Effect of TiO₂ addition on the crystallization of Li₂O–Al₂O₃–4SiO₂ precursor powders by a sol-gel process

Abstract

The activation energy for crystallization of β-spodumene in TiO2 added Li2O–Al2O3–4SiO2 (LAS) precursor powders by a sol-gel process was studied by using isothermal and nonisothermal methods. Nonisothermal kinetics for the LAS precursor powder system were investigated using differential thermal analysis (DTA) and quantitative x-ray diffraction (XRD) analysis. The rate of crystallization of LAS precursor powders decreased as the TiO2 content increased. For samples with addition of 0, 5.0, and 10.0 wt% TiO2, the activation energies for crystallization by DTA evaluation were 165.06, 194.46, and 205.38 kJ/mol, respectively. According to the quantitative XRD method, the values computed by the Johnson–Mehl–Avrami equation were 162.54, 189.42, and 196.14 kJ/mol, respectively. The values obtained by isothermal and nonisothermal kinetic methods from DTA and XRD analyses were in good agreement. The growth morphology parameters were 0.59, 0.70, and 0.76, respectively, for the LAS precursor powder with TiO2 addition of 0, 5.0, and 10.0 wt%, showing a rodlike growth. In the LAS precursor powder system, TiO2 did not act as the nucleative agent.

Thermal behavior and transformation kinetics of titanium dioxide nanocrystallites prepared by coupling agents

“…9, the growth morphology parameter n is obtained being 1.061, 0.915, 1.016, respectively. For n = 1, it describes onedimensional growth or surface nucleation from a constant number of nuclei [15]. This observation can be further evidenced by TEM, Fig.…”

Improved Figure of Merit of (Ba,Sr)TiO3-Based Ceramics by Sn Substitution

“…It was noteworthy that Sn concentration decreased the dielectric loss of (Ba 0:6 Sr 0:4 )(Ti 1Àx Sn x )O 3 ceramics, which have good sinterability (over 95%). 13) The dielectric losses of (Ba 0:6 Sr 0:4 )(Ti 0:9 Sn 0:1 )O 3 ceramics decreased from 0.007 to 0.002 with increasing sintering temperature. The dielectric loss is affected by the grain boundary.…”

Crystallization behavior of (1−x)Li2O·xNa2O·Al2O3·4SiO2 glasses

“…The XRD amount of each constituent quantitative was determined by the powder method [26][27][28]. The amount of ␤-spodumene present in the glass was determined by comparing the intensity of its major peak (2Â from 24.5 • to 26.1 • ) of the ␤-spodumene with the standard.…”