Papers by Keyword: Solid-State Synthesis

Abstract: This study explores the phase and structural transformations of new lanthanum substituted sodium lead phosphate composite, Pb_(8-x)La_xNa₂(PO₄)₆ with x=0.00 to 0.30. The main focus is to establish the limits of substitution of La³⁺ in the apatite lattice and to understand its effect after substitution. The apatite composite specimen was prepared through a solid–state reaction at 830 °C and characterized using Rietveld–XRD, FT IR and SEM techniques. The statistics suggest that the structure mostly remains a constant up to x = 0.20. However, when the amount of lanthanum exceeds the limit, secondary phases exist and become dominant showing the limit of lanthanum entry. The insertion leads to changes in the host-cation lattice; namely a nonlinear variation along the a-axis, while there is a linear variation along the c-axis in lead-apatite. FT-IR data further confirms that PO₄³⁻ is a tetrahedral ion in the structure. Microstructure is more densely packed what is new in this work is the study of the structural changes which lead to the formation of larger amounts of lead-apatite composites with a wider range of La³⁺ range. The structural changes seen in this study shed light on the structural changes that must occur for effective integration of lead-apatite composites. A fresh perspective on how this study contributes to your submission.

Abstract: The increasing demand for electric vehicles and alternative energy sources results in high demand for energy storage, such as high-capacity rechargeable batteries. Ni-based ternary cathodes like lithium nickel cobalt aluminum oxide (NCA) have become promising due to their high energy density. In this study, a facile solid-state reaction pathway for the synthesis of LiNi_0.75Co_0.20Al_0.05O₂ cathode using metal oxide precursors was investigated. Thermal analysis using TGA-DTA showed the decomposition and mass loss of the calcined precursors and revealed an endothermic reaction at about 700°C, which can be attributed to Li₂CO₃ melting. XRD analysis reveals the creation of hexagonal NCA with an α-NaFeO2 r3m structure along a secondary LCO phase. However, resintering leads to a more thorough reaction, yielding hexagonal NCA with lattice parameters a = 2.863 Å and c = 14.192 Å. In addition, SEM-EDX analysis reveals irregularly shaped agglomerated morphology and relatively homogenous distribution of Ni, Co, and Al for the resintered samples.

Abstract: The article shows the results of a research in which barium hexaferrite samples of the BaFe₁₁M₁O₁₉ (M= Al, Ti and Mn) composition were obtained by solid-state synthesis. Samples substituted with titanium, aluminum, and manganese were obtained in a tubular furnace at an exposure time of 5 hours at a temperature of 1350°C, the sample, substituted with manganese, it was obtained at a temperature of 1250°C. The chemical composition was controlled using electron microscopy the samples obtained correspond to the initial composition with sufficient accuracy. Hexagonal plates represent the structure of all the obtained samples. According to X-ray phase analysis, all samples are monophasic and have the structure of barium hexaferrite. Using the data of powder X-rays, the parameters of the unit cell of the studied samples were calculated, when iron atoms are substituted by titanium or aluminum or manganese atoms, the crystal lattice is distorted, while its change is not the same for different crystallographic directions. During the doping of barium hexaferrite with titanium, aluminum or manganese atoms, the Curie temperature decreases. This is due to a decrease in the exchange interaction forces during the modification of the barium hexaferrite matrix. The aim of this study was to study the structure and change of the lattice parameters, the Curie temperature, depending on the substitution element.

Abstract: The kinetic study for the synthesis of Fluorapatite has been done using the thermogravimetric technique under non-isothermal conditions and at four heating rates of 5, 10, 15 and 20 °C. Both model free and model-fitting methods were used to investigate kinetic parameters. Calcium oxide, phosphorus pentoxide and calcium fluoride were used as the precursor materials. The activation energy values were calculated through model-fitting and isoconversional methods and were used to predict the reaction model and pre-exponential factor. In this case several techniques were considered such as master plots and compensation effects. The results indicated that the reaction mechanism was chemically controlled with second and third order reaction models in the whole range of conversion which the activation energy varied from 25 to 43 kJ/mol.

Abstract: Results of investigations related to synthesis and thermal properties analysis of the Dy₂Zr₂O₇ phase was presented in this article. This material was obtained during high temperature synthesis in an actual pressure of 15 MPa, in vacuum of 3×10^-6 MPa, and at 1350°C with 2 hours of exposure. Feedstock materials were submicrocrystalline powders of dysprosia Dy₂O₃ and zirconia ZrO₂. Both powders were mechanically blended in alcohol before the sintering process. The final product was analysed from the phase’s composition point of view. It was revealed that main constituent elements were dysprosium zirconate with an overall formula of Dy₂Zr₂O₇ and others were Dy zirconates with a non-stoichiometric character. The presence of zirconia was found with tetragonal types of unite cell. This fact evidences that partial dissolution of Dy₂O₃ in ZrO₂ took place. The obtained material was characterized by calorimetric investigations in the thermal range from 25 to 1450°C.

Abstract: Tetracalcium phosphate (TTCP) requires the highest synthesis temperatures of all the calcium phosphates, but now a new process is available at 400 °C lower than previously, at 900 °C. Instead of ball-milling reactants for a homogeneous mix, the reactants were included in an amorphous phase. Heating produced hydroxyapatite, oxyapatite and then TTCP. Amorphous nanoparticles were synthesized and heated in air or in vacuum. The sequence of solid-state reactions were tracked with X-ray diffraction and Fourier transform infra-red spectroscopy. Heating in air stabilized the carbonate containing apatite, thereby requiring higher temperatures for decomposition, as per previous studies. Heating in vacuum promoted oxyapatite; a critical step for reaction with calcium oxide to generate TTCP. This faster process enables production at a lower temperature and reduces the use of ball milling for producing fine TTCP powders.

Abstract: In this paper, β''-alumina powders were prepared by solid-state synthesis method with different kinds of sodium compounds such as sodium carbonate, sodium bicarbonate, sodium oxalate, sodium acetate and sodium citrate. Each sodium compound was mixed with α-alumina by ball-milling, and then dried and calcined in muffle furnace, respectively. In order to confirm the superior condition for different sodium compound to prepare β''-alumina, original raw material with different powders molar ratio and calcination temperature were applied. The phase compositions of mixed powders after calcination were analyzed by X-ray diffraction (XRD). The results show that different kinds of sodium compounds which are just composed of sodium, carbon and oxygen all can be used as sodium source for preparing β''-alumina, but different sodium source compounds need different calcination temperature to form β''-alumina phase. And the molar ratio of sodium compound to α-alumina has an effect on the final content of β''-alumina.

Abstract: The Al₂O₃-FePd₃ structure was fabricated by aluminothermy, or the Goldschmidt reaction. The initial structure was prepared by the formation of a highly-ordered L1₀-FePd epitaxial film with the use of the solid-state reaction in a Fe(001)/Pd(001) bilayer system on the MgO substrate. To obtain a granular structure, the L1₀-FePd samples were oxidized in air with the subsequent deposition of an aluminum layer onto their surface and vacuum annealing. Depending on annealing time and temperature, a system of L1₂-FePd₃ grains 5 nm in size was formed in an Al₂O₃ insulating matrix. Parameters of thermal treatment of the initial structure are presented, the occurring phase transformations are described, and the magnetic characteristics are measured. It is established that the ordered L1₀-FePd phase is obtained at an initiation temperature of the reaction of about 450 ^оС and the granular L1₂-FePd₃ system forms at 600-650 °С.

Abstract: A simple method for obtaining ZnO-Fe₃O₄ nanocomposites using solid-state reaction Zn + 3Fe₂O₃ ZnO + 2Fe₃O₄ is suggested. An analysis of the characteristics and properties of ZnO-Fe₃O₄ nanocomposites was carried out by a combination of structural and physical methods (X-ray diffraction, scanning electron microscopy, photoelectron spectroscopy, Mössbauer measurements, X-ray fluorescent analysis, and magnetic measurements). The magnetization of the hybrid ZnO-Fe₃O₄ films is equal to 440 emu/cm³. The resulting Fe₃O₄ nanoparticles are surrounded by a ZnO shell and have sizes ranging between 20 and 40 nm.

Abstract: Under the conditions of the presence of surfactants and ultrasonication, the use of different cerium salt, respectively, with carbonate under solid state chemistry reactions, the synthesis of nanorare earth metal complexes of cerium carbonate crystals was formed. The solid phase was characterized by powder X-ray diffraction (XRD) and electron diffraction (ED). The particle size, its distribution, and morphology of the prepared nanocrystallite were observed by transmission electron microscopy (TEM). The results show that particle sizes are relatively uniform, the morphology of the crystal is spherical, the average particle diameter is about 60 nm, and the yield rate is approximately 93.2%. Furthermore, during the synthesis, the solid-state reaction conditions including raw materials, matching proportion of reactants, additions of inert substance, addition of trace solvents, surfactants and porphyrization time, etc, all have some influence on the morphology, particle size and size distribution of the final products. During the synthesis of the cerium carbonate nanocrystallites, the solid state reaction conditions such as changing reactant, matching proportion of reactant, adding inert substance, joining a little solvent or surface active solvent and grinding at different times may influence morphology, particle size and the size distribution of final products.