High-temperature heat capacity and thermal expansion of the MnTa2O6

• Published in: Journal of alloys and compounds 2020-09, Vol.834, p.155153, Article 155153
• Main Authors: Gulyaeva, R.I., Petrova, S.A., Chumarev, V.M., Selivanov, E.N.
• Format: Article
• Language: English
• Subjects: Anisotropy; Differential scanning calorimetry; Heat; Heat capacity; High temperature; Manganese; Manganese tantalate; Mathematical analysis; Parameters; Specific heat; Tantalum; Tantalum oxides; Thermal expansion; Unit cell
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2020.155153

The sample of the MnTa2O6 manganese tantalate was synthesized from MnO and Ta2O5 mixture by the ceramic technique. According to XRD it was a single-phase sample with an orthorhombic structure (sp.gr. Pbcn) and unit cell parameters: a = 14.4478(2) Å; b = 5.7677(1) Å; c = 5.0943(1) Å; V = 424.52(1) Å3. Heat capacity was measured by differential scanning calorimetry in the range of 323–1203 K in a dynamic mode. Experimental molar heat capacity was fitted to Сp,m = 191.33 + 67.451 × 10−3 T - 32.71 × 105 T−2 - 18.76 × 10−6 T2 equation based on which the value of the Cp,m298.15(MnTa2O6) = 173.0 ± 1.7 J mol−1K−1 was calculated. By HT-XRD thermal dependences of the MnTa2O6 unit cell parameters in the temperature range of 300–1203 K were established. From the data obtained thermal expansion coefficients and anisotropy factors were calculated. Thermal expansion anisotropy was linked to the layered structure of the oxide. The correlation among molar heat capacity values and volume thermal expansion coefficients were revealed. •High-temperature heat capacity of MnTa2O6 is measured in the range of 320–1200 K.•Temperature dependences of the unit cell parameters for MnTa2O6 are determined.•Thermal expansion coefficients of the MnTa2O6 unit cell are calculated .•Anisotropic thermal expansion of MnTa2O6 in the range of 320–1200 K is revealed.•Correlation between heat capacity and volume thermal coefficient is established.