Synthesis and physical properties of Cr-P-based intermetallic compounds: Cr3P, Cr3PC, and Cr3PN

We report the synthesis, crystal structures and electrical/thermal transport properties of polycrystalline Cr3PX (X = C, N, and vacancy) compounds. As a result, Cr3PC and Cr3PN have an orthorhombic crystal structure with space group Cmcm, while Cr3P shows a tetragonal structure with space group I−4. All samples show good metallic behavior between 2 and 350 K in the measurement of electrical transport. At the same time, the Fermi-liquid behavior is observed at low temperatures for Cr3PC (N) (2-50 K) and Cr3P (2-22 K). Based on the fitting results of low-temperature resistivity and specific heat, large Kadowaki-Woods ratio of Cr3PC (N) and Cr3P were obtained, suggesting a considerably strong electron-electron correlation for all our samples. By analyzing the thermal conductivity data, it is found that the electron thermal conductivity is predominantly stronger than the phonon one at low temperatures for Cr3P. As to Cr3PC and Cr3PN, however, both contributions are comparable in the whole temperature range investigated. Besides, phonon-drag effect was observed in the Seebeck coefficient α(T) curves for all the samples, which may explain the crossover of sign at 70 K in α(T) of Cr3PN.