Homogeneity range of the NaTl-type Zintl phase in the ternary system Li–In–Ag

The remarkably broad homogeneity range of the NaTl-type Zintl phase in the ternary phase diagram Li–In–Ag at room temperature was determined by structure evaluation using X-ray powder diffraction. The colours of the investigated Zintl phases correlate with the valence electron concentration (VEC) as already established for the quasibinary cut Li0.5(InxAg1−x)0.5 with image, i.e. with decreasing VECs the colour changes from grey over reddish to bright yellow. All compounds in the new quasibinary cut Lix(In0.5Ag0.5)1−x with image appear free from vacancies in the Li-sublattice, even for Li-deficient compositions. The partial occupation of Li-sites by excess Ag and In instead is in full agreement with the behaviour of the binary NaTl-type Zintl phases LixZn1−x and LixCd1−x (image) with a low VEC about 1.5.