Structural characterization of a new high-pressure phase of GaAsO4

• Published in: Acta crystallographica. Section B, Structural science Structural science, 2006-12, Vol.62 (6), p.1019-1024
• Main Authors: Santamaría-Pérez, David, Haines, Julien, Amador, Ulises, Morán, Emilio, Vegas, Angel
• Format: Article
• Language: English
• Subjects: Arsenates - chemistry; Chemical compounds; Chemical Sciences; Cold working, work hardening; annealing, quenching, tempering, recovery, and recrystallization; textures; Condensed matter: structure, mechanical and thermal properties; Cristallography; Cross-disciplinary physics: materials science; rheology; Crystal structure; Crystalline state (including molecular motions in solids); Crystallographic aspects of phase transformations; pressure effects; Crystallography; Crystallography, X-Ray; Exact sciences and technology; galium arsenate; Gallium - chemistry; high pressure; High-pressure and shock-wave effects in solids and liquids; Materials science; Mechanical and acoustical properties of condensed matter; Models, Molecular; Physics; powder diffraction; Pressure; Sensitivity and Specificity; structure determination; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; Treatment of materials and its effects on microstructure and properties
• ISSN: 0108-7681; 2052-5192; 1600-5740; 2052-5206
• DOI: 10.1107/S0108768106039760

As in SiO2 which, at high pressures, undergoes the α‐quartz → stishovite transition, GaAsO4 transforms into a dirutile structure at 9 GPa and 1173 K. In 2002, a new GaAsO4 polymorph was found by quenching the compound from 6 GPa and 1273 K to ambient conditions. The powder diagram was indexed on the basis of a hexagonal cell (a = 8.2033, c = 4.3941 Å, V = 256.08 Å3), but the structure did not correspond to any known structure of other AXO4 compounds. We report here the ab initio crystal structure determination of this hexagonal polymorph from powder data. The new phase is isostructural to β‐MnSb2O6 and it can be described as a lacunary derivative of NiAs with half the octahedral sites being vacant, but it also contains fragments of the rutile‐like structure.