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Modulation of quartz‐like GeO 2 structure by Si substitution: an X‐ray diffraction study of Ge 1− x Si x O 2 (0 ≤ x < 0.2) flux‐grown single crystals
Author(s) -
Lignie Adrien,
Granier Dominique,
Armand Pascale,
Haines Julien,
Papet Philippe
Publication year - 2012
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889812003081
Subject(s) - crystallography , germanium , materials science , silicon , diffraction , quartz , single crystal , x ray crystallography , crystal structure , chemistry , optics , optoelectronics , physics , composite material
The spontaneous nucleation by the high‐temperature flux method of GeO 2 and SiO 2 ‐substituted GeO 2 (Ge 1− x Si x O 2 ) compounds was improved to give single crystals free of hydroxy groups. The crystal structure and quality of these α‐quartz‐like piezoelectric materials were studied by single‐crystal X‐ray diffraction at room temperature. The refinements gave excellent final reliability factors, which are an indication of single crystals with a low level of defects. A good correlation was found between the silicon content in Ge 1− x Si x O 2 crystals determined through extrapolation from the inter‐tetrahedral bridging angle and that found from energy‐dispersive X‐ray spectroscopy. The effect of germanium replacement by silicon on the distortion of the α‐quartz‐type GeO 2 structure was followed by the evolution of the intra‐tetrahedral angle and other structural parameters. The T O 4 ( T = Si, Ge) distortion was found to be larger in α‐GeO 2 than in α‐SiO 2 and, as expected, the irregularity of the T O 4 tetrahedra decreased linearly as the substitution of Si for Ge increased.