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Acoustical properties of single crystals of mercurous halides
Author(s) -
Barta Č.,
Silvestrova I. M.,
Pisarevskij Ju. V.,
Moiseeva N. A.,
Beljaew L. M.
Publication year - 1977
Publication title -
kristall und technik
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.377
H-Index - 64
eISSN - 1521-4079
pISSN - 0023-4753
DOI - 10.1002/crat.19770120914
Subject(s) - anisotropy , ion , elastic modulus , lattice (music) , halide , crystal (programming language) , lattice energy , transverse wave , elastic energy , phase (matter) , crystallography , condensed matter physics , materials science , crystal structure , chemistry , physics , wave propagation , optics , thermodynamics , inorganic chemistry , computer science , acoustics , programming language , organic chemistry
Velocities of propagation of elastic waves along principal crystallographic directions in Hg 2 Br 2 and Hg 2 J 2 single crystals were measured using the pulse and phase‐pulse techniques. The values obtained were used to calculate the components of the elastic tensors c ik and s ik , as well as the phase and group velocities of propagation of longitudinal and transverse waves in the (100) and (001) planes, and the angular deviation of acoustic energy flux from the direction of the corresponding wave normal. Knowledge of the anisotropy of the elastic properties of Hg 2 X 2 crystals and of their change with the anion (X = Cl, Br, J) leads to deeper understanding of the character of bonds in the crystal lattice and points the way to a better utilization of technical properties of the crystals. — Minimum velocity of propagation of an elastic wave falls in the case of Hg 2 J 2 to a value v [100] [1 1 10] = 0,25 · 10 5 cm/s, what is the lowest value known among all crystals. Maximum angular deviation of acoustic energy flux — nearly 50° — is exhibited by the quasi‐longitudinal wave in Hg 2 J 2 crystals. On substituting the Cl − ions with Br − and J − ions, the anisotropy of elastic moduli C 33 / C 11 increases by nearly 80%. Different mechanisms contribute to vectorial dependence of the elastic properties along different crystallographic directions.