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Effect of pH value on the growth morphology of KH 2 PO 4 crystal grown in defined crystallographic direction
Author(s) -
Liu Fafu,
Lisong Zhang,
Yu Guangwei,
Sun Xun
Publication year - 2015
Publication title -
crystal research and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.377
H-Index - 64
eISSN - 1521-4079
pISSN - 0232-1300
DOI - 10.1002/crat.201400304
Subject(s) - supersaturation , nucleation , crystallography , chemistry , morphology (biology) , aqueous solution , crystal growth , crystal (programming language) , atomic force microscopy , nucleus , trigonal crystal system , crystal structure , materials science , nanotechnology , computer science , programming language , genetics , organic chemistry , microbiology and biotechnology , biology
KH 2 PO 4 single crystals were grown in aqueous solution at different pH values by using “point seeds” with a defined crystallographic direction at 59 degree to the Z axis. Atomic Force Microscope (AFM) was applied to observe the surface morphology of (100) face. It was found that at the same supersaturation, the larger steps appeared at the lower pH value before appearance of 2D nucleus. We found that 2D nucleus was occurred at σ ≤ 0.04 when pH value is <2.8. The occurrence of 2D nucleus was caused by the decreasing step‐edge free energy with the decreasing of pH value in the growth solution. In this paper, we observed the morphologies of (100) faces of KDP crystals which grew in solutions with different pH values. 2D nucleuses appeared on the terrace of growth steps when pH value down to 2.8 and 3.2 at supersaturation of 0.04, while pH value down to 2.4, only 2D nucleation control the growth. Therefore, the pH value can change the growth mechanism of KDP crystals.