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Long range order in Ag 3 Mg
Author(s) -
Gangulee A.,
Moss S. C.
Publication year - 1968
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889868005017
Subject(s) - superlattice , condensed matter physics , phase boundary , diffraction , quenching (fluorescence) , atmospheric temperature range , fermi surface , range (aeronautics) , boundary (topology) , phase (matter) , boundary value problem , materials science , chemistry , thermodynamics , physics , optics , mathematics , quantum mechanics , mathematical analysis , superconductivity , composite material , fluorescence
The long range order in a powder sample of Ag 3 Mg has been studied by X‐ray diffraction as a function of quenching temperature below the critical ordering temperature of 665°K. By measuring the positions and integrated intensities of fundamental, superlattice and satellite reflections, the latter arising from the periodic anti‐phase boundary structure, the variation with temperature of the overall long range order, antiphase boundary order, and anti‐phase boundary periodicity have been determined. It appears that the anti‐phase boundaries disorder slightly more with increasing temperature than the average superlattice, and that the boundary spacing, nominally equal to two ( M = 2), increases towards that ideal value with increasing disorder below the critical point. These resalts are qualitatively interpreted by extending the reasoning of Sato & Toth on equilibrium long period superlattices to include the case where the Fermi surface becomes progressively more diffuse with increasing disorder.