Publications by authors named "B A Makeev"

New remains of a Taymyr mammoth, including bones, bone collagen, hairs, skin, and soft (muscle and fat) tissues were studied comprehensively by mineralogical, spectroscopic, chromatographic, and isotope-geochemical methods. The results were used to infer the mammoth's biological age and diet, paleoclimatic conditions, and the mechanisms and degree of fossilization of the remains.

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Article Synopsis
  • Investigated the phase formation of complex pyrochlores (BiMg(Zn)NiTaO) during solid-phase synthesis, finding that α-BiTaO serves as a precursor, with significant reactions occurring above 850-900 °C.
  • Analyzed the effect of magnesium and zinc on synthesis, determining reaction temperatures of 800 °C for magnesium and 750 °C for nickel, alongside changes in the unit cell parameters with temperature variations.
  • Found that nickel-magnesium pyrochlores have a porous microstructure with 20% porosity while nickel-zinc variants are dense with under 10% porosity, with optimal conditions for pure phase production established at 1050 °C for 15 hours.
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The pyrochlore-type solid-solution formation in a BiMgCuTaO system, synthesized for the first time, is observed at ≤ 0.56. High-temperature X-ray diffraction showed that the pyrochlore phase exists in air up to 1080 °C, where its thermal decomposition leads to the segregation of (Mg,Cu)TaO.

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Thermal behavior of the orthorhombic (α) and triclinic (β) polymorphs of BiNbO was studied by the methods of high-temperature powder X-ray diffraction (HTPXRD) and differential scanning calorimetry (DCS) in the temperature range 25-1200 °C. The study revealed the sequence of thermal phase transformations and the new high-temperature modification, γ-BiNbO, which was formed above 1001 °C and existed up to the melting temperature of BiNbO. The incongruent melting of BiNbO was characterized by the formation of the cubic phase with the approximate composition BiNbO.

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