Electrical Resistance Measurement Techniques for Metal Hydrides under High-Pressure H2 Conditions & Electrical Transport and Structural Properties of FeHx

We present the newly developed electrical resistance measurement technique for metal hydrides compressed in high-pressure H2 and the first successful in-situ simultaneous measurements of electrical resistance and X-ray diffraction of FeH at high pressures and low temperatures. The electrical resistivity ρ showed a sharp increase with the formation of iron-hydride FeHx (x∼1) at 3.5 GPa. The e′-phase of FeH was found to be metallic up to 25.5 GPa. The ρ vs. T curves up to 16.5 GPa approximately follow Fermi-liquid law below 25 K. However, T5 was found to be better fitting at 25.5 GPa. This change can be related to the previously reported ferromagnetism collapse at corresponding pressures.