Ultra low loss (Mg1-xCax)2SiO4 dielectric ceramics (x=0 to 0.15) for millimeter wave applications

(Mg1 - xCax)(2)SiO4 dense ceramics (x >= 0.15) were prepared, and their microwave dielectric characteristics were investigated together with the structure evolution. The sintering temperature for Mg2SiO4 ceramics was reduced significantly with Ca(2+)substitution. (Mg1 - xCax)(2)SiO4 ceramics exhibited a small increase in dielectric constant (epsilon(r)) correlated with increased crystallite size, and ultra-high quality factor Qf value was achieved throughout the compositional range. Temperature coefficient of resonant frequency (tau(f)) was considerably tuned from -70 ppm/degrees C to -33 ppm/degrees C, and this improvement was deeply linked with the decreased bond valance. At x = 0.075, (Mg1 - xCax)(2)SiO4 ceramics exhibited the best combination of microwave dielectric characteristics: epsilon(r )= 7.2, Qf = 199,800 GHz at 26 GHz, tau(f )= -33 ppm/degrees C. The present ceramics could be expected as promising candidate of dielectric materials for millimeter wave applications.

Automated summary

(Mg1-xCax)(2)SiO4 dense ceramics were prepared and their microwave dielectric characteristics were investigated with Ca(2+) substitution reducing sintering temperature significantly. The ceramics exhibited an increase in dielectric constant with increased crystallite size, achieving ultra-high quality factor Qf value throughout the compositional range, and the best combination of microwave dielectric characteristics at x = 0.075.