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1.
《Materials Chemistry and Physics》2007,101(2-3):509-513
A low-temperature solvothermal synthetic method was developed for the large-scale synthesis of uniform-sized ferrite MFe2O4 (M = Mg, Cu, Ni) microspheres. The size of the as-prepared ferrite MFe2O4 microspheres could be controlled to be diameters 300–800 nm in diameter by adjusting some growth parameters, such as reaction time and concentration. The structures of the as-prepared ferrite MFe2O4 microspheres were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDAX). The magnetic properties of the ferrite MFe2O4 microspheres were also investigated. 相似文献
2.
Pure spinel cobalt oxide nanoparticles were prepared through hydrothermal approach using different counter ions. First, the pure and uniform cobalt carbonate (with particle size of 21.8–29.8 nm) were prepared in high yield (94%) in an autoclave in absence unfriendly organic surfactants or solvents by adjusting different experimental parameters such as: pH, reaction time, temperature, counter ions, and (Co2+:CO32?) molar ratios. Thence, the spinel Co3O4 (with mean particle size of 30.5–47.35 nm) was produced by thermal decomposition of cobalt carbonate in air at 500 °C for 3 h. The products were characterized by powder X-ray diffraction (XRD), Fourier transform infrared (FTIR), transmission electron microscope (TEM), scanning electron microscope (SEM), and thermal analysis (TA). Also, the optical characteristics of the as-prepared Co3O4 nanoparticles revealed the presence of two band gaps (1.45–1.47, and 1.83–1.93 eV). Additionally, adsorption of methylene blue dye on Co3O4 nanoparticles was investigated and the uptake% was found to be >99% in 24 h. 相似文献
3.
《Advanced Powder Technology》2014,25(3):904-909
Sol–gel combustion method has been used as an efficient and simple method to synthesize pure Ca2Co2O5 (CCO-225) ceramic powder using sucrose which play a dual role as the gelling agent and combustion fuel. The advantage of this method is simple low cost and environmental friendly. The synthesized sample is sintered at various temperatures the products were characterized by powder X-ray diffraction (XRD), Thermogravimetric and differential thermal analysis (TGA-DTA), Fourier transformer infrared spectroscopy (FTIR), Scanning electron microscope (SEM) and UV–Visible diffuse reflectance spectroscopy (DRS). X-ray diffraction pattern of sintered sample at 800 °C confirmed the formation of single phase Ca2Co2O5 and also it is proved in thermal analysis. SEM image indicates the obtained samples are diffused platelet like morphology and its grain size will be in the range of 150–300 nm. CCO-225 ceramic material has a wide range of optical and electronic applications due to its wide band gap energy of 3.50 eV. The dielectric constant, dielectric loss and AC conductivity were analyzed at different temperatures and frequencies of the applied field. The AC conductivity studies carried out in the frequency range of 50 Hz to 5 MHz at various temperatures from 30 °C to 400 °C. The result reveals that the space charge polarization leads for conduction mechanism. 相似文献
4.
《材料与设计》2015
In this study, the effect of La2O3 nanoparticles (0, 0.01, 0.03, 0.05 and 0.1 wt.%) has been investigated in Sn–3.0Ag–0.5Cu (SAC-305) alloy. The various soldering properties have been tested, such as wettability, microstructural evolution, intermetallic compound formation, micro-hardness, tensile strength, and fracture analysis of tensile tested samples. La2O3 nanoparticles are added in the Sn–3.0Ag–0.5Cu alloy by mechanical mixing of powders and melting. The structural and morphological features of the samples are characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and electron probe micro-analyzer (EPMA). The experimental results indicate that the best combination of microstructural, wetting and tensile properties is obtained at 0.05 wt.% La2O3 in the solder matrix. The sample reinforced with 0.05 wt.% La2O3 i.e., SAC-0.05 La2O3 exhibits ~ 18% increase in microhardness, ~ 26% increase in the ultimate tensile strength (UTS), and ~ 14% elongation due to the adsorption of high surface energy of La2O3 nanoparticles in the matrix. 相似文献
5.
In the present study, the synthesis of Tin doped indium oxide (ITO) nanopowder at different compositions (In/Sn = 0, 5, 10, 15 at %) was carried out by co-precipitation method. The decomposition of precipitated indium tin acetylacetonate precursor to form In2O3–SnO2 (Sn1?xInxO2) at 400 °C was confirmed by the thermal and FTIR studies. The changes in strain and grain size of the synthesized particle with respect to dopant concentration were determined from the X-ray diffraction (XRD) analysis. Transmission electron microscopy (TEM) images support to confirm the grain size. The optical properties on ITO nanoparticles were analyzed with UV–visible spectroscopy, and band gap was found to vary from 3.62 to 3.89 eV with Sn dopant concentration. This variation was ascribed to the quantum confinement effect. 相似文献
6.
《Materials Chemistry and Physics》2007,101(2-3):415-422
Complete range Zr1−xCexO2 (0 ≤ x ≤ 1) nanoparticles are synthesized by the thermal decomposition of metal-organic precursors (zirconium acetylacetonate and cerium acetylacetonate) in oleylamine. XRD and HRTEM indicate that all of the as-prepared nanoparticles are single-crystal, and the crystallinity becomes better with increasing Ce content. The Zr1−xCexO2 nanoparticles with Ce content larger than 1/8 crystallize in cubic fluorite phase. XRD measurements on the as-prepared and calcinated ZrO2 samples reveal that the tetragonal ZrO2 nanoparticles are stable below 600 °C, and the lattice parameters of ZrO2 nanoparticles decrease with decreasing particle size. The thermal stability of the cubic phase increases with increasing Ce content. The UV–vis absorption spectra reveal that the band gap energy increases with increasing cerium content. Room-temperature photoluminescence (PL) spectra of pure ZrO2 nanoparticles show strong emission peaks centered at about 441 nm at room temperature, which is attributed to the ionized oxygen vacancies in the nanoparticles. On the other hand, room-temperature PL spectra of the as-prepared CeO2 nanoparticles shows two peaks at 417 and 436 nm, which might arise from the transition from the cerium 4f and to the oxygen 2p band (valence band) in CeO2 and the presence of oxygen vacancies, respectively. 相似文献
7.
We report here the synthesis of TbMnO3 nanoparticles via an acrylamide gel route. XRD, TG analysis, DSC analysis, and FTIR spectroscopy are combinatively used to investigate the thermal decomposition process of precursor xerogels and the formation of TbMnO3 phase. It is demonstrated that high-phase-purity TbMnO3 nanoparticles can be prepared by using different chelating agents at a sintering temperature of 800 °C. SEM observation and XRD analysis reveal that the particle size and morphology of the products have a dependence on the chelating agent. The particles prepared using citric acid as the chelating agent appear to be regularly spherical in shape and highly uniform in size with a diameter of ~67 nm, while the sample prepared by using the chelating agent EDTA mainly consists of sphere-, ellipsoid-, and rod-like particles and exhibits a relatively broad particle size distribution with an average particle size centered around 115 nm. The use of a combination of citric acid and EDTA generally results in sphere- and ellipsoid-like particles with an average particle size between those of the samples prepared separately by using the two chelating agents. 相似文献
8.
Zeinab Mosayebi Mehran Rezaei Narges Hadian Fazlollah Zareie Kordshuli Fereshteh Meshkani 《Materials Research Bulletin》2012,47(9):2154-2160
A surfactant assisted co-precipitation method was employed for the low temperature synthesis of magnesium aluminate spinel with nanocrystalline size and high specific surface area. Pluronic P123 triblock copolymer and ammonia solution were used as surfactant and precipitation agent, respectively. The prepared samples were characterized by thermal gravimetric and differential thermal gravimetric analyses (TG/DTG), X-ray diffraction (XRD), N2 adsorption (BET) and transmission electron microscopy (TEM) techniques. The effects of several process parameters such as refluxing temperature, refluxing time, pH, P123 to metals mole ratio (P123/metals) and calcination temperature on the structural properties of the samples were investigated. The obtained results showed that, among the process parameters pH and refluxing temperature have a significant effect on the structural properties of samples. The results revealed that increase in pH from 9.5 to 11 and refluxing temperature from 40 °C to 80 °C increased the specific surface area of prepared samples in the range of 157–188 m2 g?1 and 162–184 m2 g?1, respectively. The XRD analysis showed the single-phase MgAl2O4 was formed at 700 °C. 相似文献
9.
Magnetite (Fe3O4) nanoparticles were controllably synthesized by aerial oxidation FeIIEDTA solution under different monowavelength light-emitting diode (LED) lamps irradiation at room temperature. The results of the X-ray diffraction (XRD) spectra show the formation of magnetite nanoparticle further confirmed by Fourier transform infrared spectroscope (FTIR) and the difference in crystallinity of as-prepared samples. Fe3O4 particles are nearly spherical in shape based on transmission electron microscopy (TEM). Average crystallite sizes of magnetite can be controlled by different irradiation light wavelengths from XRD and TEM: 50.1, 41.2, and 20.3 nm for red, green, and blue light irradiation, respectively. The magnetic properties of Fe3O4 samples were investigated. Saturation magnetization values of magnetic nanoparticles were 70.1 (sample M-625), 65.3 (sample M-525), and 58.2 (sample M-460) emu/g, respectively. 相似文献
10.
In this work, spinel-type Co3O4 spherical nanoparticles were easily prepared via decomposition of the hexamminecobalt(III) nitrate complex, [Co(NH3)6](NO3)3, at low temperature (200 °C). The product was characterized by thermal analysis (TGA/DTA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, UV–vis spectroscopy, transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), Brunauer–Emmett–Teller (BET) specific surface area measurement and magnetic measurements. The results confirmed that pure single-phase Co3O4 nanoparticles with weak ferromagnetic behavior were obtained by this method. TEM images showed that the Co3O4 nanoparticles are sphere-like with an average diameter size of around 15 nm. The optical spectrum indicated two direct band gaps at 2.15 and 3.56 eV which are blue-shifted relative to reported values for the bulk sample. Using this fast and simple method, Co3O4 nanoparticles can be produced without expensive and toxic solvents or complicated equipment. 相似文献
11.
Manickam Sasidharan Nanda Gunawardhana Masaki Yoshio Kenichi Nakashima 《Materials Research Bulletin》2012,47(9):2161-2164
Nb2O5 hollow nanospheres of average diameter ca. ~29 nm and hollow cavity size ca. 17 nm were synthesized using polymeric micelles with core–shell–corona architecture under mild conditions. The hollow particles were thoroughly characterized by transmission electron microscope (TEM), X-ray diffraction (XRD), infrared spectroscopy (FTIR), thermal (TG/DTA) and nitrogen adsorption analyses. Thus obtained Nb2O5 hollow nanospheres were investigated as anode materials for lithium ion rechargeable batteries for the first time. The nanostructured electrode delivers high capacity of 172 mAh g?1 after 250 cycles of charge/discharge at a rate of 0.5 C. More importantly, the hollow particles based electrodes maintains the structural integrity and excellent cycling stability even after exposing to high current density 6.25 A g?1. The enhanced electrochemical behavior is ascribed to hollow cavity coupled with nanosized Nb2O5 shell domain that facilitates fast lithium intercalation/deintercalation kinetics. 相似文献
12.
Indium oxide nanoparticles of ~12 nm were synthesized by a simple chemical route using indium(III) nitrate. Nanoparticles are formed after calcining the dried precursor in air at 400 °C for 10 h. TEM analysis showed that the morphology and size of the In2O3 samples were affected by ultrasonication. FTIR and Raman studies reveal that the nanoparticles are single-phase cubic structure of In2O3. NEXAFS study was used to quantify the Indium and oxygen valence state. Magnetic behavior of indium oxide nanoparticles was found to be diamagnetic. UV spectra show a weak band at ~308 nm corresponds to optical band gap energy of 4.03 eV. 相似文献
13.
A modified solution combustion approach was used in the preparation of nanosize LaAlO3 (~23.6 nm) using mixture of citric acid and oxalic acid as fuels with corresponding metal nitrates. The synthesized and calcined powders were characterized by Fourier transform infra red spectrometry (FTIR), Differential thermal analysis-Thermogravimetry analysis (DTA–TGA), X-ray diffractometry (XRD) and Transmission electron microscopy (TEM). The FTIR spectra show the lower frequency bands at 656 and 442 cm?1corresponds to metal–oxygen bonds (possible La–O and Al–O stretching frequencies) vibrations for the perovskite structure compound. DTA confirms the formation temperature of LaAlO3 varies between 830–835 °C. XRD results show that mixture of fuels ratio is influential on the crystallite size of the resultant powders. The average particle size of LaAlO3-1 as determined from TEM was about 41 nm, whereas for LaAlO3-2 and LaAlO3-3 samples, particles are seriously aggregated. 相似文献
14.
M. Parthibavarman V. Hariharan C. Sekar 《Materials science & engineering. C, Materials for biological applications》2011,31(5):840-844
Tin oxide hexagonal-shaped nanodiscs (SnO) and spherical nanoparticles (SnO2) have been prepared by using a simple household microwave irradiation method with an operating frequency of 2.45 GHz. This technique permits us to produce gram quantity of homogeneous nanoparticles in just 10 min. The crystallite size was evaluated from powder X-ray diffraction (XRD) studies and was in the 20 to 25 nm range. Transmission electron microscopy (TEM) analysis showed that the as prepared SnO form as hexagonal-shaped nanodiscs and upon subsequent annealing at 500 °C for 5 h in air, the SnO gets converted to spherical-shaped nanoparticles of SnO2. The SnO2 sample shows good sensitivity towards the relative humidity. The calculated response and recovery time were found to be 32 s and 25 s respectively. These results indicate promising applications of SnO2 nanoparticles in a highly sensitive environmental monitoring and humidity controlled electronic devices. The samples were further subjected to thermal analyses (TG–DTA) and UV–VIS diffusion reflectance spectroscopy (DRS) studies. 相似文献
15.
Co coated Fe3O4 core/shell-type nanoparticles were fabricated by hydrothermal technique and electroless plating process. X-ray powder diffraction (XRD), X-ray fluorescence spectrometer (XRF) and transmission electron microscope (TEM) were employed to investigate the crystal structure, element composition and morphology of the prepared nanoparticles. Vibrating sample magnetometer (VSM) and vector network analyzer were used to measure the magnetic properties and electromagnetic parameters of pure Fe3O4 and Fe3O4/Co core/shell-type nanoparticles, then reflection losses (RL(dB)) were calculated in the frequency range of 2–18 GHz. Magnetic studies revealed typical ferromagnetic behavior for the pure Fe3O4 and Fe3O4/Co core/shell-type nanoparticles with their saturation magnetization (Ms = 63.1 and 72.4 emu/g) and coercivity (Hc = 99.5, and 165.4 Oe), respectively. Due to the existence of the core/shell structure, the electromagnetic characteristic of the Fe3O4/Co nanoparticles exhibit better microwave absorption performance than the pure Fe3O4 in the range of 2–18 GHz, such as more powerful absorbing property and wider frequency band of microwave absorption. 相似文献
16.
《Advanced Powder Technology》2014,25(2):567-573
Nano- and micro-sized LiFePO4 powders were synthesized by a sodium gluconate (C6H11NaO7)-assisted hydrothermal synthesis method at 220 °C for 10 h with pH = 2–7. The resulting powders were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and energy-dispersive X-ray spectrometer (EDS). The obtained data showed that the pH of synthesis solution played a key role in the formation of the LiFePO4 powders with different morphologies, such as ball-like microspheres, irregular microspheres with the agglomerated rods and particles, sphere-like nanoparticles and nano-ellipsoids. The results from electrochemical performance measurements revealed that the charge–discharge cycling characteristics of the samples were strongly dependent on their morphologies. In particular, the ellipsoidal LiFePO4 nanoparticles with the average size of 70–90 nm showed the highest initial discharge capacity of 150 mA h g−1 at 0.1 C rate, and cycling stability of the ellipsoidal LiFePO4 nanoparticles was optimum among all the samples prepared due to their dual advantages of high tap density and good diffusion property. The present study offers a simple morphology-controllable route, without carbon coating or doping with supervalent cations, to synthesize and to design high performance cathode materials for lithium-ion batteries. 相似文献
17.
《Materials Chemistry and Physics》1998,57(2):111-116
A low-melting water-resistant 40P2O5-50PbO-10ZnO glass with a glass transition temperature Tg ≅ 338°C has been prepared. Differential thermal analysis (DTA), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) absorption spectroscopy techniques were applied for both qualitative and quantitative characterization and crystallization of (Pb5/6Zn1/6)3P4O13 in glass. Kinetics of crystallization was analyzed based on the Johnson-Mehl-Avrami model. It was found that the surface nucleation mode, having the morphology index n ≅ 1, is dominant. The activation energy of crystallization was found to be 312 kJ mol−1 by a non-isothermal DTA method, while 363 and 344 kJ mol−1 by isothermal XRD and FTIR methods, respectively. These values agree with each other to a reasonable extent. Peak intensity of a specific vibrational mode in FTIR absorption spectra was found to be applicable for quantitative kinetic analysis should suitable calibration using a standard specimen be done. 相似文献
18.
A.K. Mishra T.P. Sinha S. Bandyopadhyay D. Das 《Materials Chemistry and Physics》2011,125(1-2):252-256
Single phase Sn1?xFexO2 (x = 0.1, 0.3 and 0.5) nanoparticles having size in the range 9–17 nm were prepared by a chemical route. XRD analysis of the samples confirmed the formation of cassiterite phase without any impurity. The nanocrystalline nature of the samples and their crystallinity were confirmed by TEM measurements. Raman and Mössbauer spectroscopy studies indicate structural disorder and vacancies in the nanostructures. M–H and M–T data recorded by a SQUID magnetometer show that the samples are essentially paramagnetic with a weak ferromagnetic component. Ferromagnetism is argued to be associated with the vacancies and defects present in the grain boundaries and interfaces of the nanoparticles. 相似文献
19.
Ali A. Ensafi Ali R. Allafchian B. Rezaei R. Mohammadzadeh 《Materials science & engineering. C, Materials for biological applications》2013,33(1):202-208
A magnetic nano‐composite of multiwall carbon nanotube, decorated with NiFe2O4 nanoparticles, was synthesized with citrate sol–gel method. The multiwall carbon nanotubes decorated with NiFe2O4 nanoparticles (NiFe2O4–MWCNTs) were characterized with different methods such as Fourier transform infrared spectroscopy (FT‐IR), transmission electron microscopy (TEM), atomic force microscopy (AFM), vibrating sample magnetometer (VSM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The new nano-composite acts as a suitable electrocatalyst for the oxidation of sotalol at a potential of 500 mV at the surface of the modified electrode. Linear sweep voltammetry exhibited two wide linear dynamic ranges of 0.5–1000 μmol L? 1 sotalol with a detection limit of 0.09 μmol L? 1. The modified electrode was used as a novel electrochemical sensor for the determination of sotalol in real samples such as pharmaceutical, patient and safe human urine. 相似文献
20.
《Materials Research Bulletin》2006,41(4):817-824
The H2/O2 fuel cell based on the proton conducting P2O5–ZrO2–SiO2 glasses was prepared by sol–gel technique. Structural characterization were carried out using X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (31P MAS NMR), N2 adsorption–desorption analysis, differential thermal analysis (DTA) and thermal gravimetric analysis (TGA) and impedance measurements. The absorption bonds of Si–O–Si, Si–O–P and Si–O–Zr were observed in the P2O5–ZrO2–SiO2 glasses which were heat treated at 600 °C. A sample (5P2O5–4ZrO2–91SiO2, mol%) was selected as the electrolyte for the H2/O2 fuel cell test and yielded the maximum power density value of 8.5 mW/cm2 using electrochemical measurements at 30 °C under relative humidity atmosphere. 相似文献