PROCESSING AND CHARACTERIZATION OF FERRO PIEZOELECTRICS IN THE STILLWELLITE FAMILY/

New family of stillwellite-like (CeBSiO5, sp.gr. P3(1)) ferroelectric borosilicates and borogermanates is found, their properties and possib le applications are discussed. Borophosphates ABPO(5) (sp.gr. P3(1)21, A=Ca, Sr, Ba, Pb) which are very similar in structure are classified as piezoelectrics. Structural, dielectric and optical non-linear chara cteristics of new ferroelectrics are investigated on single crystals o btained either by flux or Czochralski methods. Optical SHG data on pow ders and ceramics in an interval 300-1300 K, combined with dielectric and Xray data, allow to define ferroelectric phase boundaries on the x -T phase diagrams. Crystallization from glasses in ternary systems Ln( 2)O(3)-B2O3-SiO2 (GeO2) is investigated and good opportunity is demons trated for formation of polar glass-ceramic textures with ferroelectri c and pyroelectric properties.