Development of thermopiezic analysis for studying nitrogen and hydrogen absorption by Heusler compounds

研制了一种研究固气反应的仪器。测量气体压力的变化是为了检测固体对气体的吸收或解吸。这种方法被称为“热压分析”，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，它的强力点被标记出来。因为在反应中观察到的是气体压力的较大变化，而不是质量的较小变化。利用个人计算机对TPA进行自动测量；记录来自温度计和压力传感器的电信号。氮气、氢气、氧气、氩气和氨气的最大气体压力为0.2 Mpa。用TPA观察了CoTiSn和CoZrSn Heusler化合物的氮化和加氢过程与温度的关系。在600℃以上的CoTiSn和CoZrSn化合物中已经清楚地观察到氮的吸收过程，并且还发现后者化合物吸收氢的量高达0.5 mol。中子衍射和电子能谱分析表明，CoTiSn和CoZrSn的氮化产物为Co2TiSn和Co2ZrSn化合物。氮原子与化合物中的Ti和Zr原子选择性反应。

An instrument for studying the solid - gas reaction has been developed. 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 reaction.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 is 0.2 Mpa for nitrogen, hydrogen, oxygen, argon and ammonia.The TPA has been employed to observe the nitrogenation and hydrogenation processes with the CoTiSn and CoZrSn Heusler compounds as a function of temperature.The nitrogen absorption process has been clearly observed in CoTiSn and CoZrSn compounds above 600 C. It has also been found that the latter compound absorbs hydrogen as much as 0.5 mole.The neutron diffraction and EPMA have indicated that nitrogenation products of CoTiSn and CoZrSn are Co2TiSn and Co2ZrSn compounds. Nitrogen atoms react selectively with Ti and Zr atoms in the compounds.