CURIE TEMPERATURES AND DIELECTRIC-PROPERTIES OF DOPED AND UNDOPED KTIOPO(4) AND ISOMORPHS

The Curie temperatures and dielectric properties of KTiOPO4 (KTP), RbT iOPO4, KTiOAsO4, RbTiOAsO4, CsTiOASO4, Ba:KTP, and Ga:KTP were measure d with small-signal relative dielectric permittivity (kappa) analysis, piezoelectric resonance analysis, and optical second harmonic generat ion. All the isomorphs and the doped KTP exhibit lower Curie temperatu res than KTP, ranging from 637-degrees-C for CsTiOAsO4 to 955-degrees- C for hydrothermally (HT) grown KTP. The Curie-Weiss law is obeyed in all samples. With the exception of CsTiOAsO4, all doped and undoped cr ystals show large dielectric relaxation at frequencies below 100 KHz t hroughout the temperature range of 500-degrees-C-800-degrees-C. For th e barium doped KTP, we found the Curie temperature decreases with incr easing Ba++-doping concentration. Barium doping also significantly mod ifies dielectric and piezoelectric properties of KTP.