Transactions of the INDIAN CERAMIC SOCIETY Vol. 76 2017
Preparation and Microstructural Characterization of
Niobium Pentoxide Doped Barium Strontium Titanate
Glass and Glass-Ceramics
Bijay Kumar Barkey, Swonal Sitam Das, Avinash Meher and Partha Saha*
Pages : 21-30
DOI : 10.1080/0371750X.2017.1233830
Abstract
(Ba0.2Sr0.8)TiO3-2SiO2-B2O3-K2O compositions based glass and glass-ceramics with
and without 0.1 mol% Nb2O5 were prepared by melt-quench method. XRD and FTIR
spectra reveal the formation of amorphous structure and the presence of stretching
and deformation vibration bonds of B-O-Si linkage and Si-O-Si bridges, respectively.
Differential scanning calorimetry (DSC) of the glass sample shows that onset of
crystallization for (Ba0.2Sr0.8)TiO3 phase occurs between ~750o and 800oC. XRD confirms
the formation of (Ba0.256Sr0.744)TiO3 as major phase upon controlled crystallization of
the glass samples at ~750o-800oC for 3 h with rutile and SiO2 as minor phase(s).
Quantitative phase analysis using structural Rietveld refinement of the powder XRD
patterns shows that 0.1 mol% Nb2O5 addition in the [(Ba0.2Sr0.8)O.TiO2]-[2SiO2-B2O3]-
[K2O] glass-ceramic system promotes the formation of Ba0.256Sr0.744TiO3 phase and
suppresses the amount of rutile or TiO2 compared to undoped glass-ceramic system.
SEM-EDS microstructural analysis of undoped glass-ceramic illustrates the formation
of micrometer size flower-like Ba0.256Sr0.744TiO3, and needle-shape TiO2 crystals.
However, addition of 0.1 mol% Nb2O5 changes the crystals to irregular shape. Results
from the dielectric measurements performed from room temperature to 250oC show
that dielectric constant increases slightly with the addition of 0.1 mol% Nb2O5
compared to undoped glass-ceramic samples.
