Narrow Results

Low-temperature co-fired ceramics (LTCC) applied in millimeter/microwave and terahertz frequencies (5G/6G) have attracted a lot of attention recently. In this study, MgO-based dielectric ceramics were successfully sintered at 950°C with the sintering aids: x wt.% of LiF fluoride ($x=2$, 4, 6, 8, 10) and 0.5wt.% of BBSZ (Bi₂O₃–B₂O₃–SiO₂–ZnO) glass. BBSZ glass was introduced as another sintering aid to facilitate the sintering and densification. Crystalline structure and micro-morphology were investigated and analyzed. Dielectric properties (${\epsilon }_r$, $Q\times f$, ${\tau }_f$) at millimeter/microwave and terahertz wave frequencies were also studied. The ionic characteristics of Mg–O bond ($f_i$), the lattice energy (U) and the bond energy (E) were calculated and analyzed. It is suggested that the optimal $x=4$, where ${\epsilon }_r=10.5$, $Q\times f=120,000$GHz (@12GHz) and ${\tau }_f=-26$ppm/°C at millimeter/microwave range. When the frequency was up to terahertz (1.0THz), the ${\epsilon }_r$ values were 8.8–9.35 and the tan$\delta$ were $5.6\times 10^{-3}$–$8.7\times 10^{-3}$. The experimental results indicated that the low-temperature sintered MgO-based ceramics have potential for millimeter/microwave and terahertz communication applications.