Investigation of the polyvinylpyrrolidone amount as gelling agent to lanthanum cobaltite micropowders synthesize by sol-gel method

Abstract

The paper focuses on lanthanum cobaltite micropowders LaCoO3-δ (LCO) synthesized by the sol-gel method using polyvinylpyrrolidone (PVP) as gelling agent. The PVP content has been varied from 0.5 to 5.0 wt. % when ionic solutions of the soluble raw components were prepared. The gels were dried in a microwave oven at microwave power 90 W for 2 h to evaporate water. Xerogels were thermally treated in a muffle furnace at temperatures 800°C and 900°C, the maximum holding time was 10 h and 30 h. After heat treatment of Xerogels at 800°C for 10 h LCO micropowders were slightly aggregated and particle size were in the range from 0.24 to 0.38 µm as well as specific surface area was in the range from 2.60 to 4.10 m2/g. After heat treatment 900°C for 10 h the specific surface area range of LCO micropowders decreased from 1.00 to 3.20 m2/g, but particle size range slightly increased from 0.31 up to 1.0 µm. Xerogels heat treatment at temperature 900° C for 30 h resulted to particles size range growing from 0.50 to 1.25 μm, and the specific surface area was 2.00 m2/g for all LCO micropowders. There was no effect of PVP content in the ionic solution on phase composition for all heat treated LCO micropowders.