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Pressure‐induced tetrahedral tilting and deformation in Ge 2 N 2 O
Author(s) -
Srinivasa S. R.,
Cartz L.,
Jorgensen J. D.,
Labbe J. C.
Publication year - 1979
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/s0021889879013182
Subject(s) - tetrahedron , orthorhombic crystal system , crystallography , bond length , neutron diffraction , compressibility , molecular geometry , diffraction , materials science , lattice (music) , high pressure , chemistry , crystal structure , thermodynamics , physics , molecule , optics , organic chemistry , acoustics
High‐pressure time‐of‐flight neutron diffraction studies have been carried out on orthorhombic Ge 2 N 2 O to 25.4 × 10 8 Pa and by X‐ray diffraction to 49 × 10 8 Pa. The zero‐pressure axial compressibility coefficients are K a = 33 (2), K b = 41 (2), K c = 28 (2), and volume K v = 99 (5) × 10 −13 Pa −1 . The changes in bond angles and bond lengths at pressures from 10 5 to 25.4 × 10 8 Pa have been measured. The structure of Ge 2 N 2 O consists of GeN 3 O tetrahedra linked along the a direction by Ge–O–Ge bonds and along the b and c directions by three coordinated Ge–N bonds. This structural framework adjusts to applied pressure by tetrahedra tilting in a cooperative fashion, the biggest change being observed in the Ge–O–Ge angle which decreases by 12.4°. The behavior of Ge 2 N 2 O is very similar to its isomorph Si 2 N 2 O, though the tetrahedra deform somewhat more for Ge 2 N 2 O. The pressure changes in the lattice parameters of Ge 2 N 2 O up to ~8 × 10 8 Pa are very similar to those of Si 2 N 2 O up to ~24 × 10 8 Pa, supporting the contention that germanates behave as high‐pressure models for silicates.