High pressure orthorhombic structure of CuInSe₂

Abstract

The structural behaviour of CuInSe(2) under high pressure has been studied up to 53 GPa using angle-dispersive x-ray powder diffraction techniques. The previously reported structural phase transition from its ambient pressure tetragonal structure to a high pressure phase with a NaCl-like cubic structure at 7.6 GPa has been confirmed. On further compression, another structural phase transition is observed at 39 GPa. A full structural study of this high pressure phase has been carried out and the high pressure structure has been identified as orthorhombic with space group Cmcm and lattice parameters a = 4.867(8) Å, b = 5.023(8) Å and c = 4.980(3) Å at 53.2(2) GPa. This phase transition behaviour is similar to those of analogous binary and trinary semiconductors, where the orthorhombic Cmcm structure can also be viewed as a distortion of the cubic NaCl-type structure.

Phase stability and elastic properties of CuGaSe2 under high pressure

“…The P4/mmm space group obtained from Fm3m that can distinguish Cu and In sites in the primitive cell. These results confirm the experiments and calculations studies [10][11][12], but we can distinguish the Cu and Ga sites in Fm3m and Cmcm to the P4/ mmm and Amm2, respectively. At the transition pressure 52 GPa (P4/mmm to Amm2), the equilibrium point in cubic phase (P4/ mmm) was pressed, and changed to orthorhombic space group (Amm2) as shown in Fig.…”

“…Atomic coordinates at 0 GPa of Cu, Ga and Se are (0, 0, 0), (0, 0, 0.5) and (0.244, 0.25, 0.125), respectively. In previous experiments [7][8][9][10], it has been suggested that Fm3m and Cmcm structures are the thermodynamically stable phases of CuInSe 2 and CuGaSe 2 beyond the ambient phase (I42d), and atomic positions of Cu and Ga are not distinguish both Fm3m and Cmcm. In this calculation, we imposed the lower symmetry space groups on Fm3m and Cmcm structures which the Cu and Ga atomic positions are distinguish, so that it can be optimized by geometry optimization.…”

“…They found that the I42d-Fm3m phase transition of CuGaSe 2 occurs at 13.6 GPa. Later, Bovornratanaraks et al [10] studied structures of CuInSe 2 up to 53 GPa using angle-dispersive x-ray powder diffraction techniques. The XRD result suggested that the Fm3m space group is completely transformed to the Cmcm phase at 43.9 GPa.…”

Experimentelle Untersuchungen zu Mechanismen von druck- und temperaturinduzierten Phasenübergängen

“…Die Gitterparameter bei Standardbedingungen betragen a=5.7820(2) Å und c=11.6173(4) Å, jedoch sind Schwankungen der Parameter durch nichtstöchiometrische Elementzusammensetzung bekannt [59]. Bei einem Druck von 6 bis 8 GPa ( [81], [25], [84], [92], [8]) erfolgt eine Umwandlung in den NaCl-Typ mit einer angenommenen zufälligen Verteilung der Kationen und einer Reduktion des Elementarzellenvolumens um 17% (siehe Abbildung 3.3). Die Koordinationszahl steigt von 4 nach 6.…”

“…Eine Elementanalyse des verwendeten Probenmaterials mit der Elektronenstrahl-Mikrosonde ergab eine Zusammensetzung aus 24.98 (8) 2. Kleine Vierschraubenzelle nach modifiziertem Merrill-Bassett-Typ [47] mit Diamantsitz aus Beryllium (siehe Abbildung 4.2a).…”