QUANTITATIVE INTERPRETATION OF TG AND DTG CURVES OBTAINED FOR SOME FERROMAGNETIC SUBSTANCES IN LOW INTENSITY AC GENERATED MAGNETIC-FIELD

Earlier studies on the possibility of magnetochemical analysis, employing a simultaneous TG-DTG-DTA method, have been extended. Several magnetic samples of different chemical compositions, e.g. spinels, garnets and hexagonal ferrites, were examined. Investigations involved both soft (NiFe2O4, MnMg ferrite, Y3Fe5O12) and hard magnetic materials such as BaFe12O19, SrFe12O19. The capability of the method, referred to in the following as DTMG, for the qualitative and the quantitative analysis of a wide variety of magnetic materials is proposed. The results are discussed in terms of the basic magnetic parameters such as a magnetocrystalline anisotropy, magnetic moment and ferromagnetic Curie point temperature, Tc. The relationship between DTMG line intensities and concentrations of the respective magnetic substances was found. The results are interpreted on the basis of the Curie point measurements by means of DTMG curves in the temperature range between 20 and 1200°C. It is a proposal to call the TG and DTG curves taken simultaneously in the presence of an alternating magnetic field as the TMG and DTMG curves, respectively. The term DTMG stands for Derivative Thermo-Magneto-Gravimetry. The idea of the method has been developed in this laboratory. The DTMG method is capable of good precision within resonable time. The method can be applied to polycrystalline as well as to single crystals of the magnetic materials and the sample can be in the solid or powder state. © 1979.