The behavior of the E-2 and A(1)(LO) optical phonons of hexagonal indium nitride under hydrostatic pressure was studied using Raman spectroscopy. Linear pressure coefficients and the corresponding Gruneisen parameters for both modes were determined for the wurtzite structure up to 11.6 GPa, close to the starting pressure of the hexagonal to rocksalt phase transition of InN. Raman spectra acquired within the 11.6 to 13.2 GPa pressure range suggest that wurtzite InN undergoes a gradual phase transition, and the reverse transformation exhibits a strong hysteresis effect during the downstroke

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We report a Raman spectroscopy study of B12As2 under hydrostatic pressure up to 15 GPa. Mode Grüneisen parameters were determined for the B12As2 phonon modes. Phonon modes attributed to the As–As chain have a weak pressure dependence (0.6–1.9 cm−1 GPa−1) relative to inter- and intra-icosahedral vibrations (3.4–6.6 cm−1 GPa−1). The pressure dependence of B12As2 phonon frequencies is compared to those reported for α-boron and the origin of the mode at 505 cm−1 with its weak pressure dependence is discussed.

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A diamond-anvil cell can be operated with only one anvil in order to generate modest pressures in relatively large volumes. We demonstrate it to pressures up to 2.5 GPa with gaskets of steel, brass, and other metals, with a sample chamber 0.25 mm in diameter by 0.25-0.9 mm depth, and with various pressure media. In this form the cell is very simple to operate and is useful for much work on biological systems and soft solids which requires pressures in the 1 GPa range.