In-situ infrared imaging methodology for measuring heterogeneous growth process of a hydride phase

In the paper we report on a new methodology, which allows measuring in-situ heterogeneous growth rates of hydride phase in films during metal-hydride phase transformation. This optical method is based on infrared imaging of a wedge-shaped thin film during hydrogen loading. In the paper the method is demonstrated for Mg98.4Ti1.6 wedge-shaped thin film and main conclusions are supported by results of transmission electron microscopy. The methodology combined with the structural characterizations verified fast formation of MgH2 layer on top followed by drastically slower growth of the MgH2 phase. The initial averaged growth rate of the MgH2 phase was estimated as ∼1.3 nm/s, and as ∼0.03 nm/s subsequently.