Electrical and Nonlinear Optical Properties of KTiOPO4 Single Crystals Doped with Niobium, Antimony, and Tantalum

摘要

Single crystals of K_(1-x)Ti_(1–x)Nb_xOPO_4 (KTP:Nb), K_(1-x)Ti_(1-x)Sb_xOPO_4 (KTP:Sb), and K_(1-x)Ti_(-x)Ta_xOPO_4 (KTP:Ta) solid solutions are grown and their dielectric, conducting, and nonlinear optical properties are investigated. The maximum contents x of niobium, antimony, and tantalum impurities in the crystals are equal to 0.11, 0.23, and 0.25, respectively. The doping of the KTiOPO4 crystals with niobium, antimony, and tantalum brings about the formation of additional potassium vacancies and additional potassium positions and, as a consequence, an increase in the ionic conductivity σ_(33). An increase in the doping level leads to a smearing of the ferroelectric phase transitions and a decrease in the phase transition temperatures. The permittivity of the doped crystals exhibits a broad relaxation peak in the temperature range 200–600 ℃.