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The nature of the structural phase transition from the hexagonal (4H) phase to the cubic (3C) phase of silver

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dc.contributor.author Chakraborty, Indrani
dc.contributor.author Shirodkar, Sharmila N.
dc.contributor.author Gohil, Smita
dc.contributor.author Waghmare, Umesh V.
dc.contributor.author Ayyub, Pushan
dc.date.accessioned 2017-02-21T09:03:23Z
dc.date.available 2017-02-21T09:03:23Z
dc.date.issued 2014
dc.identifier.citation Chakraborty, I; Shirodkar, SN; Gohil, S; Waghmare, UV; Ayyub, P, The nature of the structural phase transition from the hexagonal (4H) phase to the cubic (3C) phase of silver. Journal of Physics-Condensed Matter 2014, 26 (11), 15405 http://dx.doi.org/10.1088/0953-8984/26/11/115405 en_US
dc.identifier.citation Journal of Physics-Condensed Matter en_US
dc.identifier.citation 26 en_US
dc.identifier.citation 11 en_US
dc.identifier.issn 0953-8984
dc.identifier.uri https://libjncir.jncasr.ac.in/xmlui/10572/2569
dc.description Restricted Access en_US
dc.description.abstract The phase transition from the hexagonal 4H polytype of silver to the commonly known 3C (fcc) phase was studied in detail using x-ray diffraction, electron microscopy, differential scanning calorimetry and Raman spectroscopy. The phase transition is irreversible and accompanied by extensive microstructural changes and grain growth. Detailed scanning and isothermal calorimetric analysis suggests that it is an autocatalytic transformation. Though the calorimetric data suggest an exothermic first-order phase transition with an onset at 155.6 degrees C (for a heating rate of 2 K min (-1)) and a latent heat of 312.9 J g (-1), the microstructure and the electrical resistance appear to change gradually from much lower temperatures. The 4H phase shows a Raman active mode at 64.3 cm (-1) (at 4 K) that undergoes mode softening as the 4H -> 3C transformation temperature is approached. A first-principles density functional theory calculation shows that the stacking fault energy of 4H-Ag increases monotonically with temperature. That 4H-Ag has a higher density of stacking faults than 3C-Ag, implies the metastability of the former at higher temperatures. Energetically, the 4H phase is intermediate between the hexagonal 2H phase and the 3C ground state, as indicated by the spontaneous transformation of the 2H to the 4H phase at -4 degrees C. Our data appear to indicate that the 4H-Ag phase is stabilized at reduced dimensions and thermally induced grain growth is probably responsible for triggering the irreversible transformation to cubic Ag. en_US
dc.description.uri 1361-648X en_US
dc.description.uri http://dx.doi.org/10.1088/0953-8984/26/11/115405 en_US
dc.language.iso English en_US
dc.publisher IoP Publishing Ltd en_US
dc.rights @IoP Publishing Ltd, 2014 en_US
dc.subject Condensed Matter Physics en_US
dc.subject Structural Phase Transition en_US
dc.subject Transformation Kinetics en_US
dc.subject Polytypes Of Silver en_US
dc.subject Density Functional Theory en_US
dc.subject Stacking Fault Energy en_US
dc.subject Size-Driven Transition en_US
dc.subject Differential Thermal-Analysis en_US
dc.subject Crystal-Structure en_US
dc.subject Nanowires en_US
dc.subject Transformation en_US
dc.title The nature of the structural phase transition from the hexagonal (4H) phase to the cubic (3C) phase of silver en_US
dc.type Article en_US


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