Measurement of hydrogen distribution in absorbing metals by using neutron spin in terferometer

本研究的目的是利用中子自旋干涉仪和中子反射仪测量吸氢材料中氢的含量和分布。中子因其大的散射幅度而成为探测氢的灵敏工具。而中子由于其透明性，具有在氢环境下进行测量的优点。在本研究中，我们首先研制了氢环境下测量的样品保持器。用中子反射法测量Pd薄膜中氢含量的结果表明，在0.02 Mpa氢气压力下，40 nm厚的Pd薄膜表面H/Pd=0.42，衬底H/Pd=0.69。随着氢气压力的增加，H/Pd比也增加，并且保持了硅衬底附近H/Pd比高于表面的趋势。我们还用中子反射法测量了常用的吸氢材料LaNiAl和TiCrV合金。除了上述结果之外，我们还提出了一种利用自旋分离器测量薄膜中氢含量的新方法，这使得我们能够应用中子相自旋回波技术。在新的方法中，氢含量的精度可以提高10倍。

The aim of the present research is to measure hydrogen content and distribution in the hydrogen absorbing materials using neutron spin interferometry and neutron reflectometry.Neutron is a sensitive tool to detect hydrogen because of its large scattering amplitude. And neutron has merit of performing the measurement under hydrogen environment because of its transparency.In the present research we first develop sample holder for the measurements under hydrogen environment. Hydrogen pressure is allowed from 0 Pa to 0.3MPa.The results of neutron reflectometry on measuring hydrogen content in a Pd thin film indicate that hydrogen content H/Pd in a 40nm-thick Pd film is obtained as 0.42 at the surface and as 0.69 at the substrate under 0.02MPa hydrogen pressure. As the hydrogen pressure increases, the H/Pd ratio also increases and the tendency that H/Pd ratio is higher near Si substrate than near surface, is preserved.By neutron refletometry we have also measured LaNiAl and TiCrV alloys, which are frequently used as hydrogen absorbing materials. Hydrogen content in those materials, however, does not change in the hydrogen environment.In addition to the above results, we propose a new method for measuring hydrogen content in a thin film using [ spin splitters, which enables us to apply neutron phase-spin echo technique. In the new method, precision of hydrogen content can be 10 times higer.