Solid solutions of a Jahn-Teller compound in an undistorted host. 3. The chromium/zinc Tutton salt system

A series of solid solutions of a Jahn-Teller active compound in an undistorted host has been studied by single-crystal X-ray diffraction. The end members and nine isotypic samples of the Tutton salt system (NH 4 ) 2 [Cr x Zn 1-x (H 2 O) 6 ](SO 4 ) 2 , with x varying from 0.07 to 0.93, crystallize in the monoclinic space group P2 1 /c with Z=2. The unit cell parameters vary slightly with composition, and fall within the following ranges: a, 6.247(1)-6.274(1) A; b, 12.498(3)-12.531(2) A; c, 9.239(1)-9.321(2) A; β, 106.84(1)-106.43(1) o . Except for β, the variations of these parameters are not monotonic at high Cr concentrations