An EPR and SQUID magnetometry study of bornite

Application of 57Fe Mössbauer spectroscopy as a tool for mining exploration of bornite (Cu5FeS4) copper ore

“…The discrepancies in earlier Mössbauer data (above and below the Neel temperature of 64-68 K) led researchers to different explanations of the nature of the magnetic properties of bornite: vacancy clustering [8,11], mixed-valence state of iron (Fe 2+ -Fe 3+ ) [9] and superparamagnetic relaxation [12]. However, the solution of this problem requires reexamination of low-temperature magnetic properties and Mössbauer parameters [13] together with other methods, and is out of the scope of the research reported here. We can prove here that the Mössbauer spectra for bornite Cu 5 FeS 4 minerals at RT point to the distortions of FeS 4 units in the structure which leads to a quadrupole splitting (Table I), unlike chalcopyrite CuFeS 2 which has no quadrupole splitting [14].…”

Magnetic properties of a new vanadate Cu13Fe4V10O44

“…Another reason may be the dynamic spin density transfer involving the Cu 2 þ nearest to the Fe 3 þ atoms. This would cause formation of iron-copper dynamic pairs: if the exchange coupling between these two ions is antiferromagnetic in nature, this also would result in a lowering of the effective magnetic moment [24]. The most probable explanation seems to be the structural conditions in Cu 13 Fe 4 V 10 O 44 compound that cause copper ions (nominal valence 2 þ, 3d 9 , S ¼1/2) and some iron ions (nominal valence 3 þ, 3d 5 , S ¼5/2) to be magnetically silent in the investigated temperature range.…”

“…A very small effective magnetic moment of Cu 13 Fe 4 V 10 O 44 might have a few origins [24]. One reason may be the inaccuracy of the ionic description of the bulk magnetism in terms of conventional ionic valence states of elemental constituents.…”

Changes in Bornite (Cu5FeS4) after Heating in Air: Mössbauer Effect Study

“…Natural bornite (L-bornite) crystallizes in the orthorhombic structure with space group P bca. Two other cubic polymorphs (space group F m3m) of this mineral are known: a high temperature form (H-bornite), above 262 • C, and an intermediate temperature form (I-bornite) observed in the 200 • C to 262 • C range [1][2][3][4]. Bornite is an interesting compound because it is one of the most important ore minerals for copper [5,6].…”

“…It has special semiconducting and magnetic properties used in several high-tech materials, e.g. diluted magnetic semiconductors [3,4,7]. It shows great potential as a new economical and ecofriendly thermoelectric material.…”