Improved sintering characteristics and microwave dielectric properties of NdNbO₄ ceramic system

Abstract

NdNbO₄–xCuO (x = 0, 0·15, 0·2, 0·3, 0·4, 0·5, 1 wt-%) ceramics with improved sintering characteristic and microwave dielectric properties were prepared by conventional mixed oxide route. The effects of CuO addition on the microstructures and microwave dielectric properties of NdNbO₄ ceramics were investigated systematically. Microscopic analysis showed that CuO doped NdNbO₄ ceramics possess second phases of CuNb₂O₆ and Nd₂Cu₂O₅. With a further increase in the amount of CuO, Cu₃Nb₂O₈ phase appeared in the system. The addition of CuO effectively reduced the sintering temperature of NdNbO₄ ceramics by ∼275°C. The microwave dielectric properties were strongly dependent on the CuO addition. Optimal microwave dielectric properties of ϵ_r = 19·76, τ_ƒ = −24 ppm °C⁻¹ and Q׃ = 39 000 GHz were observed for 0·2 wt-%CuO doped NdNbO₄ ceramics sintered at 975°C for 4 h.

Keywords:

• NdNbO₄ ceramics
• CuO addition
• Microwave dielectric properties
• Microstructure

Acknowledgements

This work was supported by 863 program (grant no. 2007AA03Z423) and China Postdoctoral Science Foundation.