Single crystals of UN, UAs, and USb have been examined by x-ray diffraction at low temperatures to measure the lattice parameter and search for lattice distortions associated with the magnetic ordering. We have been unable to find any distortion, implying that the external strain is less than 2 × ${10}^{-4\mathrm{}}$ in all three materials. Significant changes in the volume accompany the magnetic ordering and the first-order I-IA transition in UAs. We do, however, observe a small line broadening of the diffraction profile in all three materials as the temperature is lowered. The possible origins of this are discussed.

• Received 16 July 1979

DOI:https://doi.org/10.1103/PhysRevB.21.4159