Structural Conditionality of the Ionic Conductivity of MTiORO 4 (M = K, Rb; R = P, As) Single Crystals
- PDF / 499,346 Bytes
- 5 Pages / 612 x 792 pts (letter) Page_size
- 63 Downloads / 157 Views
ICAL PROPERTIES OF CRYSTALS First Russian Crystallographic Congress
Structural Conditionality of the Ionic Conductivity of MTiORO4 (M = K, Rb; R = P, As) Single Crystals N. I. Sorokina,*, N. E. Novikovaa, Yu. V. Shaldina, and M. Tseitlinb a Shubnikov
Institute of Crystallography, Federal Scientific Research Centre “Crystallography and Photonics,” Russian Academy of Sciences, Moscow, 119333 Russia b Crystal Growth Laboratory, Ariel University of Samaria, Ariel, 40700 Israel *e-mail: [email protected] Received September 25, 2017
Abstract—The ionic conductivity σ||c along the crystallographic axis c and the structural imperfection of the lattices of KTiOPO4, RbTiOPO4, and RbTiOAsO4 single crystals with low defect concentration, grown by the high temperature solution growth technique, have been investigated by impedance spectroscopy and X-ray diffraction analysis. Isomorphic substitutions of Rb+ ions for conduction K+ cations in MTiOPO4 crystals decreases the σ||c value, whereas the substitution of As5+ ions for framework P5+ cations in RbTiORO4 crystals increases the σ||c value. The σ||c values at 573 K are found to be 1.0 × 10–5, 5.7 × 10–6, 2.0 × 10–6, and 3.3 × 10–5 S/cm for the KTiOPO4, RbTiOPO4 {100}, RbTiOPO4 {201}, and RbTiOAsO4 crystals, respectively (the growth zone of the crystalline boule from which the samples were cut is indicated in braces). DOI: 10.1134/S106377451802027X
INTRODUCTION Compounds of the KTiOPO4 potassium titanyl phosphate family (orthorhombic system, sp. gr. Pna21) are multifunctional inorganic materials. They have promising nonlinear optical, ion-conducting, and ferro- and pyroelectric properties [1–3]. KTiOPO4 crystals are characterized by pronounced anisotropy of ionic conductivity [4, 5], which is due to the thermally activated motion of alkaline cations. The highest ionic conductivity is observed along the polar crystallographic axis c (σ||c). The σ||c values for KTiOPO4 crystals change in wide ranges (from 10–11 to 10–4 S/cm at 293 K [6–13] and from 10–5 to 10–3 S/cm at 573 K [13, 14]), depending on the impurity content, growth conditions, and thermal history. The KTiOPO4 crystals intended for use in nonlinear optics have an especially low defect concentration. The nonlinear optical highresistivity crystals of the KTiOPO4 family are used as active elements of electro-optic modulators of solid-phase lasers for parametric generation of light [15, 16]. The purpose of this study was to analyze the influence of the isomorphic substitutions of rubidium and arsenic for potassium and phosphorus, respectively, on the temperature dependence of the ionic conduc-
tivity of nonlinear optical MTiOPO4 (M = K, Pb) and RbTiOAsO4 single crystals. EXPERIMENTAL The objects of the study were the KTiOPO4, RbTiOPO4 (two samples, cut from the {100} and {201} growth zones of the crystalline boule), and RbTiOAsO4 single crystals. All single crystals under study were grown by directional solidification from high-temperature solutions–melts onto seed at the Crystal Growth Laboratory of Ariel University (Sa
Data Loading...
