Transition to metal conductivity in liquid Tl-Se alloys in the region of the intermetallic compound Tl2Se

Experimental investigations of the electrical conductivity sigma (T) and th ermo-electromotive force S(T) were performed for liquid Tl-Se alloys in the region of the stoichiometric compound Tl2Se in the wide temperature range from 600 to 1800 K. It was shown that there is no unified approach to the a nalysis of the electronic properties of Tl-Se alloys with an excess of Se o r Tl relative to Tl2Se. The results are interpreted assuming that an initia l matrix can be doped by donor impurities (Tl or Se). Due to their structur e, there are different alloys with a predomination either of hole or electr on carriers. With an increase of the Se content, a gradual transformation o f the electron spectrum is connected with changes in the acceptor zone at t he edge of the conducting band.