PHYSICAL PROPERTIES OF ALPHA AND GAMMA ARSENIC,

The unit cell dimensions and the electrical and magnetic properties of crystalline a arsenic have been measured as a function of temperature. The resistivities at 293K parallel and perpendicular to the major trigonal crystallographic axis and the temperature coefficients are given. The magnetic susceptibilities of a single crystal specimen at 292K were measured. The signs and magnitudes of these values were confirmed by the determination of the magnetic anisotropy of three single crystals in a homogeneous field. The susceptibilities of several polycrystalline specimens are recorded and discussed. The hexagonal unit cell dimensions at 295.6K are a 3.75980.0003 A c 10.547 0.002 A. Between 295 and 673K there is little or no change in the unit cell parallel to the basal plane. The coefficient of expansion along the c axis is 47.000002deg. No evidence was found for a second order transformation in alpha As at ca. 500K as suggested by Klemm. Amorphous alpha arsenic is diamagnetic, the susceptibility at 298K being -22.6 .000003 emug atom. The susceptibility is only slightly temperature dependent from 80 to 450K. Author