Phase-change sintering of BaCl2 transparent ceramics

We report on the compaction of anhydrous BaCl2 powders under severe plastic deformation and the conversion of their native orthorhombic cotunnite crystalline structure into a fine-grained cubic fluorite structure. This conversion, supported by x-ray diffraction and transmission electron microscopy data, and which enables the production of highly dense ceramics of BaCl2, occurs 500 degrees C below the known phase transition temperature of 925 degrees C for this material at 1 atm. We discuss this phase change in the context of a stress-induced polymorphic transformation and its implication on the fabrication of transparent ceramics for scintillator applications. (C) 2017 Elsevier B.V. All rights reserved.