Crystal Clamping in Lead Titanate Glass-Ceramics

Abstract

of GeCl,, SiCl,, and O2 are considered at temperatures and concentrations appropriate to the formation of germanium phosphosilicate glasses for optical communication fiber by the modified vapor deposition process. Using the best available thermodynamic values for the 32 components of the system, good agreement in absolute composition and in the dependence of germanium incorporation with oxygen and the Ge/Si ratio has been shown using an idealsolution approximation for the two condensed-state components. A question remains concerning the best choices of the published critical values of the Gibbs energy of GeOZ(l). Very satisfactory agreement between our experimental results and calculations are obtained using the values published by Pankratz."Using the element potential method to minimize the Gibbs energy of the mixture, a flexible means of calculating the concentrations of very complex chemical equilibria has been demonstrated. Calculated results agree very well with experiment and show that, in so far as the ratio, Ge/Si, is concerned in MCVD glass, the equilibrium is "frozen" at 1650 K and that satisfactorily consistent thermodynamic data have been selected. The model appears robust and its further application to vapor-phase processes for glass formation is warranted. The procedures applied would also be of use in understanding gas-phase equilibria for other electronic materials, for example, 111-V semiconductors.The primary crystalline phase developed in glass-ceramics in the system Pb0-Ba0-Ti02-B203 was investigated. X-ray diffraction and dilatometry were used to identify the primary phase as essentially pure PbTi03. Peak shifts observed in X-ray diffraction patterns resulted from lattice strain due to crystal clamping, and not from (Pb, Ba)Ti03 solid solution formation. Lattice strain was found to increase as the glass-transition temperature of the residual glass increased above the Curie temperature of PbTi03.

Study of Impedance Spectroscopy of Ferroelectric (Pb Sr)TiO3 Glass Ceramic System with Addition of La2O3

“…Crystallization, microstructure, and dielectric properties of strontium titanate glass ceramics have been widely investigated because of their technological importance [2][3][4][5][6][7]. Glass ceramics containing perovskite titanate phases such as BaTiO 3 [8][9][10], PbTiO 3 [11][12][13], and SrTiO 3 [14] have been extensively investigated for various dielectric applications. These studies reveal that the dielectric properties of glass ceramics are controlled by various factors such as the nature and content of crystalline phases, crystal clamping, and content of the doping.…”

Study of PbTiO3-Based Glass Ceramics Containing SiO2

“…This was of great advantage since according to Lynch and Shelby [9], to avoid the crystal clamping in glass-ceramics it was essential that the glass transition temperature (T g ) of the residual glass must be less than that of curie temperature of the ferroelectric crystal. This helps to prevent the large stresses at crystal glass interface.…”

Ab Initio Prediction of the Stable Polymorphs of 4-amino-3,5-dinitrobenzamide (DOPLOL)

“…It can be seen that the amine, nitro and amide functional groups in the molecules allow the important hydrogen bond linkages with the NH2 groups acting as hydrogen bond donors. The comparison studies carried out using PARST [22] revealed that experimental Form IV and predicted equivalent Str21 were crystallized through the hydrogen bond linkage between the amine and nitro functional groups attached to the central benzene ring [N(2)-H(4)···O (5) …”