Role of thermal vibrations in alloy phase transitions
DSpace at IIT Bombay
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Title |
Role of thermal vibrations in alloy phase transitions
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Creator |
PRASANNA, TRS
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Subject |
LONG-RANGE ORDER
TEMPERATURE-DEPENDENCE BAND-STRUCTURE BETA-BRASS ELECTRONIC EXCITATIONS 1ST-PRINCIPLES THEORY LATTICE-VIBRATIONS DISORDER THERMODYNAMICS SEMICONDUCTORS order-disorder transitions alloy phase transitions electron-phonon interactions diffraction |
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Description |
We resolve the fundamental contradiction that has existed from the earliest studies on order-disorder transitions between theoretical models that ignore the effect of thermal vibrations on the chemical interaction parameter, J(0), and the analysis of diffraction data that always incorporates the role of vibrations. New analysis of diffraction data shows that the temperature dependence of the order parameter, the central feature of order-disorder transitions, predicted by existing models is scientifically invalid. All models are constrained by the diffraction data to represent the interaction parameter as J(T) and the ordering energy as temperature dependent. The discrepancy between the experimental and theoretical ordering energies in Ni(3)V and Pd(3)V is direct evidence of their temperature dependence. Thermal vibrations influence order-disorder transitions through both the configurational and vibrational terms and not just the vibrational terms as hitherto believed. A modified Bragg-Williams model is proposed, which is the simplest model whose predicted order parameter can be compared with experiments.
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Publisher |
TAYLOR & FRANCIS LTD
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Date |
2012-06-26T09:55:26Z
2012-06-26T09:55:26Z 2011 |
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Type |
Article
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Identifier |
PHASE TRANSITIONS,84(2)118-134
0141-1594 http://dx.doi.org/10.1080/01411594.2010.523813 http://dspace.library.iitb.ac.in/jspui/handle/100/14341 |
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Language |
English
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