共查询到20条相似文献,搜索用时 31 毫秒
1.
Jun Wang Shunxiao Zhang Zhanshuang Li Jia You Piaoping Yang Xiaoyan Jing Milin Zhang 《Bulletin of Materials Science》2008,31(2):193-195
The nanocrystalline CuO powders were prepared by precipitation method using Cu(NO3)2 as copper raw material, water and ethanol as dispersants, and NaOH and ammonia solution as precipitates. The structure, particle
size and morphology of resulting CuO powders were characterized by X-ray diffraction (XRD), field-emission scanning electron
microscopy (SEM) and transmission electron microscopy (TEM). The mechanism of CuO formation was discussed. 相似文献
2.
Compounds of the composition MIITh(NO3)6·8H2O (MII = Mg, Mn, Co, Ni, Zn) were prepared by precipitation from solution. The structure and thermal decomposition of these compounds
were examined by X-ray diffraction and thermal analysis. The previously unknown standard enthalpies of formation of the compounds
at 298.15 K were determined by reaction calorimetry. 相似文献
3.
《Thin solid films》2005,471(1-2):100-104
Thin films of CeO2–TiO2–ZrO2 with 23 mol% of Ce, 45 mol% of Ti and 32 mol% of Zr were obtained by the sol–gel method. The precursor sol was prepared from a mixture of Ce(NH4)2 (NO3)6, Ti(OPri)4 and Zr(OPri)4 solubilized in isopropanol and then sonicated. Xerogels were characterized by Differential Scanning Calorimetry (DSC) and Thermal Gravimetric Analysis (TGA) and X-ray diffraction. The films were deposited by dip-coating technique on a glass plate coated with an indium tin oxide film (ITO) and thermally treated at 80 °C for 15 min. and heated at 450 °C for 15 min in an oxygen atmosphere. By means of the addition of a lithium salt (LiCF3SO3) to the precursor solution, films with different electrochemical performances were obtained. Their possible use as ion storage (counter-electrode) in electrochromic devices (ECD) was analyzed by spectroelectrochemical measurements using cyclic voltammetry and chronoamperometry coupled to spectrometric measurements. 相似文献
4.
In this work, nano-sized ZnO particles were prepared by a direct precipitation method with Zn(NO3)2·6H2O and NH3·H2O as raw materials, and the impact of the synthesis process was studied. The optimal thermal calcined temperature of precursor precipitates of ZnO was obtained from the differential thermal analysis (DTA) and the thermal gravimetric analysis (TGA) curves. The purity, microstructure, morphology of the calcined ZnO powders were studied by X-ray diffraction (XRD), energy dispersive X-ray spectrum (EDS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The synthesized ZnO powders had a wurtzite structure with high purity. The final products were of flower-like shape and the nanorods which consisted of the flower-like ZnO bunches were 20–100 nm in diameter and 0.5–1 μm in length. The effect of process conditions on the morphology of ZnO was discussed. 相似文献
5.
《Materials Letters》2005,59(2-3):197-200
ZnTiO3 powders with pure hexagonal phase were prepared by the sol–gel process with Zn(NO3)2·6H2O and Ti(OC4H9)4 materials. The thermal behavior and phase transformation of the gels were investigated by the differential scanning calorimetry–thermogravimetry (DSC–TG) analysis, X-ray diffraction (XRD) patterns, Fourier-transforming infrared (FT-IR) spectroscopy, and Raman scattering spectroscopy. The results revealed that pure hexagonal phase of ZnTiO3 could be obtained at low temperature of 800 °C. However, in further increased temperature above 900 °C, hexagonal ZnTiO3 would decompose into cubic Zn2TiO4 and rutile TiO2. 相似文献
6.
Zhengwei Cai Donglin Zhao Xiaoya Fan Longcheng Zhang Jie Liang Zixiao Li Jun Li Yongsong Luo Dongdong Zheng Yan Wang Tingshuai Li Hong Yan Binwu Ying Shengjun Sun Abdulmohsen Ali Alshehri Hong Yan Jia Xu Qingquan Kong Xuping Sun 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(30):2300620
Electroreduction of nitrite (NO2−) to valuable ammonia (NH3) offers a sustainable and green approach for NH3 synthesis. Here, a Cu3P@TiO2 heterostructure is rationally constructed as an active catalyst for selective NO2−-to-NH3 electroreduction, with rich nanosized Cu3P anchored on a TiO2 nanoribbon array on Ti plate (Cu3P@TiO2/TP). When performed in the 0.1 m NaOH with 0.1 m NaNO2, the Cu3P@TiO2/TP electrode obtains a large NH3 yield of 1583.4 µmol h−1 cm−2 and a high Faradaic efficiency of 97.1%. More importantly, Cu3P@TiO2/TP also delivers remarkable long-term stability for 50 h electrolysis. Theoretical calculations indicate that intermediate adsorption/conversion processes on Cu3P@TiO2 interfaces are synergistically optimized, substantially facilitating the conversion of NO2−-to-NH3. 相似文献
7.
Lian Lian Li Shu Ya Wu Xiang Ming Chen 《Journal of Materials Science: Materials in Electronics》2009,20(12):1159-1163
Multiferroic YMn2O5 fine powders were synthesized by a hydrothermal process from Y(NO3)3 · 6H2O and Mn(NO3)2, and their structure and magnetic characteristics were evaluated. YMn2O5 fine powders with orthorhombic structure were synthesized by the present process with aqueous NaOH as the mineralizer, and the synthesis conditions such as temperature and [NaOH] have significant effects upon the grain size and morphology. The single phase YMn2O5 fine powders with the most uniform morphology were synthesized at 523 K from the solution with [NaOH] = 1 M, and then the good sinterability was expected at lower temperatures where the phase separation in YMn2O5 ceramics could be avoided. YMn2O5 fine powders derived by the present hydrothermal process indicated the weak ferromagnetism below 45 K. 相似文献
8.
Xiaoya Fan Donglin Zhao Zhiqin Deng Longcheng Zhang Jun Li Zerong Li Shengjun Sun Yongsong Luo Dongdong Zheng Yan Wang Binwu Ying Jing Zhang Abdulmohsen Ali Alshehri Yuxiao Lin Chengwu Tang Xuping Sun Yinyuan Zheng 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(17):2208036
Electrochemical nitrate (NO3−) reduction reaction (NO3−RR) is a potential sustainable route for large-scale ambient ammonia (NH3) synthesis and regulating the nitrogen cycle. However, as this reaction involves multi-electron transfer steps, it urgently needs efficient electrocatalysts on promoting NH3 selectivity. Herein, a rational design of Co nanoparticles anchored on TiO2 nanobelt array on titanium plate (Co@TiO2/TP) is presented as a high-efficiency electrocatalyst for NO3−RR. Density theory calculations demonstrate that the constructed Schottky heterostructures coupling metallic Co with semiconductor TiO2 develop a built-in electric field, which can accelerate the rate determining step and facilitate NO3− adsorption, ensuring the selective conversion to NH3. Expectantly, the Co@TiO2/TP electrocatalyst attains an excellent Faradaic efficiency of 96.7% and a high NH3 yield of 800.0 µmol h−1 cm−2 under neutral solution. More importantly, Co@TiO2/TP heterostructure catalyst also presents a remarkable stability in 50-h electrolysis test. 相似文献
9.
Xiaolei Su Fa Luo Yan Jia Junbo Wang Jie Xu Xinhai He Chong Fu Songtao Liu 《Journal of Materials Science: Materials in Electronics》2014,25(11):5101-5106
Al-doped SnO2 powders have been prepared by coprecipitation method at 550 °C, using tin chloride (SnCl4·5H2O) as the raw material, ammonium hydroxide (NH3·H2O) as the precipitator, and aluminum nitrate (Al(NO3)3·9H2O) as the doping source, respectively. The microstructure of the prepared powders has been characterized by X-ray diffraction and scanning electron microscope, respectively. Results show that the prepared powders were Sn(1?x)AlxO2 (x = 0, 0.03, 0.06, and 0.09) solid solution powders and the lattice constant decreased with increasing Al doping content. The electromagnetic property in the frequency range of 8.2–12.4 GHz of prepared powders has been determined. The real part (ε′) and imaginary part (ε″) of permittivity of prepared powders increased with increasing Al doping content. There was little change of real part (μ′) and imaginary part (μ″) of permeability of prepared powders. The electromagnetic loss mechanism has been discussed. 相似文献
10.
The present study examined the thermal properties of phosphate-bonded investments, a gypsum-bonded investment and an experimental investment powder when the basic powders were heated to high temperatures by simultaneous differential thermal analysis (DTA) and thermogravimetry (TG). The phosphate-bonded investments showed values of about 59 kcal mol–1 (247 kJ mol–1) (thermal decomposition of NH4H2PO4) and about 11 kcal mol–1 (46 kJ mol–1) (formation of NH4MgPO4). Thermal reactions occurred clearly on the DTA-TG curves for the investment powders, using powders of NH4H2PO4, and MgO with NH4H2PO4/MgO = 1 as main components in the investment. 相似文献
11.
《Materials Research Bulletin》2006,41(11):2130-2136
Nanometer nickel powders have been prepared using the polyol method with NaOH, Ni(NO3)2·6H2O, ethylene glycol (EG), and polyvinylpyrrolidone (PVP) as raw materials. The thermodynamics of the reaction system was studied, and the E–pH diagram of Ni–EG–H2O was plotted. The oxidation products of EG were predicted from the E–pH diagram, and CO32− in alkaline solutions was identified as the product through the IR spectrum and CaCO3 sediment. Field-emission scanning electron micrograph (FE-SEM) showed that spherical nanometer nickel powders were obtained. 相似文献
12.
Heng Guo Mengyue Li Yuantao Yang Rui Luo Wei Liu Fengying Zhang Chun Tang Guidong Yang Ying Zhou 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(10):2207743
Electrochemical nitrate (NO3−) reduction to ammonia (NH3) offers a promising pathway to recover NO3− pollutants from industrial wastewater that can balance the nitrogen cycle and sustainable green NH3 production. However, the efficiency of electrocatalytic NO3− reduction to NH3 synthesis remains low for most of electrocatalysts due to complex reaction processes and severe hydrogen precipitation reaction. Herein, high performance of nitrate reduction reaction (NO3−RR) is demonstrated on self-supported Pd nanorod arrays in porous nickel framework foam (Pd/NF). It provides a lot of active sites for H* adsorption and NO3− activation leading to a remarkable NH3 yield rate of 1.52 mmol cm−2 h−1 and a Faradaic efficiency of 78% at −1.4 V versus RHE. Notably, it maintains a high NH3 yield rate over 50 cycles in 25 h showing good stability. Remarkably, large-area Pd/NF electrode (25 cm2) shows a NH3 yield of 174.25 mg h−1, be promising candidate for large-area device for industrial application. In situ FTIR spectroscopy and density functional theory calculations analysis confirm that the enrichment effect of Pd nanorods encourages the adsorption of H species for ammonia synthesis following a hydrogenation mechanism. This work brings a useful strategy for designing NO3−RR catalysts of nanorod arrays with customizable compositions. 相似文献
13.
Lubomir Medvecky Tibor Sopcak Juraj Durisin Jaroslav Briancin 《Materials Letters》2011,65(23-24):3566-3569
Nanocrystalline hydroxyapatites were prepared by the precipitation method using a water soluble Ca2+ organic compounds and (NH4)2HPO4. The fine nanohydroxyapatites had spherical, needle-like or mixed morphology and specific areas around 150 m2/g. The nanocrystalline powders differed by thermal stability and they were transformed to bi- or three-phasic systems with hydroxyapatite, βTCP and αTCP phases after annealing at 1000 °C. 相似文献
14.
Lianyun DengJingxuan Lei Ying Shi Ting LinYuying Ren Jianjun Xie 《Materials Letters》2011,65(4):769-771
Aluminum oxynitride(AlON) phosphors co-doped by Tb3+ and Ce3+ were synthesized by nitridation of the precursor which was co-precipitated from Al(NO3)3 solution and nanosized carbon black at 1750 °C for 2 "hrs" in flowing nitrogen atmosphere. The obtained AlON based powders were composed of polycrystalline spinel typed particles with sizes in the range of 1-3 μm. Under an excitation of 275 nm, it was found that co-doping of Ce3+ could drastically enhance the luminescence of AlON:Tb3+ powder by energy transfer. The product with 0.5 mol% Ce3+ and 0.67 mol% Tb3+ exhibited a strong broad green emission at 540 nm. The critical quenching concentration of Tb3+ in AlON:0.5 mol% Ce3+/xmol% Tb3+ phosphor was determined to be 0.67 mol%. It was supposed that the mechanism of concentration quenching of Tb3+ in AlON:0.5 mol% Ce3+ xmol% Tb3+ phosphor was dipole-dipole interaction. 相似文献
15.
The properties of precipitated materials are highly dependent upon the complex ionic equilibria of the species in the solutions used for precipitation. Concentration, temperature, and pH dictate the complex species present within aqueous systems, and therefore affect the final precipitate properties. This paper discusses the effect of pH on the properties of PbTiO3 precursor powders prepared by adding stoichiometric mixtures of TiCI4 and Pb(NO3)2, in aqueous solution, to NH4OH solutions. Several powders were prepared between pH 8.00 and 10.50. The pH does not affect the amorphous structure, but does have a pronounced effect upon the specific surface area and growth mechanisms of the precipitates.Since previous studies indicated that hydrogen peroxide (H2O2) affects the hydroxylation of the precipitated powders, the effect of (H2O2) concentration on the precipitate properties was also studied. Several precipitates were prepared from solutions containing (H2O2): PbTiO3 ratios between 0:1 and 6:1. When (H2O2) was not added to the solutions used for precipitation, atmospheric CO2 dissolved in solution caused precipitation of carbonate species. Thus, addition of the (H2O2) to the solutions inhibited precipitation of the carbonates. 相似文献
16.
《Materials Letters》2007,61(8-9):1675-1678
Zinc-containing ZSM-5 zeolite with novel morphology was firstly synthesized in a one-step route using [Zn(NH3)4]2+ aqueous solution as zinc resource and n-butylamine as template. The materials were characterized by XRD, SEM, diffuse reflectance UV–vis spectra, FTIR for pyridine adsorption. The results showed that the formation of this novel structure might be related to the introduction of [Zn(NH3)4]2+ aqueous solution and the zinc existent state in zeolite. 相似文献
17.
Compounds M 2 I Th(NO3)6 (MK = NH4, K, Rb, Cs) were precipitated from a solution. The structure and thermolysis of these compounds were studied by X-ray diffraction, precision IR spectroscopy, and thermal analysis. Their previously unknown standard enthalpies of formation at 298.15 K were determined by reaction calorimetry. 相似文献
18.
DongEn Zhang Wei Wu XinJiang Ni XiaoYan Cao XiaoBo Zhang XingYou Xu ShanZhong Li GuiQuan Han Ailing Ying ZhiWei Tong 《Journal of Materials Science》2009,44(13):3344-3348
Bowknot-like CeO2 bundles crystals were successfully prepared from a single precursor via a thermal decomposition route. The precursor was
synthesized by a hydrothermal reaction using Ce(NO3)3 · 6H2O with CO(NH2)2 at 150 °C in a water-glycerol complex solution. Glycerol plays a very important role for the formation of precursor bowknot-like
structures. The morphology of the precursor was maintained during the heating process. The optical absorption spectrum indicates
that the CeO2 dendrites have a direct band gap of 3.42 eV, which is mostly larger than values of bulk powders due to the quantum size effect.
The electrochemical characters of the CeO2 bundles structures are studied by their investigation of cyclic voltammetry (CV). It was found that the CeO2 bundles can greatly improve the electron transfer ability. 相似文献
19.
We study the influence of the concentrations of AgNO3 (0.06–0.32 mole/liter) and NH4NO3 (0.1–0.5 mole/liter) in the initial solution and the hydrodynamic conditions for Rev varying within the range 12,950–46,700 on the physicochemical properties of silver powders obtained from secondary solutions of silver (I) nitrate by contact precipitation with magnesium chips within the range 293–323°K. At a temperature of 313°K, for the stoichiometric amount of magnesium chips, turbulization of the medium corresponding to Re v = 24,200, and the contents of AgNO3 and NH4NO3 in the initial solution equal to 0.06–0.1 mole/liter and 0.25 mole/liter, respectively, we obtain silver powders with a bulk density of 1.09 g/cm3, a specific surface area of 2520 cm2/g (determined according to the gas permeability), and mean particle sizes of 1.0–3.0 μm. Powder particles have perfect geometric shapes with tetragonal and hexagonal symmetry about the axis of growth. The content of Ag in the powder is equal to 99.9 wt.%. It is shown that, by choosing and combining the conditions of contact precipitation, we can get powders with prescribed physicochemical properties. 相似文献
20.
《Materials Research Bulletin》2006,41(4):791-803
Monolithic Al2O3 and Al2O3/SiC nanocomposite powders were prepared by sol–gel processing. The process involved the precipitation of Al(NO3)3·9H2O with NH4OH in excess water to form boehmite (AlOOH). XRD indicates that the subsequent thermal reaction proceeds by the phase transformation sequence AlOOH, γ-, δ-, θ-, to α-Al2O3. The 27Al NMR spectra indicate a gradual increase in the proportion of Al in the tetrahedral sites of the γ-, δ- and θ-Al2O3 formed at increasing calcination temperatures. Complete transformation to octahedral Al (α-Al2O3) is marked by the abrupt disappearance of tetrahedral Al. Al2O3/SiC nanocomposite powders were prepared by adding α-SiC powder to the boehmite precursor at the precipitation stage. Upon heating, the 29Si NMR spectra of the Al2O3/SiC powders reveal α-SiC, Al2O3·xSiO2 and SiO2 phases. Stable α-Al2O3 and α-Al2O3/SiC nanocomposite powders are formed at 1200 and 1300 °C, respectively. It appears likely that the presence of SiC modifies the thermal behaviour of the Al2O3 in the nanocomposites by stabilising the Al2O3 phases with concomitant oxidation of SiO2. 相似文献