Thermodynamic Modeling of Phase Diagrams in Binary Alkali Silicate Systems

Abstract

A thermodynamic modeling of phase diagrams in binary alkali silicate systems is described by using the Gibbs free energy of the phases. Simple models employing regular, quasi-regular, and subregular solution models were applied to describe the liquid phase. The interaction parameters of the liquid phases were obtained by using the liquidus curves of silica (and subliquidus data) through a multiple linear regression method. The present calculated liquidus curves agree very well with CszO-SiOz and RbzO-SiOz systems. In the KzO-, NazO-, and LizO-SiOz systems, the calculations permitted discrimination between sets of data and, based upon the calculation choices, could be correctly made to select the most appropriate phase diagram. Also, the spinodals were calculated where phase separation can occur by a spinodal decomposition process. [

Effect of LiYO2 on the synthesis and pressureless sintering of Y2SiO5

“…2(a)] show liquid-phase formation at 980°C, which was slightly lower than that reported in Ref. 16. This liquid phase was aroused by LiYO 2 and should be a Li-Si-Y-O phase.…”

“…In this paper, we successfully obtained single-phase Y 2 SiO 5 powders utilizing a novel solid-liquid reaction As reported in previous work by Kim et al, at 1225°C, LiYO 2 and SiO 2 could form a liquid phase, 16 which would act as a "molten pool" and allow for rapid transportation of various substances. The DSC results [ Fig.…”

Pressureless sintering of silicon nitride with lithia and yttria

“…11,12 In the Li 2 O-Y 2 O 3 system the lowest liquidus temperature is 1350 C. 13 The low melting point in the Li 2 O-SiO 2 system leads to the formation of a Li 2 O-rich liquid in M1 materials, locally enhancing the densification before Y 2 O 3 undergoes melting. This promotes differential sintering.…”

Thermodynamic Assessment of the Miscibility Gaps and the Metastable Liquidi in the B2O3–RO Systems (R = Mg, Ca, Sr, and Ba)

“…Using experimental liquid miscibility data, the interaction parameters in Eqs. (10a,b) can be optimized through a multiple linear regression method 18,19,[25][26][27][28] , which is based on least squares. And then the metastable liquidus as well as the equilibrium miscibility gap can be assessed as a function of temperature and composition.…”