碳酸钡单晶微米锥阵列在方解石（104）面上的外延生长

摘要

Heteroepitaxial growth of single-crystal ine witherite (BaCO3) microcone arrays on the (104) face of calcite (CaCO3) was realized, by the interface-coupled dissolution-precipitation reaction in water/ethanol at room temperature. The witherite microcone long axis was parallel to the [001] direction of witherite and [001] direction of the calcite substrate. The top of the microcones appeared as uniform tri-symmetrical hexagons while the long axis of the witherite microcones was parallel to the electron beam. The witherite microcones increased in size and decreased in length:diameter ratio with extending crystallization time. The size and morphology of the epitaxially grown witherite could be tuned by changing the water:ethanol volume ratio, or the Ba(NO3)2 concentration of the precursor solution. Increasing the water:ethanol volume ratio or Ba(NO3)2 concentration yielded smal er, denser witherite single-crystal ine microstructures. The witherite microcone arrays were thought to form by the synergetic epitaxial growth of witherite and dissolution of calcite. Carbonate crystals of witherite and calcite contained middle-high misfits on calcite (104) and (001) faces. Witherite microcones may have grown epitaxially on these two calcite faces, according to the Volmer-Weber model.%通过液固界面上的溶解-沉淀耦合反应在Ba(NO3)2乙醇-水溶液中实现了毒重石晶型的碳酸钡在方解石(CaCO3)晶体基底上的外延生长，得到碳酸钡的单晶微米锥阵列。碳酸钡微米锥的长轴平行于毒重石晶体的[001]方向，同时也与方解石基底[001]晶向相同，其俯视图为六边形，具有近似的六方对称性。随反应时间的增加，外延生长形成的碳酸钡微米锥的尺寸增加，但其轴径比逐渐减小。通过改变乙醇-水混合溶剂中的乙醇含量或者Ba(NO3)2浓度也能调控碳酸钡晶体的尺寸和形貌。随着混合溶剂中乙醇含量与Ba(NO3)2浓度的提高，溶液中BaCO3的过饱和度增加，通过外延生长在方解石的(104)表面形成的BaCO3阵列结构的密集程度逐渐增加，尺寸逐渐减小，形貌从微米锥逐渐转变为微米柱状结构。经过对晶化过程及毒重石和方解石晶体结构分析，提出了在方解石表面外延生长形成的毒重石微米锥单晶阵列结构的形成过程机理：该过程为界面溶解-沉淀耦合反应的过程，方解石的溶解和毒重石的外延生长过程同时进行，由于两种晶体在方解石基底的(104)晶面与(001)晶面上具有中高度错配值，毒重石晶体在方解石的这两个晶面上发生Volmer-Weber型的外延生长，逐渐形成在靠近基底处包覆有方解石台阶的毒重石微米锥单晶阵列结构。