Microscopic Structure Studies to understand the Thermal Stability of Amorphous Copper-Telluride-Phases

通过微观结构研究了解非晶碲化铜相的热稳定性

• 批准号: 453205576
• 负责人: Professor Dr. Wolf-Christian Pilgrim
• 金额: --
• 依托单位: Fachgebiet Physikalische Chemie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/453205576?language=en
• 关键词: Microscopic; Structure; Studies; understand; Thermal

Two different groups of amorphous Ge-Cu-Tellurides (GCT) are currently regarded to comprise great potential for possible technical applications. While compositions Cux+yGe20 xTe80-y (0≤x≤20, 0≤y≤10) show excellent thermoelectric properties, mixtures on the (FeTe) – (CuTe) quasi-binary line in the GCT-phase diagram, were identified as Phase-Change-Materials (PCM) and are candidates for non-volatile digital data storage-applications. These two material groups are located relatively close to each other in the GCT phase diagram yet, a fundamentally different thermal stability is observed with varying Cu-concentration. While the crystallization temperature of the thermoelectric materials (TE) drops strongly when Copper is constantly added, a significant rise is observed in the PCMs up to relative high Cu-concentrations, where it finally starts dropping however remaining always above the TE-values. Especially for the TE-systems a high crystallization temperature, implying high thermal stability, would be desirable for their use in technical applications. The origin for this different behavior is yet unidentified. More generally, the reasons determining crystallization temperature and related thermal stability in multi component glasses in general are still widely unknown although such an understanding is highly desired for the thermal optimization of technical glasses.Only one structural study yet exists for each of the systems, both carried out with EXAFS, at completely different Cu-concentrations. Only information about the chemical short range order was obtained and no notable cognition on the thermal stability or other physical properties was acquired. In the requested project we would like to systematically study the variation of the microscopic structure of both systems with rising Cu-content to identify the structural origin for the different stability behavior. For this we will us Anomalous X-ray scattering (AXS) combined with Reverse Monte Carlo simulations, which allows to gain atom-specific structural information on the chemical short range order but also on larger length scales. This allows characterizing structural correlations between chemically ordered short range structures. It will be investigated if such structural correlations, or even more specific the resulting similarities to the corresponding crystal phase, affects the stabilities of the amorphous phases. This is indicated by results obtained from a preceding study on amorphous Ge-Sb-Te-compositions. It would be an important first step towards a universal understanding of the thermal stability in amorphous multi component systems if such a relation could be verified and therefore also highly important for directed progress in the development of new amorphous materials.

两类不同的非晶锗铜碲化物（GCT）目前被认为具有很大的技术应用潜力。虽然组合物Cux+ yGe 20 xTe 80-y（0≤x≤20，0≤y≤10）显示出优异的热电性能，但在GCT相图中的（FeTe）-（CuTe）准二元线上的混合物被识别为相变材料（PCM），并且是非易失性数字数据存储应用的候选者。这两种材料组在GCT相图中彼此相对接近，但随着Cu浓度的变化，观察到根本不同的热稳定性。虽然热电材料（TE）的结晶温度在不断添加铜时强烈下降，但在PCM中观察到显著上升直到相对高的Cu浓度，其中其最终开始下降，但始终保持在TE值以上。特别是对于TE体系，高的结晶温度，意味着高的热稳定性，对于它们在技术应用中的使用是期望的。这种不同行为的起源尚未确定。更一般地说，决定多组分玻璃中结晶温度和相关热稳定性的原因通常仍然是未知的，尽管这种理解对于技术玻璃的热优化是高度期望的。对于每个系统，只有一个结构研究还存在，都是在完全不同的Cu浓度下进行的。仅获得了关于化学短程有序的信息，并且没有获得关于热稳定性或其他物理性质的显著认识。在所要求的项目中，我们希望系统地研究两个系统的微观结构随Cu含量增加的变化，以确定不同稳定性行为的结构起源。 为此，我们将使用异常X射线散射（AXS）与反向蒙特卡罗模拟相结合，它允许获得化学短程有序的原子特定结构信息，但也可以在更大的长度尺度上。这允许表征化学有序的短程结构之间的结构相关性。它将被调查，如果这种结构的相关性，或甚至更具体的相应的晶体相的相似性，影响的非晶相的稳定性。这是由先前对非晶Ge-Sb-Te组合物的研究所获得的结果所表明的。如果这种关系能够得到验证，这将是普遍理解非晶多组分体系热稳定性的重要第一步，因此对于新型非晶材料开发的直接进展也非常重要。