Crystal structure, Raman spectroscopy and microwave dielectric properties of novel (1-x)MgGa2O4-xBaCu(B2O5) based LTCC materials

A novel series of (1- x )MgGa 2 O 4 - x BaCu(B 2 O 5 ) ( x  = 0.1–0.5) microwave dielectric ceramics were prepared by solid phase method. By adding BaCu(B 2 O 5 ) additives, the sintering temperature of MgGa 2 O 4 ceramics was reduced from 1410 °C to 925 °C. Through an analysis of the trend in packing fraction and FWHM value of T 2g Raman peak, the underlying influence mechanism of various intrinsic factors on the dielectric loss of ceramic were revealed. And the density, as the external factors, exhibits a positive correlation with the dielectric constant and Q × f value. In addition, the high bond strength of Ga-site reduces lattice distortion and consequently enhances the frequency temperature coefficient. The microwave dielectric properties of (1- x )MgGa 2 O 4 - x BaCu(B 2 O 5 ) ( x  = 0.3) are found to be superior at a sintering temperature of 925 °C (ε r  = 9.42, Q × f = 35,480 GHz, τ f  = −22.7 ppm/°C, at 14 GHz). Moreover, the chemical compatibility of ceramics cofiring with Ag electrode makes them a highly promising substrate for microwave communications.