HIGH-TEMPERATURE QUANTUM PARAELECTRICITY IN PEROVSKITE-TYPE TITANATESLN(1 2)NA(1/2)TIO(3) (LN = LA, PR, ND, SM, EU, GD AND TB)/

The La3+ ion of a quantum paraelectric perovskite La1/2Na1/2TiO3 was s ubstituted with the smaller tripositive lanthanide ions Ln(3+). The X- ray structural study and Rietveld refinement of Ln(1/2)Na(1/2)TiO(3) f or Ln = Pr to Tb showed that they are synthesized as orthorhombic pero vskite structure with the space group Pnma. Their lattice parameters a nd dielectric constants decreased from Pr to Tb with an increasing vol ume of TiO6-octahedron. A high temperature quantum paraelectricity was found for Ln = Pr to Eu. Because of negative extrapolated Curie tempe rature, the process of explanation used for the typical quantum parael ectric SrTiO3 is not applicable to the quantum paraelectricity in Ln(1 /2)Na(1/2)TiO(3) for Ln = La similar to Eu.