CeCl_(3)对工业电解液中钴电沉积层的晶粒细化作用

Grain refinement of cobalt electrodeposited layers in industrial electrolytes by CeCl3

稀土元素具有较强的吸附性,可以提高电沉积过程中的形核率,从而通过阻碍晶粒长大来改善沉积层的微观组织。本文为了研究不同浓度的氯化铈(CeCl_(3))对工业电解液中钴电沉积层的晶粒细化作用,采用普林斯顿电化学工作站,通过阴极极化曲线、循环伏安曲线和计时电流曲线分析不同浓度的CeCl_(3)对钴电结晶行为的影响;利用扫描电子显微镜和原子力显微镜分析沉积层微观组织及粒径尺寸,并通过X射线衍射分析其择优取向和晶体结构。结果表明:工业电解液中添加不同浓度的CeCl_(3)会使得钴的沉积电位发生负移,过电位增大,形核弛豫时间tm缩短,加快了钴电沉积过程的形核速率;但是添加CeCl_(3)并不会改变钴的电结晶形核/生长机制,在峰值电流之前均为三维瞬时形核方式;随沉积时间的延长,形核曲线逐渐偏离三维瞬时形核曲线并趋于稳定,且钴沉积层晶体结构也不会发生改变,仍为密排六方结构(HCP)。当添加0.4 g/L的CeCl_(3)时,晶粒取向由(■)面择优生长转变为(■)和(■)晶面择优生长,沉积层的晶粒分布均匀,晶粒也得到了明显的细化。

Due to the strong adsorption properties of rare earth elements,they can increase the nucleation rate during electrodeposition,thus improve the structure of the deposited layer by hindering grain growth.In this paper,in order to investigate the effect of different concentrations of cerium chloride(CeCl_(3))on the grain refinement of cobalt electrodeposited layers in industrial electrolyte,the effect of different concentrations of CeCl_(3) on the electrocrystallization behavior of cobalt was analyzed by cathodic polarization curves,cyclic voltammetry curves,and timing current curves using Princeton electrochemical workstation;the microscopic morphology and particle size of the deposited layers were analyzed by scanning electron microscopy and atomic force microscopy,and preferred orientation and crystal structure were analyzed by X-ray diffraction.The results show that the addition of different concentrations of CeCl_(3) causes a negative shift in the deposition potential of cobalt in industrial electrolyte,an increase in the overpotential and a shortening of the nucleation relaxation time tm,which accelerate the nucleation rate of the cobalt electrodeposition process.However,the addition of CeCl_(3) does not change the nucleation/growth mechanism of cobalt electrocrystallization,which is a three-dimensional instantaneous nucleation mode before the peak current.With the increase of deposition time,the nucleation curve gradually deviates from the three-dimensional instantaneous nucleation curve and tends to be stable,and the crystal structure of the cobalt deposited layer also does not change,it is still close-packed hexagonal structure(HCP).When 0.4 g/L of CeCl_(3) is added,the grain orientation changes from(■)plane preferred growth to(■)and(■)planes preferred growth,the grain distribution of the deposited layer is uniform,and the grains are also obviously refined.