Low temperature heat capacity and thermodynamic properties of zinc ferrite

Abstract

The heat capacity of zinc ferrite (ZnFe,O,) has been determined over the range 5 to 350°K. Molal values of C~,S', and HO-H,O computed from the thermal data are 32,99&t-0.03 cal/deg., 36.01 f0.03 cal/deg., and 18,00&0.02 Cal, respectively, at 298,lS"K. A co-operative thermal anomaly associated with antiferromagnetic ordering occurs at 9.5" and extends toward higher temperatures probably as a consequence of persisting short range order.

Ferrimagnetic zinc ferrite fine powders

“…llus is shown in Fig. 1, where data for the normal curve is taken from the literature [4]. The high temperature data are mostly associated with lattice vibration, which is greatly enhanced in the asprepared powders.…”

Structure of Spinel

“…50 The scientific literature is overrun with debate regarding the centrosymmetric versus noncentrosymmetric nature of spinel structures, especially for the mineral compound MgAl 2 O 4 . 51 [60][61][62][63] However, other metallic spinels, such as the strongly coupled superconductor CuRh 2 Se 4 , seem to conform to Fd3m symmetry. 64,65 In regard to the symmetry of spinel, it is interesting to consider the results of recent electronic structure calculations for the compounds MgAl 2 O 4 , MgGa 2 O 4 , and MgIn 2 O 4 .…”

Immiscibility in the nickel ferrite–zinc ferrite spinel binary

“…[17 -19] an apparent error exists in the zinc ferrite heat capacities plotted in Fig. 1 of Vologin [18]: it is necessary to multiply the reported values of C V /RT by a factor of 7.6 in order to reproduce the values reported by Westrum and Grimes [17]. )…”

“…Residual is plotted along bottom axis of graph. Calculated vs. experimental [17,18] heat capacity of franklinite. Residual is plotted along bottom axis of graph.…”

“…by the polynomial ln │-σ n mag (T)/R│ = d n + e n T 3 (17) where the d n coefficients were constrained to give the T = 0 intercept, i.e., d n = ln )S n mag (∞)/R, and the e n coefficients were related to the Curie temperatures for solid solutions in the (Ni 1-n Zn n )Fe 2 O 4 spinel binary. The composition dependency of )S mag (∞) was modeled by linearly interpolating between end-member values )S n mag (∞)/R = 3.160 n + 4.121 (1 -n) (18) while the measured Curie temperatures [9] were fitted to a third order Redlich-Kister and by less than 16 K from the results of Landiya et al [26].…”