Title :
Structural and dielectric characteristics of 0.50 Bi2O 3-0.25 V2O5-0.25 SrB4O7 glass-ceramic
Author :
Shankar, M.V. ; Varma, K.B.R.
Author_Institution :
Mater. Res. Centre, Indian Inst. of Sci., Bangalore, India
Abstract :
Novel 0.50 Bi2O3-0.25 V2O5 -0.25 SrB4O7 glasses have been prepared via a conventional splat-quenching technique. Differential thermal analysis (DTA) carried out on the as-quenched samples confirms their glassy nature and shows a prominent exothermic peak at 400°C. The X-ray powder diffraction (XRD) pattern of the heat treated sample could be indexed to an orthorhombic ferroelectric Bi2VO5.5 phase with the lattice parameters a=5.543, b=5.615 and c=15.321 A. The presence of nano-crystallites of bismuth vanadate, Bi2VO5.5 (BiV) dispersed in the glassy matrix of strontium tetraborate, SrB4O7 (SBO) is confirmed in the heat treated (at 400°C for 12 h) samples, by high resolution transmission electron microscopy (HRTEM). The dielectric constant (ετ), measured as a function of temperature, exhibits an anomaly around the transition temperature of the parent crystalline BiV. The ετ of the glass-ceramic at 300K is comparable with that predicted by Maxwell´s model and logarithmic mixture rule
Keywords :
X-ray diffraction; bismuth compounds; borate glasses; ceramics; ferroelectric materials; glass structure; glass transition; lattice constants; permittivity; splat cooling; strontium compounds; thermal analysis; transmission electron microscopy; transparency; vanadium compounds; 12 h; 400 degC; Bi2O3-V2O5-SrB4 O7; Bi2O3-V2O5-SrB4 O7 glass-ceramic; Bi2VO5.5; Bi2VO5.5 nanocrystallites; Maxwell´s model; X-ray powder diffraction pattern; as-quenched samples; conventional splat-quenching technique; dielectric characteristics; dielectric constant; differential thermal analysis; glassy matrix; glassy nature; heat treated sample; high resolution transmission electron microscopy; lattice parameters; logarithmic mixture rule; orthorhombic ferroelectric Bi2VO5.5 phase; parent crystalline BiV; prominent exothermic peak; structural characteristics; temperature dependence; transition temperature; Bismuth; Dielectrics; Ferroelectric materials; Glass; Lattices; Powders; Strontium; Temperature; X-ray diffraction; X-ray scattering;
Conference_Titel :
Applications of Ferroelectrics, 1996. ISAF '96., Proceedings of the Tenth IEEE International Symposium on
Conference_Location :
East Brunswick, NJ
Print_ISBN :
0-7803-3355-1
DOI :
10.1109/ISAF.1996.598149
