Espectroscopia Müssbauer da Jacobsita : (Mn,Fe)304, tratada termicamente

Abstract

Mõssbauer spectroscopy and x-ray powder diffraction have been used to study the natural manganese ferrite known as jacobsite (Mn,FeJ3 o 4 , after calcination at temperatures varying from 400 °C up to 1160° c. It is shown that calcfnation at 40o 0 c results in the destruction of defects such as vacancies. Calcination at temoeratures between 400 ° c and 900°c results in the formation of hematite anct bixbyite ( M n , F e ) 2 O 3 . The room temperature Mõssbauer spectrum of samples calcined above 900º c indicate that the hematite and the bixbyite transform, as the calcination temperature is increased, gradual ly into synthetic manganese ferrite. The room temperature Mõssbauer spectrum of bixbyite indicates that the sample is in the paramagnetic phase. At low temperature, 15K, the results show that the sample exhibits a magnetic order. The results suggest that Mõssbauer spectroscopy of ferrites can supply information about the thermal history of the samples.