The solid solutions of Sn_1–𝑥Ti_𝑥O₂ (0.0 < 𝑥 < 0.25) were prepared by the usual high temperature ceramic processing techniques with small amounts of dopants such as Nb, Co, Al. The electrical measurements (log 𝐼–log 𝑉) on the ohmically metal electroded sintered pellets showed the non-linear behaviour. The nonlinear coefficient was found to decrease from 12 to 3 with increase in 𝑥. On the other hand, the breakdown voltage (𝐸_b) showed the increase with the increase in 𝑥. This complex electrical behaviour is explained on the effects of the three dopants (as varistor former, performance enhancer and highlighter) on the microstructural features of the dense pellet.

A simple coprecipitation technique is described for the preparation of tin substituted zirconium titanate ceramic powders.

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.

A simple gel to crystal conversion route has been followed for the preparation of nanocrystalline SnO₂ at 80–100°C under refluxing conditions. Freshly prepared stannic hydroxide gel is allowed to crystallize under refluxing and stirring conditions for 4–6 h. Formation of nano crystallites of SnO2 is confirmed by X-ray diffraction (XRD) study. Transmission electron microscopic (TEM) investigations revealed that the average particle size is 30 nm for these powders.

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.

A gel was formed when a aqueous solution of BaCl₂, NbF₅ and citric acid in stoichiometric ratio is heated on a water bath. This gel on decomposition at 600°C yielded the nano crystallites of BaNb₂O₆, as confirmed by X-ray diffraction study (XRD). This is a much lower temperature as compared to that prepared by traditional solid state method (1000°C) as reported for the formation of BaNb₂O₆. Transmission electron microscopic (TEM) investigations revealed that the average particle size is 50 nm for the calcined powders. The room temperature dielectric constant at 1 kHz is found to be 1000. The ferroelectric hysteresis loop parameters of these samples were also studied.

A simple coprecipitation technique was successfully applied for the preparation of pure ultrafine single phase, ZnNb₂O₆ (ZN). Ammonium hydroxide was used to precipitate Zn²⁺ and Nb⁵⁺ cations as hydroxides simultaneously. This precursor on heating at 750°, produced ZN powders. For comparison, ZN powders were also prepared by the traditional solid state method. The phase contents and lattice parameters were studied by the powder X-ray diffraction (XRD). Particle size and morphology were studied by transmission electron spectroscopy (TEM).

A gel was formed when a aqueous solution of Li(NO₃), TaF₅ and citric acid in stoichiometric ratio was heated in a water bath. This gel on decomposition at 700°C produced fine crystallites of ternary oxide, LiTaO₃ (LT). The phase contents and lattice parameters were studied by powder X-ray diffraction (XRD). Particle size and morphology were studied by transmission electron spectroscopy (TEM).

A gel was formed when a aqueous solution of Mg(NO₃)₂, NbF₅ and citric acid in stoichiometric ratio was heated on a water bath. No precipitation was observed at acidic pH and gellation was complete with evaporation of the solvent. This gel on decomposition at 750°C produced nanocrystallites of ternary oxide, Mg₄Nb₂O₉ (M4N2). The phase contents and lattice parameters were studied by powder X-ray diffraction (XRD) at various temperatures. Particle size and morphology were studied by transmission electron spectroscopy (TEM). For comparison, M4N2 powders were also prepared by conventional ceramic route at 900°C.

A simple coprecipitation technique has been used successfully for the preparation of pure, ultrafine, single phases of NaNbO₃ (NN) and NaTaO₃ (NT). An alcoholic solution of ammonium carbonate and ammonium hydroxide was used to precipitate Na⁺ and Nb⁵⁺ (or Ta⁵⁺) cations under basic conditions as carbonate and hydroxide, respectively. On heating at 700°C, these precursors produce respective products. For comparison, both NN and NT powders were also prepared by the traditional solid state method. The phase purity and lattice parameters were studied by powder X-ray diffraction (XRD). The particle size and morphology were studied by scanning electron microscopy (SEM).

An aqueous mixture of ammonium oxalate and ammonium hydroxide was used to coprecipitate barium and strontium ions as oxalates and niobium ions as hydroxide under basic conditions. This precursor on calcining at 750°C yielded Sr_0.5Ba_0.5Nb₂O₆ phase. This is a much lower temperature than that prepared by traditional solid state method (1000°C) as reported for the formation of Sr_0.5Ba_0.5Nb₂O₆ (SBN). Transmission electron microscopic (TEM) investigations revealed that the average particle size was 80 nm for the calcined powders. The room temperature dielectric constant at 1 kHz was found to be 1100. The ferroelectric hysteresis loop parameters of these samples were also studied.

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 (𝐸_B, ∼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.