Phase‐transition variation with composition in solid solutions of K 2 Cd 2 (SO 4 ) 3 with Tl 2 Cd 2 (SO 4 ) 3

Polycrystalline samples of (K x Tl 1 − x ) 2 Cd 2 (SO 4 ) 3 have been prepared with x = 0[0.125]1.0. The phase transition temperature, liquidus and solidus temperatures, lattice parameters and unit‐cell volume at 298 K have been determined for each composition. The phase transition temperature varies linearly with x for 0.125 ≤ x ≤ 1.0, and the solidus curve varies linearly with x over the entire range. Mixed crystals are cubic at 298 K for x ≤ 0.645 and are orthorhombic at higher values of x . The cubic lattice parameter varies linearly with x for 0.125 ≤ x ≤ 0.645, the lengths of the orthorhombic a , b and c axes vary linearly with x for 0.645≤ x ≤ 1.0, and the unit‐cell volume varies linearly with x for 0.125≤ x ≤ 1.0.