• N Veeraiah

      Articles written in Bulletin of Materials Science

    • Dielectric properties of NaF-B2O3 glasses doped with certain transition metal ions

      M Krishna Murthy K S N Murthy N Veeraiah

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      Dielectric constant ε, loss tan δ, a.c. conductivity Σ and dielectric breakdown strength of NaF-B2O3 glasses doped with certain transition metal ions (viz. Cu2+, VO2+, Ti4+ and Mn4+) are studied in the frequency range 102-107 Hz and in the temperature range 30–250°C. The values of ε, tan δ, Σa.c. are found to be the highest for Cu2+ doped glasses and the lowest for Mn4+ doped glasses. Activation energy for a.c. conduction and the value of dielectric breakdown strength are found to be the lowest for Cu2+ doped glasses and the highest for Mn4+ doped glasses. With the help of infrared spectra, increase in the values of ε and tan δ of these glasses with frequency and temperature are identified with space charge polarization. An attempt has been made to explain a.c. conduction phenomenon on the basis of quantum mechanical tunneling model (QMT)/carrier barrier hopping model.

    • Acoustic investigations on PbO–Al2O3–B2O3 glasses doped with certain rare earth ions

      M Rami Reddy S Bangaru Raju N Veeraiah

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      Elastic moduli (𝑌, 𝜂), Poisson’s ratio (𝜎), microhardness (𝐻) and some thermodynamical parameters such as Debye temperature (𝜃𝐷), diffusion constant (𝐷𝑖), latent heat of melting (𝛥 𝐻𝑚) etc of PbO–Al2O3–B2O3 glasses doped with rare earth ions viz. Pr3+, Nd3+, Sm3+, Eu3+, Tb3+, Dy3+, Ho3+, Er3+ and Yb3+, are studied as functions of temperatures (in the temperature range 30–200°C) by ultrasonic techniques. All these parameters are found to increase with increasing atomic number 𝑍 of the rare earth ions and found to decrease with increasing temperature of measurement. From these results (together with IR spectra of these glasses), an attempt is made to throw some light on the mechanical strength of these glasses.

    • Composition dependence of electrical properties of ZnF2–MO–TeO2 glasses

      D K Durga N Veeraiah

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      Dielectric constant (𝜀'), loss (tan 𝛿), a.c. conductivity (𝜎) of ZnF2–MO–TeO2 glasses with varying concentrations of MO (P2O5, As2O3 and Bi2O3) were measured as a function of frequency and temperature over moderately wide ranges. From the analysis of these studies along with IR spectra and DTA results of these glasses, the structural changes in the systems with the concentration of metal oxides are discussed.

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