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The normal growth rate R , hillock slope p and step velocity v = R / p of spiral growth hillocks on the (1 1 1) face of a Sr(NO 3 ) 2 crystal growing in aqueous solutions were measured as a function of supersaturation σ for various growth temperatures T g by in situ Michelson interferometry. At given temperatures, p and v increased linearly with σ and, thus, R was proportional to σ 2 in the supersaturation range σ = 0.40 – 3.0 % . Based on these data, the step free energy α s and the step kinetic coefficient β s were calculated. In the temperature range T g = 10.5 – 37.3 ° C , the step free energy was almost constant. By assuming that growth hillocks consist of single-, double- and triple-arm spiral steps, the values of step free energy were estimated to be α s = 4.0 , 8.0 and 12 mJ/m 2 , respectively. Meanwhile, the coefficient β s increased exponentially with temperature. An Arrhenius plot showed a linear dependence of ln β s on 1 / T g in the temperature range studied, from which the activation energy of step advance was estimated as E = 53 kJ / mol . |
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