Preparation of NiNb2O6 Columbite Ceramics by a Reaction-Sintering Process

ABSTRACTPreparation of NiNb2O6 columbite ceramics by a reaction-sintering process has been investigated. The mixture of raw materials was pressed and sintered into ceramics without any calcination stage involved. Columbite NiNb2O6 ceramics were obtained after being sintered at 1250–1450°C for 2 h and 4 h from mixture of Nb2O5 and 50%Ni(NO3)2-50%NiO (NN1). In pellets from mixture of Nb2O5 and NiO (NN2), columbite NiNb2O6 ceramics were obtained after being sintered at 1150–1350°C for 2 h and 4 h. A density of 4.47 g/cm3 was obtained in NN1 for 2 h sintering at 1400°C. For NN2, a higher density 5.62 g/cm3 (99.8% of the theoretical value) was obtained for 2 h sintering at 1300°C. The reaction-sintering process has proven to be a simple and effective method in preparing columbite NiNb2O6 ceramics. A higher density could be obtained at lower sintering temperature by using NiO instead of 50%Ni(NO3)2-50%NiO in the reaction with Nb2O5.