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Temperature-dependent magnetic susceptibility of marcasite (Fe S 2 )

1979; American Physical Society; Volume: 20; Issue: 9 Linguagem: Inglês

10.1103/physrevb.20.3897

1095-3795

M. S. Seehra, M. S. Jagadeesh,

Mineralogy and Gemology Studies

The magnetic susceptibility $\ensuremath{\chi}$ of a natural sample of marcasite (Fe${\mathrm{S}}_{2}$) has been measured with a Faraday balance in the temperature range 4.2-380 K. For $T<150$ K, the data follow the expression ${10}^{6}\ensuremath{\chi}=64+(\frac{787}{T})$ ${\mathrm{cm}}^{3}$/mole, where the Curie-type contribution is from a magnetic impurity. For $T>180$ K, $\ensuremath{\chi}$ increases weakly with increasing $T$. The estimated $\ensuremath{\chi}$ for pure marcasite varies from 64 \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}6}$ ${\mathrm{cm}}^{3}$/mole at 4.2 K to 68 \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}6}$ ${\mathrm{cm}}^{3}$/mole at 380 K. The observations suggest a low-spin configuration for ${\mathrm{Fe}}^{2+}$ in marcasite leading to Van Vleck paramagnetism, similar to the case of iron pyrite. Some details of the Faraday balance used in these studies are also given.