• V Rajendran

      Articles written in Bulletin of Materials Science

    • Self-propagating combustion synthesis of Pb1–𝑥Sr𝑥ZrO3 (0 ≤ 𝑥 ≤ 0.20) ceramics and their dielectric properties

      K Boopathy A Samson Nesaraj V Rajendran

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      Lead strontium zirconate, Pb1–𝑥Sr𝑥ZrO3 (0 ≤ 𝑥 ≤ 0.20) ceramics, were prepared by novel glycine–nitrate self-propagating combustion technique. The crystal structure of the ceramics was investigated as a function of composition via X-ray diffraction (XRD). The XRD patterns obtained on these powders showed the formation of pure orthorhombic phase of lead strontium zirconate without impurities and all the compounds retained the orthorhombic structure. The samples were sintered at 900–1100°C for 2 h. It has been observed that the dielectric constant decreases with increase in strontium content (100 kHz). In all compositions, dielectric constant showed a peak at transition temperature and the magnitude of the peak was found to decrease with strontium doping level.

    • Synthesis and characterization of electrochemically-reduced graphene

      M Selvam K Sakthipandi R Suriyaprabha K Saminathan V Rajendran

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      Graphene has superior electrical conductivity than graphite and other allotropes of carbon because of its high surface area and chemical tolerance. Electrochemically processed graphene sheets were obtained through the reduction of graphene oxide from hydrazine hydrate. The prepared samples were heated to different temperatures such as 673 and 873 K. X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDXS), transmission electron microscopy (TEM), Raman spectra and conductivity measurements were made for as-prepared and heat-treated graphene samples. XRD pattern of graphene shows a sharp and intensive peak centred at a diffraction angle (2𝜃) of 26.350. FTIR spectra of as-prepared and heated graphene were used to confirm the oxidation of graphite. TEM results indicated that the defect density and number of layers of graphene sheets were varied with heating temperature. The hexagonal sheet morphology and purity of as-prepared and heat treated samples were confirmed by SEM–EDX and Raman spectroscopy. The conductivity measurements revealed that the conductivity of graphene was decreased with an increase in heating temperature. The present study explains that graphene with enhanced functional properties can be achieved from the as-prepared sample.

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