Specific heat anomalies in RMn2(H,D) hydrides

Specific heat of YMn2H and HoMn2H

“…3. The relevant data from Tb-and Er-hydrides [6,10] are also included. Although no straightforward explanation is apparent for the x dependence, the data showed a breaking up at x = 2.0 into two hydrogen concentration regions.…”

Critical Systematic Evaluation and Thermodynamic Optimization of the Mn-RE System (RE = Tb, Dy, Ho, Er, Tm and Lu) with Key Experiments for the Mn-Dy System

“…13, the experimental S 298°o f the Mn 12 Tb from Piqué et al [48] was taken into account, and the S 298°o f the Mn 2 Tb calculated from the low temperature C p measured by Shiga and Wada [49] was believed to be more reasonable than that from Kolwicz-Chodak et al [50] because the C p of Shiga and Wada [49] was coherent with the C p above 298 K evaluated by N-K rule. Moreover, the S 298°o f the Mn 2 Tb calculated from the C p data of Kolwicz-Chodak et al [50] was too small to reproduce the congruent melting of Mn 2 Tb in the phase diagram. The DH 298°o f the compounds were assumed to be the same as those in the Mn-Dy system as seen in the predicted enthalpies of formation from the modified Miedema model (See Table 9).…”

“…Shiga and Wada [49] measured the C p of the Mn 2 Tb from 1.5 to 300 K using an adiabatic calorimeter. The magnetic transition temperature (T N : Néel temperature) was reported to be about 45 K. The calculated S 298°o f Mn 2 Tb was 152.9 J/mol-K. Kolwicz-Chodak et al [50] measured the C p of the Mn 2 Tb using two different methods, a quasi-adiabatic method in the temperature range 50 to 320 K and a relaxation method using Quantum Design physical properties measuring system (PPMS) in the temperature range 2 to 350 K. It was reported that a good agreement was obtained for the data from the two different measurements and the T N was about 47 K. The S 298°w as calculated from the experimental data (136.8 J/mol-K). The Fig.…”

Specific heat and magnetization of RMn2(H,D)2

“…For specific heat measurements the composite pellets of sample material mixed with micron-size copper or silver powder were prepared and measured by using a standard quasi-adiabatic method in the temperature range 50-300 K and by a relaxation method in Quantum Design Physical Properties Measuring System (PPMS) [6]. …”