Properties of Rochelle Salt Related to the Piezo-electric Effect

Abstract

+ 3o' C., was undertaken to determine which of them seem to be related to the piezo-electric effect, which increases rapidly between -2o and -x5' C. and decreases rapidly between + 2o and + 3o C. In this way it was hoped to get information as to the nature of the structure underlying piezo-electric phenomena. Refractive indices were measured for the three principal directions for six wavelengths from 4SS4 to 6Soo A. and at temperatures of -7o, -II. S, o, + 2x. 3 and + 4o' C. The variation with temperature, however, is linear, the average coefficient being S9 X xo ' per degree. The thermal expansion betweenxo and + 2o' C. the piezo-electric changes.Nevvman's Principle of Symmeh y in Crystal Optics. -Rochelle salt, if it belongs to the hemihedral class of the orthorhombic system, seems to form an exception to this principle since most of its electrical properties in the direction of the a axis depend on the direction of the field.Infra-red absorption band for Rochelle salt is computed from the constants of the dispersion formula to be at about Sg p. 64.0 JOSEPH VA I.A SEK, t SECOND SERIES.' Valasek, PHvs. Rmv. , XIX., 478, Igz2.

Thermal expansion and phase transitions of sodium potassium tartrate tetrahydrate (RS)

“…The discontinuous changes of thermal expansion coefficients of RS, observed at both Curie points, are generally in agreement with the recently published results of Imai (1976a, b). The earlier published results of Valasek (1922), Habliitzel (1935, Vigness (1935) and Ubbelohde & Woodward (1946) also show some anomalies near the Curie points, but the discontinuity of the ~(t) function was not observed.…”

“…Thermal expansion measurements with macroscopic methods were made by Valasek (1922;optical interferometer: average value of coefficients between 263 and 293 K is reported), Vigness (1935;optical lever: change of dimensions at about ten different points in a temperature range between 295 and 308 K is reported), Hablfitzel (1935; Abbe-Pulfrich dilatometer: expansion coefficient, but not actual change of dimensions, is The Bond method of precise lattice-parameter determination to an accuracy of 10-5 may be applied as a sensitive monitor of the structural changes occurring in the crystal. Very accurate data obtained for RS with the Bond diffractometer (Lukaszewicz, Kucharczyk, Malinowski & Pietraszko, 1978) in the Department of Crystallography of the Institute of Low Temperature and Structure Research in Wroctaw are presented below.…”

The effect of external factors on dielectric permittivity of Rochelle salt: humidity, annealing, stresses, electric field

“…Significant changes of the piezoelectric properties of Rochelle salt were observed in the samples kept in the air with a high concentration of ethanol vapor [17]. An essential effect of humidity on the relaxation times of the dielectric permittivity of Rochelle salt was also observed in [18] and attributed to the concentration changes of water vacancies in the lattice.…”

Decoding the Fingerprint of Ferroelectric Loops: Comprehension of the Material Properties and Structures

“…(2) Ferroelectric Materials It is almost one century since the discovery of ferroelectricity in Rochelle salt, [17][18][19] after which, there are many developmental milestones along the way, which have been well reviewed by Kanzig, 20 Cross and Newnham, 21 Fousek, 22 and Haertling. 23 Here, we only survey some important events in the development of ferroelectric materials.…”