Crystal Structures and Electrical Properties of Alkali Antimonides

抄録

Both X-ray study and electrical measurement were simultaneously carried out keeping the specimen in vacuum. In K–Sb and Na–Sb, the crystallization into the hexagonal structure from amorphous state and the transition from p-type semiconductor to n-type one occur simultaneously with successive activation by alkali metal. But Cs–Sb keeps constantly p-type in spite of the crystallization into the cubic structure from amorphous state. In Rb–Sb, the transition of the structure occurs, i.e., amorphous→cubic→hexagonal, and n-type conduction appears in the hexagonal structure. In order to explain these facts, the relation between the excess alkali atoms and the crystal structure was considered.
The cubic phase of Rb₃Sb was found to be the same as the structure of Cs₃Sb. The unit cell (a=884±0.02Å) is described by the space group Fd3m–O_h⁷ with eight rubidium atoms at (0, 0, 0; 0, \frac12, \frac12; \frac12, 0, \frac12; \frac12, \frac12, 0)+0, 0, 0 and \frac14, \frac14, \frac14 and four antimony and four rubidium atoms occupying at random the other positions (0, 0, 0; 0, \frac12, \frac12; \frac12, 0, \frac12; \frac12, \frac12, 0)+\frac12, \frac12, \frac12 and \frac34, \frac34, \frac34.