• S C Sharma

      Articles written in Bulletin of Materials Science

    • Fabrication of PZT-polymer composite materials having 3-3 connectivity for hydrophone applications

      N M Gokhale S C Sharma Ramji Lal

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      Lanthanum-modified lead zirconate titanate (PZT) powder and volatilisable polymethylmethacrylate (PMM) polymer particles have been used for fabrication of porous sintered ceramics of interconnected porosity varying from 25% to 59%. Sintered ceramics are converted into piezoelectric PZT-polymer composites by incorporating silicone rubber elastomer followed by electroding and poling. Influence of the variation of PZT-PMM ratio and sintering temperatures on the open and closed porosity of the sintered ceramics as well as volume fraction PZT in the composites has been studied and correlated for the optimization of piezoelectric properties. The PZT-polymer composites possess low density, considerably high piezoelectric voltage coefficient and considerably lower ageing characteristics and are therefore considered suitable for designing highly sensitive hydrophone systems.

    • Structural, thermal and optical properties of Cu$^{2+}$ doped methacrylic acid–ethyl acrylate (MAA:EA) copolymer films

      Y MADHAVA KUMAR N O GOPAL Ch RAMU S BABU J LAKSHMANA RAO H NAGABHUSHANA S C SHARMA

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      Pure and Cu$^{2+}$ doped methacrylic acid–ethyl acrylate (MAA:EA) copolymer films were prepared using thesolution cast technique. The amorphous feature of the copolymer was depicted using X-ray diffraction scans and degreeof crystallinity was found to vary with increasing doping content. UV–Vis absorption spectra in the wavelength region200–900 nm were used to evaluate the optical properties like direct band gap, indirect band gap and absorption edge. Theoptical band gap decreased with the increase of mol% of Cu$^{2+}$ ions. Fourier transform infrared spectral studies on pureMAA:EA and Cu$^{2+}$ ions-doped films revealed the vibrational changes that occurred due to the effect of dopant salt inthe copolymer. Thermal properties of these films were investigated by employing differential scanning calorimetry andthermogravimetric analysis. The variation in film morphology was examined by scanning electron microscopy. Electronparamagnetic resonance (EPR) spectra of all the doped samples exhibited signals due to Cu2+ ions with the effective$g$-values $g_{\parallel} = 2.177$ and $g_{\perp} = 2.058$. The observed variation in the EPR signal intensity is due to the isolated and aggregated copper ions. The photoluminescence spectra of Cu$^{2+}$ ions-doped MAA:EA copolymer exhibited four emissionpeaks at 480 (blue), 579 (yellow), 604 (red) and 671nm (red).

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