Papers by Keyword: Molten Salt Synthesis

Abstract: The paper presents the results of experimental studies of a photoactive catalyst in the form of barium titanate fibers with deposited particles of nickel, platinum and gold. Barium titanate fibers were synthesized by the molten salt method. The obtained barium titanate fibers were studied by SEM, TEM, XRD, and Raman spectroscopy. Photocatalytic studies showed that barium titanate fibers with platinum nanoparticles are the most active of the three prepared Metal/BaTiO3 samples.

Abstract: Titanium carbide-coated carbon black particles (TCBs) were synthesized via reaction of metallic titanium powder with carbon black powder in a molten potassium chloride at 900°C for 4 hours in argon atmosphere to study their biological properties to be used as a bioactive ceramic compound for bone formation. Phase compositions and morphologies were characterized by electron diffraction spectroscopy (EDS) and scanning electron microscope (SEM). Core-shell structure was examined by transmission electron microscope (TEM). Biofunctionalities were considered by cell proliferation and protein synthesis. titanium and carbon peak were found, on an EDS curve of the as-synthesized powder, indicating the complete reaction. The shape and size of as-synthesized powder and as-received carbon black powder are similar, as it is noticed the template growth mechanism of the reaction. However, the surface morphology of as-synthesized powder is different because of its rough surface. Core-shell structure of the as-synthesized powder was revealed by TEM that an ultra-thin layer of titanium carbide was successfully coated on a carbon black particle. Biological testing showed, as compared to a control, a significant enhancement in cell proliferation and protein synthesis of the as-synthesized TCBs suggesting a good candidate as a bioactive compound for biomedical applications.

Abstract: Alkaline earth titanates and zirconates and their binary systems are of interest for their temperature in sensitive dielectric properties. Calcium titanate and calcium zirconate perovskite ceramics find applications in pulse discharge, energy storage and microwave capacitors. These dielectric materials have been used in electric hybrid and fuel cell vehicles. In the present work, fine crystalline compound powders of calcium titanate and calcium zirconate were prepared by a single step molten salt synthesis. Calcium oxide and titanium dioxide/zirconium oxide were used as precursors to obtain the calcium titanate and calcium zirconate compound powders respectively. The prepared calcium titanate and calcium zirconate compound powders were characterized by TGA, FTIR, XRD, SEM and EDS analysis.

Abstract: Nickel oxide nanoparticles were prepared via molten salts and microwave assisted synthesis from nickel nitrate and the parameters of obtained nanopowders were compared. NiO nanoparticles with crystallite size in the range of 6-8 nm have been prepared by combining microwave assisted treatment of Ni (NO₃)₂ and urea solution with calcination at 300-320 °C. Molten salts (NaNO₂-NaCl) ensured direct formation of NiO from Ni (NO₃)₂.6H₂O and salts mixture at 350 °C but crystallite size of the particles reached 51-69 nm.

Abstract: Magnesium aluminate spinel (MgAl₂O₄) porous ceramics were in-situ synthesized by heating the mixture of Al₂O₃ and MgCO₃ with MgCl₂ salt at 1400~1600 °C for 3 h, and then characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The morphology of as-prepared MgAl₂O₄ porous ceramics was dependent on the addition of MgCl₂, and it indicated that the MgCl₂ molten salt not only acted as a template for pore formation of the porous ceramics, but also provided a liquid environment for the synthesis of MgAl₂O₄.

Abstract: SnS₂ nanoparticles with perfectly crystalline morphology were synthesized via a molten salt synthesis route at a relatively low temperature. The resulting SnS₂ nanoparcticles were characterized by X-ray diffraction (XRD), field scanning electron microscopy (FESEM), and UV-vis diffuse reflectance spectra (UV-vis). The observations of FESEM images showed that the sample consists of a large number of aggregates assembled with numerous nanoparticles packed into compact texture. The photocatalytic activity of the as-prepared SnS₂ samples was evaluated by the degradation of RhB aqueous solution. The effect of the molar ratio of thiourea to SnCl₂ on the photocatalytic activity was also investigated, and the result showed that the as-prepared SnS₂ sample has high photocatalytic activity efficiency in the degradation of RhB aqueous solution when the molar ratio of thiouea to SnCl₂ was 3.

Abstract: Plate-like Sr₃Ti₂O₇ powders with anisotropy were prepared by KCl molten salt synthesis (MSS) method, the effect of different SrCO₃/TiO₂ ratio and calcination condition on the phase transition, particle size and morphology of powders were investigated. The results show that SrTiO₃ phase coexist with Sr₃Ti₂O₇ phase and SrTiO₃ is the main phase as the SrCO₃/TiO₂ ratio is 1.15~1.25:1. Pure Sr₃Ti₂O₇ phase can be obtained as the SrCO₃/TiO₂ ratio is 1.55~1.65:1. The aspect ratio of plate-like particles increases firstly and then decreases as the SrCO₃/TiO₂ ratio increases. The sealed and unsealed condition has no influence on the phase structure of the powders. But the aspect ratio of unsealed particles is smaller than that of sealed particle. Finally, the formation mechanism for Sr₃Ti₂O₇ particles was discussed.

Abstract: The characteristics and sinterability of the Al₂O₃-ZrO₂(Y₂O₃) nanoparticles produced by simple and effective microwave and molten salts methods and processed by using spark plasma sintering were studied and compared. The crystalline powders with the specific surface area in the range of 72–108 m²/g and crystallite size of 5–13 nm were obtained by calcination of samples prepared by both methods at 800 °C. The content of t-ZrO₂ phase depends on concentration of Al₂O₃, Y₂O₃ and on calcination temperature but the impact of the preparation method is insignificant. The phase transition of tetragonal ZrO₂ to monoclinic for the samples without Y₂O₃ started at 1000 °C though it was incomplete in the case of high content of Al₂O₃. The bulk materials with relative density of 86.1–98.7% were fabricated by the spark plasma sintering method at 1500–1600 °C depending on the content of Al₂O₃ and Y₂O₃.

Abstract: High-quality flaky α-Al₂O₃ powder with regular morphology, uniform size, larger diameter-thickness proportion and excellent dispersibility in water and free from agglomeration and staggered growth was obtained on the basis of molten salt synthesis method. The effects of experiment parameter on the particle size and morphology of flaky alumina powder were studied. The mechanism of morphology control was discussed.

Abstract: The influence of different molten salt environments on formation of tungstates has been studied. Well crystalline and pure Bi₂WO₆ have been prepared in potassium nitrite KNO₂ (350°C), potassium chloride KCl (800°C) and mixture of potassium-sodium sulphates K₂SO₄-Na₂SO₄ (800°C), but ZnWO₄ have been successfully synthesized in sodium nitrate NaNO₃ (350°C), mixture of sodium-potassium chlorides NaCl-KCl (680°C), potassium chloride KCl (780°C) and mixture of potassium-sodium sulphates K₂SO₄-Na₂SO₄ (850°C). The higher surface area and photocatalytic activity show powders prepared at lower temperature.