High Temperature Hydro Thermal Synthesis and Crystal Growth of Inorganic Oxides

技术概述：这项新提案概述了利用水热法探索新材料类别的计划，特别强调极难熔氧化物。水热法在极高的温度和压力下使用水，已被证明是一种制备各种无机材料作为高质量单晶的优秀技术。克莱姆森开发的技术可以在更高的温度（750°C）下与更强的浓缩矿化剂（例如25m氢氧化物或卤化物）进行反应，这比以前在这些实验室的任何工作都要高。这些条件使合成和良好的晶体生长的化学系统，迄今为止太惰性或耐火，否则是不可接近的。要研究的固体的具体类别有：1)宽禁带氧化物，特别是s块金属硼酸盐和铍酸盐；2)超难熔氧化物，如半酸盐、钍酸盐和钇酸盐；3)用于中子衍射研究的大单晶铁磁氧化物。我们将系统地探讨每一类材料的基本反应化学。在所有情况下，单晶都是目标。我们的晶体生长可以分为三大类，即足够大的晶体用于单晶衍射（0.3mm），足够大的晶体用于单晶磁性和压电表征（1-2mm），以及足够大的晶体用于光学器件表征（1cm）。每种尺寸体系都将采用适当的水热生长方法。例如，对于在深紫外光学应用中使用的宽带隙氧化物，在原型光学器件中需要1厘米/边的单晶进行表征。相比之下，在附近的橡树岭散裂中子源上为单晶磁性结构专门生长的铁磁体，每条边需要1-2毫米的单晶。非技术总结：这项工作将采用一种相对模糊的技术来生长固体单晶，否则很难研究。固体晶体将在许多先进技术中得到应用，特别是激光、先进光学、磁性材料和传感器。晶体生长领域几乎已经从美国大学的研究项目中消失了。这一缺点造成了陆上材料科学能力技能的重大差距。有大量证据表明，这一缺陷正在对关键材料的国家竞争力产生重大影响。此外，这一缺点对学生的研究能力也有很大的负面影响。这对科学研究是有害的，对学生来说是令人沮丧的。理性和系统地培养足够大小和质量的晶体以进行物理性质评估的能力，会显著提高学生发展的广度。这项工作通常会产生专利，由此产生的商业应用为学生提供了一个重要的视角，他们因此可以更好地准备对实验设计做出更好的决定。最后，这项技术非常“绿色”，这提高了学生对他们的科学的社会影响的认识。

TECHNICAL SUMMARY: This new proposal outlines plans to exploit the hydrothermal method to explore new categories of materials with particular emphasis on extremely refractory oxides. The hydrothermal method employs water at extremely high temperatures and pressures and has proven to be an excellent technique for the preparation of a wide variety of inorganic materials as high quality single crystals. Technology was developed at Clemson to do reactions at substantially higher temperatures (750¢ªC) with more powerful and concentrated mineralizers (e.g.25M hydroxide or halide) than any previously work in these labs. These conditions enable synthesis and good crystal growth on chemical systems heretofore too inert or refractory to be otherwise accessible. The specific categories of solids to be investigated are; 1) wide bandgap oxides, specifically the s block metal borates and beryllates; 2) ultrarefractory oxides like hafnates, thorates and yttrates; and 3) large single crystal ferromagnetic oxides for neutron diffraction study. The fundamental reaction chemistry will be systematically explored for each class of materials. Single crystals will be targeted in all cases. Our crystal growth can be divided into three broad regimes, namely crystals large enough for single crystal diffraction (0.3mm), crystals large enough for single crystal magnetic and piezoelectric characterization (1-2mm), and crystals large enough for optical device characterization (1cm). Each of these size regimes will employ an appropriate hydrothermal growth method. For example, for wide bandgap oxides to find use in deep UV optical applications, single crystals of 1 cm/edge will be required for characterization in prototype optical devices. In contrast, ferrimagnets specifically grown for single crystal magnetic structures on the nearby Oak Ridge Spallation Neutron Source will require single crystal 1-2 mm per edge.NON-TECHNICAL SUMMARY: This work will employ a relatively obscure technology to grow single crystals of solids that are otherwise difficult to study. The solid crystals will have applications in many advanced technologies, especially lasers, advanced optics, magnetic materials and sensors. The field of crystal growth has all but disappeared from university research programs in the United States. This shortcoming has created a major gap in the skill set of onshore materials science capabilities. There is substantial evidence that this shortcoming is having a significant impact on national competitiveness in key materials. Furthermore this shortcoming has a significant negative impact on the students¡¯ research abilities. This is detrimental to scientific research and discouraging to students. A rational and systematic ability to grow crystals of sufficient size and quality for physical property evaluation leads to a dramatic improvement in the breadth of student development. Often patents result from this work and the resultant commercial application provides an important perspective to the students who are much thus better prepared to make better decisions about experimental design. Finally the technology is very ¡°green¡±, which raises the awareness of the students to societal impact of their science.