Effects of non-stoichiometry on the microstructure and microwave dielectric properties of Ba1+xCu2V2O8 (x = 0.15, 0.25, 0.35) ceramics

The Ba 1+ x Cu 2 V 2 O 8 ( x  = 0.15, 0.25, 0.35) ceramics were synthesized using the conventional solid-state reaction sintering method. The effects of the non-stoichiometry on the crystalline phases, densification sintering, microtopography, and microwave dielectric properties of the Ba 1+ x Cu 2 V 2 O 8 ( x  = 0.15, 0.25, 0.35) ceramics were studied. In the sample ( x  = 1) prepared according to the stoichiometry, only the single crystalline phase of BaCu 2 V 2 O 8 existed. The excess of Ba 2+ ions directly led to the precipitation of a new Ba 2 V 2 O 7 phase. The detection of element composition using EDS also confirmed the results of the phase composition. The SEM results indicated that the microstructure of the ceramics became loose with the increase of Ba 2+ ion content. The theoretical microwave dielectric properties were calculated according to the general formula of compounds. The results of the calculation showed that the precipitation of the Ba 2 V 2 O 7 phase was the main factor affecting the microwave dielectric properties of the ceramics. The measured results of microwave dielectric properties were consistent with the calculated results. The microwave dielectric properties of the Ba 1.35 Cu 2 V 2 O 8 sample calcined at 725 °C for 6 h were shown as follow: ε r  = 12.25, Q f  = 46,320 GHz, τ f = − 35.3 ppm/°C.