A new layer structure compound PrRh4.8B2 was obtained by a molten metal flux growth method, using Cu as a flux. This compound belongs to the orthorhombic system with the space group Fmmm. Lattice parameters were a=0.9697(4)nm, b=0.5577(2)nm and c=2.564(3)nm. The structure of the compound is of a modified CeCo3B2-type, which is explained by a stacking model of Pr-B and rhodium layers. X-ray photoelectron spectra were taken under three conditions: (i) surface of fractured in the vacuum of the spectrometer; (ii) surface exposed to air after fracture in the spectrometer; and, (iii) surface fractured in air. The X-ray photoelectron spectroscopic study and electron probe micro-analysis results show that a few monolayers of Cu atoms exist between the crystals of PrRh4.8B2. The thermo-gravimetric curve shows that oxidation of the PrRh4.8B2 proceeds above 873K. Weight gain of the specimen heated up to 1473K in air is 13.44%. Sample forms PrBO3 and Rh as a result of the oxidation. The temperature dependence of the inverse static magnetic susceptibility χ-1 obeys the Curie-Weiss law at temperatures above 50K. The magnetic moment μeff is 4.2μB and the Curie-Weiss temperature Θp is-13K. The value of micro Vickers hardness for c-plane with the orthorhombic symmetry of PrRh4.8B2 is 6.7±0.6GPa.
