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1.
M. I. B. Bernardi S. C. L. Crispim A. P. Maciel A. G. Souza M. M. Conceiçăo E. R. Leite E. Longo 《Journal of Thermal Analysis and Calorimetry》2004,75(2):475-480
The synthesis and the characterization of Al2O3-based nanocrystalline inorganic pigments are reported. The pigments were synthesized by the polymeric precursor (Pechini
method) using Cr2O3 as chromophore. XRD results only evidenced the corundum phase. The average particle size was about 34 nm. The samples were
also characterized by differential scanning calorimetry (DSC) and thermogravimetry (TG), and CIE-L*a*b* calorimetry. The pigments
obtained in this work presented different colors, ranging from green to rose.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
2.
Alumina-based pigments were synthesized by the proteic sol–gel method. In this method, coconut water is employed as polymeric
agent instead of the conventional alkoxide precursors. To this study, three common chromophore metallic ions (Mn3+, Co3+, and Cr3+) were chosen in order to verify the method efficiency. Differential thermal analysis (DTA), thermogravimetry (TG), and XRD
techniques were used to characterize the synthesis process. The colorimetric characterization of the produced pigments was
done according to the CIE-L*a*b* 1976 norm which is recommended by the CIE (International Commission on Illumination). The
synthesized pigments presented intense and uniform colors in accordance to the literature results for each chromophore ion.
The produced pigments also presented agglomerated with an average grain size of 180 nm when calcined at 800 °C. 相似文献
3.
T. M. Milão J. F. A. Oliveira V. D. Araújo M. I. B. Bernardi 《Journal of Thermal Analysis and Calorimetry》2011,103(3):873-877
Zinc oxide is a widely used white inorganic pigment. Transition metal ions are used as chromophores and originate the ceramic
pigments group. In this context, ZnO particles doped with Co, Fe, and V were synthesized by the polymeric precursors method,
Pechini method. Differential scanning calorimetry (DSC) and thermogravimetry (TG) techniques were used to accurately characterize
the distinct thermal events occurring during synthesis. The TG and DSC results revealed a series of decomposition temperatures
due to different exothermal events, which were identified as H2O elimination, organic compounds degradation and phase formation. The samples were structurally characterized by X-Ray diffractometry
revealing the formation of single phase, corresponding to the crystalline matrix of ZnO. The samples were optically characterized
by diffuse reflectance measurements and colorimetric coordinates L*, a*, b* were calculated for the pigment powders. The pigment
powders presented a variety of colors ranging from white (ZnO), green (Zn0.97Co0.03O), yellow (Zn0.97Fe0.03O), and beige (Zn0.97V0.03O). 相似文献
4.
Ahmed IS Dessouki HA Ali AA 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,71(2):616-620
The synthesis of a new nano-blue ceramic pigment CoxMg1-xAl2O4 (0 < or = x < or = 0.1) using the combination between co-precipitation and combustion synthesis (CS) method. The structure of pigments is assigned based on thermogravimetric and differential thermogravimetric analysis (TG-DTGA), X-ray diffractions (XRD), and UV-vis spectroscopy. Also, diffuse reflectance spectroscopy (DRS) using CIE L*a*b* parameter measurement method, infrared spectroscopy (IR) and transmission electron microscopy (TEM) is used. The result revealed that the nano-size particle pigment was obtained in range 24-35 nm by using 3-methyl-pyrozole-5-one (3MP5O) as a fuel at 400 degrees C in open furnace. Also, results show the varying colors and particles' size as a result of different calcination temperatures from 500 to 1200 degrees C for 2h. 相似文献
5.
Danniely S. de Melo M. R. C. Santos Iêda M. G. Santos L. E. B. Soledade M. I. B. Bernardi E. Longo A. G. Souza 《Journal of Thermal Analysis and Calorimetry》2007,87(3):697-701
SnO2-based
materials are used as sensors, catalysts and in electro–optical devices.
This work aims to synthesize and characterize the SnO2/Sb2O3-based
inorganic pigments, obtained by the polymeric precursor method, also known
as Pechini method (based on the metallic citrate polymerization by means of
ethylene glycol). The precursors were characterized by thermogravimetry (TG)
and differential thermal analysis (DTA). After characterization, the precursors
were heat-treated at different temperatures and characterized by X-ray diffraction.
According to the TG/DTA curves basically two-step mass loss process was observed:
the first one is related to the dehydration of the system; and the second
one is representative to the combustion of the organic matter. Increase of
the heat treatment temperature from 500 to 600°C and 700°C resulted
higher crystallinity of the formed product. 相似文献
6.
Layered LiNi1/3Co1/3Mn1/3O2 nanoparticles were prepared by modified Pechini method and used as cathode materials for Li-ion batteries. The pyrolytic
behaviors of the foamed precursors were analyzed by use of simultaneous thermogravimetric and differential thermal analysis
(TG-DTA). Structure, morphology and electrochemical performance characterization of the samples were investigated by X-ray
diffraction (XRD), field emission scanning electron macroscopy(SEM), Brunauer-Emmett-Teller (BET) specific surface area and
charge–discharge tests. The results showed that the samples prepared by modified Pechini method caclined at 900 °C for 10 h
were indexed to pure LiNi1/3Co1/3Mn1/3O2 with well hexagonal structure. The particle size was in a range of 100–300 nm. The specific surface area was larger than
that of the as-obtained sample by Pechini method. Initial discharge capacity of 163.8 mAh/g in the range 2.8–4.4 V (vs. Li/Li+) and at 0.1C for LiNi1/3Co1/3Mn1/3O2 prepared by modified Pechini method was obtained, higher than that of the sample prepared by Pechini method (143.5 mAh/g).
Moreover, the comparison of electrochemical results at different current rates indicated that the sample prepared by modified
Pechini method exhibited improved rate capability. 相似文献
7.
The lanthanum strontium titanate (LST) has to be calcined at significantly high temperature (above 1,300 °C) to obtain its pure perovskite structure when synthesized by conventional solid-state method, which is main reason for reducing active surface area. In this study, A-site deficient (La0.3Sr0.7)0.93TiO3 was synthesized by Pechini method. Although the prepared powders were calcined at 600 °C, the pure perovskite structure can be obtained without any secondary phase such as TiO2. Moreover, the porosity and surface area are 6 times and one order of magnitude higher in the LST powders synthesized by Pechini method than in the powders synthesized by solid-state method. Based on these results, the LST electrode (Pechini) leads to two times lower electrode resistance than the LST electrode (solid-state). Thus, the LST powders synthesized by Pechini can contributes to saving the energy needed for calcination process as well as increasing the porosity and active surface area, enhancing physical and electrochemical properties in SOFC anode. 相似文献
8.
N. Vargas-Becerril L. Téllez-Jurado J. Reyes-Gasga M. A. Alvarez-Perez L. M. Rodríguez-Lorenzo 《Journal of Sol-Gel Science and Technology》2014,72(3):571-580
Pechini method is a materials synthesis method based on the preparation of a polymeric matrix. The advantage of this method is the ability to obtain materials with different particle sizes depending on the synthesis condition with a homogeneous distribution. In this work, carbonated hydroxyapatite (c-OHAp) nanoparticles were obtained by a modified Pechini method. To obtain the polymeric precursor of the c-OHAp, the polymeric matrix was prepared through a polyesterification reaction between citric acid and ethylene-glycol. Adding calcium hydroxide and ortophosphoric acid in aqueous solutions, raising the temperature up to 140 °C/2 h and keeping constant the pH at 8. The polymeric matrix was calcinated at different ranges of temperature from 200 to 600 °C in order to obtain the c-OHAp powder. The results show the presence of c-OHAp a as unique phase. The thermal analysis indicates that the c-OHAp phase was obtained at 600 °C. The particle size of the obtained material was <50 nm. 相似文献
9.
J. Calbo A. Mestre A. Garcia M.A. Tena M. Llusar G. Monros 《Journal of Sol-Gel Science and Technology》2003,26(1-3):191-194
Ferrites and chromites of Ni and Co synthesised by solid reaction method are usually used as black colour ceramic pigments. Due to the presence of Co and Ni in their composition they are classified as harmful substances. In this work, Co, Cr and Fe have been partially substituted by harmless Mg and Al ions, and the optimised compositions have also been synthesised by coprecipitation and gel polymeric route. Samples obtained have been characterised by CIEL*a*b colour parameters, XRD, DTA-TG, and SEM-EDAX techniques. Samples obtained by gel polymeric route presents the best reactivity and black colouring results. 相似文献
10.
The Ni0.75Co2.25O4 catalysts were prepared by a coprecipitation method and modified with cesium cations by impregnation with a solution of cesium nitrate or cesium nitrate with citric acid and ethylene glycol additives (the Pechini method). The catalysts obtained were investigated by X-ray diffraction analysis, the BET method, X-ray photoelectron spectroscopy, temperature-programmed reduction, and the temperatureprogrammed desorption of oxygen. The activity of the samples in a reaction of nitrous oxide decomposition was determined at temperatures of 200–300°C, in particular, in the presence of oxygen and water in the reaction mixture. It was found that the use of the Pechini method for supporting Cs makes it possible to obtain a more active catalyst, as compared with that prepared by impregnation with cesium nitrate, at the same cesium content (~2%) of the samples. 相似文献
11.
Georg Gramm Gerda Fuhrmann Fabian Zimmerhofer Martin Wieser Hubert Huppertz 《无机化学与普通化学杂志》2020,646(21):1722-1729
In this work, the development of a novel class of eco-friendly red pigments based on doped Li2MnO3 is reported. These new compounds offer red color values of a* > 34, which are recognizably higher than the red value provided by the commonly used red pigment iron oxide Bayferrox 4130. However, the real outstanding attribute of these novel substances is their strikingly high NIR-reflectance that gives promise for a new class of materials for the practical utilization as cool pigments in building components and ceramics. We have synthesized the inorganic pigments by conventional solid-state reactions at 900 °C and subsequently carried out the structural characterizations by X-ray powder diffraction (XRPD) and Rietveld analysis. We recorded the diffuse reflectance spectra of the obtained powders and determined the color properties by means of CIE L*a*b* coordinates. Finally, we measured the NIR reflectance and calculated the NIR solar reflection of these compounds affording values above 85 % in the range from 700 to 2500 nm. 相似文献
12.
A. Sh. Khaliullina V. M. Kuimov S. A. Belyakov L. A. Dunyushkina 《Russian Journal of Applied Chemistry》2017,90(3):342-348
CaZr0.9Y0.1O3–δ powders were synthesized by chemical solution methods: modified Pechini method and from solutions of inorganic salts in water and ethanol. The structure crystallizes into the orthorhombic type upon annealing at 1000°C for powders prepared by the Pechini method and from solution of salts in water. It was shown that CaZr0.9Y0.1O3–δ powders synthesized by various methods have different dispersities. The results obtained in a study of the granulometric composition by the sedimentation method and microscopic analysis enable fabrication of dense and mechanically strong electrolyte films and ceramics. 相似文献
13.
Xiaodong Zhu Xinbing Chen Yixing Yuan Kening Sun Naiqing Zhang 《Journal of Solid State Electrochemistry》2012,16(1):313-319
SrCo0.8Fe0.2O3-δ (SCF), as a promising cathode material for intermediate temperature solid oxide fuel cells, possesses a high catalytic activity
for the reduction of O2 to 2O2−. The SCF powder was successfully synthesized by the solid state reaction method and Pechini method and characterized using
XRD, particle analysis, and electrochemical performance measurements. Smaller-particle-size SCF materials (SCF-P) with single
phase are obtained at lower synthesis temperature by the Pechini method and possess better electrochemical performance as
compared with those prepared by the solid state reaction method. The reason is that the Pechini method involves the mixing
of elements at atomic level, so pure SCF phase formation can be accelerated and showed high electrocatalytic activity. The
preparation procedure of SCF cathode was firstly investigated using electrochemical impedance spectroscopy. Results show that
the total polarization resistance and the low-frequency resistance decrease gradually with the reduction of the calcination
temperature for the SCF cathodes. The SCF-P cathode sintered at 1,000 °C possesses the highest porosity and the best electrochemical
performance. It is the result of a comprehensive function of three-phase boundary length, porosity of cathode, and the adhesion
between cathode and electrolyte. The charge-transfer process, together with the adsorption, dissociation, and diffusion of
oxygen, has a strong influence on the whole reaction process of the cathode. The influence of binder amounts on the performance
of the SCF-P cathodes was also studied. 相似文献
14.
《Comptes Rendus Chimie》2017,20(2):97-106
Two sol–gel methods (the citric acid gel and the Pechini methods) were used for the preparation of nano-sized undoped, Bi-doped and Bi, Cu co-doped SrTiO3 samples to optimize their properties for the photocatalytic degradation of dibutyl phthalate. The perovskite-like phase was detected for the samples prepared by the citric acid gel method after calcination at 800 °C for 3 h, while in the case of the Pechini method; it was detected after calcination at 800 °C for 9 h. The particle size of the samples prepared by the citric acid gel method is greater than that of the samples prepared by the Pechini method. Cu doping in both methods increased the particle size. Cu doping, Bi doping and Bi, Cu co-doping in both methods shifted the absorption edge to the visible light range as well. The band gap of Bi, Cu co-doped SrTiO3 is smaller than that of Bi doped SrTiO3, which in turn is smaller than that of undoped SrTiO3. The highest removal of the total organic carbon (TOC) of DBP was obtained using a Bi, Cu co-doped SrTiO3 sample prepared by the citric acid gel method. TOC removal of DBP followed pseudo-first order kinetics. 相似文献
15.
S. F. Santos M. C. de Andrade J. A. Sampaio A. B. da Luz T. Ogasawara 《Journal of Thermal Analysis and Calorimetry》2007,87(3):743-746
TiO2–CeO2 oxides
for application as ceramic pigments were synthesized by the Pechini method.
In the present work the polymeric network of the pigment precursor was studied
using thermal analysis. Results obtained using TG and DTA showed the occurrence
of three main mass loss stages and profiles associated to the decomposition
of the organic matter and crystallization. The kinetics of the degradation
was evaluated by means of TG applying different heating rates. The activation
energies (E
a) and
reaction order (n) for each stage were
determined using Horowitz–Metzger, Coats–Redfern, Kissinger and
Broido methods. Values of E
a
varying between 257–267 kJ mol–1 and n=0–1 were found. According to the kinetic
analysis the decomposition reactions were diffusion controlled. 相似文献
16.
Marina A. Melkozerova Nadezda V. Tarakina Lidia G. Maksimova Alexander P. Tyutyunnik Ludmila L. Surat Ivan I. Leonidov Vladimir G. Zubkov Elena V. Zabolotskaya Rina F. Samigullina 《Journal of Sol-Gel Science and Technology》2011,59(2):338-344
A modified Pechini method followed by conventional and microwave heating was used to synthesise the new promising Ln2MGe4O12 (Ln = Y, Eu; M = Ca, Zn, Mn) optical hosts. Comparison between solid-state and Pechini synthesis methods showed that the
latter reduces the temperature required for cyclo-tetragermanate formation. The highest yield of cyclo-tetragermanates for both methods is observed at 1,000–1,100 °C, with significantly shorter time of annealing in the case
of the Pechini synthesis. Compositional, structural and morphological characterisations of the samples obtained by both routes
were carried out using X-Ray powder diffraction, thermogravimetry, electron spin resonance spectroscopy, energy-dispersive
X-Ray spectroscopy and scanning electron microscopy. 相似文献
17.
Mohammad Edrissi Meysam Soleymani Mahnaz Naderi 《Journal of Sol-Gel Science and Technology》2012,64(2):485-492
Nanocrystalline manganese aluminate (MnAl2O4) has been synthesized by Pechini and sequential homogenous precipitation methods and the results have been compared. The Taguchi L4 statistical design was utilized to optimize the production of MnAl2O4 nanoparticles by Pechini method. The MnAl2O4 nanocrystallites obtained by Pechini and sequential homogenous precipitation methods had the average particle size of 26.5 and 49.5 nm, respectively. The products were characterized with X-ray diffraction, laser light scattering, thermogravimetry analysis, Fourier transform infrared, UV–visible, energy dispersive X-ray, scanning electron microscope and inductively coupled plasma analyses. The photocatalytic activities of MnAl2O4 nanoparticles synthesized by two methods were investigated using aqueous solution of methylene blue under irradiation of visible light. 相似文献
18.
Niedzwiedzki DM Sullivan JO Polívka T Birge RR Frank HA 《The journal of physical chemistry. B》2006,110(45):22872-22885
Xanthophylls are a major class of photosynthetic pigments that participate in an adaptation mechanism by which higher plants protect themselves from high light stress. In the present work, an ultrafast time-resolved spectroscopic investigation of all the major xanthophyll pigments from spinach has been performed. The molecules are zeaxanthin, lutein, violaxanthin, and neoxanthin. beta-Carotene was also studied. The experimental data reveal the inherent spectral properties and ultrafast dynamics including the S(1) state lifetimes of each of the pigments. In conjunction with quantum mechanical computations the results address the molecular features of xanthophylls that control the formation and decay of the S* state in solution. The findings provide compelling evidence that S* is an excited state with a conformational geometry twisted relative to the ground state. The data indicate that S* is formed via a branched pathway from higher excited singlet states and that its yield depends critically on the presence of beta-ionylidene rings in the polyene system of pi-electron conjugated double bonds. The data are expected to be beneficial to researchers employing ultrafast time-resolved spectroscopic methods to investigate the mechanisms of both energy transfer and nonphotochemical quenching in higher plant preparations. 相似文献
19.
Raman spectra have been obtained from a Madonna and Child tondo painting, known as the de Brécy Tondo. Despite the provision
of only a small number of microscopic samples, definitive spectra were obtained from mineral pigments. From one specimen,
spectra of an organic binder enabled the consideration of several possibilities to be accomplished and a suggestion proposed
for the medium. In another specimen the identification of the spectral signatures of Prussian blue, which was only synthesised
some 200 years after the predicated date of execution of the painting, indicated that some unrecorded restoration had been
undertaken later in the painting’s history. Research* carried out on this tondo from 1987 to 1991 indicated the probability
that it is the work of Raphael, a conclusion supported by further research recently undertaken on the provenance. The stylistic
similarity of the tondo to Raphael’s Sistine Madonna is very clear; the pigments identified in this analysis are consistent
with a Renaissance attribution for the de Brécy Tondo.
*Dr Murdoch Lothian, The Methods Employed to Provenance and to Attribute Putative Works by Raphael, Ph.D. Thesis, 1991. 相似文献
20.
Cooling rate dependence of the cooperative relaxation in 1,2-propanediol was investigated in terms of the nonlinear Adam-Gibbs (AG) enthalpy relaxation theory using differential scanning calorimetry. The AG parameters were obtained using a curve-fitting method. The results indicated that the model parameters show strong dependence on the cooling rates. Those obtained at higher cooling rates are in good agreement with the published data. The fitting results were used to estimate the microscopic parameters of the cooperative rearranging region (CRR), in particular the size of the CRR (z*) and the configurational state available to it (W*). It was found that the W* recommended for polymers led to physically meaningless z* for 1,2-propanediol. Johari's method, which was based on the AG theory, yielded around 3 molecules in the CRR, but the W* was anomalistically higher than those of polymers. It is di±cult to reconcile the Adam-Gibbs' z* with the results obtained using Donth's formula. An argument is presented that a new physical meaning should be given to conventional Adam-Gibbs' z* for molecular H-bond liquids. 相似文献