Magnetic heat capacity antiferromagnet

Heat capacities taken over the range 1.3°-20°K. 19) show an extremely narrow peak at 4.58 0.03 °K. at the EuSe ferromagnetic Curie temperature and one at 9.64 0.06 °K. in EuTe identified with the antiferromagnetic transition. The magnetic transition entropy increments are 4 and 3 cal./(mole °K.). 

The adopted values are based on the low temperature heat capacities by Hu and Johnston (, 15-297 K) and the high temperature enthalpies by Mah et al. (3, 410-1400 K). Changes are made where appropriate to adjust to the 1975 atomic weights (20) and the IPTS-68 temperature scale (2 ). A small anomaly in the heat capacity is observed in the 210-230 K region. Magnetic measurements of O Keefe and Stone (22) and neutron diffraction studies of Brockhouse (23) suggest that this is a Neel point associated with antiferromagnetism. 

The heat capacity of anhydrous nickel chloride was studied between 15 to 300 K. The anomalous region associated with the transition from the antiferromagnetic to the paramagnetic state was investigated in detail. A maximum of C° T) was found near 52 K. This temperature corresponds with the temperature of the magnetic susceptibility maximum within the accuracy of the magnetic measurements. 

The measurements carried out in [68KOS] were discussed from the point of view of the magnetic spectrum of layered antiferromagnets. The molar heat capacities of NiCl2 from... 

The heat capacities of the non-magnetic oxychalcogenides ThOS(cr) and ThOSe(cr) and of the isomorphous antiferromagnetic UOS(cr) and UOSe(cr) were measured from ca. 5 to ca. 300 K. The samples were prepared by mixing stoichiometric amounts of the dioxides and disulphides and annealed in vacuo in silica tubes at 1273 K for three days. X-ray diffraction analysis of the thorium compounds showed the expected PbFCl structure. For ThOS, a weak extra line due to Th02 was detected, and for ThOSe, several non-identified very weak extra lines were foimd. For the adiabatic heat capacity... 

HojFcjSij crystallizes with the SCjFCjSij-type of structure P4/mnc, a = 10.39(1), c = 5.44(1) (X-ray powder analysis, Braun, 1980). Ho2FejSi5 orders antiferromagnet-ically at = 2.9 K. Magnetic susceptibility data = 10.4(1) jUg and = 0.3(7)] as well as Mossbauer spectra indicate the absence of a magnetic moment at the iron site (Braun et al., 1981). For sample preparation, see Dy2FejSi5. For low temperature heat capacity data, see Vining and Shelton (1983), = 2.82 K. Yarovets (1978)... 

Fig. 9. Temperature dependence of the magnetic susceptibility in paramagnets, ferromagnets and antiferro-magnets. Below the Neel temperature of an antiferromagnet the spins have antiparallel orientations the susceptibility attains its maximum value at where there is a well-defined kink in the curve of / vs. T. The transition is also marked by peaks in the heat capacity and the thermal expansion coefficient.

The low temperature heat capacity and magnetic properties of CeNiSn2 were measured by Pecharsky et al. (1991). The susceptibility follows the Curie-Weiss law from 40 to 300 K, at 4 K CeNiSn2 undergoes an antiferromagnetic transition. 

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