“…In particular, adopting low melting‐point additives is the most effective and least expensive method, because the liquid phases during sintering can promote the densification and gain coarsening at low temperature. Therefore, in literature, the dielectric properties of many microwave ceramics have been investigated while different additives such as V 2 O 5 , CuO, LiF, and B 2 O 3 were adopted 31‐41 . Specifically, B 2 O 3 is a widely applied low melting‐point additive to aid sintering 27,37‐41 .…”