Studies on etching kinetics and assessment of defects in flux grown ErAlO3 crystals

• Published in: Materials chemistry and physics 2000-02, Vol.62 (3), p.214-225
• Main Authors: Bamzai, K.K., Dhar, P.R., Kotru, P.N., Wanklyn, B.M.
• Format: Article
• Language: English
• Subjects: Cross-disciplinary physics: materials science; rheology; Defect; Erbium Aluminate crystal; Etching kinetics; Exact sciences and technology; Flux growth; Growth from melts; zone melting and refining; Materials science; Methods of crystal growth; physics of crystal growth; Physics
• ISSN: 0254-0584; 1879-3312
• DOI: 10.1016/S0254-0584(99)00192-3

Surface structural studies on as-obtained flux grown crystals of ErAlO3 are reported. As grown surfaces of these crystals reveal formation of microdisc elevations and etch pits. The etch patterns in the form of microdiscs, isolated and crowded etch pits on as-grown surfaces are attributed to the cleaning process used to remove flux from the crystal surfaces. Etching experiments are performed on (110), (1̄10) and (001) surfaces of ErAlO3 crystals at different temperatures viz., 170, 190, 210, 230 and 250°C. Dislocation etching kinetics of the H3PO4 ErAlO3 surface system are investigated. It is shown that phosphoric acid in the temperature range 170–250°C is a dislocation etchant suitable for all the three surfaces. The chemical reactivity of H3PO4 with ErAlO3 surfaces in the temperature range 170–250°C does not lead to passivity unlike in the case of HNO3–LaAlO3 surface system as reported in the literature. The defect structure in ErAlO3 crystals as delineated by H3PO4 etchant includes impurity sites, dislocations, low angle tilt boundaries and twinning. The activation energies and Arrhenius factor for dissolution parallel and perpendicular to the surfaces are estimated.