The electronic state and microwave dielectric properties of MgAl₂O₄ prepared using solid-state (MA-S) and molten salt (MA-M) methods and those of Mg_0.4Al_2.4O₄ (M04A24) were investigated. The λ values, which correspond to the fraction of Al³⁺ cations in tetrahedral sites, for MA-S, MA-M, and M04A24 were 0.23, 0.41, and 0.60, respectively. In molecular orbital calculations, a larger overlap was observed between Al-3s or Al-3p in tetrahedral sites and O-2p orbitals for M04A24, and the bond order for AlO at tetrahedral sites of M04A24 (0.241) was higher than those for MA-S (0.178) and MA-M (0.205). The dielectric constant, ε_r, for M04A24 (7.6) was lower than those for MA-S and MA-M (both 7.9), and the highest quality factor, Q·f, was obtained for M04A24 (235, 800 GHz). It was found that the covalency of the AlO bonds in the MO₄ tetrahedra is closely related to the Q･f values of the present ceramics.

研究了用固态法（MA-S）和熔盐法（MA-M）制备的MgAl ₂ O ₄的电子态和微波介电性能，以及Mg _0.4 Al _2.4 O ₄（M04A24）的电子态和微波介电性能。对于MA-S，MA-M和M04A24，与四面体位点中的Al ³⁺阳离子分数相对应的λ值分别为0.23、0.41和0.60。在分子轨道计算中，观察到四面体位点的Al-3 s或Al-3 p与M04A24的O-2 p轨道有较大的重叠，并且Al的键序M04A24的四面体位点的O（0.241）高于MA-S（0.178）和MA-M（0.205）的O. 介电常数，ε _{- [R} ，用于M04A24（7.6）显着高于对MA-S和MA-M（均为7.9）低，并且最高品质因数，Q · ˚F，是为M04A24（235，800千兆赫）获得。结果发现，将Al的共价性的O键中号ö ₄四面体是密切相关的Q · ˚F本陶瓷的值。