Cryogel synthesis and solid state reactivity of NdCaCoO4

The synthesis of NdCaCoO4 precursors was performed by coprecipitation followed by freeze drying. The thermal decomposition of the freeze dried product at T = 800 °C results in the formation of finely grained NdCaCoO4 while at higher temperatures the appearance of perovskite-like (Nd,Ca)CoO3-δ among reaction products is observed. Reaction of NdCaCoO4 with Al2O3 and ZrO2 at 900–1000 °C results in the complete disappearance of the initial phases while thermal processing of NdCaCoO4 mixtures with Gd-doped ceria or with MgO is not accompanied by the appearance of new reaction products. The doping of NdCaCoO4 with 2–10 mass.% of MgO by means of cryoimpregnation method causes a substantial decrease in NdCaCoO4 grain growth rate at 1000 °C and promoting its thermal stability.