Sp. Taneja et Vk. Garg, MOSSBAUER AND MAGNETIC STUDY OF BRAUNITE MINERAL, Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms, 76(1-4), 1993, pp. 239-241
Braunite mineral from Triodi (India) (21-degrees-41'N, 79-degrees-47'E
) manganese deposits has been studied by Mossbauer spectroscopy, and m
agnetic susceptibility. The room temperature Mossbauer spectrum shows
a well resolved quadrupole splitting which has been attributed to the
substitution of iron in Mn(2) site. Emergence of another doublet at li
quid nitrogen temperature has been attributed to the location of small
quantities of iron in Mn(4) site. Iron is in FeIII and high spin stat
e. At 60 K a poorly resolved sextet and a well resolved doublet is obs
erved. Collapse of Mossbauer spectrum at 50 K has been attributed to s
pin-lattice relaxation and below this temperature there are two sextet
s of internal magnetic fields of the order of 415 kOe each. One magnet
ic transition is between 70 and 60 K while the other magnetic transiti
on is between 60 and 50 K.