Study of Transition Temperatures through Mixed Crystal Formations. Part-III.

It has been previously reported that a new method has been developed in determining transition temperatures with a radioactive isotopes. The component whose transition temperature is to be deter­mined is at tracer level and does not manifest its existence as such but gives its evidence through mixed crystal formation. Study of distribution coefficient of a morphologically analogous host having a greater range of stability with the guest at tracer level gives a prominent break at the transition temperatures of the guest component. This new method of approach has been applied in the present investigation to the study of transition temperatures of orthorhombic and monoclinic Mn.SO₄.7H₂O-6H₂O. Ferrous sulphate (FeSO₄.7H₂O) was taken as host for monoclinic variety and MnSO₄.7H₂O was the host for ortho­rhombic variety. Homogeneous distribution factors at different temperatures was studied with these two hosts and ⁵⁴Mn as guest at tracer level. Transition temperatures of orthorhombic and monoclinic variety of MnSO₄.7H₂O-6H₂C) has been found respectively to be 10°± 0.5° and 10.5°±0.5°. Orthorhom­bic MnSO₄.7H₂O is metastable with respect to monoclinic variety. The transition temperatures of these two varieties are near about the same and similar to ZnSO₄.7H₂O which has been previoaly reported¹⁺².