Zirconium Nitrate Research Articles

Preparation and characterization of tetragonal-ZrO 2 nanopowders by a molten hydroxides method

Pure tetragonal-ZrO 2 nanopowders are prepared by a molten hydroxides method, using hydrated zirconium nitrate as the starting material at 200 °C. X-ray diffraction analysis and transmission electron microscopy observation reveal that the nanopowders exhibit poor crystalline quality. After heat treated at 400 °C for 10 h in air, the nanopowders are crystalline with size range of ∼10–12 nm and most of them are agglomerated. The formation mechanism of the ZrO 2 nanopowders has been proposed. The heat treated nanopowders have a BET surface area of ∼27.3 m 2/g due to agglomeration. The photoluminescence of the heat treated nanopowders has been investigated at room temperature.

Preparation and corrosion resistance studies of zirconia coating on fluorinated AZ91D magnesium alloy

Novel anti-corrosion zirconia coating was prepared via the sol–gel method for AZ91D magnesium alloy using zirconium nitrate hydrate as a precursor modified with acetylacetone (AcAc). Magnesium alloy substrates were first fluorinated in 20% HF aqueous solution at room temperature for 20 h, then, the zirconia coating was deposited on the fluorinated sample by dip coating. Basing on the sol–gel process, a chelate complex from the reaction of zirconium coordinating AcAc was formed which was supported by UV–vis spectrum analysis. The result showed that the absorption peak could be seen for the sol at 308 nm, which was red-shifted by 36 nm from that of methanol form of AcAc (272 nm). Moreover, Fourier transform infrared (FT-IR) spectrum analysis was performed to examine the structural differences between the gel and AcAc. The results indicated that the chelate complex with a bidentante structure was formed through the interaction chemically between zirconium nitrate and AcAc. The surface morphology of the zirconia coating was characterized by scanning electron microscope (SEM), an uniform coating can be obtained on the fluorinated sample. The corrosion resistance of the substrate, the fluorinated with and without the zirconia coating in the 3.5 wt.% NaCl solution was studied using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests, respectively. The results demonstrated that the zirconia coating could greatly improve the corrosion resistance of the AZ91D magnesium alloy. Furthermore, the effect of the different heat-treatment temperatures for the zirconia coating on corrosion resistance was also discussed.

Extraction of zirconium with tributyl phosphate from nitric acid solutions

The extraction of zirconium with tributyl phosphate (TBP) in organic diluent was studied. The dependence of the distribution ratio of Zr on the TBP concentration in the organic phase and also the IR spectra of Zr-TBP extracts obtained at different concentrations of Zr and HNO3 in the aqueous phase show that at least two kinds of extractable zirconium nitrate solvates with TBP are formed in extraction with 30% TBP. The solvate formed at HNO3 concentration not exceeding 3 M contains water molecules. The extract-able species formed at higher nitric acid concentration in the aqueous phase is anhydrous zirconium nitrate disolvate with TBP.

Preparation and characterization of Y 2Zr 2O 7 nanocrystals and their photocatalytic properties

The yttrium zirconate (Y 2Zr 2O 7) nanocrystals with cubic structure in the size range of 50 nm were prepared by stearic acid method (SAM) using zirconium nitrate and yttrium nitrate as raw materials, stearic acid as solvent and dispersant. The synthesis process was monitored by TG–DTA. The product was characterized by XRD, FT-IR, TEM, HRTEM, EDS and BET. The effect of thermal treatment temperature on crystal size and lattice distortion of the nanocrystals was studied. Y 2Zr 2O 7 nanocrystals obtained by SAM were well dispersed with average size of 20–40 nm. The interplanar distances measured from the HRTEM image were 0.294 and 0.185 nm, respectively, coinciding with the theoretical values. Moreover, the photocatalytic properties of Y 2Zr 2O 7 nanocrystals were measured and discussed.

Synthesis and characterization of lead zirconate titanate powders obtained by the oxidant peroxo method

Abstract Lead zirconate titanate (PbZr 1− x Ti x O 3 ) was synthesized by the “oxidant peroxo method (OPM)” with “ x ” between 0.25 and 0.50. Titanium metal was dissolved into a hydrogen peroxide/ammonia aqueous solution, followed by the addition of lead and zirconium nitrate solution. The amorphous precipitated precursor obtained was crystallized by heat treatment between 400 and 1000 °C. Images of transmission microscopy showed spherical particles with average diameter between 20 and 60 nm, and the presence of necks between particles treated at 700 °C. All of the unpressed powders were characterized by X-ray diffractometry and FT-Raman spectroscopy. Powder samples with “ x ” up to 0.35 showed rhombohedral structure when treated at temperatures higher than 500 °C, and tetragonal structure when “ x ” was higher than 0.40. Analysis of XRD and Raman spectroscopy of the precursor powders showed amorphous-like structures, however powders treated at 400 °C showed a structure identified as an intermediate pyrochlore phase, independently of the Zr and Ti mole ratio.

Microwave-induced synthesis and characterization of nanometer Ce 0.5Zr 0.5O 2 solid solution for the acidic catalytic reaction

Ce 0.5Zr 0.5O 2 solid solution was successfully synthesized using cerium nitrate, zirconium nitrate, and urea as raw materials by the microwave irradiation method and characterized by X-ray diffraction, fluorescence spectrum, transmission electron microscopy, and infrared spectrum. Its acid catalytic activity was evaluated in the esterification reaction of acetic acid and n-butyl alcohol. The results show that Ce 0.5Zr 0.5O 2 solid solution has cubic fluorite structure, and its particle diameter is in the nanometer scale. As a sort of solid acid, it possesses a higher acid catalytic activity and can be easily separated from reaction liquids. It can be used for several times, and basically, its activity keeps constant. The proton acid sites and Lewis acid sites exist in the structure of Ce 0.5Zr 0.5O 2 solid solution.

Characterization and their photocatalytic properties of Ln 2Zr 2O 7 (Ln = La, Nd, Sm, Dy, Er) nanocrystals by stearic acid method

Fine-particle rare-earth metal zirconates Ln 2Zr 2O 7 (Ln = La, Nd, Sm, Dy, Er) with cubic structure were prepared by stearic acid method. Zirconium nitrate and rare-earth nitrate were as raw materials, and stearic acid was used as solvent and dispersant. The as-prepared Ln 2Zr 2O 7 nanocrystals were characterized by XRD, FT-IR, TEM and HRTEM. The results showed that the preparation temperature was lowered (from 1500 °C to 800 °C) and the reaction time was shortened (from at least 10 h to 5 h) by stearic acid method, compared with transitional solid-state method. The photocatalytic activity of Ln 2Zr 2O 7 nanocrystals was evaluated by the photocatalytic degradation of methyl orange. With the increase of the atomic number, the photocatalytic activity trend of obtained Ln 2Zr 2O 7 (Ln = La, Nd, Sm, Dy, Er) nanocrystals was in agreement with the change trend of magnetic moment of the rare-earth metal ion. The photoactivity of Ln 2Zr 2O 7 was strongly dependent on Ln, decreasing in the sequence of Dy > Nd > Er > Sm > La.

Biomorphic Mesoporous Ce1−xZrxO2 Nanostructures Fabricated from Paper Templates

AbstractA simple and versatile procedure was developed for synthesizing biomorphic mesoporous Ce1-xZrxO2. Aqueous cerium nitrate and zirconium nitrate solutions, and paper were used as the starting materials. Under the structure-directed effect offered by the active hydroxyl radicals of the cellulose in the paper templates, porous and fibrous structures of paper were replicated by the self-assembly of Ce1-xZrxO2 nanocrystallites after the paper underwent chemical infiltration and calcinations. The product, composing of interwoven network of fibers with diameter ranging from 10 to 20 <mu>m, was a replica of the original paper structure only that each fiber was assembled by Ce1-xZrxO2 nanocrystallites with grain size of 3-10 nm. The templating function of cellulose and the mechanism in the formation of nanocrystallites were proposed.

Catalytic combustion of methane over nano ZrO 2-supported copper-based catalysts

The nano ZrO 2-supported copper-based catalysts for methane combustion were investigated by means of N 2 adsorption, TEM, XRD, H 2-TPR techniques and the test of methane oxidation. Two kinds of ZrO 2 were used as support, one (ZrO 2-1) was obtained from the commercial ZrO 2 and the other (ZrO 2-2) was issued from the thermal decomposition of zirconium nitrate. It was found that the CuO/ZrO 2-2 catalyst was more active than CuO/ZrO 2-1. N 2 adsorption, H 2-TPR and XRD measurements showed that larger surface area, better reduction property, presence of tetragonal ZrO 2 and higher dispersion of active component for CuO/ZrO 2-2 than that of CuO/ZrO 2-1. These factors could be the dominating reasons for its higher activity for methane combustion.

Preparation and characterization of pyrochlore La2Zr2O7 nanocrystals by stearic acid method

Pyrochlore La2Zr2O7 nanocrystals with cubic structure were prepared by stearic acid combustion method using zirconium nitrate and lanthanum nitrate as raw materials, stearic acid as solvent and dispersant. The La2Zr2O7 was characterized by XRD, Raman, FT-IR, BET, TEM, HRTEM and Emission/excitation spectra. The effect of thermal treatment temperature on crystal size of the nanocrystals was studied and a single phase of La2Zr2O7 was completely formed at 900 °C. The interplanar distances of d222 and d400 measured from the TEM images were 0.322 nm and 0.263 nm, respectively, coinciding with the theoretical values. Moreover, the strong fluorescent property of the La2Zr2O7 was measured, with the maximum emission peak at ca. 389 nm upon excitation at ca. 324 nm.

Electrical Characteristics and Preparation of Nanostructured Pb(Zr0.5Ti0.5)O3 Films by Spray Pyrolysis

Nanostructured thin films of Pb(Zr0.5Ti0.5)O3 on Pt (1000 Å)/Ti (100 Å)/SiO2 (2000 Å)/Si substrates are prepared by spray pyrolysis and subsequently rapid thermal annealing. Lead nitrate, zirconium nitrate and titanium isopropoxide are used as starting material with ethylene glycol as solvent. The crystal structure of the as-sprayed films are transformed from the amorphous, pyrochlore and multiple phases of pyrochlore and perovskite to the single phase of perovskite as the annealing temperature is increased up to 500 °C. For the formation of single phase perovskite, excess lead of 10 mol % is required to compensate the loss of lead during the processing of the primitive films. The physical characteristics of the resultant films show the dielectric constant (εr) of 400, remanent polarization (2Pr) of 30.0 µC/cm2 and coercive field (2Ec) of 70.0 kV/cm, respectively.

Synthesis of monophasic Ce0.5Zr0.5O2 solid solution by microwave-induced combustion method

Nanocrystalline monophasic Ce0.5Zr0.5O2 solid solution (1:1 molar ratio) has been synthesized by microwave-induced combustion method in a modified domestic microwave oven (2.45 GHz, 700 W) in approximately 40 min from cerium nitrate and zirconium nitrate precursors using urea as ignition fuel. For the purpose of better comparison, a CexZr1 − xO2 solid solution (1:1 molar ratio) was also synthesized by a conventional co-precipitation method from nitrate precursors and subjected to different calcination temperatures. The synthesized powders of both methods were characterized by means of X-ray powder diffraction, thermogravimetry/differential thermal analysis, scanning electron microscopy, and BET surface area techniques. Oxygen storage capacity (OSC) measurements were performed to understand the usefulness of these materials for various applications. The characterization results reveal that the sample obtained by microwave-induced combustion-synthesis route exhibits homogeneous monophasic Ce0.5Zr0.5O2 solid solution whereas the co-precipitated sample displays compositional heterogeneity. The OSC measurements reveal that the materials synthesized by both methods exhibit comparable oxygen vacancy content (δ).

Direct synthesis of Zr-SBA-15 mesoporous molecular sieves with high zirconium loading: Characterization and catalytic performance after sulfated

The Zr-SBA-15 mesoporous materials with high Zr/Si ratio (0–2.32) were first synthesized directly using zirconium nitrate and tetraethyl orthosilicate as precursor, displaying higher thermal stability after activated at 600 °C. 29Si NMR spectra revealed the part existance of ZrO 2 in the framework of SBA-15. After sulfated, the SO 4 2 - / Zr-SBA- 15 exhibited high activity in the isomerization of n-pentane at 35 °C, and the conversion of n-pentane reached 93.9% after reacting 180 min with the SO 4 2 - / Zr-SBA- 15 of Zr/Si = 1.3, which was higher compared with the bulk sulfated zirconia material and the SBA-15 modified with SO 4 2 - / ZrO 2 by incipient wetness method.

Synthesis and mechanism research of an ethylene glycol-based sol-gel method for preparing PZT nanopowders

Lead zirconate titanate nanopowders Pb(Zr0.52Ti0.48)O3 (PZT) were prepared by modified sol-gel process in ethylene glycol system with zirconium nitrate as the zirconium source. The research showed that it was critical to add lead acetate after the reaction of zirconium nitrate and tetrabutyl titanate in ethylene glycol system for preparing PZT of exact titanium content. The reaction mechanisms of the sol synthesis, preparation of xerogel and agglutinating process were characterized through using FT-IR, NMR, TG-FTIR, and GC-MS. The experiment proved that ethylene glycol system did not rely on hydrolysis and condensation reactions in the process of the sol formation, but on the formation of chain or network large molecules from complexation of ethylene glycol and all Ti and minor Pd, Zr. In the preparation of xerogel, the complexation reaction was so completed that it formed large molecules network composed of metal and dioxyethyl. Bulk weight loss happened before 350°C in the process of sintering xerogel to prepare PZT nanopowders. Volatile matters and vapor phase decomposition resultants were primarily oxy-compounds including ethylene glycol, aldehyde-ketone compounds, carbon dioxide and nitrate radical conversion matters. After 350°C, primary vapor phase decomposition resultants were carbon dioxide and minor carbonyl compound.

Preparation of BaZrO 3 nanopowders by spray pyrolysis method

Barium zirconate based solid solutions of various compositions become ionic and/or electronic conductors and they are potential candidates for numerous types of applications in the field of electroceramics. This work investigated application of ultrasonic spray pyrolysis method based on thermal decomposition of barium and zirconium nitrate solution for preparation of fine barium zirconate powders. The aerosols of nitrate solutions of 0.1, 0.01 and 0.001 M were thermally treated at 800, 1000 and 1200 °C. The prepared powders were composed of the spherical particles which sizes, from 90 to 500 nm, were mainly depended on the concentration of nitrate solution and less depended on the pyrolysis temperature. The particles consisted of the crystallites of 25–60 nm in size. Their sizes strongly depended on the pyrolysis temperature and to the lesser extend on the solution concentration.

RETRACTED: Enhanced photocatalytic degradation of 4-chlorophenol by Zr4+ doped nano TiO2

Abstract Zr 4+ doped nano titania was prepared by sol–gel method using titanium(IV) isopropoxide and zirconium nitrate as precursors. The materials were characterized by XRD, BET, UV–vis, FT-IR, SEM-EDX and TEM techniques. The nanoparticles of pure TiO 2 contained both anatase and rutile phases together but Zr 4+ doped TiO 2 gave anatase phase only. The framework substitution of Zr 4+ in TiO 2 was established by XRD, SEM-EDX and FT-IR techniques. The band gap value of Zr 4+ doped TiO 2 was higher than the parent nano TiO 2 . TEM observations confirmed the nanocrystalline nature of Zr 4+ doped TiO 2 . The presence of dopants therefore could suppress the growth of TiO 2 grains, increase the surface area, decrease the anatase–rutile phase transformation and accelerate the surface hydroxylation. These properties resulted higher photocatalytic activity for Zr 4+ doped nano TiO 2 than undoped nano TiO 2 . The presence of anatase type structure in TiO 2 with high crystallinity and high phase stability, even after annealing at 800 °C substantially indicated that the dopants might inhibit densification and crystallite growth by providing dissimilar boundaries. The photocatalytic activity in the degradation of 4-chlorophenol was found to be higher for Zr 4+ doped TiO 2 than both nano TiO 2 and commercial TiO 2 (Degussa P25). The experimental parameters such as initial concentration of 4-chlorophenol, catalyst loading, pH and light intensity were optimized for maximum degradation efficiency.

The influence of alcohol additives on the crystallization of ZrO2 under hydrothermal conditions

ZrO2 small particles with different crystal habits were prepared from zirconium nitrate under hydrothermal conditions. The ZrO2 particles were characterized by XRD, TEM and SEM. The crystal structure, morphology and size of the ZrO2 particles were strongly dependent on the glycerin additive in the reaction solution. The phase-pure t-ZrO2 with the size about 10 nm formed from the reaction solution added with glycerin while the rod-like phase-pure m-ZrO2 with the size about 30 × 80 nm formed from the reaction solution without glycerin (180 °C, 18 h, pH = 13). The t-ZrO2 could also form under the same hydrothermal conditions in the presence of other polyhydric alcohol additives, such as trimethylolpropane and tetramethylolmethane. But monohydric and dihydric alcohols were not benefits to formation of phase-pure t-ZrO2. The mechanisms for formation of phase-pure t-ZrO2 were supposed according to the experimental results.

Surface evaluation and electrochemical behaviour of doped silane pre-treatments on galvanised steel substrates

The present work aims at evaluating the surface morphology and the corrosion resistance of galvanised steel substrates pre-treated with bis-[triethoxysilylpropyl] tetrasulfide silane (BTESPT) solutions doped with cerium nitrate or zirconium nitrate. The silane pre-treatment leads to the formation of a silane coating in the metallic surface. The surface morphology of this coating was studied by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The corrosion behaviour of the pre-treated substrates during immersion in 0.05 M NaCl was assessed by the scanning vibrating electrode technique (SVET) and by electrochemical impedance spectroscopy (EIS). The results show that the presence of dopant improves the protective properties of the silane pre-treatment. Moreover, it was found that pre-treatments based on silanes doped with cerium nitrate are more resistant against corrosion development due to the corrosion inhibition properties of the cerium ions.

The Synthesis, Characterization and DC Electrical Conductivity of Polypyrrole‐Zirconium Complex

Polypyrrole‐zirconium complex has been synthesized by reacting 2‐amino‐3,4‐dicyano‐5‐mercaptopyrrole with zirconium nitrate in absolute ethanol under reflux for 24 h. The product has been characterized by elemental analyses, FTIR spectroscopy, in addition to thermal analysis (TGA and DSC) and its solubility has been investigated. The DC electrical conductivity variation of polypyrrole‐zirconium complex has been studied in the temperature range 300–500 K after annealing for 24 h at 100°C and doping with I2, FeCl3 and CuCl2 · H2O for comparison. An attempt has been made to interpret the DC electrical conductivity behavior and thermal properties to chain length, dopant used, polymer structure and attached groups.

Modification of microstructure and electrical conductivity of plasma-sprayed YSZ deposit through post-densification process

4.5 mol% yttria-stabilized zirconia (YSZ) coating was deposited by atmospheric plasma spraying (APS) as an electrolyte for solid oxide fuel cells (SOFCs) applications. The post treatment was employed using zirconium and yttrium nitrate solution infiltration to densify the coating microstructure for improvement of gas permeability. The deposition of YSZ through nitrate in voids of the coating was examined. Microstructure of the as-sprayed and densified coatings was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The effect of infiltrating treatment on coating microstructure and electrical conductivity was examined. The electrical conductivity of APS-sprayed YSZ coating at the direction perpendicular to coating surface was much lower than that of bulk materials. Post-densification treatment improved the electrical conductivity of YSZ coating by about 25% compared with as-sprayed coating. It was found that the deposition of YSZ resulting from decomposition of nitrate in the lamellar interface gaps was different from that in vertical cracks in lamella owing to the orthogonal feature of those two types of gaps. The nanopores were formed in the deposited YSZ in nonbonded interface gaps while large pores were residued in vertical cracks in splats. The microstructural examination suggests that nanopores in the deposited YSZ in nonbonded interfaces in the coating were isolated from each other, which led to the significant reduction of gas permeability after densification. Moreover, the nanocontacts between lamellae resulted in high contact resistance and limit improvement of electrical conductivity of the coating after densification.