Effects of BaCu(B 2 O 5 ) additives on the crystal structures and dielectric properties of CaMgGeO 4 ceramics for LTCC applications

• Published in: CrystEngComm Vol. 22; no. 28; pp. 4768 - 4777
• Main Authors: Xiao, En-Cai, Shi, Feng, Fu, Guangen, Ren, Qi, Dou, Gang, Lei, Wen, Qi, Ze-Ming
• Format: Journal Article
• Language: English
• Published: 20.07.2020
• ISSN: 1466-8033; 1466-8033
• DOI: 10.1039/D0CE00620C

A CaMgGeO 4 (CMG) ceramic with an olivine structure was fabricated by the traditional solid-phase reaction method; this material was dense at 1300 °C/6 h and exhibited excellent dielectric properties ( ε r = 6.83, Q × f = 125 432, f = 14.9 GHz). The effects of BaCu(B 2 O 5 ) (BCB) on the sintering characteristics, crystal structures and microwave dielectric properties of CMG systems were studied. BCB can effectively reduce the sintering temperature ( T s ) of the CMG ceramic, and when the amount of BCB is 16 wt%, the T s can be lowered to 875 °C. The CMG ceramic containing 8 wt% BCB shows excellent dielectric properties ( ε r = 7.01, Q × f = 73 962, f = 14.8 GHz) at 940 °C/6 h. Raman mode 11 moves to a lower wavenumber with increasing BCB content, while the BCB content has the opposite effect on the dielectric constant; however, the full width at half-maximum (FWHM) value of mode 11 correlates negatively with the Q × f values. In addition, the change in the packing fraction is similar to that in the Q × f values with increasing BCB content. A decrease in the packing fraction means an increase in the vibrational space and possibly non-resonance, which in turn reduces the Q × f value. In addition, the ceramic has good chemical compatibility with the Ag electrode, indicating broad application prospects in low-temperature co-fired ceramics (LTCCs) for CMG.