The Magnetic Susceptibility of MnO as a Function of the Temperature

The magnetic susceptibility of manganous oxide for temperatures from 26 to -202°C.—There is a sharp discontinuity in the susceptibility-temperature curve at the same point, $t=-156\mathrm{}°$C, as that in the specific heat temperature curve and a second one at a lower temperature, -188°C. The mass susceptibility at 26°C was found to be $\chi =68.6\mathrm{}\times {10}^{-6\mathrm{}}$ c.g.s. units. At -38.4°C, $\chi =73.6\mathrm{}°\times {10}^{-6\mathrm{}}$. At -154.7°C, $\chi =85.8\mathrm{}\times {10}^{-6\mathrm{}}$. At -188°C, $\chi =78.1\mathrm{}\times {10}^{-6\mathrm{}}$. At -202°C, $\chi =91.4\mathrm{}$. The susceptibility-temperature curve follows Weiss' modification of Curie's law down to $t=-156\mathrm{}°$C. The constants of this law were found to be $C=0.0575\mathrm{}$ and $\theta =-548\mathrm{}°$K. The number of Bohr magnetons in the compound calculated from experimental data is 5.7.