Determination of the deuterium order-disorder structure transition in Pd-DO.65 at '50K'

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dc.contributor.authorKennedy, SJen_AU
dc.contributor.authorWu, Een_AU
dc.contributor.authorKrisi, EHen_AU
dc.contributor.authorGray, EMen_AU
dc.contributor.authorKennedy, BJen_AU
dc.date.accessioned2022-12-22T01:34:07Zen_AU
dc.date.available2022-12-22T01:34:07Zen_AU
dc.date.issued1994-02-09en_AU
dc.date.statistics2022-04-04en_AU
dc.description.abstractAnomalies in the heat capacity and the electrical resistance of Palladium Hydride at ~50K were first reported in the 1950's(l). Since then a number of experimental techniques have been applied in attempts to determine the origin of these anomalies. These techniques have included XRD and neutron diffraction. All crystallographic studies have been hampered by the sluggishness of this transition (i.e. it takes several days to complete). Early powder diffraction results suggested a phase transition involving migration of H (or D) atoms from sites of octahedral symmetry to sites of tetrahedral symmetry(2). Later evidence from single crystal neutron diffraction studies indicated an order-disorder transition within the octahedral sites(3). Neither description has found global support because conclusive evidence has not been produced. We have just completed a time resolved powder neutron diffraction study of the structural transition in b-Pd-DO 6 5 at S4K using the new Medium Resolution Neutron Powder Diffractometer (MRPD) at the HIFAR research reactor. Our results show that the latter description of an order-disorder transition of the octahedral sites is correct. The 'ordered' crystal structure can be accurately described with space group Pm3n and by doubling the lattice constant from the high temperature structure (Fm3m). The transition to the ordered phase involves diffusion from specific 'D' sites from nearest 'D' neighbour positions to second nearest 'D' neighbour positions. This eventually produces 97% and 33% occupancy of the favoured and unfavoured sites respectively.en_AU
dc.identifier.citationKennedy, S. J., Wu, E., Krisi. E. H., Gray, E. M., & Kennedy, B. J. (1994). Determination of the deuterium order-disorder structure transition in Pd-DO.65 at '50K'. Poster presented to the 18th Annual Condensed Matter Physics Meeting, Charles Sturt University, Wagga Wagga, NSW, 9-11 February 1994.en_AU
dc.identifier.conferenceenddate11 February 1994en_AU
dc.identifier.conferencename18th Annual Condensed Matter Physics Meetingen_AU
dc.identifier.conferenceplaceWagga Wagga, NSWen_AU
dc.identifier.conferencestartdate9 February 1994en_AU
dc.identifier.otherWP75en_AU
dc.identifier.urihttps://apo.ansto.gov.au/dspace/handle/10238/14232en_AU
dc.language.isoenen_AU
dc.publisherAustralian and New Zealand Institutes of Physicsen_AU
dc.subjectDiffractionen_AU
dc.subjectHydridesen_AU
dc.subjectHydrogen compoundsen_AU
dc.subjectNucleien_AU
dc.subjectPhase transformationsen_AU
dc.subjectRadiation effectsen_AU
dc.subjectScatteringen_AU
dc.subjectStable isotopesen_AU
dc.subjectSymmetry groupsen_AU
dc.subjectTemperature rangeen_AU
dc.subjectTransition element compoundsen_AU
dc.titleDetermination of the deuterium order-disorder structure transition in Pd-DO.65 at '50K'en_AU
dc.typeConference Posteren_AU
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