High pressure apparatus for growth of diamond based on thermal pressure produced by constraining thermal expansion

用于金刚石合成和生长的高压装置通常是基于外力产生的应力的机械类型的静态高压装置。但这种装置需要大型液压机和固体传压介质，并有滑动部分。该装置结构复杂，且存在摩擦力。这些问题尤其阻碍了仪器的扩大。基于约束热膨胀产生的内力的静态高压装置不需要大型液压机，也不伴有摩擦力。因此，该装置的高压室可以在不因摩擦力而损失压力的情况下扩大。此外，通过监测用于约束热膨胀的力，可以连续测量装置中产生的高压。在本研究中，为了证明该装置适合金刚石的生长，在装置内对由石墨和合成金刚石的金属催化剂组成的样品施加压力，并利用该装置尝试合成金刚石，监测约束热膨胀的力。本研究得到的结果如下：1。从约束热膨胀的力估计的压力几乎等于用铅和铝熔点的压力依赖关系测量的压力。2. 通过x射线衍射研究估计，样品中含有的一部分石墨可以转化为金刚石。3. 该装置能够产生金刚石生长所需的持续高压。

The high pressure apparatus used for synthesis and growth of diamond has been usually a mechanical type of static high-pressure apparatus based on stress produced by an external force. But this type of apparatus requires a large hydraulic press and a solid pressure-transmitting medium and has a sliding part. The apparatus is complicated in structure and is accompanied by frictional force. Such problems are obstacles especially to scaling up of the apparatus.A static high-pressure apparatus based on an internal force produced by constraining thermal expansion does not require a large hydraulic press and is not accompanied by frictional force. Therefore, the high-pressure chamber of this apparatus can be enlarged without losses of pressure due to frictional force. Furthermore, the high pressure created in the apparatus can be continuously measured by monitoring the force applied to constrain thermal expansion. In this study, in order to show that the apparatus is suitable for growth of diamond, a specimen composed of graphite and metallic catalyst for synthesis of diamond was subjected to pressure within the apparatus and attempt to synthesize diamond was done by using the apparatus, monitoring the force constraining thermal expansion. Results obtained by this study are as follows : 1. Pressures estimated from the force constraining thermal expansion are almost equal to those measured by using pressure dependence of melting points of lead and aluminum. 2. It was estimated by an x-ray diffraction study that a part of the graphite contained in the sample can be transformed into diamond. 3. The apparatus is capable of creating sustained high pressures required for growth of diamond.