Pyroelectric properties of RbTiOAsO₄ single crystals in the 4.2-300 K temperature range

The temperalure dependence of the pyroelectric coefficient, λ_s, of RbTiOAsO₄ single crystals grown by seeded pulling from high-temperature self-fluxes has been studied in the low-temperature range. The results show that in the 4.2-250 K temperature range the λ_s (T) behavior is similar to those of the isomorphic crystals belonging to the KTP (KTiOPO₄) family of compounds, and at temperature of 250 K the RTA pyroelectric coefficient λ_s=-(5.6 ± 0.3) × 10^-5 C/m² K. However, at temperatures above 275 K, the superionic conductivity increases significantly, while the electrical conductivity originating from the release of charge carriers associated with trace impurity point defects increases additionally above room temperature. These effects have been taken into account in experimental evaluation of the true λ_s values, especially above 275 K. The peculiarities revealed in the RTA pyroelectric coefficient temperature dependence are also discussed in terms of the structural changes associated with the temperature increase and isomorphic ion substitutions.