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

The Curie temperatures and dielectric properties of KTiOPO4 (KTP), RbTiOPO4, KTiOAsO4, RbTiOAsO4, CsTiOASO4, Ba:KTP, and Ga:KTP were measured with small-signal relative dielectric permittivity (kappa) analysis, piezoelectric resonance analysis, and optical second harmonic generation. All the isomorphs and the doped KTP exhibit lower Curie temperatures 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 crystals show large dielectric relaxation at frequencies below 100 KHz throughout the temperature range of 500-degrees-C-800-degrees-C. For the barium doped KTP, we found the Curie temperature decreases with increasing Ba++-doping concentration. Barium doping also significantly modifies dielectric and piezoelectric properties of KTP.