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Dziaugys A.,Vilnius University | Banys J.,Vilnius University | MacUtkevic J.,Semiconductor Physics Institute | Sobiestianskas R.,Vilnius University | Vysochanskii Y.,Chemistry of Uzhgorod University
Physica Status Solidi (A) Applications and Materials Science | Year: 2010

The dielectric properties of CuInP 2S 6 and Ag 0.1Cu 0.9InP 2S 6 crystals were investigated in wide frequency (20 Hz-3 GHz) and temperature ranges (25-360 K). The low frequencies dielectric spectra at high temperatures are highly influenced by the high ionic conductivity. The temperature dependences of the static dielectric permittivity and the mean relaxation time reveal the first order order-disorder ferrielectric phase transition at Tc=288K in Ag 0.1Cu 0.9InP 2S 6. The conductivity and its activation energy exhibit only a weak change close to the ferrielectric phase transition temperature in both investigated crystals. The freezing phenomena in CuInP 2S 6 and Ag 0.1Cu 0.9InP 2S 6 revealed the complex dielectric permittivity behaviour characteristic for transition into dipolar glass state. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Samulionis V.,Vilnius University | Banys J.,Vilnius University | Dziaugys A.,Vilnius University | Gurzan M.I.,Chemistry of Uzhgorod University | And 2 more authors.
Ferroelectrics | Year: 2011

The ultrasonic and piezoelectric investigations were performed in CuInP 2S 6 family layered crystals, where Cu, In, S were substituted by Ag, Bi and Se. We have shown that in CuBiP 2Se 6 crystals the anomalies of piezoelectric sensitivity and ultrasonic velocity appears in the vicinity of two phase transitions at 145 K and 220 K. In AgBiP 2S 6 layered crystals the only one anomaly of ultrasonic velocity and attenuation was observed at 220 K. In these crystals below room temperature the large ultrasonic attenuation and corresponding velocity dispersion were observed. Such ultrasonic behaviour was supposed to be determined by acoustoionic interaction due to large ionic conductivity of Ag + cations. Copyright © Taylor & Francis Group, LLC.

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