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Results are presented for lattice-parameter and magnetic-susceptibility measurements on a series of solid solutions SmSb"S~". Low-temperature magnetic-susceptibility measurements indicate an inhomogeneous mixed valence for alloys containing low antimony concentrations and a homogeneous intermediate valence at larger concentrations. The susceptibilities of antimony-rich samples illustrate the disappearance of the antiferromagnetic ordering observed in pure SmSb. The alloys of intermediate composition display a nonmagnetic ground state associated with intermediate valence of the samarium cations. The effect of slight sulfur substitution in SmSb on crystalline electric fields is also discussed.

In this paper, the authors will delineate between two approximations and demonstrate the importance of making the equilibrium assumption at the appropriate step in the calculation.

Results are presented for the lattice parameter and magnetic susceptibility as a function of temperature for a series of solid solutions of SmS with SmP. At room temperature the SmS~"P"alloys with x «0.06 exhibit a metallic appearance and a much smaller lattice constant and magnetic susceptibility as compared with SmS. For x «0.15 the susceptibilities do not show a Curie-law divergence or magnetic ordering. These properties are consistent with the Sm ions being in a homogeneous intermediate-valence state similar to that of SmS under pressure. The intermediate valence estimated from the lattice parameter is 2.8 at x =0.06 and increases toward the pure trivalent value with increasing phosphorous concentration. Also, the color of the alloys changes from gold to red to silver grey. The alloys with 0.03 & x (0.06 exhibit a varying mixture of two distinct phases, the gold intermediate-valence phase and the black phase characteristic of the x (0.03 alloys. The properties of the black phase are consistent with a mixture of Sm + and Sm + ions where Sm ions with one or more P ions as nearest neighbors are trivalent. The 0.04~x «0.08 alloys exhibit a transition from the gold phase to the black phase with decreasing temperature. This transition which is continuous at higher concentrations changes to a discontinuous one near x =0.06 as seen in the temperature variation of the lattice parameter.