Synthesis and Study of Electrical Properties of Di Ethylene Glycol Embedded ZrO2 Films as a Gas Sensor

In this paper, the effects of Di ethylene glycol (DEG) embedded Zirconium dioxide (ZrO2) microstructure and Liquid Petroleum Gas (LPG) Sensing characteristics of ZrO2 thin films prepared by spray pyrolysis method were investigated. The films are prepared at X wt. % concentrations (X= 1, 2, 3, 4 and 5) of Di ethylene Glycol. Microstructure of ZrO2 thin film was drastically changed by the addition of DEG, indicating that the addition of DEG was effective to prevent the agglomeration of ZrO2 particles. The high material and phase purities are found from the characterization studies in all as-prepared films. The better sensitivity factor (SF) values SF ~102 (at T = 450C) and SF = 100 (at T = 37oC) are obtained at 1 wt. % and 5 wt. % of Di ethylene Glycol respectively. It is observed that the gas sensing characteristics of these films are strongly influenced by the optimum concentration of DEG due to the high surface area of nano-sized ZrO2 particles

Synthesis of bismuth titanate (Bi₄Ti₃O₁₂) powders via calcination of microwave-hydrothermally (MH) derived precursor

51-54Micrometer sized platelet-like particles of bismuth titanate (Bi₄Ti₃O₁₂) are prepared successfully by the calcination of a mixed-precursor in air. The mixed precursor is precipitated under microwave-hydrothermal (MH) treatment via dissolution-recrystallization kinetics. The mixed precursor is precipitated in-situ by giving MH treatment (at 200°C, 200 psi, and 30 min hold time) to the hydrolysed slurry containing Bi and Ti cations. The slurry was prepared by adding 20% aqueous KOH precipitant solution to a well-mixed stoichiometric nitrate solution containing Bi and Ti cations. XRD results revealed that the as-dried precursor consisted of a homogeneous mixture of non-crystalline particles of Bi₂O₃ and TiO₂. The calcination of the as-dried precursor at 700°C/2 h in air resulted in the formation of micron sized platelet like single-phase Bi₄Ti₃O₁₂ powders having orthorhombic structure

Unusual charge disproportionation and associated magnetic behaviour in nanocrystalline LaMn<SUB>0.5</SUB>Co<SUB>0.5</SUB>O<SUB>3</SUB>

Evidence for an unusual double charge disproportionation, Mn<SUP>4+</SUP> + Co<SUP>2+</SUP> → Mn<SUP>3+</SUP> + Co<SUP>3+</SUP> → Mn<SUP>4+</SUP> + Co<SUP>2+</SUP>, is observed in nanocrystalline LaMn<SUB>0.5</SUB>Co<SUB>0.5</SUB>O<SUB>3</SUB> synthesized by a low-temperature method and annealed in the temperature range 200-1300°C. The Curie temperature of nanocrystalline LaMn<SUB>0.5</SUB>Co<SUB>0.5</SUB>O<SUB>3</SUB> is increased from 150 to 230 K when annealed in the temperature range 200-700°C and is further decreased back to 150 K when annealed in the temperature range 700-1300°C. This increase and decrease in T<SUB>c</SUB> is found to be associated with the conversion of the spin states of Mn and Co from Mn<SUP>4+</SUP> and Co<SUP>2+</SUP> to Mn<SUP>3+</SUP> and low-spin Co<SUP>3+</SUP>, and again back to Mn<SUP>4+</SUP> and Co<SUP>2+</SUP> as evidenced from X-ray photoelectron spectroscopic studies