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Mangalore, India

Saranya L.,Jamal Mohamed College | Chandra Shekar N.V.,Indira Gandhi Center for Atomic Research | Amirthapandian S.,Indira Gandhi Center for Atomic Research | Hussain S.,UGC DAE CSR Node | And 2 more authors.
Physica B: Condensed Matter | Year: 2014

The phase stability of nanocrystalline Pr2O3 has been investigated under pressure by in-situ high pressure X-ray diffraction using Mao-Bell type diamond anvil cell. The ambient structure and phase of the praseodymium oxide have been resolved unambiguously using x-ray diffraction, SEM and TEM techniques. Under the action of pressure the cubic phase of the system is retained up to 15 GPa. This is unusual as other isostructural rare earth oxides show structural transformations even at lower pressures. From the best fit to the P-V data with the Murnaghan equation of state yields a bulk modulus of 171 GPa. © 2014 Elsevier B.V.

Ponnamma D.,Qatar University | Ramachandran R.,Indira Gandhi Center for Atomic Research | Hussain S.,UGC DAE CSR Node | Rajaraman R.,Indira Gandhi Center for Atomic Research | And 3 more authors.
Composites Part A: Applied Science and Manufacturing | Year: 2015

Abstract The microstructure, mechanical strength, dielectric properties, Doppler broadening measurements and positron life time studies of the composites containing multi walled carbon nanotubes (MWCNTs) and natural rubber (NR) are investigated. The uniform distribution of MWCNTs in the elastomer medium is studied by Raman spectroscopy and the electron microscopy images show the composite's internal microstructure. Free volume sizes and interstitial mesopore sizes of the nanocomposites are determined by positron annihilation lifetime spectroscopy (PALS). PALS investigates the influence of the nanotubes in regulating the interphase nanoscale character. Strong interfacial interaction causes an apparent reduction of the free-volume fraction of NR probably by depressing the formation of free-volume holes in the interfacial region. The mechanical percolation and percolation observed from the dielectric measurements are correlated with the life time values. It is established that the sub-nano level free volumes and nano level structure of the composites have significant roles in regulating the mechanical properties. © 2015 Elsevier Ltd.

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