The temperature dependencies of the unit cell volumes of rs-Mn 1-x Zn x O solid solutions are presented in Fig. . For the stoichiometries 0.2 ≤ x ≤ 0.4, unit cell volumes change non-linearly with temperature. The corresponding coefficients α 1 and α 2 of Eq. ( ) are given in Table . For the equilibrium cubic solid solution (x = 0.1), as well as for pure rs-MnO, a practically linear dependence V(T) is observed (coefficient α 2 is small), whereas for the metastable solid solutions (x = 0.2, 0.3, 0.4) this dependence is quadratic (coefficient α 2 is relatively large).