THERMODYNAMIC AND ELECTROPHYSICAL CHARACTERISTICS OF THE Nd₂O₃–MgO–NiO–Mn₂O₃ SYSTEM

Kasenov, B.K.; Kasenova, Sh.B.; Sagintayeva, Zh.I.; Kuanyshbekov, E.E.; Turdiev, M.T.

THERMODYNAMIC AND ELECTROPHYSICAL CHARACTERISTICS OF THE Nd₂O₃–MgO–NiO–Mn₂O₃ SYSTEM

Kasenov B.K., Kasenova Sh.B., Sagintayeva Zh.I., Kuanyshbekov E.E., Turdiev M.T.

Chemical and Metallurgical Institute named after J. Abishev

100009, Karaganda, Republic of Kazakhstan, Ermekova Street, 63

Modification and combination of alloying elements in NdMnO₃-based compounds allow for the production of materials with valuable physical and chemical properties.

In the Nd₂O₃-MgO-NiO-Mn₂O₃ system, the compound NdMg₂NiMnO₆ was synthesized using a high-temperature ceramic method at 400–1200 °C.

The temperature dependence of the heat capacity of NdMg₂NiMnO₆ in the range 298.15–673 K was studied using the IT-C-400 calorimeter, the principle of operation of which is described in detail in [1].

The temperature dependence of the heat capacity of NdMg₂NiMnO₆ shows λ-shaped peaks at 348 and 473 K, which are probably related to phase transitions. Using these peaks, the following equations for C⁰_p~f(T), [J/(mol⋅K)], have been calculated:

С⁰_р = -(75±3) + (1024±41)⋅10^-3Т, (298-348 К)

С⁰_р = (1004±40) - (2077±84) ⋅10^-3Т, (348-398 К)

С⁰_р = (2109±85) - (2286±92) ⋅10^-3Т -(1618±65) ⋅10⁵Т^-2, (398-473 К)

С⁰_р = (1187±48) -(1867±75) ⋅10^-3Т, (473-548 К)

С⁰_р = (541±22) + (33±1,32) ⋅10^-3Т -(1185±48) ⋅10⁵Т^-2. (548-673 К)

S⁰(298,15) of the NdMg₂NiMnO₆ compound is estimated by the method of ion entropy increments of Kumok. Using the experimental dependence of C⁰_p~f(T) and the calculated S⁰(298,15), C⁰_p(T), S⁰(T), H⁰(T)-H⁰(298,15), Ф^xx(Т) are determined.

Using the LCR-781 setup in the 293-483 K (1, 5, and 10 kHz) range, it was found that the dielectric constant of NdMg₂NiMnO₆ increases sharply with increasing temperature (ε ≈ 1.16×10⁷ at 483 K), while the resistance decreases (1.53×10⁶ → 1.38×10⁴ Ohm), confirming the semiconductor nature of the conductivity.

1. Kasenova Sh.B., Sagintaeva Zh.I., Kasenov B.K., Kuanyshbekov E.E., Ordabaeva A.T., Isabaeva M.A. Heat Capacity and Thermodynamic Characteristics of Sodium and Potassium Nickelite-Manganites of Neodymium of NdNa₂NiMnO₅ and NdK₂NiMnO₅ // Applied Sciences, 2025, 15, 6751. https://doi.org/10.3390/app15126751

This research has been/was/is funded by the Science Committee of the Ministry of Science and Higher Education of the Republic of Kazakhstan (Grant No. AP23486147).