An in situ neutron diffraction measurement of the pressure–temperature evolution of a MgD₂:TiD₂ mixture

Abstract

The hydrogen storage capacity of Mg–Ti–H films is approximately five times that of conventional metal hydride electrodes in NiMH-batteries. Mg and Ti are considered to be immiscible in the bulk and the ambient pressure phase diagram of Mg and Ti indicates that no binary stable bulk compounds are formed. However, in the presence of hydrogen, an Mg–Ti–H phase has been obtained by Kyoi et al. using a high pressure synthesis – where magnesium hydride is compacted with different TM-hydrides in an anvil cell at pressures of the order several GPa (4–8 GPa) and at a temperature of 873 K. In this work, we have proved the feasibility of in situ powder diffraction using the Paris–Edinburgh high pressure cell for the observation of structural changes on this system and we propose modifications to improve the output of the experiment.

Keywords:

• structure
• phase transition
• metal hydrides
• neutron diffraction
• high pressure cell

Acknowledgements

Funding from the European Commission DG Research through contracts MRTN-CT-2004-512443/HYTRAIN (DM) and SES6-2006-518271/NESSHY (DN, DJB, DKR) is greatefully acknowledged. The authors are indebted to the ISIS Pulsed Neutron Facility for provision of beam-time.

Additional information

Notes on contributors

J. S. Cowpe

Present address: SEAES, University of Manchester, Williamson Building Room 1.61, Oxford Road, Manchester, M13 9PL, UK.