Relationship of the structural phase transition and microwave dielectric properties in MgZrNb 2 O 8 –TiO 2 ceramics

Abstract The phase transition, microstructure and microwave dielectric properties were systematically investigated in TiO 2 modified MgZrNb 2 O 8 ceramics. The X-ray diffraction and Raman spectrum revealed four distinct phase regions from wolframite, ixiolite, ixiolite–rutile mixture to rutile with increasing the TiO 2 content. This phase transition was considered as a result of the destruction of the ordered array of octahedra in wolframite structure and then the shortening of cation–cation distances in ixiolite structure. Moreover, the addition of TiO 2 was found to improve the sintering behavior of the MgZrNb 2 O 8 ceramics and simultaneously promote grain growth. The microwave dielectric properties were found to be closely related to the phase transition, packing fraction, Raman shift and full width at half-maximum of A 1g stretch mode. A near-zero temperature coefficient of the resonant frequency could be achieved together with a middle dielectric permittivity of e r ~43 and a relatively high Q × f value of 46,110 GHz for the 0.63MgZrNb 2 O 8 –0.37TiO 2 samples sintered at 1300 °C for 4 h.