Reducing-atmosphere resistant mechanism on microwave dielectric enhancement of CaMgSi2O6 glass-ceramics

This work highlights a reducing-atmosphere resistance using amphoteric ion doping to reduce defects and to enhance microwave dielectric properties in CaMgSi2O6 glass-ceramics. Amphoteric Al3+ ion (Al2O3 doping) was selected with both donor and acceptor roles to restrict free electrons and oxygen vacancies in specimens sintered in reducing atmosphere. The X-ray absorption and X-ray photoelectron spectra indicate decreased oxygen vacancies and a valence shift from a mixture of Si2+ and Si3+ to Si4+ in the Al3+-doped CaMgSi2O6 glass-ceramics sintered in reducing-atmosphere. The amphoteric Al3+ ion plays an acceptor role as entering Si4+ site to form oxygen vacancies, meanwhile Al3+ plays a donor role as entering Mg2+ site to compensate free electrons. The amphoteric Al-doped diopside glass-ceramic can increase the electric resistivity and quality factors. This work can provide an efficient approach for the base-metal-electrode (BME) in low-temperature co-fired ceramics (LTCC) and multilayer ceramic capacitors (MLCC).