Dielectric properties of new lamellar Ag_0.10Cu_0.90InP₂S₆ samples

ISSN： 0141-1594

Source： Phase Transitions: A Multinational Journal, Vol.84, Iss.9-10, 2011-09, pp. : 858-864

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Abstract

Frequency and temperature investigations of the dielectric parameters of a new lamellar Ag_0.10Cu_0.90InP₂S₆ crystal are made. Frequency measurements of the capacity are realized in the interval from 50 Hz to 13 MHz. Temperature measurements are realized in the interval 273–411 K at frequencies 1 5, and 10 kHz. The first-order phase transition is observed at temperature T _C = (286 ± 0.5) K. Using experimental dependences the following parameters for Ag_0.10Cu_0.90InP₂S₆ crystal are obtained: Curie temperature T ₀ = T _C = (286 ± 0.5) K, Curie–Weiss temperatures T ₀₁ = 266.23 K and T ₀₂ = 286.52 K. A significant difference among temperatures T ₀₁, T ₀₂, and T _C is the evidence of a first-order type phase transition. The Curie–Weiss temperature constants for the ferroelectric C_w_, _fe and paraelectric C_w _,pa phases are calculated: C_w _,fe = 3519 and C_w_, _pa = 25,546. The ratio = 7. Character of frequency–temperature dependences of the dielectric parameters and their behavior in the paraelectric phase are significantly affected by Cu^I and In^III motion ions, which cause great increase in the values and considerable dispersion in the paraelectric phase up to the end of the investigated temperature interval.