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The greenness of a chemical precipitation process was attempted in the synthesis of SnO2nanoparticles through the use of safe, environmental-benign citric acid as a chelating agent. Thermogravimetric analysis (TGA) of the precipitates was used to study thermal decomposition. Presence of functional groups was examined by Fourier Transform Infrared Spectroscopy (FTIR). Negligible traces of functional groups were detected after calcination at 800°C. Phase formation and the degree of crystallinity were probed by X-ray diffraction (XRD). The process with chelation by citric acid resulted in larger crystallite sizes compared to those from the non-chelated system. The morphology of the nanoparticles was investigated by transmission electron microscopy (TEM). Although the SnO2phase could not be obtained at ambient temperature due to oxidative constraint, chelation by citric acid did indeed reduce the calcination temperature required for the change in the oxidation number and thus emergence of the SnO2phase. Such results could be indicative of lessened energy requirement in the synthesis of SnO2nanoparticles. [ABSTRACT FROM AUTHOR]

SrTiO3 nanoparticles were synthesized by sol-gel method using acetic acidas a chelating agent. Complete decomposition from thermogravimetric analysis occurred at 650°C. The -OH ligand should be gradually replaced by the acetyl group, slowing down the reactivity between the Ti and Sr cations. X-rays diffraction demonstrated only SrC2O4 with a small trace of anatase TiO2 between 400°C and 500°C. Perovskite peaks were observed starting at 600° C. The crystallite sizes were smaller at higher amount of acetic acid; this could be explained by retardation in the hydrolysis reaction. The nanoparticles were isotropic in shape with agglomeration due to partial sintering. [ABSTRACT FROM AUTHOR]

SrTiO3nanoparticles were synthesized by sol-gel method using acetic acid as a chelating agent. Complete decomposition from thermogravimetric analysis occurred at 650°C. The –OH ligand should be gradually replaced by the acetyl group, slowing down the reactivity between the Ti and Sr cations. X-rays diffraction demonstrated only SrC2O4with a small trace of anatase TiO2between 400°C and 500°C. Perovskite peaks were observed starting at 600°C. The crystallite sizes were smaller at higher amount of acetic acid; this could be explained by retardation in the hydrolysis reaction. The nanoparticles were isotropic in shape with agglomeration due to partial sintering. [ABSTRACT FROM PUBLISHER]

Abstract: This study aims at investigating the processing and sinterability of Zn0.92Sn0.04Bi0.02Co0.02Oβ nanosized powders synthesized by chemical precipitation method. Addition of tin has been reported to influence the non-linear properties in ZnO-based systems. The precipitates were calcined at 800̊C, as determined by Thermogravimetric analysis (TGA) and Fourier Transform Infrared Spectroscopy (FTIR), to remove organic residues. X-ray diffraction (XRD) revealed zincite as a main phase with small traces of Bi2O3. The averaged crystallite sizes were anisotropic (60.4 nm along [100], 27.9 nm along [002] and 46 nm along [101]). These sizes, along with elongated shape, were confirmed by Transmission electron microscopy (TEM). Sintering with a relative density of 95% was readily obtained at 1000̊C. However, comparing with the undoped sample (Zn0.96Bi0.02Co0.02Oβ), the densification rate of the currently investigated samples was slower at temperatures below 1000̊C. This lower sintering rate could possibly be related to the increase in crystallinity of Bi2O3 and formation of another secondary phase (spinel Zn2SnO4) as seen by XRD. The phasic nature in these samples was highly dynamic; the spinel phase disappeared at the sintering temperatures of 1200̊C and higher. Reduction in the averaged grain size was observed, and elemental analysis confirmed the composition of the phases previously found by XRD. The grain boundary liquid phase contained both Zn and Bi, indicating the plausible solubility between these two species. The smaller averaged grain size, in addition to the superior properties of SnO2, resulted in a higher breakdown voltage (1730 V/cm comparing to 310 V/cm for the undoped sample). [Copyright &y& Elsevier]

The use of zinc oxide nanoparticles to enhance the production of plant metabolites has gained considerable attention as a novel nanotechnology application in plant biotechnology and agriculture. This study aimed to investigate the effect of different concentrations (0, 0.1, 1, 10, 100, and 1,000 mg/L) of biosynthesised zinc oxide (BZnO) on growth parameters, bromelain production and antioxidant activities of the shoot culture of pineapple (Ananas comosus). The results showed that the highest amount of shoot (7.2 shoots/explant), fresh weight (FW) (5.390 g), leaf number (68.8 leaves/plantlet) and chlorophyll content (1,161.58 μg/g FW) were achieved at 1 mg/L of BZnO. A significant increase in bromelain production was also observed in the shoot culture of pineapple at 1 mg/L BZnO. The shoot of pineapple grown on plant tissue culture medium supplemented with 1 mg/L BZnO demonstrated the highest total phenolic content (20.11 μg gallic acid equivalent/g FW), reducing power (4.05 μg FeSO4/g FW) and 2,2-diphenyl-1-picrylhydrazyl-scavenging activity (60.75%). The results revealed that physiological parameters, secondary metabolite production and antioxidant activity increased when the concentration of BZnO was elevated up to 1 mg/L. However, a sudden decrease was observed when the concentration of BZnO was over 1 mg/L BZnO, and it reached to the minimum amount at 1000 mg/L BZnO. [ABSTRACT FROM AUTHOR]

Ceramic pigments have been widely used in a variety of industries because of their excellent properties, such as high thermal stability, low-cost productions, and simple manufacturing processes. Re-use of mirror waste, which consists of silicon dioxide greater than 70%, is a method that can reduce raw materials cost. In this work, ceramic pigment with forsterite structure, Mg₂SiO₄, was synthesized via conventional solid state reaction by using mirror waste as a precursor. Solid solutions of Co-doped forsterite pigment, Co x Mg (2- x ) SiO₄ where x = 0.02⁻1.6, were calcined at 1000 °C for 2 h. The calcined powders were characterized by X-ray diffraction technique (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), UV-Vis spectrophotometer, and color measurement (CIEL*a*b*). XRD results confirmed that forsterite phase was found as a main phase in the ceramic powder. However, the forsterite phase decreased with increased concentration of Co to x = 0.8⁻1.6. This could be because of the solubility limit of Co in solid solution. In addition, the use of mirror waste as a raw material was able to reduce calcination temperature compared to the use of oxide reagents. Color measurements or CIEL*a*b* color space of forsterite pigments were located in red-blue quadrant for Co-doped pigment.