High-pressure evolution of silver iodate (AgIO3) and the γ- AgIO3 phase
A phase of silver iodate, γ-AgIO3, has been obtained at ambient temperature by compressing α-AgIO3 to 1.60(5) GPa. The γ-AgIO3 crystal structure was identified via Rietveld refinement of high-pressure powder synchrotron x-ray diffraction. The γ-AgIO3 reflections were indexed to an orthorhombic latti...
| Autores: | , , , , , , , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2023 |
| País: | España |
| Institución: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/348128 |
| Acceso en línea: | http://hdl.handle.net/10261/348128 |
| Access Level: | acceso abierto |
| Palabra clave: | Crystal structure Energy gap Gamma raysIodine compounds Light absorption Rietveld refinement Silver compounds Single crystals Density functional theory |
| Sumario: | A phase of silver iodate, γ-AgIO3, has been obtained at ambient temperature by compressing α-AgIO3 to 1.60(5) GPa. The γ-AgIO3 crystal structure was identified via Rietveld refinement of high-pressure powder synchrotron x-ray diffraction. The γ-AgIO3 reflections were indexed to an orthorhombic lattice (Pbca) with unit-cell dimensions of a=7.2945(12), b=15.0013(24), c=5.3904(9)Å, and V=589.85(29)Å3 at 2.20(5) GPa. Density-functional theory calculations predict that γ-AgIO3 is more stable than α-AgIO3 above 0.15 GPa. The α→γ-phase transition is characterized by a decrease in the volume per formula unit of approximately 2% and it is reversible on decompression. Single-crystal optical-absorption measurements and density-functional theory calculations reveal the electronic band gap to decrease monotonically with increasing pressure in both α and γphases, however the α→γ-phase transition (indirect → indirect) is characterized by an abrupt band-gap energy increase of approximately +0.18eV. This pressure induced band-gap evolution is rationalized based on the I-O bond lengths. The γphase may correspond to an intermediate step between the previously known α and β phases. |
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