A pure spinel-type phase was attained by solid state reactions at room temperature, with no intermediate compounds. Its formation and the structural evolutions have been characterized by thermogravimetry-differential scanning calorimetry (TG/DSC) tests, X-ray diffraction (XRD) and scanning electron microscopy (SEM). Related electrical analyses were also performed. The results showed that the powders and ceramics prepared by the solid state reactions at room temperature exhibit a good electrical property because of narrow grain size distribution, controlled morphology, and high purity. Most importantly, this new approach greatly simplifies the preparation processes.