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Synthesis, physical properties, and atomic structure of niobium-doped RbTiOPO4 crystals

Research paper by V. I. Voronkova, V. K. Yanovskii, E. P. Kharitonova, S. Yu. Stefanovich, N. I. Sorokina, O. D. Krotova, N. I. Kononkova

Indexed on: 01 Jan '05Published on: 01 Jan '05Published in: Crystallography Reports



Abstract

Single crystals of solid solutions Rb1−xTi1−xNbxOPO4(RTP: Nb) were grown and the temperature dependences of their dielectric and nonlinear optical properties and electric conductivity were studied. The maximum possible niobium content in these crystals is close to x = 0.1. The niobium impurities decelerate growth of {100} faces, and crystals take a plate-like habit. With increasing doping level, ferroelectric phase transitions diffuse and their temperature decreases. A specific feature of the dielectric properties of RTP: Nb crystals is the appearance of a broad relaxation maximum ε33 in the temperature range 200–600°C caused by the formation of vacancies in the rubidium cation sublattice. The intensity of second-harmonic generation under laser irradiation decreases with increasing niobium content. The atomic structure of a crystal with x = 0.01 is studied and it is established that niobium substitutes for titanium only in Ti(1) positions.