THE INFLUENCE OF LOW TEMPERATURE (293DEGREESK-4.5DEGREESK) ON STRUCTURE OF MANGANESE-RICH MANGANESE FERRITE

The lattice parameter of two powder samples from the system MnxFe3-xO4 having x-values 1·66 and 1·88, both cubic at room temperature, was measured in the temperature range of 293°K to 4·5°K. An anomalous course was observed of the function lattice parameter vs. temperature but in neither case was there a macroscopic transformation from cubic to tetragonal symmetry or a segregation of a second phase. Moreover, no structural changes could be checked when the sample x = 1·88 was subjected to a magnetic field of about 10 kOe at the temperature of 8°K. Based on the idea of lattice distortions of the second kind a model is proposed of manganese-rich regions, the formation of which may precede the transformation. © 1968.