume fraction of product phase as a function of pressure can be well fitted by a compression-rate-dependent sigmoidal curve. The resulting parameters indicate that the activation energy related to this phase transition, as well as the onset transition pressure, shows a compression-rate-dependent performance. A strong dependence of over-pressurization on compression rate occurs under rapid compression. A formula for over-pressure has been proposed, which can be used to quantify the over-pressurization. [ABSTRACT FROM AUTHOR]

The work functions of the (110) and (100) surfaces of LaB are determined from ambient pressure to 39.1 GPa. The work function of the (110) surface slowly decreases but that of the (100) surface remains at a relatively constant value. To determine the reason for this difference, the electron density distribution (EDD) is determined from high-pressure single-crystal x-ray diffraction data by the maximum entropy method. The EDD results show that the chemical bond properties in LaB play a key role. The structural stability of LaB under high pressure is also investigated by single-crystal x-ray diffraction. In this study, no structural or electronic phase transition is observed from ambient pressure to 39.1 GPa. [ABSTRACT FROM AUTHOR]

The pressure-induced structural transitions of ZnTe are investigated at pressures up to 59.2 GPa in a diamond anvil cell by using synchrotron powder x-ray diffraction method. A phase transition from the initial zinc blende (ZB, ZnTe-I) structure to a cinnabar phase (ZnTe-II) is observed at 9.6 GPa, followed by a high pressure orthorhombic phase (ZnTe-III) with Cmcm symmetry at 12.1 GPa. The ZB, cinnabar (space group P3121), Cmcm, P31 and rock salt structures of ZnTe are investigated by using density functional theory calculations. Based on the experiments and calculations, the ZnTe-II phase is determined to have a cinnabar structure rather than a P31 symmetry. [ABSTRACT FROM AUTHOR]