VPW: Role of Impurities in Compositional Changes in Copper Sulfides During Anodic Dissolution (Manufacturing Processes)

将制备含有一定量杂质元素的硫化铜合成样品，以研究杂质对这些材料阳极溶解的影响。用电子探针和x射线衍射测定反应前后的样品组成。反应的硫化物圆盘电极将被垂直于暴露的表面，这样成分的变化就可以作为深度、施加电位和反应时间的函数来测量。已知部分反应的硫化铜的组成是施加电位、反应时间和样品来源的函数，并且假设存在与暴露表面距离有关的组成梯度，并且组成也与存在的杂质有关。电化学技术，包括差分电容、电阻率和循环伏安法，将用于表征硫化物的电学性质，并确定参与溶解反应的电活性表面物质。循环伏安图的峰高数据将在一段较长的时间间隔内收集，并进行整合，以确定溶解反应中转移的电子数量是否随时间不变；已知这个量是潜在依赖的。带有可拆卸硫化物盘的旋转环盘电极将用于测量可溶性导电体Cu(I)和Cu（II）的浓度，因此这些物质的形成速度可以与固体中的成分变化和存在的杂质相关联。这种研究工作是为了检查含有一定量的各种杂质的半导体硫化铜的电化学，这在技术上是有意义的，因为在湿法冶金过程中也会发生类似的反应。它之所以具有科学意义，是因为在化学成分发生变化的半导体的电化学动力学方面，很少有研究发表。该项目进一步推进了VPW项目的目标，即通过研究为女性提供在科学或工程领域发展的机会，并通过研究人员在东道国校园中作为榜样的知名度提高，鼓励其他女性在这些领域追求职业。在这个项目中，有助于第二个目标的拟议活动包括：举办研讨会课程，非正式指导主修工程或有意从事该领域职业的女本科生和研究生。

Synthetic samples of copper sulfides will be prepared containing controlled amounts of impurity elements in order to investigate the effects impurities have on the anodic dissolution of these materials. Specimen composition will be determined before and after reaction by electron microprobe and x-ray diffraction. Reacted sulfide disk electrodes will be sectioned normal to the exposed surface so that composition changes can be measured as a function of depth, applied potential, and reaction time. The composition of a partially reacted copper sulfide is know to be a function of applied potential, reaction time, and sample origin, and it is hypothesized that there is a composition gradient with distance from the exposed surface and that the composition is also related to the impurities present. Electrochemical techniques, including differential capacitance, resistivity, and cyclic voltammetry, will be used to characterize the electrical properties of the sulfides and to identify electroactive surface species involved in the dissolution reactions. Peak height data from the cyclic voltammograms will be collected at intervals over an extended period and integrated in order to determine whether the number of electrons transferred in the dissolution reactions is constant over time; this quantity is already know to be potentially dependent. Rotating ring disk electrodes with demountable sulfide disks will be used to measure the concentrations of soluble conducts, Cu(I) and Cu (II), so that the rate of formation of these species can be correlated with composition changes in the solid and with the impurities present. This research effort to examine the electrochemistry of semiconducting copper sulfides which contain controlled amounts of various impurities is of technological interest because of similar reactions occurring in hydrometallurgical processing, and is of scientific interest because little work has been published on the kinetics of the electrochemistry of semiconductors that undergo chemical-composition changes. The project furthers VPW program objectives to provide opportunities for women to advance their careers in science or engineering through research, and to encourage other women to pursue careers in these areas through the investigators' enhanced visibility as role models on the host campuses. In this project, the proposed activities which contribute to the second objective include: conducting a seminar course, and informal mentoring of undergraduate and graduate women students enrolled in engineering or interested in careers in the field.