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Elastic Properties of the Triclinic Pseudo‐Trigonal Room‐Temperature Phase of KIO 3
Author(s) -
Haussühl S.,
Jyang Wang,
Mengkai LÜ
Publication year - 1995
Publication title -
crystal research and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.377
H-Index - 64
eISSN - 1521-4079
pISSN - 0232-1300
DOI - 10.1002/crat.2170300419
Subject(s) - triclinic crystal system , piezoelectricity , trigonal crystal system , phase transition , softening , condensed matter physics , thermal expansion , quartz , phase (matter) , materials science , chemistry , crystallography , mineralogy , composite material , crystal structure , physics , organic chemistry
Weakly twinned triclinic crystals of the room temperature γ‐phase of KIO 3 , grown from aqueous solutions, exhibit a quasi‐trigonal behaviour of point symmetry group 3m in respect to thermal expansion, piezoelectric effects, and elastic properties. The elastic tensor and its temperature derivative were determined from ultrasonic resonance frequencies of thick plane‐parallel plates and their shift upon variation of temperature, respectively. The static piezoelectric constants d 222 and d 211 are about fifty times larger than d 111 of α‐quartz resulting in strong piezoelectric coupling coefficients of elastic waves ( k 1 = 0.42; k 66 = 0.60). Approaching the γ‐β transition at 345.6 K from lower temperatures, the shear stiffness c E 66 shows a drastic softening. The transition appears to be of second‐order ferroelastic.