过饱和度对KDP晶体生长及表面形貌的影响

Influence of Supersaturation on Growth and Surface Morphology of Potassium Dihydrogen Phosphate Crystals

采用原子力显微镜对35℃附近,在不同过饱和度下生长的KDP晶体(100)面生长台阶的推移进行了系统的研究,用激光偏振干涉手段实时测量了KDP晶体(100)面的台阶推移速率与过饱和度之间的关系。结果表明:台阶的推移速率ν随过饱度σ的增加而增大,过饱和度死区σ_d和线性区σ*的值分别为0.018和0.033。当σ=0.07时,晶体推移速率ν增加变缓,进入延长线通过原点的线性区。台阶宽度随σ的增加呈现出先增大后降低的趋势,当σ=0.01、0.05和0.08时,台阶聚并程度和斜率都高;当σ=0.08时,晶体表面出现树枝状支台阶。在不同过饱和度区间内台阶推移方式发生的变化可能是影响台阶聚并程度和推移速率的原因。

The surface morphology of potassium dihydrogen phosphate （KDP） crystals grown at different supersaturation （σ） values and 35 ℃ was investigated by atomic force microscopy. The prismatic faces growth rate （v） of KDP crystal was measured by laser polarization interference system. The results show that the step speed increases with the increase of supersaturation value, and the values of supersaturation dead zone （σd） and linear zone （σ^＊） are 0.018 and 0.033, respectively. At a greater supersaturation value （σ=0.07）, the increase amplitude of the speed reduces, and the dependence v（σ） becomes a straight line through the origin. In addition, the step width first increases and then decreases with the increase of supersaturation value. The step bunching and slope both are great as σ=0.01, 0.05 and 0.08. The dendritic branch step appears on the crystal surface as σ=0.08. At different supersaturation values, the variation of steps evolution way may cause considerable step bunching and velocity variation.