The charge transfer and ion formation in liquid Li–Tl alloys

The ⁷Li NMR Knight shift, K, and the spin-lattice relaxation time, T₁, were measured for liquid Li–Tl alloys. The K decreases rapidly with the addition of Tl up to 20 at.% Tl. In the concentration from 20 to 50 at.% Tl, the K decreases only slightly and the K of 50 at.% Tl is 60% of K for the pure liquid Li. Such a decrease of K is considered as an indication for the strong charge transfer from Li to Tl. These tendencies are similar to those from previous studies for liquid Li–Ga and Li–In alloys. However, beyond 50 at.% Tl, the K increases and reaches to an almost constant value (70% of K for the pure liquid Li). Such a back donation of charge is absent for liquid Li–Ga and Li–In alloys. It is considered that the tendency of the formation of ionic structural unit for liquid Li–Tl alloys is slightly weaker compared with the cases of liquid Li–Ga and Li–In alloys. The T₁ is also discussed with the relation to the Knight shift and the electronic properties.