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1.
An amorphous TiO 2 gel was obtained by hydrolysing titanium(IV) isopropoxide with a stoichiometric amount of water using SnCl 2 as catalyst. In these operative conditions, a TiO 2 gel matrix containing a lower fraction of organic residual was obtained with respect to samples prepared by previously modifying the titanium alkoxide precursor with chelating ligands. Dried gel powders were characterized by N 2 adsorption analyses, FT-IR and XRD measurements. Thermogravimetric (TG) and differential thermal analysis (DTA) coupled with mass spectrometric (MS) and gas chromatographic (GC) measurements were performed in order to identify the organic products released from TiO 2 gel pyrolysis. The Tg-MS semiquantitative analysis of the main evolved species allowed to describe both the chemical composition of the initial TiO 2 gel and the chemical rearrangements occurring in the matrix during heating up to its crystallisation to anatase form at 420°C.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
2.
The products of microwave-hydrothermal (MW-HT) treatment of amorphous hydrous zirconia and hafnia xerogels were studied by
powder X-ray diffraction and thermal analysis. Decreasing gel precipitation pH leads to an increase in ZrO 2 and HfO 2 crystallization rates and enhances the formation of stable monoclinic ZrO 2. 相似文献
3.
A microcomposite powder in the system TiO 2—ZrO 2 as a precursor of zirconium titanate (ZT) materials has been studied by thermal methods (DTA-TG) and X-ray diffraction (XRD). The microcomposite powder has been prepared by chemical processing of crystalline TiO 2 (rutile, 10 mass% anatase),as inner core, coated with in situ precipitated amorphous hydrated zirconia gel, asouter core. The morphology and chemical composition of the resultant powders has been examined by SEM-EDX (Scanning electron microscopy-energy dispersive X-ray spectroscopy). Thermal behaviour of the microcomposite powder was reported, showing the dehydration and dehydroxylation of the zirconia gel, the crystallization into metastable cubic/tetragonal zirconia at temperatures 400—470°C, and the feasibility of preparing ZT powder materials by progressive reaction of TiO 2 and ZrO 2 at higher temperatures (1400°C).This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
4.
The effects of UV-irradiation on the properties of ZrO 2 and TiO 2 gel films prepared from corresponding metal-butoxides modified with acetylacetone (AcAc) or benzoylacetone (BzAc) have been studied. It was found that the chelate bonds of -diketones remaining in the gel films were dissociated by the UV-irradiation. The UV-irradiation also changed the properties of the gel films such as solubility; the solubility in acidic solutions was decreased for ZrO 2 gel films modified with AcAc and TiO 2 gel films modified with BzAc became insoluble in alcohol. Based on these findings, a new fine-patterning process has been established, which enables us to make fine-patterns of ZrO 2 and TiO 2 films on a variety of substrates. 相似文献
5.
Homogeneous, transparent and crack-free P 2O 5–ZrO 2 and P 2O 5–ZrO 2–SiO 2 membranes have been synthesized by the sol–gel process. A first step has been oriented to the optimization of the synthesis and characterization of different compositions by TGA, FE-SEM, FTIR and EIS to choose the best inorganic composition in terms of chemical and mechanical stability, and proton conductivity. The addition of SiO 2 improves the mechanical and chemical stability. On the other hand, compositions with higher content in P 2O 5 have demonstrated lower mechanical and chemical stability against water, but higher proton conductivity. The water retention and high porosity of inorganic membranes leads to high proton conductivity, 10 −2 S/cm, at 140 °C and 100% relative humidity. The second step has been focused in the study of doped inorganic membranes of molar composition 99.65(40P 2O 5–20ZrO 2–40SiO 2)–0.35PWA. The high homogeneity, transparency and SEM-EDX analysis of these membranes indicates no phase separation suggesting that PWA is well dispersed in the inorganic structure. The incorporation of PWA in sol–gel oxides provides an increase of the proton conductivity at low relative humidity due to the adequate distribution of PWA in the inorganic network. Conductivity increases in two orders of magnitude at low humidity (10 −4 S/cm at 50 °C and 62% RH) compared with undoped sol–gel oxide membranes. 相似文献
6.
Composite scaffolds are commonly used strategies and materials employed to achieve similar analogs of bone tissue. This study aims to fabricate 10% wt polylactic acid (PLA) composite fiber scaffolds by the air-jet spinning technique (AJS) doped with 0.5 or 0.1 g of zirconium oxide nanoparticles (ZrO 2) for guide bone tissue engineering. ZrO 2 nanoparticles were obtained by the hydrothermal method and characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). SEM and fourier-transform infrared spectroscopy (FTIR) analyzed the synthesized PLA/ZrO 2 fiber scaffolds. The in vitro biocompatibility and bioactivity of the PLA/ZrO 2 were studied using human fetal osteoblast cells. Our results showed that the hydrothermal technique allowed ZrO 2 nanoparticles to be obtained. SEM analysis showed that PLA/ZrO 2 composite has a fiber diameter of 395 nm, and the FITR spectra confirmed that the scaffolds’ chemical characteristics are not affected by the synthesized technique. In vitro studies demonstrated that PLA/ZrO 2 scaffolds increased cell adhesion, cellular proliferation, and biomineralization of osteoblasts. In conclusion, the PLA/ZrO 2 scaffolds are bioactive, improve osteoblasts behavior, and can be used in tissue bone engineering applications. 相似文献
7.
In the study, hydroxypropyl guar gum (HPG) gel is prepared by using Nano‐ZrO 2 particles as the cross‐linking agent. The Nan‐ZrO 2 particles are prepared by using oil‐water interface method. The physical properties such as morphology, particle size, and crystal structure of the Nano‐ZrO 2 particles are analyzed by SEM, particle size analyzer, FT‐IR, and XRD, respectively. The results show that the Nano‐ZrO 2 particles are spherical particles with a little agglomeration; these spherical particles have a tetragonal structure and higher crystallinity, and the mean diameter of the first‐level grain is 24 nm. The rheological properties including shear stress, complex modulus, elasticity modulus (G′), and viscosity modulus (G′′) of the Nano‐ZrO 2 cross‐linked HPG gel are investigated. The results show that the Nano‐ZrO 2 cross‐linked HPG gel is a pseudo‐plastic non‐Newtonian fluid with higher elastic modulus (G′ > G′′) and lower tanδ (tanδ < 1, the ratio of viscous and elastic modulus), which indicate that the Nano‐ZrO 2 cross‐linked HPG gel may have potential application in fracturing. 相似文献
8.
Ag doped ZrO 2 thin films were deposited on quartz substrates by sol–gel dip coating technique. The effect of Ag doping on tetragonal to monoclinic phase transformation of ZrO 2 at a lower temperature (500 °C) was investigated by X-ray diffraction. It is found that the Ag doping promotes the phase transformation. The phase transformation can be attributed to the increase in the tetragonal grain size and concentration of oxygen vacancies in the presence of the Ag dopant. Accumulation of the Ag atoms at the film surface and surface morphology changes in the films were observed by AFM as a function of varying Ag concentration. X-ray photoelectron spectroscopy gave Ag 3 d and O 1 s spectra on Ag doped thin film. The chemical states of Ag have been identified as the monovalent state of Ag + ions in ZrO 2. The Ag doped ZrO 2 thin films demonstrated the tailoring of band gap values. It is also found that the intensity of room temperature photoluminescence spectra is suppressed with Ag doping. 相似文献
9.
Synthesis of ZrO 2 and hetero-layered TiO 2/ZrO 2 ultrathin films was investigated by two-dimensional sol-gel process assisted by n-octadecylacetoacetate (C 18AA). When a hexane solution of tetrabutoxyzirconium (TBZ) and C 18AA was spread on the water surface, Zr-based gel films stabilized with C 18AA were formed at the air/water interface. After deposition on substrates, the gel films were successfully transformed into ZrO 2 ultrathin films by heating at 773 K for 0.5 h, the thickness of which was controllable on the order of sub-nanometer level by the number of gel-layer deposition and the molar ratio of [TBZ]/[C 18AA]. Well-organized hetero-multilayers composed of ultrathin TiO 2 and ZrO 2 layers could be fabricated by the alternate deposition of C 18AA-stabilized Ti- and Zr-gel films. 相似文献
10.
A novel material ZrO 2/SiO 2 was synthesized on SiO 2 support by means of electrostatic self‐assembly technique and sol‐gel method. After treating this material with 0.7 mol·L ?1 H 2SO 4, a nanostructural solid superacid catalyst SO 42?‐ZrO 2/SiO 2 was prepared. The material was characterized by Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), Brunauer Emmett Teller method (BET) and Hammett indicator method. The catalytic activity of the catalyst was carried out for the esterification between acetic acid and butanol. Results show that the catalytic activity of this catalyst was much higher than that of powdered superacid catalyst SO 42?/ZrO 2. Due to the SiO 2 spherical support, the solid superacid catalyst could be separated and recovered easily. The nanostructural ZrO 2/SiO 2 will be a promising material for the chemical industry in the future. 相似文献
11.
Composite ZrO 2-SiO 2 powders, with different ZrO 2 contents, including pure ZrO 2 powders, were prepared by precipitation in SiO 2 suspensions, of zirconia gels from solutions of zirconyl chloride at pH = 11. These products were investigated in connection with the phase changes in ZrO 2 caused by heat-treatments. ZrO 2-SiO 2 mixtures containing 0–100% mol ZrO 2, were studied by differential thermal analysis (DTA), X-ray powder diffraction (XRD), temperature programmed desorption combined with mass spectroscopy (TPD-MS), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX), to obtain information on the morphological and structural features of the particles before and during the heat treatment up to 1200°C. Specific surface areas were determined using nitrogen adsorption by the BET method. The results offer an explanation about some of the factors which can be influencing on the stabilization of metastable-cubic/tetragonal (C/T) phase of ZrO 2 and the evolution of surface areas (vulcano profile) observed in the composites. 相似文献
12.
A series of nano-sized particle materials containing ZrO 2 was prepared and their compositions were determined by elemental analysis and thermogravimetric analysis (TGA). The effect of particle size and crystal structure type (lattice and space group) on the ER performance of these materials was investigated by X-ray diffraction (XRD) analysis, Raman spectra, the particle size analysis and rheological measurement. Their electrorheological (ER) effects show that the ER activities of the ZrO 2 materials doped with rare earth ( RE=Y, La, Ce, Gd, Tb), whose grain sizes were less than that of pure ZrO 2, were lower than that of pure ZrO 2, which belongs to the tetragonal crystal system. The ER activity of Y 2O 3-ZrO 2 is the strongest among all the RE-doped ZrO 2 materials. The ER activity of the tetragonal phase ZrO 2 is higher than that of the monoclinic phase ZrO 2. 相似文献
13.
New polypyrrole (PPy)-derived polymer/ZrO2 nanocomposite materials are prepared by single-step oxidative polymerization of pyrrole (Py) and/or N-methylpyrrole (mPy) in the presence of HCl-functionalized ZrO2 nanoparticles and ammonium persulfate. The physicochemical features of the PPy–ZrO2, poly(Py-co-mPy)–ZrO2 and PmPy–ZrO2 hybrids were analyzed by XPS, FTIR, XRD and UV–Vis techniques. To explore the advantages of these nanocomposites for potential applications, their thermal, conductive and electrochemical properties were investigated. The characterization reveals that a chemical bonding, based on electrostatic interactions, is established between the polymers and the ZrO2 nanoparticles. Interestingly, it is found that the growth of polymer on the surface of Cl-functionalized ZrO2 becomes more significant as the Py moiety (–NH– species) content in the polymer increases. The thermal stability and conductivity of the polymers increase by hybridization with the ZrO2 nanoparticles. This is assigned to the affective interaction of the polymers with the ZrO2 nanoparticles. Particularly, the resulting nanocomposites keep high conductivities, ranging between 0.323 and 0.929 S cm−1. Finally, voltammetric characterization shows that the PPy–ZrO2 and poly(Py-co-mPy)–ZrO2 nanocomposites are electroactive, thus demonstrating their capability for electrochemical applications. These results highlight the great influence of the nanoparticle interface and the nature of monomer on the nanocomposite formation and properties. 相似文献
14.
The structural evolution of zirconia thin films and gel powders has been evaluated by X-ray diffraction. Maxima ( r
1 and r
2) of the experimental radial distribution function RDF and the bond angles were determined and correlated with TGA (thermogravimetric analysis), DTA (differential thermal analysis) and MS (mass spectrometry). The results indicate that the topological short-range structure (<5 Å) of amorphous zirconia thin films, independent of drying temperature, resembles that of crystalline tetragonal ZrO 2. In contrast, amorphous zirconia powder gels dried at temperatures below 120°C show atomic arrangements similar to that of tetragonal ZrO 2. The structure of these gels annealed at temperatures between 165–340°C resembles a distorted tetragonal ZrO 2, monoclinic-like structure. Zirconia powders and films contain crystalline tetragonal ZrO 2 at 400°C. 相似文献
15.
Monoclinic Zirconia (ZrO 2NPs) nanoparticles were successfully prepared by non-toxic and low-cost production using green synthesis analysis from the methanolic extract of Helianthus annuus (sunflower) seeds as the reducing agent. Mechanism of the chemical reaction has shown the reduction and which confirmed the formation of nanoparticles via chemical bonding in the IR spectrum at 502-498 cm -1 ZrO 2 nanoparticles were characterized as sharp peak at 275 nm in the UV-Vis spectrum with 3.7eV in photon energy bandgap, it confirms the monoclinic crystal structure, as well as x-ray diffractometry, reveals zirconia crystallite is 40.59 nm. The internal morphology of crystal structure is exhibited by Scanning Electron Microscopy (SEM), and Transmission Electron Microscope (TEM). The stability of nanoparticles is represented in terms of zeta potential (-9.32 mV) and particle size distribution (~331 nm). Biosynthesized ZrO 2NPs were indicated as superior antimicrobial activity for biomedical applications. 相似文献
16.
Homogeneous TiO 2 powders were obtained, via sol-gel method, hydrolysing titanium(IV) isopropoxide, previously reacted with oxalic acid in
order to better control the gelling process. The characterization of the amorphous TiO 2 powders was carried out by using different techniques such as FT-IR, XRD and N2 adsorption analysis. Coupled thermogravimetric
(TG) gas chromatographic (GC) and mass spectrometric (MS) analyses were performed to quantify the organic content present
in the titania gel and its release during pyrolysis. A detailed semiquantitative analysis of the evolved chemical species
from TG-MS data allowed to describe the chemical composition of the TiO 2 gel and the chemical rearrangements occurring in matrix during pyrolysis up to its crystallization to anatase form at 530°C.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
17.
The zirconia ceramics offers the required biocompatibility and corrosion resistance in the physiological medium, making it
applicable for biomaterials. But, adequate utilization of porous zirconium dioxide (ZrO 2) thin film has not been assessed. Hence, in the present work an attempt has been made to utilize the corrosion resistance
and biocompatibility property of porous ZrO 2. The ZrO 2 were prepared using the sol–gel process and coated on 316L SS substrate via dip-coating technique. The phase composition,
morphology and the elemental distribution of the coatings were investigated using X-ray diffraction analysis, atomic force
microscopy, Fourier transform infrared spectroscopy, scanning electron microscopy and energy dispersive X-ray analysis. The
results revealed that the coated surface was porous, uniform and relatively well crystalline on the substrate. In vitro evaluation
of the ZrO 2 coated 316L SS samples were carried out in simulated body fluid and the corrosion resistance of the ZrO 2 coated samples were examined using potentiodynamic cyclic polarisation and electrochemical impedance spectroscopy in simulated
body fluid. 相似文献
18.
ZrO 2 nanoparticles were synthesized through arc discharge of zirconium electrodes in deionized (DI) water. X-ray diffraction (XRD) analysis of the as prepared nanoparticles indicates formation a mixture of nanocrystalline ZrO 2 monoclinic and tetragonal phase structures. Transmission electron microscopy (TEM) images illustrate spherical ZrO 2 nanoparticles with 7–30 nm diameter range, which were formed during the discharge process with 10 A arc current. The average particle size was found to increase with the increasing arc current. X-ray photoelectron spectroscopy (XPS) analysis confirms formation of ZrO 2 at the surface of the nanoparticles. Surface area of the sample prepared at 10 A arc current, measured by BET analysis, was 44 m 2/g. Photodegradation of Rhodamine B (Rh. B) shows that the prepared samples at lower currents have a higher photocatalytic activity due to larger surface area and smaller particle size. 相似文献
19.
For the utilization as inorganic/organic hybrid nanomaterials for optical purposes, nanocrytalline tetragonal ZrO 2 was synthesized by hydrothermal method using zirconium(IV)-n-propoxide as precursor material. Surface of the ZrO 2 particles was then modified with 2-acetoacetoxyethyl methacrylate used as a copolymer for coatings. X-ray diffraction analysis
revealed that both ZrO 2 and modified ZrO 2 are in tetragonal crystalline phase. As proved by transmission electron microscope and particle size analysis, average particle
sizes of ZrO 2 and modified ZrO 2 were found as 6.22 and 14.7 nm, respectively. ZrO 2 powder was easily dispersed either in water or n-hexane. Ultraviolet diffuse reflectance spectrophotometer analysis for ZrO 2 and surface modified ZrO 2 showed that maximum absorption peaks are at 215 and 225 nm, respectively. 相似文献
20.
A homogeneous TiO 2 gel was obtained by hydrolysing titanium(IV) isopropoxide that was previously modified by reaction with acetic acid. The so stabilized precursor was hydrolysed under strong acidic medium (pH=0 by HCl). Dried TiO 2 powders were characterized by FT-IR, XRD, N 2 adsorption analyses, coupled thermogravimetric (TG) gas chromatographic (GC) and `mass spectrometric (MS) analyses. A semiquantitative analysis of the main evolved chemical species allowed to depict both the chemical rearrangements occurring in the TiO 2 matrix during pyrolysis and the chemical composition of the initial gel.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
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