Ferroelectric properties of the mixed Aurivillius phase Bi/sub 7/Ti/sub 4/NbO/sub 21/

Abstract

Room and high temperature X-ray diffraction, DSC, dilatometric and dielectric measurements have shown that the mixed Aurivillius phase Bi/sub 7/Ti/sub 4/NbO/sub 21/ presents two characteristic temperatures. The first one-close to 675/spl deg/C-seems to be attributed to a ferroelectric-paraelectric transition connected with a structural change from orthorhombic to tetragonal. The second one, strongly observed by dielectric measurements concerns a possible ferroelastic-paraelastic phase transition.