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Full-Text Articles in Physics
Vibrational Spectra In Ordered And Disordered Ni3al, Jeffrey D. Althoff, Dane Morgan, Didier De Fontaine, Mark Asta, S. M. Foiles, Duane D. Johnson
Vibrational Spectra In Ordered And Disordered Ni3al, Jeffrey D. Althoff, Dane Morgan, Didier De Fontaine, Mark Asta, S. M. Foiles, Duane D. Johnson
Duane D. Johnson
We calculate the vibrational density of states (DOS) and corresponding thermodynamic properties of L12 ordered and disordered Ni3Al in the quasiharmonic approximation using the embedded-atom method. Vibrational and thermodynamic properties, including vibrational entropy differences between ordered and disordered states, are found to be in good agreement with experiment. The DOS of the configurationally disordered alloy resembles a broadened version of the DOS of the L12 phase, not a one-atom per cell fcc DOS, and is shifted downward in frequency because the disordered state has a larger volume than the ordered phase. Calculations of the projected DOS indicate that high-frequency modes …
Synthesis Of Bulk, Polycrystalline Gallium Nitride At Low Pressures, Alberto Argoitia, John Angus, Cliff Hayman, Long Wang, Jeffrey Dyck, Kathleen Kash
Synthesis Of Bulk, Polycrystalline Gallium Nitride At Low Pressures, Alberto Argoitia, John Angus, Cliff Hayman, Long Wang, Jeffrey Dyck, Kathleen Kash
Jeffrey Dyck
Bulk, polycrytalline gallium nitride was crystallized from gallium saturated with nitrogen obtained from a microwave electron cyclotron resonance source. The polycrystalline samples are wurtzitic and n-type. Well-faceted crystals give near-band-edge and yellow band photo-luminescence at both 10K and 300K. The results show that atomic nitrogen is an attractive alternative to high pressure molecular nitrogen for saturation of gallium with nitrogen for synthesis of bulk gallium nitride.
Growth Of Bulk, Polycrystalline Gallium And Indium Nitride At Sub-Atmospheric Pressures, John Angus, Alberto Argoitia, Cliff Hayman, Long Wang, Jeffrey Dyck, Kathleen Kash
Growth Of Bulk, Polycrystalline Gallium And Indium Nitride At Sub-Atmospheric Pressures, John Angus, Alberto Argoitia, Cliff Hayman, Long Wang, Jeffrey Dyck, Kathleen Kash
Jeffrey Dyck
Bulk polycrystalline gallium nitride and indium nitride were crystallized at sub-atmospheric pressures by saturating the pure metals with nitrogen from a microwave electron cyclotron resonance source. Saturation of Ga/In melts with nitrogen led only to the crystallization of gallium nitride. The polycrystralline samples were wurtzitic. The gallium nitride was well faceted, with narrow Raman lineshapes, and showed near-band-edge and yellow band photo-luminescence at both 4K and 300K. The indium nitirde was formed in smaller amounts, was less well faceted, and showed no photoluminescence.