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Highlights: [•] First high-pressure study of the thiospinel Cu?Fe?Cr2S4. [•] First determination of the bulk modulus and its pressure derivative. [•] Phase transition, reducing symmetry to lower than cubic, at 14.5GPa. [•] Jahn–Teller activity of Cu(2+) and high-spin to low-spin transition of Fe(2+). [ABSTRACT FROM AUTHOR]

Abstract: High-pressure X-ray diffraction in ScB2, TiB2, YB4 and HoB4 powders and single crystals has been studied using synchrotron radiation as well as conventional X-rays. The experimental results are supported by calculations using density functional theory. ScB2, YB4 and HoB4 are hard materials (bulk modulus 180–200GPa), while TiB2 may be classified as superhard (bulk modulus about 260GPa). We report here first experimental and theoretical determinations of the bulk modulus for HoB4 (195(5) and 198.2GPa, respectively), and first experimental values of the bulk modulus for ScB2 (196(2)GPa) and YB4 (185(4)GPa). No pressure-induced phase transformations are observed in any of the above borides up to about 20GPa. A continuous temperature-driven orthorhombic distortion is observed for HoB4 below 285K. Values of the thermal expansion coefficient are reported for ScB2 and HoB4 at 293, 200 and 100K. The thermoelastic behavior is explained in terms of bonding characteristics. [Copyright &y& Elsevier]

The bulk modulus and thermal expansion of Zn3P2 has been investigated at pressures up to 21 GPa and temperatures down to 100 K. The experimental zero-pressure bulk modulus is 80.7±1.8 GPa, in accordance with the bulk modulus scaling and lattice properties of the related compound Cd3P2. A tetragonal to orthorhombic phase transformation occurs above 11 GPa with a relative volume change of-7.1%. Values for the thermal expansion coefficient are reported at 293, 200 and 100 K. [ABSTRACT FROM AUTHOR]

It is argued that mainly the selenium sublattice determines the overall compressibility of the cubic spinel selenides, AB2Se4, and that the bulk modulus for these compounds is about 100 GPa. The hypothesis is supported by experiments using high-pressure X-ray diffraction and synchrotron radiation, and by first-principles calculations using density functional theory. [ABSTRACT FROM AUTHOR]

The high-pressure structural behavior of Sr2CrReO6 has been studied experimentally using synchrotron radiation and the diamond anvil cell and theoretically using density functional theory. The experimental zero-pressure bulk modulus is B0=170±4 GPa and the pressure derivative is B0'=4.7±1.0. These results compare well with the calculated values 172.6 GPa and 5.7. A pseudo-cubic unit cell can describe the crystal structure at low pressure, but the tetragonal structure becomes evident at high pressure. [ABSTRACT FROM AUTHOR]

L-ALANINE has been studied by X-ray diffraction at ambient temperature and pressure up to 10.3 GPa. The material is found to transform to a tetragonal structure between 2 and 3 GPa and to a monoclinic structure between 8 and 10 GPa. The experimental bulk modulus is 25(5) GPa for the orthorhombic phase. The results are compared with previous measurements of L-ALANINE. [ABSTRACT FROM AUTHOR]

Abstract: The high-pressure structural stability of CeN is investigated by experiment and theory. Experiments are carried out by energy-dispersive X-ray diffraction and synchrotron radiation, using a diamond anvil cell, to a maximum pressure of 77GPa. The experimental results are in remarkably good agreement with ab initio calculations using the full-potential linear muffin-tin orbital method within the generalized gradient approximation (GGA). The experimental zero pressure bulk modulus is B 0 =156(3)GPa, the pressure derivative being constrained to B 0′=4.00. The corresponding calculated data are B 0 =158.1GPa and B 0′=3.3. We report here the first experimental observation of the transformation of CeN from the ambient B1 type crystal structure to the B2 type. The onset of the transition is in the range 65–70GPa, and the relative volume change at the transition is ΔV/V =−10.9(3)%. These data compare well with the calculated transition pressure P tr =68GPa and ΔV/V =−10.8%. Experimentally, the transition is found to be rather sluggish. [Copyright &y& Elsevier]