Y1-xSe with the NaCl-type structure above 275°C and a defect ordered superstructure below 275°C was prepared and analyzed by powder X-ray diffraction. The ordered superstructure has cubic symmetry with twice the NaCl-type a parameter. The data favor a structure with Fd3m symmetry.
The polycrystalline samples of (UAs)x(YSe)1-x solid solutions with 0.90 ? x ? 0.30 were measured in constant and pulsed high magnetic fields in the temperature range 4.2-200 K. The simultaneous replacing of uranium and arsenium atoms