Study on Nitrogenation and Hydrogenation of MgAgAs-type Compounds

我们研制了一台用于研究高温下的固气反应的仪器。通过测量气体压力的变化来检测固体对气体的吸收或解吸。这种方法被称为“热分析”，简称TPA。它使我们能够非常灵敏地检测气体与固体的反应。当使用氢气时，它的优点是明显的。由于在反应中观察到的是气体压力的较大变化，而不是质量的微小变化，因此尝试了对气体压力极小变化的精确检测。对TPA设备中的硬件和软件进行了许多修改。对TPA进行精密的自动测量。使用个人计算机进行TPA的自动测量；记录来自温度计和压力传感器的电信号。氮气、氢气、氧气、Ar和氨气的最大气压提高到0.2 Mpa。在600℃以上，观察到了CoTiSn中氮气的吸收过程。用中子衍射法和电子探针研究了CoTiSn氮化产物。结果表明，氮原子与化合物中的钛原子发生选择性反应

We have developed an instrument for studying the solid-gas reaction at elevated temperatures above R.T. The change in gas pressure is measured to detect gas absorption or desorption by/from solid. This method is called "thermopiezic analysis", TPA. It allows us great sensitive detection of gas reaction with solid. When hydrogen gas is employed, its strong point is marked. Since larger changes in gas pressure are observed rather than small changes in mass in the reactionA precise detection of very small change in gas pressure was tried. Many modifications have been given to the hardware as well as software in the TPA apparatus. Sophisticated automatic measurement of TPA was performed. A personal computer is used to make an automatic measurement of TPA ; electric signals from a thermometer and a pressure transducer are recorded. The maximum gas pressure was raised up to 0.2 MPa for nitrogen, hydrogen, oxygen, argon and ammoniaThe CoTiSn compound was investigated mostly by the TPA. The nitrogen absorption process has been clearly observed in CoTiSn above 600 C. The nitrogenation products of CoTiSn was extensively investigated by means of the neutron diffraction and EPMA. It was indicated that the nitrogen atoms react selectively with Ti atoms in the compounds