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Crystallization Kinetics and Mechanism of Strontium Zinc Silicate Glass
Author(s) -
Tiwari Babita,
Dixit Anupam,
Pillai C. G. Sivan,
Gadkari Sanjay C.,
Kothiyal Govind Prasad
Publication year - 2012
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2012.05082.x
Subject(s) - crystallization , materials science , activation energy , crystal growth , strontium , silicate , strontium carbonate , differential thermal analysis , mineralogy , differential scanning calorimetry , analytical chemistry (journal) , chemical engineering , crystallography , thermodynamics , chemistry , diffraction , physics , organic chemistry , optics , chromatography , engineering
The non‐isothermal crystallization kinetics of the strontium zinc silicate ( SZS ) glasses, having composition 51 SrO ‐9 ZnO ‐40 SiO 2 (wt%), was studied using the differential thermal analysis ( DTA ). Glasses prepared by quenching the melt in air, were subjected to different heat treatments for studying the crystallization behavior. Formation of crystalline phases and microstructure were studied by using powder X ‐ray diffraction and scanning electron microscopy. The activation energy and mechanism of crystallization were determined according to K issinger, O zawa and M atusita‐ S akka equations. The DTA exotherm observed at around 920°C consists of two overlapping crystallization peaks corresponding to two different crystalline phases. Strontium silicate ( Sr 3 Si 3 O 9 ) and SZS ( Sr 2 ZnSi 2 O 7 ) phases crystallize almost simultaneously as major phases. The activation energies for the these crystallization peaks are 700 kJ/mol and 704 kJ/mol. Higher activation energies indicate that the kinetics are more thermally activated making the control of crystallization more difficult. The values of growth morphology parameters n ( A varami parameter) and m (dimensionality of crystal growth) suggest a diffusion controlled bulk crystallization with three‐ and two‐dimensional growth. This is also confirmed by an interconnected growth of stubby granular/prismatic shaped crystals in the glass‐ceramic. The microstructural evolution of the glass upon heating suggests the occurrence of phase separation with an apparently spinodal decomposition mechanism prior to the crystallization.