• S R Dhage

      Articles written in Bulletin of Materials Science

    • Nonlinear 𝐼–𝑉 characteristics study of doped SnO2

      S R Dhage V Ravi S K Date

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      When tin oxide is doped with Sb2O3 and CoO, it shows highly nonlinear current (𝐼)–voltage (𝑉) characteristics. Addition of CoO leads to creation of oxygen vacancies and helps in sintering of SnO2. Antimony oxide acts as a donor and increases the conductivity. The results are nearly the same when antimony oxide is replaced by tantalum oxide. The observed nonlinear coefficient, 𝛼 = 30 and the breakdown voltage is 120 V/mm.

    • Synthesis of nanocrystalline TiO2 by tartarate gel method

      S R Dhage S P Gaikwad V Ravi

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      A gel was formed when a mixture of TiOCl2 and tartaric acid was heated on a water bath. Ultrafine powders of TiO2 in the anatase phase were formed, when the gel was decomposed at 623 K and the mole ratio of tartaric acid to titanium was 2. The anatase phase was converted into rutile phase on annealing at higher temperatures, > 773 K. When initial ratio of titanium to tartaric acid was < 2, the decomposition of gel leads to the formation of mixed phases of rutile and anatase. However, pure rutile phase was not formed by the decomposition of gel for any ratio of tartaric acid and titanium. These powders were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and surface area measurements. The average particle size obtained for anatase phase was 3 nm whereas it was 30 nm for rutile phase. Raman scattering experiments were also performed to confirm both anatase and rutile phases.

    • Low voltage varistor ceramics based on SnO2

      S R Dhage V Ravi O B Yang

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      The nonlinear current (𝐼)–voltage (𝑉) characteristics of tin dioxide doped with either Nb2O5 and CoO or Sb2O3 and CoO show promising values of nonlinear coefficient (𝛼) values (∼11) with low breakdown voltages (𝐸B, ∼40 V mm-1). The pentavalent antimony or niobium acts as donor and increases the electronic conductivity. The crucial parameter for obtaining low breakdown voltage is the grain size, which depends upon sintering duration and temperature of these oxide ceramics.

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