Қазақ ұлттық қыздар педагогикалық университеті / Казахский национальный женский педагогический университет

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    Synthesis and electrophysical characterization of a three-phase Ca–Nd–Mn–Ni–O oxide system
    (Nature Portfolio, 2026-06-25)
    Zhenisgul Imangalievna Sagintaeva
    ;
    Shuga Bulatovna Kasenova
    ;
    Bulat Kunurovich Kasenov
    ;
    Erbolat Ermekovich Kuanyshbekov
    ;
    Aigul Tanirbergenovna Ordabaeva
    The three-phase Ca-Nd-Mn-Ni-O oxide system was synthesized by a conventional solid-state ceramic method. The phase composition was investigated by X-ray diffraction (XRD) analysis using the PDF-5+/Rigaku SmartLab Studio II software package and was further confirmed by Rietveld refinement employing the GSAS-II software suite. According to the WPPF/Rietveld refinement results, the synthesized material predominantly consists of the Nd₀.₂₅Ca₁.₇₅MnO₄ phase (67.2 wt%), together with the perovskite-like Ca₀.₅Nd₀.₅Mn₀.₉₇Ni₀.₀₃O₃ phase (25.6 wt%) and a minor (Ni₀.₉₄Mn₀.₀₆)O phase (7.2 wt%). SEM analysis revealed an agglomerated granular morphology with porous regions, while elemental mapping confirmed the presence of Ca, Nd, Mn, Ni, and O in the synthesized material. FTIR spectroscopy showed characteristic metal-oxygen vibrational bands associated with [MnO₆] and [NiO₆] octahedral units. The electrical properties were investigated in the temperature range of 293-483 K at a frequency of 1 kHz. The material exhibited semiconducting behavior, and the calculated activation energies of electrical conduction were found to be 0.49 and 0.56 eV for the temperature intervals of 293-353 K and 393-483 K, respectively.
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    Combined-Method Synthesis of CaTiO3 and SrTiO3 Perovskites with n-Hexane: Impact on Structure and Microstructure
    (2026-07-17)
    Zh.A. Abdimomyn
    ;
    M.M. Mataev
    ;
    Zh.I. Tursyn
    ;
    A.N. Torgaeva
    ;
    K. Ramachandran
    This study reports the synthesis of CaTiO3 and SrTiO3 with a perovskite structure by a combined route involving preliminary wet mixing of CaCO3/SrCO3 carbonates and TiO2 in n-hexane, followed by a solid – state reaction during high-temperature calcination. The phase composition and crystal structure of the obtained materials were examined by X-ray diffraction with Rietveld refinement, while the microstructure and elemental distribution were studied using SEM\EDX, and local structure and surface groups were probed by ATR– FTIR spectroscopy. It is shown that the presence of the organic solvent and the applied thermal treatment lead to the formation of single-phase CaTiO3 and SrTiO3 with orthorhombic and cubic modifications, respectively, and with crystallographic parameters with reference PDF cards. The average crystallite size calculated using the Sherrer equation confirmed the nanocrystalline nature of the powders, whereas SEM/EDX analysis reveals a highly porous microstructure and a homogeneous elemental distribution without noticeable metallic impurities. It is established that A-site cation substitution Ca2+/Sr2+ in combination with n-hexane wet mixing induces systematic changes in lattice symmetry, IR band positions and agglomerate morphology, enabling targeted tuning of the texture and potential functional properties of perovskite titanates. The proposed combined approach is a technologically simple and scalable method for producing nanostructured oxide perovskites that are promising as supports and active phases in catalytic systems for combustion processes, plasma-chemical oxidation and functional ceramics.