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We synthesized and characterized (Bi0.4Sr0.6)Sr2CoO5−δ using X-ray diffraction (XRD) and scanning electron microscopy with energy dispersive spectroscopy (SEM–EDS). In the next step the heat capacity and enthalpy increments of (Bi0.4Sr0.6)Sr2CoO5−δ were measured by physical property measurement system (PPMS), differential scanning calorimetry (DSC) and drop calorimetry. Oxygen non-stoichiometry was determined using thermogravimetric measurement (TG) and reduction in hydrogen atmosphere. Above room temperature the temperature dependence of the molar heat capacity in the form Cpm = (201.0 + 0.09261 × T − 2184097 × T−2) J K−1 mol−1 was derived by the least squares method from the experimental data. The heat capacity was also analyzed in terms of a combined Debye–Einstein model. The molar entropy S m ° (298.15) = 219.65 J mol−1 K−1 was evaluated from the low temperature heat capacity data.

The structure and oxygen non-stoichiometry of misfit layered cobaltite Bi1.85Sr2Co1.85O7.7−δ was determined by Rietveld analysis and by thermogravimetric measurements. The heat capacity and enthalpy increments of pseudo-ternary oxide Bi1.85Sr2Co1.85O7.7−δ was measured by the relaxation time method (PPMS) from 2 K to 256 K, by differential scanning calorimetry (DSC) from 258 K to 355 K and by the drop calorimetry from 573 K to 1153 K. Above room temperature the temperature dependence of the molar heat capacity in the form Cpm = (305.8 + 0.07325 · T − 4702536 · T−2) J K−1 mol−1 was derived by the least-squares method from the experimental data. The heat capacity was analyzed in terms of a combined Debye–Einstein model. The molar entropy S m ∘ ( 298.15 ) = 317.7 J mol−1 K−1 was evaluated from the low temperature heat capacity measurements.

Heat capacity and enthalpy increments of two ternary strontium cobalt mixed oxides Sr 14 Co 11 O 33 and Sr 6 Co 5 O 15 were measured by the relaxation time method (2–250 K), DSC (258–355 K) and drop calorimetry (573–1173 K). Temperature dependencies of the molar heat capacity in the form C p m = 1359.46 + 0.355826· T –19.5816·10 6 · T −2 J K −1 mol −1 for Sr 14 Co 11 O 33 and C p m = 515.81+ 0.313326· T –5.07872·10 6 · T −2 J K −1 mol −1 for Sr 6 Co 5 O 15 respectively, were derived by the least-squares method from the experimental data. The heat capacity was analyzed in terms of a combined Debye–Einstein model. The molar entropies at 298.15 K, S m (298.15 K) = 1339.76 J K −1 mol −1 for Sr 14 Co 11 O 33 and S m (298.15 K) = 578.77 J K −1 mol −1 for Sr 6 Co 5 O 15 were evaluated from the low temperature heat capacity measurements.

Heat capacity and enthalpy increments of ternary strontium bismuth(III) oxides SrBi2O4 and Sr2Bi2O5 were measured by the relaxation time method (2–210 K), DSC (253–352 K) and drop calorimetry (570–1072 K). Temperature dependencies of the molar heat capacity in the form Cpm = 161.97 + 45.936 × 10−3 T – 1.7862 × 106/T2 J K−1 mol−1 and Cpm = 197.48 + 87.463 × 10−3 T – 1.9282 × 106/T2 J K−1 mol−1 for SrBi2O4 and Sr2Bi2O5, respectively, were derived by the least-squares method from the experimental data. The molar entropies at 298.15 K, S°m(298.15 K) = 206.1 ± 1.1 J K−1 mol−1 for SrBi2O4 and S°m(298.15 K) = 261.2 ± 1.4 J K−1 mol−1 for Sr2Bi2O5, were evaluated from the low temperature heat capacity measurements.

The heat capacity of the Al3Ni phase had been measured for the first time, by means of relaxation method over the low temperature range 2–323 K and by measuring heat content increments using drop calorimetry over the higher temperature range of 583–1073 K. The Debye function was employed to fit the low-temperature heat capacities, and from the function, the absolute entropy was evaluated, S 298 ∘ = 25.4 J/mol-atoms K . A three-term polynomial representation, a + b·T + c·T−2, was used for describing heat capacity above 298.15 K. The Gibbs energy function of the Al3Ni phase was derived with a fixed reference state by incorporating the polynomial expression of the heat capacity, the recently reported enthalpy of formation and the related phase equilibria in the Al–Ni system. A revised thermodynamic description of the entire Al–Ni system together with the calculated phase diagram is also presented.

The empirical Neumann–Kopp rule (NKR) for the estimation of temperature dependence of heat capacity of mixed oxide is analyzed. NKR gives a reasonable estimate of Cpm for most mixed oxides around room temperature, but at both low and high temperatures the accuracy of the estimate is substantially lowered. At very low temperatures, the validity of NKR is shown to be predominantly determined by the relation between the characteristic Debye and Einstein temperatures of a mixed oxide and its constituents. At high temperatures, the correlation between their molar volumes, volume expansion coefficients and compressibilities takes the dominance. In cases where the formation of a mixed oxide is not accompanied by any volume change, the difference between dilatation contributions to heat capacity of a mixed oxide and its constituents is exclusively negative. It turns out that in the high-temperature range, where the contribution of harmonic lattice vibrations approached the 3NR limit, ΔoxCp assumes negative values. For more complex oxides whose heat capacity has contributions from terms such as magnetic ordering, electronic excitations, the applicability of NKR is only restricted to lattice and dilatation terms.

The heat capacity and the enthalpy increments of strontium niobate Sr2Nb2O7 and calcium niobate Ca2Nb2O7 were measured by the relaxation time method (2–300 K), DSC (260–360 K) and drop calorimetry (720–1370 K). Temperature dependencies of the molar heat capacity in the form Cpm = 248.0 + 0.04350T − 3.948 × 106/T2 J K−1 mol−1 for Sr2Nb2O7 and Cpm = 257.2 + 0.03621T − 4.434 × 106/T2 J K−1 mol−1 for Ca2Nb2O7 were derived by the least-square method from the experimental data. The molar entropies at 298.15 K, S m ° (298.15 K) = 238.5 ± 1.3 J K−1 mol−1 for Sr2Nb2O7 and S m ° (298.15 K) = 212.4 ± 1.2 J K−1 mol−1 for Ca2Nb2O7, were evaluated from the low-temperature heat capacity measurements.

The heat capacities and enthalpy increments of strontium bismuth niobate SrBi 2 Nb 2 O 9 (SBN) and strontium bismuth tantalate SrBi 2 Ta 2 O 9 (SBT) were measured by the relaxation method (2–150 K), Calvet-type heat-conduction calorimetry (305–570 K) and drop calorimetry (773–1373 K). The temperature dependences of non-transition heat capacities in the form C p m = 324.47 + 0.06371 T − 5.0755 × 10 6 / T 2 J K −1 mol −1 (298–1400 K) and C p m = 320.22 + 0.06451 T − 4.7001 × 10 6 / T 2 J K −1 mol −1 (298–1400 K) were derived for SBN and SBT, respectively, by the least-squares method from the experimental data. Furthermore, the standard molar entropies at 298.15 K S m ° ( SBN ) = 327.15 ± 0.80 and S m ° ( SBT ) = 339.23 ± 0.72 J K − 1 mo l − 1 were evaluated from the low-temperature heat capacity measurements.