Glass Formation and Polyamorphism in Rare‐Earth Oxide–Aluminum Oxide Compositions

Abstract

compositions underwent a liquidliquid phase transition which resulted in glasses with a cloudy appearance due to spheroids of one glass in a matrix of a second glass. The two glasses were isocompositional within the limits of experimental error. Clear, brilliant, single-phase glasses were obtained from La 3 Al 5 O 12 , ErLaYAl 5 O 12 , and compositions containing >5 mol% La 2 O 3 substituted for the other rare-earth oxides. Formation of two glasses is attributed to nucleation and growth of the second liquid at a temperature below the equilibrium liquid-liquid transition temperature. Addition of lanthanum depresses the phase transition temperature below the glass transition temperature and the liquidliquid phase transition is not observed. The results are discussed in the context of first-order liquid-liquid phase transitions (polyamorphism) and formation of single-phase glass from liquids that contain a high proportion of 4-coordinate aluminum ions.

Microstructure of rapidly quenched YAG-based glass–ceramics prepared by aerodynamic levitation

“…The optical transparency of the sample increased with increasing glass forming ability because the number of micro-sized crystals, which act as a scattering center to visible light, was diminished. R. Webber et al [13] reported that the addition of the larger lanthanum (La) ion stabilizes the 4-coordinate Al 3+ (AlO 4…”

Fabrication of transparent ceramics through melt solidification of near eutectic compositions in HfO2–Al2O3–GdAlO3 system

“…Thus, the eutectic or near eutectic compositions would give amorphous phase by rapid cooling (quenching). There exist no data in the system Al 2 O 3 -GdAlO 3 as far as we know, but Weber et al [19][20][21] reported amorphous formation in the system Al 2 O 3 -Y 2 O 3 by rapid quenching.…”

Fabrication of transparent LaAlO3/t-ZrO2 nanoceramics through controlled amorphous crystallization

“…21 In this study, the melting point of the ALZ system reached 1665 • C. 22 Although the flame spray process provided a high temperature up to 3200 • C, only the smaller particles could be heated to a temperature above the melting point during the supersonic spray process. As shown in Fig.…”