NSF-Germany Materials Collaboration: Defects and Orientation-Dependent Transport in Orthosilicates

NSF-德国材料合作：原硅酸盐中的缺陷和方向相关的传输

• 批准号: 0502728
• 负责人: Ruediger Dieckmann
• 金额: --
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-08-15 至 2011-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0502728&HistoricalAwards=false
• 关键词: NSF; Germany; Materials; Collaboration; Defects

Orthosilicates of the type Me2SiO4+d with Me = Co, Mn and Ni are solids which crystallize in the olivine structure. This structure has a very significant lattice anisotropy, which causes a large orientation-dependence of the transport of matter and charge. Details on this subject are known so far only for the iron silicate fayalite. The observed orientation dependences for fayalite are among the largest so far known for non-layered crystal structures. A completely open question is how the replacement of Fe by Co, Mn and Ni will influence the orientation dependence of the transport of matter and charge. This question will be systematically investigated for the transport of matter and charge in orthosilicates of the type Me2SiO4+d with Me = Co, Mn and Ni. The research will be performed in an international collaboration with the group of Klaus-Dieter Becker at the Technical University of Braunschweig (Germany). The emphasis at Cornell will be to establish the crystal orientation and oxygen activity dependence of tracer diffusion coefficients of the cations. Complementary studies of the electrical conductivity and on the kinetics of the reequilibration after oxygen activity jumps will be performed in Germany. In addition, to allow modeling of the observed oxygen activity dependences, thermogravimetric studies will be performed at Cornell University whenever necessary. To enable the proposed studies of the orientation dependence, single crystal growth will be performed at Cornell by using the floating zone method. The program will provide training at the graduate and undergraduate level and will also provide experiences in international collaboration.The results of this fundamental research will very significantly improve the basic understanding of transport of matter and charge in an important class of materials, which crystallize in the olivine structure. For example, in the applied geosciences, olivine structure minerals are common materials in the upper mantle of the Earth. An improved knowledge of this type of materials will aid to better understand the history of the Earth. On the other hand, lithium iron phosphate is an olivine structure material with a very high electrical conduction, making it a promising candidate for being used as the cathode in lithium batteries. Therefore, the field of solid-state electrochemistry and others will also benefit from this research program. This broad relevance clearly justifies public support of the proposed research. The research will focus on the transport of matter and charge in orthosilicates with the olivine structure and will include the growth of single crystals and measurements related to the transport of cations and of electrical charge. Due to its collaborative nature, the program involves an exchange of graduate students between the Technical University of Braunschweig (Germany) and Cornell University. In addition, there will be significant research experiences for undergraduates. Outreach to local schools and to other institutions will continue.

Me = Co、Mn和Ni的Me 2SiO 4 +d型正硅酸盐是以橄榄石结构结晶的固体。这种结构具有非常显著的晶格各向异性，这导致物质和电荷的输运具有很大的取向依赖性。关于这一主题的详细资料迄今为止只知道铁硅酸盐fayalite。所观察到的取向依赖性fayalite是迄今为止已知的最大的非层状晶体结构。一个完全开放的问题是如何取代Fe的Co，Mn和Ni将影响的物质和电荷的传输的取向依赖性。这个问题将被系统地研究的物质和电荷的正硅酸盐的类型Me_2SiO_4 +d与Me = Co，Mn和Ni的传输。该研究将与布伦瑞克技术大学（德国）的Klaus-Dieter Becker小组进行国际合作。康奈尔大学的重点将是建立阳离子示踪剂扩散系数的晶体取向和氧活度依赖性。 将在德国进行电导率和氧活度跳跃后再平衡动力学的补充研究。此外，为了对观察到的氧活度依赖性进行建模，必要时将在康奈尔大学进行热重研究。为了使所提出的取向依赖性的研究，单晶生长将在康奈尔大学通过使用浮区法进行。该计划将提供研究生和本科生水平的培训，并将提供国际合作的经验。这项基础研究的结果将非常显着地提高对橄榄石结构中结晶的重要一类材料中物质和电荷输运的基本理解。例如，在应用地球科学中，橄榄石结构矿物是地球上地幔中常见的物质。对这类材料的进一步了解将有助于更好地了解地球的历史。另一方面，磷酸铁锂是具有非常高的导电性的橄榄石结构材料，使其成为锂电池中用作阴极的有希望的候选者。因此，固态电化学和其他领域也将受益于该研究计划。这种广泛的相关性显然证明了公众对拟议研究的支持。研究将侧重于橄榄石结构正硅酸盐中物质和电荷的传输，并将包括单晶的生长以及与阳离子和电荷传输有关的测量。由于其合作性质，该计划涉及布伦瑞克技术大学（德国）和康奈尔大学之间的研究生交流。此外，还将为本科生提供重要的研究经验。将继续与当地学校和其他机构开展外联活动。