Recent development of A ₂B ₂O ₇ system transparent ceramics

Abstract

A ₂B ₂O ₇ system compounds, which usually present three phase structures mainly based on the ionic radius ratios of r _A and r _B ( r _A/ r _B), have been studied for potential applications in many fields, such as thermal barrier coatings, luminescence powders, fast-ion conductors, photocatalysts, and matrices for immobilization of highly active radionuclides. Since 2005, La ₂Hf ₂O ₇ was fabricated into transparent ceramics and much more attentions were paid on A ₂B ₂O ₇ transparent ceramics for new applications. In this review, the development of A ₂B ₂O ₇ system transparent ceramics was described. The structure characteristics, powder synthesis method, and sintering techniques of the final A ₂B ₂O ₇ transparent ceramics were summarized. After that, the mostly reported A ₂Hf ₂O ₇, A ₂Zr ₂O ₇, and A ₂Ti ₂O ₇ system transparent ceramics were systematically introduced. The potential application fields and future development trends were also discussed, focusing on scintillators, optical elements, and other luminescent materials.