BaMoO_4薄膜在电化学法制备中生长基元的实验研究

Experimental researches on the growth unit of BaMoO_4 thin film deposited by electrochemical method

在采用恒电流电化学技术研究BaMoO4薄膜的初期生长特性实验中,发现了若干很重要的实验现象:薄膜生长初期形成的晶核首先具有白钨矿结构的骨架;晶核和刚开始长大生成的晶粒都是疏松的,晶粒都明显显示有蜂窝状空隙存在;随着制备时间的增加,白钨矿结构骨架原先疏松的程度逐渐减弱,经过一定时间,晶粒趋于饱满,晶粒表面基本光滑;在薄膜形成的过程中,新生成的晶核也具有类似情况。结合BaMoO4薄膜电化学制备机制分析,作者认为:利用电化学技术制备BaMoO4晶态薄膜时,在生长初期基体Mo以[MoO4]2-的形式构成负离子配位多面体生长基元,这些生长基元优先选择在基体缺陷处作为白钨矿结构的晶核堆砌和生长,并进而与溶液中的[Ba]2+相连接,键合成BaMoO4晶粒,再逐渐长大。显然,该发现和研究对于丰富晶体生长动力学知识及指导利用电化学技术制备晶态薄膜都具有重要意义。

In the research experiments on the early growth characteristics of BaMoO4 thin film deposited by constant-current electrochemical technique, some important experimental phenomena were discovered. They are mainly as follows： the crystalline nucleuses formed at the initial stage of the film growth possess the skeleton of the scheelite-structure; the crystalline nucleuses and the crystal granules which are just growing up are all porous, and the crystalline granules have the interstices of the beehive form obviously; along with the increase of growing time, the porous degree of the scheelite-structure framework is dieing down gradually, and the crystalline granules tend to become full and the surfaces of the crystalline granules tend to become smooth for certain time; and the crystalline nucleuses that are just growing up also have the similar characteristic in the process of film growth. From the growing mechanism analysis of BaMoO4 thin film prepared by electrochemical technique, it is considered that at the early stage of film growth the Mo atoms of the substrate make up the polyhedron growth units with the form of [MoO4]^2- through electrochemical reaction; the places where these units pile up and grow prior are those of the defects at the substrate to form the crystalline nucleus with scheelite-structure, and then the growth units combine with [Ba]^2＋ in solution to synthesize BaMoO4 crystalline granules, and afterwards the granules grow up gradually. Obviously, these findings will enrich the knowledge of crystal growth dynamics and conduct the experiments of thin film growth by using electrochemical technique.