Anomalous patterns of Saffman–Taylor fingering instability during a metastable phase separation

A phase separation is important in biology, biochemistry, industry, and other areas, and is divided into two types: a spinodal decomposition type and a nucleation and growth type. It has...

Thermodynamic Prediction of Spinodal Decomposition in Multi-component Silicate Glass for Design of Functional Porous Glass Materials

The authors have investigated metastable phase separation in multi-component silicate glass for the fabrication of porous glass from multi-component slag. Spinodal decomposition forms an interconnected microstructure in glass spontaneously, and porous glass is obtained by leaching one of the decomposed phases with an acid solution. This porous glass can be used for a filter to remove impurities in polluted water or air. In this study, the metastable miscibility gap was predicted in multi-component silicate glass using thermodynamic analyses where glass was regarded as a super-cooled liquid phase. Occurrence of spinodal decomposition was observed in annealed glass, and it corresponded to the predicted miscibility gap. Then, we fabricated porous glass using spinodal decomposition in multi-component borosilicate glass and by removing one of the decomposed phases. Furthermore, for the creation of functional porous glass applicable for environmental purification, the spinodal decomposition was prepared in multi-component borosilicate glass containing titanium oxide based on the predicted metastable miscibility gap in multi-component silicate glass.

Estimation of phase separation rates of PbO–B2O3 melts

The rate of liquid-liquid phase separation was experimentally studied in the PbO-B2O3 system. The in situ measurements were made by observing the melts with a videocamera continuously as the melts were cooled down from homogenization temperatures at a rate of 2.5 °C/min. The time interval between the beginning and the completion of the darkening of the visual field was determined as a measure of the separation rate. The phase-separation rate was estimated to be at least 900 times larger than that of the metastable phase separation below the liquidus.

Kinetics of Phase Separation in Lithium Bearing HLW Alkaliborosilicate Glasses

A TEM study on the kinetics of metastable phase separation in a lithium bearing HLW glass frit is presented. As nothing was known about the kinetics of metastable phase separation below the glass transformation temperature we had to carry out annealing experiments just above and below the transformation temperature, in order to achieve phase separation on a laboratory time scale- Particle growth in the WAKID5 HLW glass frit at 550 °C occurs by a diffusion controlled Ostwald ripening process (about 40 °C above Tg). Metastable phase separation in the lithium bearing glasses even at lower temperatures cannot be excluded from the present study. In NaBSi3O8 glass (Tg ≈ 580 °C) phase separation could be detected at 500 °C well below Tg after about 160 days.