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Jutharatana Klinkaewnarong Ekaphan Swatsitang Santi Maensiri 《Solid State Sciences》2009,11(5):1023-1027
Nanocrystalline hydroxyapatite (HAp) powders were successfully synthesized by a simple method using chitosan–polymer complex solution. To obtain HAp nanopowders, the prepared precursor was calcined in air at 400–800 °C for 2 h. The phase composition of the calcined samples was studied by X-ray diffraction (XRD) technique. The XRD results confirmed the formation of HAp phase with a small trace of monotite phase. With increasing calcination temperature, the crystallinity of the HAp increased, showing the hexagonal structure of HAp with the lattice parameter a in a range of 0.94030–0.94308 nm and c of 0.68817–0.68948 nm. The particle sizes of the powder were found to be 55.02–73.36 nm as evaluated by the XRD line broadening method. The chemical composition of the calcined powders was characterized by FTIR spectroscopy. The peaks of the phosphate carbonate and hydroxyl vibration modes were observed in the FTIR spectra for all the calcined powders. TEM investigation revealed that the prepared HAP samples consisted of rod-like nanoparticles having the particle size in the range of 100–300 nm. The corresponding selected-area electron diffraction (SAED) analysis further confirmed the formation of hexagonal structure of HAp. 相似文献
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Kwanruthai Wongsaprom Rung-arun Bornphotsawatkun Ekaphan Swatsitang 《Applied Physics A: Materials Science & Processing》2014,114(2):373-379
This paper reports the synthesis and characterization of nanocrystalline tin oxide (SnO2) powders by a simple method using a chitosan–polymer complex solution. To obtain SnO2 nanocrystalline powders, the precursor was calcined at 500–600 °C in air for 2 h. The phase composition of calcined samples was studied by X-ray diffraction (XRD). The XRD results confirmed the formation of a SnO2 phase with tetragonal structure. The particle sizes of the powder were found to be 22–23 nm as evaluated by the XRD line broadening method. TEM investigation revealed that the SnO2 samples consist of crystalline particles of 19–21 nm. The corresponding selected area electron diffraction analysis further confirmed the formation of the tetragonal structure of SnO2 without any impurity phases. The optical properties of the samples were explored by Fourier transform infrared spectroscopy, optical absorption and Raman studies. The estimated band gaps of the samples were in the range of 3.44–3.73 eV. 相似文献
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Santi Phumying Sarawuth Labuayai Chunpen Thomas Vittaya Amornkitbamrung Ekaphan Swatsitang Santi Maensiri 《Applied Physics A: Materials Science & Processing》2013,111(4):1187-1193
Magnetite (Fe3O4) nanoparticles have been successfully synthesized by a novel hydrothermal method using ferric acetylacetonate (Fe(C5H8O2)3) and aloe vera plant-extracted solution. The influences of different reaction temperatures and times on the structure and magnetic properties of the synthesized Fe3O4 nanoparticles were investigated. The synthesized nanoparticles are crystalline and have particle sizes of ~6–30 nm, as revealed by transmission electron microscopy (TEM). The results of X-ray diffraction (XRD), High resolution TEM (HRTEM) and selected area electron diffraction (SAED) indicate that the synthesized Fe3O4 nanoparticles have the inverse cubic spinel structure without the presence of any other phase impurities. The hysteresis loops of the Fe3O4 nanoparticles at room temperature show superparamagnetic behavior and the saturation magnetization of the Fe3O4 samples increases with increasing reaction temperature and time. 相似文献
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Swatsitang Ekaphan Karaphun Attaphol Phokha Sumalin Hunpratub Sitchai Putjuso Thanin 《Journal of Sol-Gel Science and Technology》2017,81(2):483-492
Journal of Sol-Gel Science and Technology - Pure orthorhombic phase of La1?xSmxFeO3 (x?=?0, 0.1, 0.2, and 0.3) nanoparticles can be obtained by sol–gel method after... 相似文献
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Noppakorn Thanamoon Narong Chanlek Pornjuk Srepusharawoot Ekaphan Swatsitang Prasit Thongbai 《Molecules (Basel, Switzerland)》2021,26(22)
Giant dielectric (GD) oxides exhibiting extremely large dielectric permittivities (ε’ > 104) have been extensively studied because of their potential for use in passive electronic devices. However, the unacceptable loss tangents (tanδ) and temperature instability with respect to ε’ continue to be a significant hindrance to their development. In this study, a novel GD oxide, exhibiting an extremely large ε’ value of approximately 7.55 × 104 and an extremely low tanδ value of approximately 0.007 at 103 Hz, has been reported. These remarkable properties were attributed to the synthesis of a Lu3+/Nb5+ co-doped TiO2 (LuNTO) ceramic containing an appropriate co-dopant concentration. Furthermore, the variation in the ε’ values between the temperatures of −60 °C and 210 °C did not exceed ±15% of the reference value obtained at 25 °C. The effects of the grains, grain boundaries, and second phase particles on the dielectric properties were evaluated to determine the dielectric properties exhibited by LuNTO ceramics. A highly dense microstructure was obtained in the as-sintered ceramics. The existence of a LuNbTiO6 microwave-dielectric phase was confirmed when the co-dopant concentration was increased to 1%, thereby affecting the dielectric behavior of the LuNTO ceramics. The excellent dielectric properties exhibited by the LuNTO ceramics were attributed to their inhomogeneous microstructure. The microstructure was composed of semiconducting grains, consisting of Ti3+ ions formed by Nb5+ dopant ions, alongside ultra-high-resistance grain boundaries. The effects of the semiconducting grains, insulating grain boundaries (GBs), and secondary microwave phase particles on the dielectric relaxations are explained based on their interfacial polarizations. The results suggest that a significant enhancement of the GB properties is the key toward improvement of the GD properties, while the presence of second phase particles may not always be effective. 相似文献
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Ba0.5Sr0.5Ti1?xNixO3 (BSTN) ceramics were prepared from BSTN nanopowders synthesized by a hydrothermal method. The phase and microstructure of samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy. XRD results indicate a cubic structure of the pure BST nanopowders. The cubic structure can be converted to the orthorhombic phase with increasing of Ni content to x = 0.01 and returned to the cubic structure with the presence of Ni(OH)2 impurity phase for x = 0.03 and 0.05. However, the BSTN ceramics sintered at 1,200 °C for 3 h revealed the orthorhombic phase structure with NiO impurity phase for all Ni content. The doping of Ni in Ba0.5Sr0.5TiO3 structure can increase the grain size of samples from 1.47 to 3.26 μm. The dielectric constant, loss tangent (tanδ) and phase transition temperature of BSTN ceramics were reduced with increasing Ni content. 相似文献
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