Studies on etching kinetics and assessment of defects in flux grown ErAlO3crystals

Surface structural studies on as-obtained Bur 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, iso lated and crowded etch pits on as-grown surfaces are attributed to the clea ning process used to remove flux from the crystal surfaces. Etching experim ents are performed on(110). ((1) over bar 10) and (001) surfaces of ErAlO3 crystals at different temperatures viz., 170, 190, 210, 230 and 250 degrees C. Dislocation etching kinetics of the H3PO4 ErAlO3 surface system are inv estigated. It is shown that phosphoric acid in the temperature range 170-25 0 degrees C is a dislocation etchant suitable for all the three surfaces. T he chemical reactivity of H3PO4 with ErAlO3 surfaces in the temperature ran ge 170-250 degrees C does not lead to passivity unlike in the case of HNO3- LaAlO3 surface system as reported in the literature. The defect structure i n ErAlO3 crystals as delineated by H3PO4 etchant includes impurity sites, d islocations, low angle tilt boundaries and twinning. The activation energie s and Arrhenius factor for dissolution parallel and perpendicular to the su rfaces are estimated. (C) 2000 Elsevier Science S.A. All rights reserved.