Dielectric and Thermal Study of K₂SeO₄Transitions

X-ray diffraction, thermal analysis, and Raman scattering study ofK2BeF4and comparison to other members of theSoláns1, González-Silgo2, Calvet3 et al. 1998Phys. Rev. B

“…The results of DTA and TG analysis show that the K 2 BeF 4 undergoes a phase transition with onset temperature 10 Cell parameters were refined using all identified maxima ͑as the holder was open the number of used reflections changed from 35 reflections before heating the sample to 900 K to 24 reflections after heating͒. Peaks of two phases are observed from 903 to 913 K, so cell parameters of two phases were determined in this range.…”

Thermal Conduction Across Ferroelectric Phase Transitions: Results on Selected Systems

“…It undergoes an IC phase transition at T 3 , below which the crystal is commensurate and ferroelectric with a small spontaneous polarization along the c direction. Many experimental studies such as dielectric measurements (Aiki et al, 1969, Aiki et al, 1970, X-ray and neutron diffraction Ohama, 1974;Terauchi et al, 1975), ESR (Aiki, 1970), Raman and Brillouin scattering (Wada et al, 1977a;Wada et al, 1977b;Yagi et al, 1979), ultrasound velocity, attenuation and dispersion studies (Hoshizaki et al, 1980;Shiozaki, 1977) etc have been reported near T 2 and T 3 . The variations in specific heat capacity and thermal expansion of K 2 SeO 4 in the low temperature phase have also been reported before (Aiki et al, 1970;Gupta et al, 1979).…”

“…Thermal expansion along the c-axis exhibits a discontinuity at the incommensurate to commensurate transition. Specific heat measurements show anomalies at T 2 and T 3 , indicating that the transition at T 2 is second order and that the one at T 3 is first order (Aiki et al, 1970). In spite of all these measurements reported at temperatures T 3 and T 2 , only very few experimental results have been reported near T 1 ( Unruh et al, 1979;Inoue et al, 1979;Cho & Yagi, 1980;Gupta et al, 1979) because of the inherent difficulties involved in carrying out precision experiments at high temperatures.…”

Echtzeit-Untersuchungen der ferroelektrischen Phasenumwandlungen in K2SeO4 und SrTiO3 unter dem Einfluss eines elektrischen Feldes

“…Analog zu Abschnitt 3.2.1 werden zunächst die Ergebnisse der γ -Diffraktionsmessungen aus [189] zusammengefasst und anschließend die Daten der elastischen Neutronenstreuung präsentiert. Eine detaillierte Analyse der statischen γ -Diffraktion ist in [5] [98,115]. Diese Publikationen beruhen auf Messungen der Dielektrizitätszahl, die bei kontinuierlicher Temperaturänderung mit Raten von 0.1 bis 0.5 K/min ausgeführt wurden.…”

“…Dieses Verhalten wird in dielektrischen Messungen bestätigt, die bei konstanten Kühlraten ausgeführt wurden [98,115]. …”