The transition metal fluorides KMF3 (M = Mn, Co, and Ni) were synthesized through a simple solution route. The crystal structure, morphology and electrical transport property of the resulting products were investigated. The compound KMF3 crystallizes in a cubic perovskite structure with space group Pm-3m (No. 221). A crystal structure of KMF3 was refined by the Rietveld method based on the X-ray powder diffraction data. The unit-cell parameters are 4.189 46(4), 4.075 58(4), and 4.025 70(2) for KMnF3, KCoF3 and KNiF3, respectively. A metal–insulator transition was observed in temperature-dependent electrical transport characterization in the temperature range from 250 to 280 K for these three compounds, which is considered to be related to spin-exchange in this kind of material.
