Title: Crystallisation surface microtopography of [1120]- direction growth sapphire crystal

Authors: Lunyong Zhang; Hongbo Zuo; Fuyang Cao; Xiaohong Wang; Dawei Xing; Jicai Han; Jianfei Sun

Addresses: School of Materials Science and Engineering, Harbin Institute of Technology, Harbin, 150001, China ' Center for Composite Materials, Harbin Institute of Technology, Harbin, 150001, China ' School of Materials Science and Engineering, Harbin Institute of Technology, Harbin, 150001, China ' Center for Composite Materials, Harbin Institute of Technology, Harbin, 150001, China; Harbin Aircraft Industry Group Co. Ltd., Harbin, 150066, China ' School of Materials Science and Engineering, Harbin Institute of Technology, Harbin, 150001, China ' Center for Composite Materials, Harbin Institute of Technology, Harbin, 150001, China ' School of Materials Science and Engineering, Harbin Institute of Technology, Harbin, 150001, China

Abstract: Observations of the microtopography evolution on a crystallisation surface of sapphire crystal grown from Al2O3 melt show the smooth region was formed by thin atomic layers with wave-like edge trace and the rough region was mainly of aligning long bar-like structure formed by many spiral hillocks spreaded along lines corresponding to the direction [8803]. Moreover, decreasing the undercooling would enhance the width of the bars and decrease the width of the grooves adjacent the bars. According to these observations, the growth mechanism of the smooth region is believed to be the 2D nucleation mechanism and that of the rough region is the spiral growth mechanism. Consequently, a conclusion was drew that the controlling growth mechanism of sapphire crystal grown from melt through SAPMAC method is 2D nucleation mechanism.

Keywords: crystallisation surface; melt growth; sapphire crystals; surface microtopography; undercooling; 2D nucleation; spiral growth; alumina melt.

DOI: 10.1504/IJSURFSE.2013.051913

International Journal of Surface Science and Engineering, 2013 Vol.7 No.1, pp.1 - 13

Available online: 05 Feb 2013 *

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