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Experimental investigations on the extreme, pressure-induced stiffening of smart and phase change materials

智能相变材料极端压力诱导硬化的实验研究

基本信息

批准号：
202555040
负责人：
Professor Dr. Martin Müser
金额：
--
依托单位：
Lehrstuhl für Materialsimulation
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2011
资助国家：
德国
起止时间：
2010-12-31 至 2016-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/202555040?language=en
关键词：
Experimental investigations extreme pressure induced

项目摘要

The rate at which the stiffness of some materials increases with pressure can exceed that of regular crystals by more than a factor of ten. An example is the quasi-linear increase of the bulk modulus of hydrogenated zinc phosphates with pressure from 30 GPa at ambient conditions to 280 GPa at 5 GPa. Materials with the ability to adjust their response functions to an external stimulus in this or related ways have been coined “smart”. In the present context they prove useful when used as anti-wear coatings on rubbing surfaces. Sometimes, however, materials soften under compression, such as CrN, which reduces its bulk modulus by 25% in the denser phase. As of now, no general guidelines are known what factors influence the way in which the stiffness of a material changes in response to pressure, because most investigations are material specific. In our research we would like to explore the hypothesis that a change in symmetry drives the stiffness change, specifically that high symmetry implies stiff irrespective of the density. This simple behavior may often be suppressed by a bi-linear coupling between strain and the relevant order parameter. Understanding the connection between symmetry and stiffness will allow us to identify desired ingredients for new coating materials. A peculiarity of our research will be that we will investigate the coupling of the strain not only to displacive modes but also to the electronic structure. This analysis allows us to explore the possibility of designing materials that can be switched reversibly by stress between a semi-conducting and a semi-metallic phase. In order to validate our research hypothesis and to construct Landau theories for specific materials, we plan on conducting high-pressure experiments incl. in situ structure analysis of a large variety of compounds including metal phosphates as well as doped and oxidized solids formed by group 15 elements.

某些材料的刚度随压力增加的速率可以超过规则晶体的十倍以上。一个例子是氢化磷酸锌的体积模量随着压力从环境条件下的30 GPa到5 GPa下的280 GPa的准线性增加。具有以这种或相关方式调整其对外部刺激的反应功能的能力的材料被创造为“智能”。在本发明的上下文中，当用作摩擦表面上的抗磨涂层时，它们被证明是有用的。然而，有时材料在压缩下会软化，例如CrN，这会使其在致密相中的体积模量降低25%。到目前为止，还不知道什么因素会影响材料刚度随压力变化的方式，因为大多数研究都是针对材料的。在我们的研究中，我们想探索对称性的变化驱动刚度变化的假设，特别是高对称性意味着刚性与密度无关。这种简单的行为通常可以通过应变和相关序参量之间的双线性耦合来抑制。了解对称性和刚度之间的联系将使我们能够确定新涂层材料所需的成分。我们的研究的一个特点将是，我们将调查的耦合应变不仅位移模式，而且电子结构。这种分析使我们能够探索设计材料的可能性，这些材料可以通过应力在半导体和半金属相之间可逆地切换。为了验证我们的研究假设，并构建特定材料的朗道理论，我们计划进行高压实验，包括。包括金属磷酸盐以及由第15族元素形成的掺杂和氧化固体在内的多种化合物的原位结构分析。