Papers by Keyword: Low Temperature Synthesis

Abstract: This work reports the structural and humidity-sensing properties of Tin (Sn)-doped Zinc Oxide (ZnO) nanostructures deposited on Aluminum-doped Zinc Oxide/Polyethylene Terephthalate (AZO/PET) substrates via the sol-gel immersion method. Accordingly, X-ray Diffraction (XRD) and FESEM analyses confirmed that low-level Sn incorporation (1 at.%) enhanced the (002) orientation and crystallinity, while higher doping introduced lattice distortion and defects. Meanwhile, humidity sensing measurements revealed that undoped ZnO exhibited the highest sensitivity (178.5), though it recorded a very slow response (231 s) and recovery (648 s). In contrast, 1 at.% Sn-doped ZnO achieved a balanced performance, combining high sensitivity (144.4) with much faster response (121 s) and recovery (411 s). These results demonstrate that controlled Sn doping optimizes ZnO nanostructures for flexible humidity-sensing applications. Overall, the findings provide valuable insight for developing real-time environmental and wearable sensing devices, with future work focusing on stability testing and mechanical flexibility evaluation.

Abstract: Amorphous and low crystalline calcium phosphates are prospective candidates for bone implant manufacturing. Amorphous calcium phosphate (ACP) preparation technologies could be improved in terms of specific surface area (SSA) of obtained products. Current study is dedicated to the effect of synthesis temperature and Ca and P molar ratios (Ca/P) on SSA of ACP. Higher SSA can improve bioactivity of biomaterials. ACP was characterized by XRD, FT-IR, SEM and BET N₂ adsorption techniques. Spherical nanoparticles (<45 nm in size) were obtained independently of initial Ca/P ratio and synthesis temperature. For the first time comparison of SSA was shown for ACP obtained at different temperatures (0 °C and 20 °C) and Ca/P molar ratios (1.5, 1.67 and 2.2).

Abstract: Aluminum titanate (AT) ultrafine powder with high productivity ratio was prepared via hydrolytic sol-gel (HSG) method at 1250 °C, using aluminum nitrate (Al (NO₃)₃·9H₂O) and titanium tetrachloride (TiCl₄) as precursors, ethanol as solvent through solvothermal treatment process. Water required for hydrolysis reaction was supplied by the crystal water of aluminum nitrate itself. The effect of process parameters including filling ratio, solvothermal temperature and soaking time on the synthesis of AT powder was investigated by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The cause of low temperature synthesis of AT was investigated. The result showed that excessive or insufficient filling ratio, too high or low solvothermal temperature, too long soaking time was not beneficial for the preparation of AT. The optimized ultrafine AT powder appeared at the decomposition temperature of 1250 °C with average particle size less than 1μm at a relatively high productivity ratio of 98 % with filling ratios of 60 %, solvothermal temperatures of 130 °C and soaking time of 30 min. The refinement of particles in the AT xerogel through solvothermal treatment process, and increasing reactivity of precursor, plays the key role in the low temperature synthesis of AT.

Abstract: Using tetraethyl orthosilicate and anhydrous aluminum chloride as precursors, ethyl ether as oxygen donor, LiF as mineralizer, and Na2SO4-NaCl as compound molten salt, mullite whisker was synthesized in the low temperature by nonhydrolytic sol-gel process combined with molten salt method. The phase transformation of mixed powder composed of mullite xerogel and molten salt during the heat treatment and the microstructure of mullite whisker corresponding to different temperature were characterized by means of DTA-TG, XRD SEM and TEM. The results show that mullite crystal phase can be formed via non-hydrolytic sol-gel process combined with the molten salt method at 750°C. The synthetic effect of mullite get better as the temperature increased to 850°C, while NaAlSiO4 crystal phase is also detected. Mullite whisker, with diameters ranging from 300~500 nm and lengths of 3~5μm, is prepared at the temperature of 850°C.

Abstract: Zircon nano–powder has been synthesized via the non-hydrolytic sol–gel route, using industral zirconium tetrachloride (ZrCl₄) and tetraethoxysilane (TEOS) as precursors, lithium fluoride (LiF) as mineralizer, PEG1000 as dispersant. The effects of solvents on the synthesis and dispersion of zircon nano-powder were investigated by means of XRD and TEM. The results indicate that the aprotic solvent N, N-dimethyl formamide (DMF) is not conducive to the nucleophilic substitution reaction, which directly affect the zircon synthesis, and the particles are easy to agglomerate due to the large surface tension; the powder with size of 30nm and good dispersion can be obtained using dichloromethane (CH₂Cl₂) as solvent; different anhydrous alcohols as solvents influence zircon synthesis, the order of the synthesis ratio is listed as EtOH›propanol (PrOH)› isopropanol (PrⁱOH). Powder particles are larger than 50nm with wide distribution and serious agglomeration when taking PrOH and PrⁱOH as solvents. Nano-zircon with good dispersion and synthesis ratio up to 94.5% can be obtained via using ethanol as solvent.

Abstract: Our Recent Works on the Search for New Superconductors Using Soft-Chemical Techniques Are Reviewed. We Have Found New Mg-Intercalated Superconductors of Mg_xZrNCl and Mg_xHFNCl with Tc ~ 13 K and 25 K, Respectively. Moreover, we Have Succeeded in Preparing Bulk Samples of Hole-Doped (La,Ca)₂CuO₄ with the Nd₂CuO₄-Type, Namely, the so-Called T’-Type Structure by Reduction of (La,Ca)₂CuO₄ with the K₂NiF₄-Type, Namely, the so-Called T-Type Structure Using CaH₂ at a Temperature as Low as 300°C and Subsequent Oxidation. This Result Is in Contrast with the Synthesis of (La,Ca)₂CuO₄ with the K₂NiF₄-Type Structure by the Conventional Solid-State Reaction Method at a Temperature as High as ~1000°C.

Abstract: The aim of this study was to evaluate the osteoconductive properties of synthetic porous hydroxyapatite prepared by low-temperature microwave processing OssaBase^® HA (SPHA) in comparison with biological apatite, non-sintered deproteinized bovine bone Bio-Oss^® (DBB). The materials were implanted into the bone sockets of the tibia of Beagle dogs for 3 and 6 months. The bone response to granules of the materials of similar sizes was compared. Histological analysis of the specimens with histomorphometry was performed at different times after in vivo implantation. Based on the histological analysis, the level of bone formation in the spaces between the implanted granules and through the interconnected pores of both implanted materials within a cortical region was significantly higher (bone area ingrowth 72–85%) than within a cancellous bone site (bone area ingrowth 16–28%) at three and six months after implantation. According to our study, the bioactive and osteoconductive properties (bone implant contact and bone area ingrown) of the synthetic porous hydroxyapatite are very high and comparable with the biological apatite, non-sintered deproteinized bovine bone. The favourable influence of the high specific surface area and carbonate content of the synthetic, porous hydroxyapatite on bone formation was confirmed.

Abstract: In the present study, a method based on sulfuric acid dehydration of sugar was developed to synthesis a precursor material, which can yield B4C/ TiB2 composites at much lower temperatures compared to traditional carbothermal methods. The precursor material for pure B4C and B4C / TiB2 composites were heat treated at 1650oC under Ar and Ar+H2 atmosphere. Then the samples were characterized by X-ray diffraction (XRD) and crystallized B4C and B4C / TiB2 composites can be obtained at 1650oC

Abstract: Fine TiO2 particles were synthesized from titanate precursor, Na16Ti10O28, dissolved in aqueous HNO3 solution. Crystalline rutile TiO2 powders were prepared by reflux of dissolved powders in the aqueous HNO3 solution under 100 °C. Prepared TiO2 powders were characterized by X-ray diffraction, thermogravimetry, scanning electron microscopy and BET specific surface area analysis.

Abstract: In the present study, a method based on sulfuric acid dehydration of sugar was developed to synthesize a precursor material, which can yield B4C/SiC composites at much lower temperatures compared to traditional carbothermal methods. The precursor material for pure B4C was heat treated at the temperatures between 400 and 1600oC under inert atmosphere. The precursor material for B4C /SiC composites was heat treated only at 1600oC under an inert atmosphere. Then the samples were characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The results showed that B-C bonds formed as low as 400oC. On the other hand, crystallized B4C and B4C / SiC composites can be obtained at the heat treatment temperatures between 1400 and 1600oC.