High Temperature Hydro Thermal Synthesis and Crystal Growth of Inorganic Oxides

技术概要：这项新提案概述了利用水热方法探索新材料类别的计划，特别强调了极难熔氧化物。水热法在极高的温度和压力下使用水，并且已被证明是用于制备多种无机材料作为高质量单晶的优异技术。在克莱姆森开发的技术是在比这些实验室以前的任何工作都更高的温度（750 ℃）下用更强大和更浓缩的矿化剂（例如25 M氢氧化物或卤化物）进行反应。这些条件使得能够在迄今为止太惰性或难熔而不能以其他方式获得的化学体系上进行合成和良好的晶体生长。要研究的固体的具体类别是：1）宽带隙氧化物，特别是s块金属硼酸盐和铍酸盐; 2）超难熔氧化物，如铌酸盐，钍酸盐和钇;和3）用于中子衍射研究的大单晶铁磁氧化物。基本反应化学将系统地探讨每一类材料。在所有情况下，目标都是单晶。我们的晶体生长可以分为三个广泛的制度，即晶体大到足以单晶衍射（0.3毫米），晶体大到足以单晶磁性和压电表征（1- 2毫米），晶体大到足以光学器件表征（1厘米）。这些尺寸范围中的每一个将采用适当的水热生长方法。例如，对于要在深紫外光学应用中使用的宽带隙氧化物，将需要1 cm/边的单晶用于原型光学器件的表征。相比之下，在附近的橡树岭斯普林中子源上专门为单晶磁性结构生长的亚铁磁体将需要每边1-2 mm的单晶。非技术摘要：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的大学研究计划中消失了。这一缺陷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，这一缺陷对学生的研究能力有很大的负面影响。这不利于科学研究，也不利于学生。一个合理的和系统的能力，生长足够的大小和质量的晶体物理性能评估导致学生发展的广度显着改善。通常专利来自这项工作，由此产生的商业应用为学生提供了一个重要的视角，从而更好地准备对实验设计做出更好的决定。最后，这项技术是非常“绿色”的，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.