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1.
《Ceramics International》2015,41(4):5537-5546
A new kind of composite mica pigments were prepared by coating Co2−xMxTiO4 composite oxide nanoparticles onto mica, to investigate the effects of doping ions Mg2+, Mn2+, Ni2+, Cu2+ and Zn2+ on the properties of the doped composite pearlescent pigments, such as the crystal structure, color and shading power. The structure, morphology, color and shading power of the coated pigments were characterized by the X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–vis spectrophotometer and CIE L*a*b* methods. SEM images of coated pigments showed that mica were coated uniformly with a single layer of dispersed nanoparticles. Research of the doped composite pigments showed that the doping ions had entered into the spinel crystal structure, forming a new kind of composite mica pearlescent pigments coated with Co2−xMxTiO4. For the analysis of color and shading power of the pigments, doping of Ni2+ and Zn2+ can improve the color and shading power of the doped pigments, but the larger dosage of Zn2+ doping can weaken the color and shading power of the doped pigments. Doping of Mg2+, Mn2+ and Cu2+ metal ions can also weaken the color and shading power of the doped pigments. 相似文献
2.
The efficiency of catalytic ozonation with homogeneous (containing dissolved ions of Fe2+, Mn2+, Cu2+, Ni2+, Co2+, V5+, Cr3+, Mo6+) and heterogeneous (MnO2, Ni2O3, Fe2O3, CuO, Al2O3, CoO, V2O5, Cr2O3, MoO3, TiO2) catalysts and non-accompanied ozonation was compared for degradation of m-dinitrobenzene (m-DNB). Several transition metals in homogeneous and heterogeneous form improved significantly the ozone performance for degradation of m-DNB. This improvement was found to be due to supplementary formation of reactive species (hydroxyl radicals) and better ozone utilization. The effects observed were found to be strongly dependent on the treatment conditions. 相似文献
3.
Xiangchun Yin Jianguo Huang Zidie Pu Jinfeng Li Hao Feng Xiaoyang Wang Yiqun Wang 《Ceramics International》2021,47(12):17167-17176
In this study, a blue-green pigment has been prepared by partially replace Co2+ and Cr3+ in CoCr2O4 spinel structure with Mg2+ and Al3+ using a gel casting method The gel precursor was calcined at various temperatures (900–1400 °C) to obtain Mg0.5Co0.5CrAlO4 spinel pigment. Combining the Rietveld refinement method of XRD and peak fitting of XPS high-resolution spectra, the relationships between the cation distributions (Co2+, Mg2+, Al3+, and Cr3+) in the tetrahedron and octahedron of the spinel structure and the calcination temperature were examined. In the octahedron, the contents of Co2+ and Al3+ decreased with increasing calcination temperature, and the Mg2+ and Cr3+ contents exhibited the opposite trend. The bond lengths of A-O and B–O change with increasing calcination temperature, thereby leading to a change in the unit cell. The optical performance of the pigments was investigated via UV–vis and CIE L*a*b* spectrophotometry, and the study shows that the blue-green hue of the pigment powder is caused by the absorption at υ3~υ8 (370 nm–640 nm) in the visible light region. The varied contents of Co2+ and Cr3+ in the spinel structure among calcination temperatures cause the absorption spectrum intensity change, thereby resulting in various blue-green tones. This study lays the foundations for subsequent investigations of colour modification in MgxCo1-xAlyCr2-yO4 spinel. 相似文献
4.
《Journal of Catalysis》2005,229(2):470-479
Michael reaction of β-ketoesters with vinylketones at room temperature under solvent-free condition is investigated with various Fe3+ catalysts, including FeCl3 ⋅ 6H2O supported on various supports (Fe–mica, Fe–mont, Fe–SiO2, Fe–Al2O3, Fe–NaY) and homogeneous catalysts, FeCl3 ⋅ 6H2O and Fe(NO3)3 ⋅ 9H2O. Fe3+-exchanged fluorotetrasilicic mica (Fe–mica) shows highest activity. Fe–mica exhibits almost quantitative yields of Michael adducts, high turnover numbers (TON = 1000), and a low level of Fe leaching. After simple work-up procedures, Fe–mica can be recycled without a loss in activity. The relationship between catalytic activity and the catalyst structure determined by XRD, UV–vis, and Fe K-edge XANES/EXAFS is discussed in terms of the effect of clay support on the structure and reactivity of Fe3+ species. The Fe3+ cation, highly dispersed in the interlayer of clay (mica or mont) or on SiO2, is more active than the cluster-like Fe3+ oxide or hydroxide species in Fe–NaY and Fe–Al2O3. UV–vis and XAFS results for the catalysts treated with reactants suggest that, during the reaction, the FeCl2(O)4 octahedral species in FeCl3 ⋅ 6H2O or those on Fe–SiO2 are converted to the β-diketonato complexes with two β-diketonato ligands, whereas in Fe–mica β-diketonato complexes with one β-diketonato ligand are formed. The formation of β-diketonato complexes results in a slight lowering of the Fe oxidation number from 3+, probably as a result of the electron donation from the β-diketonato ligand to Fe3+ as a Lewis acid site. The lower numbers of β-diketonato ligand coordinated with Fe3+ in Fe–mica should result in a larger coordination strength for β-diketonato ligand than that in Fe–SiO2, which was confirmed by acetylacetone-TPD. Thus, the central carbon atom of the β-diketonato ligand in Fe–mica is more reactive toward nucleophilic attack by the coordinated enone, leading to higher activity for the Michael reaction. 相似文献
5.
The authors consider the possibility of producing ceramic pigments based on natural wollastonite using the gel method, which contributes to the formation of an amorphous structure in wollastonite under the effect of hydrochloric acid. The chromophores are soluble salts containing Fe3+, Ni2+, Cr3+, Cu2+, and Co2+ ions. The wollastonite structure is restored under firing; the color characteristics of pigments after the gel-formation stage improve. The use of the gel method does not require a cardinal modification of the technological scheme and equipment but facilitates a significant improvement of the color properties of pigments and paints.__________Translated from Steklo i Keramika, No. 1, pp. 25 – 27, January, 2005. 相似文献
6.
《Journal of the European Ceramic Society》2005,25(9):1525-1530
The effect of various nuclei on crystallization mechanism of SiO2–Al2O3–CaO–MgO(R2O) glasses were investigated by differential thermal analysis (DTA) through Matusita, Marotta and modified Kissinger methods. The Avrami constant, n, and the activation energy for crystallization of the most promising specimens containing Cr2O3, Fe2O3 and TiO2 in the single, double and triple nuclei series were determined. According to the results the Avrami constants derived from the Marotta method were more consistent with the other experimental observation. While glasses containing TiO2 as the single nucleant represents surface crystallization and those containing Cr2O3 or Fe2O3 one-dimensional bulk crystallization, the crystallization mechanism of specimens containing both Cr2O3 and Fe2O3 and also the glasses containing the triple nuclei, are bulk and two dimensional. 相似文献
7.
Synthesis and color properties of the TiO2@CoAl2O4 blue pigments with low cobalt content applied in ceramic glaze
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Xuanmeng He Fen Wang Hui Liu Lijun Niu Xinzhen Wang 《Journal of the American Ceramic Society》2018,101(6):2578-2588
The TiO2@CoAl2O4 complex blue pigments with low cobalt content were synthesized through calcinations of the precursor obtained from coprecipitating Co2+ and Al3+ to form Co‐Al LDHs (layered double hydroxides) on the surface of TiO2 particles. The structure and the properties of the synthesized pigments were characterized by XRD, SEM, TEM, UV‐Vis spectroscopy, XPS, and colorimeter. The precursors of the blue TiO2@CoAl2O4 complex pigments were consisted of LDHs shell layer encapsulated TiO2 microsphere. After calcinations at 1100°C, the LDHs shell layer were absolutely transformed to the spinel CoAl2O4, and the pigments presented a core‐shell structure and uniform sphere morphology (the diameter of microsphere was about 780 nm). The absorption bands at around 547, 584, and 624 nm in the Uv‐Vis absorption spectra of the TiO2@CoAl2O4 complex pigments were corresponded to the characteristic absorption bands of the spinel CoAl2O4, revealed the pigments with a bright blue hue. In addition, as the mass ratio of CoAl2O4/TiO2 increased to 0.4, the blue component of the pigments reached to 27.89 and slight color variation with the increase in the CoAl2O4 content in a range, possessed low cobalt content and exhibited a stabile performance in commercial low‐temperature ceramic glazes. The XGT results showed that the TiO2@CoAl2O4 complex pigments with low cobalt content presented bright color in ceramic glaze. Especially, the synthesized pigments reduced the usage and toxicity of cobalt, which were efficiency for economy and environmental protection. 相似文献
8.
The oxidative dehydrogenation of ethane into ethylene by carbon dioxide over unsupported Cr2O3, Cr2O3/SiO2 and a series of Cr2O3/SiO2 catalysts modified by sulfate was investigated. The results show that Cr2O3/SiO2 is an effective catalyst for dehydrogenation of ethane and CO2 in the feed promotes the catalytic activity. Sulfation of silica will influence the catalytic behavior of Cr2O3/SiO2 in dehydrogenation of ethane with carbon dioxide depending on the amount of sulfate. Cr2O3/6 wt% SO
4
2-
–SiO2 catalysts exhibit an excellent performance for this reaction, giving an ethylene yield of 55% at 67% ethane conversion at
650°C. Characterizations indicate that addition of sulfate changes the bulk and surface properties of Cr2O3/SiO2, promoting the reduction of Cr6+ to Cr3+ and favoring the catalytic conversion.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
9.
This paper studies the decomposition of formic, oxalic and maleic acids by O3, O3/catalyst, and O3/H2O2. The catalytic effect of Co2+, Ni2+, Cu2+, Mn2+, Zn2+, Cr3+, and Fe2+ ions is investigated. The results showed that—Co2+ and Mn2+ have the highest catalytic activity for the decomposition of oxalic acid while the catalytic effect of the studied ions is insignificant on the rate of decomposition of formic acid. Maleic acid decomposes by ozone into formic acid and glyoxylic acid, which subsequently oxidizes to oxalic acid. Though the studied ions have no effect on the decomposition of maleic acid, they have a significant effect on the produced oxalic and glyoxylic acids. In the presence of Cu2+ ions glyoxylic acid is mainly transformed into formic acid and traces of oxalic acid. In such case, a complete decomposition of maleic acid and its degradation products is achieved within 45 min. The results also show that combining H2O2 with O3 results in an increase in the rate of decomposition of oxalic acid. However, O3/H2O2 system is less active than O3/Co2+ or O3/Mn2+. 相似文献
10.
Monika Bosacka Anna Blonska-Tabero Elzbieta Filipek Jana Luxová Petra Šulcová 《Ceramics International》2021,47(17):24607-24614
A new pyrophosphate(V) of the formula Co5Cr2(P2O7)4 was obtained in the system Co2P2O7–Cr4(P2O7)3 as a result of solid-state reactions taking place between different reactants. The new compound crystallizes in the orthorhombic system and belongs to the family of pyrophosphates of the general formula M52+M23+(P2O7)4 and is probably isostructural with Fe52+Fe23+(P2O7)4. Powder diffraction pattern, infrared spectrum and SEM image of the new compound were presented. As a new potential inorganic pigment, Co5Cr2(P2O7)4 was tested for its thermal stability, particle size distribution and colour properties, which were studied both for powder and after introduction into organic matrix and leadless ceramic glaze. The colour of Co5Cr2(P2O7)4 powder was defined as deep grey with the colour coordinates L*/a*/b* = 60.63/-1.42/-3.41 and according to the hue angle (h° = 247.39°) it belongs to the blue region. Co5Cr2(P2O7)4, with its relatively high thermal stability (t m = 1230 ± 10 °C) and appropriate colour properties, is a good candidate to be used as inorganic pigment for colouring of acrylic paints. In the case of leadless glaze, the obtained compound acts as a dye. 相似文献
11.
Because of the low content of TiO2, the utilization of low and medium Ti-bearing blast furnace slag is a difficult problem. In this study, glass-ceramics with diopside as the main crystalline phase was made by using TiO2 in the blast furnace slag as the nucleating agent and adding additional elements of TiO2, Fe2O3 and Cr2O3. The effects of these three nucleating agents on the phase composition and structural properties of the prepared glass-ceramics were evaluated by DSC, XRD, and SEM to determine their optimal dosage. Research results show that the suitable mass percentages of the TiO2, Fe2O3 and Cr2O3 crystal nucleation agents of the glass-ceramics are 7.69%, 0.96%, and 2.88%, respectively. The prepared glass-ceramics have excellent physical and chemical properties, e.g., a bending strength of 114.74 MPa, a bulk density of 2.77 g/cm3, a water absorption rate of 0, and a mass-loss rate of only 0.085%. 相似文献
12.
Wen-Sheng Wang Yan-Bin Li Bao-Jiao Gao Xiao-Wei Huang Yong-Qi Zhang Yang Xu Fu-Qiang An 《Chemical Engineering Research and Design》2013
Rare earth is a very important resource. But, impurities, such as Fe2+, have great influence on the properties of rare earth material. In this paper, a novel Fe2+-ionic imprinted polyamine functionalized silica gel adsorbent was prepared by a surface imprinting technique for selective adsorption of Fe2+ from rare earth solution. Firstly, functional macromolecule polyethyleneimine (PEI) was grafted onto the surfaces of silica gel particles, and the PEI/SiO2 was formed. Secondly, the ionic imprinting process was carried out using Fe2+ ion as a template, and Cr3+ ionic imprinting polyamine IIP-PEI/SiO2 was prepared. The adsorption and recognition properties of IIP-PEI/SiO2 for Fe2+ were studied in detail, and the effects of main imprinting conditions, such as the amount of crosslinking agent and reaction time, on the adsorption property of the imprinted material IIP-PEI/SiO2 were examined. The experimental results showed that the IIP-PEI/SiO2 possesses strong adsorption affinity, specific recognition ability, and excellent selectivity for Fe2+. The adsorption capacity could reach to 0.334 mmol g−1, and relative selectivity coefficients to Pr3+ and Ce3+ are 23.25 and 18.42, respectively. Besides, the IIP-PEI/SiO2 was regenerated easily using diluted hydrochloric acid solution as eluent and IIP-PEI/SiO2 possesses better reusability. 相似文献
13.
Md. Amir A. D. Korkmaz A. Baykal M. Geleri H. Sözeri H. Güngüneş M. Sertkol Sagar E. Shirsath 《Journal of Inorganic and Organometallic Polymers and Materials》2017,27(6):1740-1749
In this study, oleylamine (OAm) capped FeMnyCoyFe2?2yO4 (0.0?≤?y?≤?0.4) nanocomposites (NCs) were prepared via the polyol route and the impact of bimetallic Co3+ and Mn3+ ions on the structural and magnetic properties of Fe3O4 was investigated. The complete characterization of FeMnyCoyFe2?2yO4@OAm NCs were done by different techniques such as XRD, SEM, TGA, FT-IR, TEM, and VSM. XRD analyses proved the successful formation of mono-phase MnFe2O4 spinel cubic products free from any impurity. The average crystallite sizes were calculated in the range of 9.4–26.4 nm using Sherrer’s formula. Both SEM and TEM results confirmed that products are nanoparticles like structures having spherical morphology with small agglomeration. Ms continued to decrease up to Co3+ and Mn3+ content of y?=?0.4. Although Mössbauer analysis reveals that the nanocomposites consist three magnetic sextets and superparamagnetic particles are also formed for Fe3O4, Co0.2Mn0.2Fe2.6O4 and Co0.4Mn0.4Fe2.2O4. Cation distributions calculation was reported that Co3+ ions prefer to replace Fe2+ ions on tetrahedral side up to all the concentration while Mn3+ ions prefer to replace Fe3+ ions on the octahedral. 相似文献
14.
Jesús I Pe?a-Flores Abraham F Palomec-Garfias César Márquez-Beltrán Enrique Sánchez-Mora Estela Gómez-Barojas Felipe Pérez-Rodríguez 《Nanoscale research letters》2014,9(1):499
The effect of Fe ion concentration on the morphological, structural, and optical properties of TiO2 films supported on silica (SiO2) opals has been studied. TiO2:Fe2O3 films were prepared by the sol-gel method in combination with a vertical dip coating procedure; precursor solutions of Ti and Fe were deposited on a monolayer of SiO2 opals previously deposited on a glass substrate by the same procedure. After the dip coating process has been carried out, the samples were thermally treated to obtain the TiO2:Fe2O3/SiO2 composites at the Fe ion concentrations of 1, 3, and 5 wt%. Scanning electron microscopy (SEM) micrographs show the formation of colloidal silica microspheres of about 50 nm diameter autoensembled in a hexagonal close-packed fashion. Although the X-ray diffractograms show no significant effect of Fe ion concentration on the crystal structure of TiO2, the μ-Raman and reflectance spectra do show that the intensity of a phonon vibration mode and the energy bandgap of TiO2 decrease as the Fe+3 ion concentration increases. 相似文献
15.
P. Dutta N. O. Elbashir A. Manivannan M. S. Seehra C. B. Roberts 《Catalysis Letters》2004,98(4):203-210
Results of the characterization of six Co-based Fischer–Tropsch (FT) catalysts, with 15% Co loading and supported on SiO2 and Al2O3, are presented. Room temperature X-ray diffraction (XRD), temperature and magnetic field (H) variation of the magnetization (M), and low-temperature (5 K) electron magnetic resonance (EMR) are used for determining the electronic states (Co0, CoO, Co3O4, Co2+) of cobalt. Performance of these catalysts for FT synthesis is tested at reaction temperature of 240 °C and pressure of 20 bars. Under these conditions, 15% Co/SiO2 catalysts yield higher CO and syngas conversions with higher methane selectivity than 15% Co/Al2O3 catalysts. Conversely the Al2O3 supported catalysts gave much higher selectivity towards olefins than Co/SiO2. These results yield the correlation that the presence of Co3O4 yield higher methane selectivity whereas the presence of Co2+ species yields lower methane selectivity but higher olefin selectivity. The activities and selectivities are found to be stable for 55 h on-stream. 相似文献
16.
Aaron Gryzia Hans Predatsch Armin Brechling Veronika Hoeke Erich Krickemeyer Christine Derks Manfred Neumann Thorsten Glaser Ulrich Heinzmann 《Nanoscale research letters》2011,6(1):486
We report on the characterization of various salts of [MnIII6CrIII]3+ complexes prepared on substrates such as highly oriented pyrolytic graphite (HOPG), mica, SiO2, and Si3N4. [MnIII6CrIII]3+ is a single-molecule magnet, i.e., a superparamagnetic molecule, with a blocking temperature around 2 K. The three positive charges of [MnIII6CrIII]3+ were electrically neutralized by use of various anions such as tetraphenylborate (BPh4-), lactate (C3H5O3-), or perchlorate (ClO4-). The molecule was prepared on the substrates out of solution using the droplet technique. The main subject of investigation was how the anions and substrates influence the emerging surface topology during and after the preparation. Regarding HOPG and SiO2, flat island-like and hemispheric-shaped structures were created. We observed a strong correlation between the electronic properties of the substrate and the analyzed structures, especially in the case of mica where we observed a gradient in the analyzed structures across the surface. 相似文献
17.
Ho Kim Dan Nguyen Minh Ty Dacheng Zhou Jianbei Qiu Anh-Luan Phan 《Journal of the American Ceramic Society》2020,103(11):6356-6368
In this paper, we study the influence of Cr3+ on yellowish-green upconversion (UC) emission and the energy transfer (ET) of Er3+/Cr3+/Yb3+ tri-doped in SiO2–ZnO–Na2O–La2O3 (SZNL) zinc silicate glasses under excitation of the 980 nm laser diode (LD). The influence of Cr3+ on enhancing the red UC emission of Er3+/Cr3+/Yb3+ tri-doped in SiO2–ZnO–Na2O–La2O3 zinc silicate glasses under the excitation of 980nm LD was also investigated. The ET processes between Yb3+, Cr3+, and Er3+, together with the combination of Yb3+-Cr3+-Er3+, which led to the green UC emission intensity of Er3+/Cr3+/Yb3+ tri-doped in SiO2–ZnO–Na2O–La2O3 zinc silicate glasses bands centered at ~546 nm have been significantly enhanced. By increasing the concentration of Cr3+ from 0 up to 5 mol.%, we can locate the Commission Internationale de l'éclairage (CIE) 1931 (x; y) chromaticity coordinates for UC emissions of Er3+/Cr3+/Yb3+ tri-doped in the central position of the yellowish-green color region of CIE 1931 chromaticity diagram. Besides, the ET processes between the Yb3+, Cr3+, and Er3+ are also proposed and discussed. 相似文献
18.
Yanhui Zhang Yingxian Zhao Zhifeng Wang Longan Shang 《International Journal of Applied Ceramic Technology》2020,17(5):2368-2375
A green nano-sized ceramic pigment Co0.6Zn0.4Al0.8Cr1.2-xSmxO4 has been successfully prepared by doping ions Zn2+, Cr3+, and Sm3+ into the crystalline CoAl2O4 spinel and using the complex-gel method along with agar as complexing and combustion agent. The Infrared Spectroscopy, X-ray diffraction, Thermo-gravimeter, High resolution transmission electron microscopy, Automatic color reader, and UV Vis diffuse reflectance were applied to characterize the pigment power and its gel precursor. The results reveal that the introduction of Zn2+, Cr3+, and Sm3+ could change the occupation status of ions in the tetrahedral and octahedral framework of CoAl2O4 spinel, leading to the colorant variation of the blue cobalt pigment CoAl2O4, With increasing the content of Sm3+ ion, the reflection peak position of the pigments in visible spectrum appeared a red-shift, ie the color transition from blue green to yellow green, and the average reflectivity in the violet region decreased to 13.31%, and the band gap energy also changed from 3.47 to 3.20 eV. This illustrates the better UV absorption of this green pigment and can be used as UV shielding material. With the hydrochloric acid or sodium hydroxide solution treatment, this pigment was found to be durable in chemical stability. 相似文献
19.
The subject of this paper is the effect of foreign cations on the reactivity of the CaO-SiO2-Al2O3-Fe2O3 system. One reference mixture and eighteen modified mixtures, prepared by mixing the reference sample with 1% w/w of chemical grade MnO2, CuO, V2O5, PbO, CdO, ZrO2, Li2O, MoO3, Co2O3, NiO, WO3, ZnO, Nb2O5, CrO3, Ta2O5, TiO2, BaO2 and H3BO3 were studied. The effect on the reactivity is evaluated on the basis of the free lime content in samples sintered at 1200 and 1450 °C. At 1200 °C, the reactivity of the mixture is greatly increased in the presence of Cu and Li oxides. Based on their effect at 1450 °C, the added elements can be divided into three groups. W, Ta, Cu, Ti and Mo show the most positive effect, decreasing the free CaO (fCaO) content by 30-60%, compared with the pure sample. Cr and B cause an increase of fCaO content, while the rest of the elements exhibit a marginal positive effect. According to their volatility at 1450 °C, the added compounds can be subdivided into three groups of low (Ti4+, Cu2+, Mo6+, W+6, V5+, Zn2+, Zr4+), moderate (Cr6+, Co3+, Ni2+, Mn4+) and high volatility (Cd2+, Pb2+). All burned samples, analyzed by means of X-ray diffraction, have a final mineralogical composition, which corresponds to the structure of a typical clinker. 相似文献
20.
P. Kripylo I. Hohlstamm J. Koppe P. Kraak I. Rapthel A. Hofmann 《Advanced Synthesis \u0026amp; Catalysis》1993,335(8):699-704
The Mutual Promotion Effect of Molybdates in Multicomponent Molybdate Catalysts Multicomponent molybdate catalysts (e.g. of the composition Bi2Fe1,5Co7Cr10Mo19Oy) are produced by coprecipitation, drying and calcination. These catalysts exhibit high activity and selectivity in the ammoxidation of propene to acrylonitrile. The individual molybdates (Co-, Fe- and Cr-molybdate) exhibit no selectivity in the ammoxidation of propene. Therefore a mutual promotion effect of these molybdates exists. The cause of the promotion effect is the formation of the active and selective phase from the β-phase of Co-molybdate by exchange of protons with ions of Fe3+ and Cr3+ from the molybdates of Fe and Cr. The structure of this catalytic active and selective phase is similar to the structure of the β-phase of Co-molybdate. 相似文献