Improvement of TSFZ method and characterization of grown large single-crystals of high-Tc superconducting oxides and their suitable substrate oxides

TSFZ 方法的改进和高温超导氧化物大单晶及其合适基底氧化物生长的表征

基本信息

批准号：
03650567
负责人：
KAJITANI Tsuyoshi
金额：
$ 1.34万
依托单位：
The Institute for Materials Research, Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1992
项目状态：
已结题

项目摘要

Traveling Solvent Floating Zone method that is a kind of the infrared heating floating zone method with the use of the flux-growth technique can be utilized to obtain oxide single-crystals that crystallize incongruently from the solvent. Present authors had been working to grow 214-type superconducting copper oxide single-crystals and related oxide single-crystals by the TSFZ method and had studied the detailed crystal structures by means of x-ray and neutron diffraction measurements. It was difficult but possible, to obtain small and low quality 214-type oxide single crystals. Their simple crystal structures and relatively broad first crystalization field in the phase diagram might have made the single-crystal growth easier relative to the other complex superconducting oxides. But we could not grow high quality high-Tc single-crystals. Our computer simulation indicated that it was not only crucial to control temperature gradient in the feed rods appropriately, particularly near the mo … More lten zone, but also crucial to keep the chemical composition of the molten zone rigidly throughout the growth process. It was planed to equip a conventional infrared heating floating zone furnace with a computer controlled feed rod driving mechanism to traverse the molten floating zone across the sintered oxide feed rod at an optimized speed which changes non-linearly from the seeding regime to the ending regime. By the Grant-in-Aid for Scientific Research(c) from the ministry of education, science and culture, we could introduce a personal computer controlled feed rod driving mechanism for our infrared floating zone furnace, Nichiden-Machinary-SC4. After intensive efforts to grow good single-crystals, it was found that there were two essential factors for the successful growth. The first was the packing density of the feed rods. The higher the packing density, the better became the grown crystals. It was concluded that the feed rods must be made from finely pulvelized oxide powders in which each grain has a size less than 5mum in diameter. The powders must have the same chemical compositions as the grown single-crystals. When the packing density of the feed rods may be low, the chemical compositions of the molten zone may be changed during the growth and a part of the molten oxide and the solvent, e.g. molten CuO flux plus target oxides, would be penetrated into the loose feed rods. The second point was the temperature gradient in the feed rod in the vicinities of molten floating zone. The steeper the temperature gradient, the better became the quality of the grown crystals. To obtain steep temperature gradient, the physical design of the infrared bulbs set at the focus points of the oval reflectors was optimized. Shading of a part of the reflectors caused similar effect. At the end of the efforts, good single-crystals have been grown repeatedly. The yield of the good single-crystals has sharply increased as high as 90% in these days. High-T_cLa_<1.8>Sr_<0.2>CuO_4At this stage, we can conclude that we succeeded to obtain a growth technique for the 214-type high-T_c oxide single-crystals as well as an appropriate growth equipment by the Grant-in-Aid for Scientific Research(c) from the ministry of education, science and culture during 1991 through 1993. Less

可以利用使用通量生长技术来获取氧化物单晶体，从而从溶解度不一致地结晶。目前的作者一直在努力通过TSFZ方法增长214型超导氧化铜单晶和相关的氧化物单晶，并通过X射线和中子衍射测量来研究详细的晶体结构。很难但可能获得小质量和低质量的214型氧化物单晶。它们的简单晶体结构和相对较宽的第一结晶场在相图中可能使单晶生长更加容易地对其他复杂的超导氧化物更容易。但是我们无法种植高质量的高-TC单晶。我们的计算机模拟表明，适当地控制进料棒中的温度梯度，尤其是在Mo…更多的LTEN区域，而且对于在整个生长过程中保持熔融区域的化学成分至关重要。它计划以常规的红外加热浮动区炉配备计算机控制的进料杆驱动机构，以优化的氧化物进料杆穿越熔融的浮动区，以优化的速度从播种状态转变为结束机构。由教育，科学和文化部的科学研究赠款（C），我们可以为我们的红外浮动区炉（Nichiden-AhniChinary-sc4）介绍个人计算机控制的进料杆驱动机制。经过深入发展良好的单晶的努力，发现成功增长有两个基本因素。首先是进料棒的填料密度。包装密度越高，变成了成年的晶体越好。结论是，进料棒必须由细化的氧化物粉末制成，其中每种谷物的直径小于5MUM。粉末必须具有与生长的单晶相同的化学成分。当进料棒的堆积密度可能很低时，在生长过程中可能会改变熔融区的化学成分，以及一部分熔融氧化物和溶液，例如熔融的CuO通量加目标氧化物将被渗透到松散的进料棒中。第二点是熔融浮动区欺诈杆中进料棒中的温度梯度。钢筋的温度梯度越好，变成了生长晶体的质量。为了获得钢温度梯度，优化了在椭圆形反射器焦点的受影响灯泡的物理设计。一部分反射镜的阴影引起了相似的效果。在努力结束时，良好的单晶反复种植。在当今，良好的单晶产量急剧高达90％。 High-T_Cla_ <1.8> SR_ <0.2> CUO_4在此阶段，我们可以包括我们成功地获得了214型高-T_C氧化物单晶体的增长技术，以及1991年至1993年教育，科学和文化部的科学研究（C）的赠款（C）的适当增长设备（C）。