Papers by Keyword: Solvothermal Reaction

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Authors: Atthaphon Maneedaeng
Abstract: The aim of this study is to develop the synthetic procedure of Zinc Oxide (ZnO) nanoparticles by using surfactant-assisted solvothermal technique in order to produce highly uniform nanosize of ZnO particles. The solvothermal reaction evidently produces smaller ZnO particle sizes compared with those obtained from hydrothermal reaction. The zwitterionic surfactant is employed in this work and it typically works well under extremely conditions i.e. high pH levels, strong electrolytes, and high temperature. The key success of surfactant utilization in the solvothermal reaction is to create reversed micelles which act as nanoreactors or templates. Because micelle consist of polar cores that may occupy a finite amount of water forming a water pool for ZnO nanomaterial synthesis. Synthesized ZnO nanoparticles were obtained from solvothermal reaction at 180°C and 18 hours in a hydrothermal reactor. The ZnO colloidal particles were separated by paper filter and cellulose nitrate membrane, respectively. The XRD pattern shows that the structure of the synthesized ZnO nanoparticles is hexagonal wurtzite and the use of surfactant does not interfere the crystal growth and structure. The particle size distribution reveals a high uniform ZnO nanoparticles obtained via this method. The UV absorption spectrum of ZnO nanoparticles synthesized by this method presents exciton peak at approximate value of 365 nanometers. The energy band gap determined by Tauc plot is 3.31 eV. Moreover, TEM images confirm the particle size consistency showing the morphology of the prepared ZnO nanoparticles.
Authors: Titipun Thongtem, Sulawan Kaowphong, Somchai Thongtem
Abstract: MWO4 (M = Ca, Sr, Ba and Pb) was solvothermally prepared using metallic nitrates and sodium tungstate in 25/5 volume ratios of glycerol/water (SGL) and propylene glycol/water (SPG) at 160 oC for 6 h. XRD revealed the presence of MWO4 single phase with tetragonal scheelite structure. The strong W-O stretching band of WO4 tetrahedrons was detected at 705-875 cm-1. The product images show nano-sized particles in basic SGL and SPG solvents and flower-like particles in SPG solvent with pH of 6.7. Central peaks of the luminescent spectra are 445, 446, 443 and 440 nm, respectively.
Authors: Xiao Wei Wang, Shi Jing Liang, Wei Ming Wu, Guo Dong Liu, Shi Long Zhang, Hua Rong Zheng, Ling Wu
Abstract: Nanocrystalline SrSiO3 with different morphologies was first selectively prepared by a facile template-free solvothermal method at different water/ethanol volume ratios. The as-prepared samples were characterized by X-ray diffraction, N2-sorption, field emission scanning electron microscopy. The results showed that the as-prepared samples SrSiO3 displayed nanoflakes in pure water while obtained nanofibres in mixed solvent of water and ethanol (the volume ratio of water to ethanol is 1:1.). The BET specific surface area of SrSiO3 nanofibre is 161.7 m2 g-1, which is much higher than that of nanoflake one. The mechanisms about the formations of shape-controlled SrSiO3 are proposed and discussed based on a reaction-crystallization process. As a novel photocatalyst, the photocatalytic activity of as-prepared samples SrSiO3 were evaluated by the photocatalytic degradation of orange II (20 mg L-1) and the total organic carbon (TOC) value indicated that orange II solution can be mineralized in 120 min.
Authors: Titipun Thongtem, Anukorn Phuruangrat, Somchai Thongtem
Abstract: CdS was synthesized by solvothermal reaction of CdCl2.2.5H2O and (NH2)2CS in ammonia solution at 200 oC for 10 h. XRD, TEM and SAED show that the products are nanocrystalline CdS. The phase is 100 % hexagonal (hcp) in pure water, gradually transformed into cubic with the increase of NH3 concentration, and 100 % cubic in 25 % NH3 solution. By using FTIR, no solvents were detected in the products. Raman analysis revealed the presence of 1LO (longitudinal optical) and 2LO phonon peaks at 297.0 and 597.1 cm-1 for CdS (hcp), and 295.9 and 596.9 cm-1 for CdS (cubic), respectively. Strong peaks of the photoluminescent (PL) spectra were detected at 450 nm for hcp, and 519 nm for cubic.
Authors: Sung Wook Kim, Shinji Iwamoto, Masashi Inoue
Abstract: Solvothermal reaction of aluminum alkoxides in various alcohols at 250-300 oC yielded alkyl derivatives of boehmite (alkoxyalumoxanes; AlO(OH)1-x(OR)x) in which alkyl groups were incorporated between the boehmite layers through the covalent bondings. In the present work, pore textures of aluminas prepared by calcination of the products were examined. The alumina obtained from the ethyl derivative of boehmite had a broad pore-size distribution, while the pore-size of the alumina obtained from the dodecyl derivative of boehmite distributed in a narrow range in the mesopore region. The mode pore diameter of the latter alumina increased with the increase in calcination temperature (600 oC, 39 Å; 800 oC, 54 Å; 1000 oC, 74 Å), but narrow pore-size distribution was maintained even after calcination at high temperatures.
Authors: Guang Yin Wang
Abstract: In this paper, the characteristics, potential applications and preparation methods of functional nano materials were briefly introduced, and in particularly, the virtue of solvothermal reactions, as well as the solvents, were introduced
Authors: Sulawan Kaowphong, Titipun Thongtem, Somchai Thongtem
Abstract: CaWO4 was prepared by solvothermal reaction of Na2WO4.2H2O and calcium salts (CaCl2.2H2O, Ca(NO3)2.4H2O and Ca(CH3COO)2) in solvent containing a variety of glycerol/water ratios at 160 oC for 6 h. By using XRD, SEM, TEM and ED, the products compose of nano-sized CaWO4 particles with scheelite structure but different morphologies. Interplanar spaces between (101) planes were determined from HRTEM image, ED patterns and XRD spectra are 0.424, 0.474 and 0.476 nm, respectively. Luminescent intensities of the products prepared in pure water are the highest and their central peaks are the same at 444 nm. In addition, Ca, W and O were detected using EDX.
Authors: Rui Xing Li, Shu Yin, Qing Tang, Tsugio Sato
Abstract: Because of the low refractive indices, plate-like cerium phosphates (CePs) are expected to be used as one of active ingredients in personal suncare cosmetics. Plate-like Ce2(PO4)2HPO4・H2O particles were synthesized via solvothermal reactions of Ce(NH4)2(NO3)6 or Ce(SO4)2・4H2O in phosphoric acid with or without nitric acid and sulfuric acid solutions. The variation of morphology of Ce2(PO4)2HPO4・H2O particles significantly depended on the variety of cerium salt, isothermal temperature and time, although all reaction products consisted of plate-like particles. This plate-like compound showed excellent UV light absorption and transparency in the visible light region. Consequently, it is suggested that the plate-like Ce2(PO4)2HPO4・H2O particles might be used as suncare products to give an ideal optical effect of both UV-shielding ability and transparency in the visible light region, as well as a good feeling on the skin.
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