Rare earth oxides in zirconium dioxide:How to turn a wide band gap metal oxide into a visible light active photocatalyst

In the present study, we investigated the effect of cerium and erbium doping of the zirconium dioxide matrix. We synthesized doped samples using hydrothermal process. The amounts of dopant used were 0.5%, 1% and 5% molar(rare earth oxide over zirconium dioxide) respectively. The samples have been studied via X-ray Diffraction measurements for the structural characterization. UV visible diffuse reflectance was used for the optical analysis, Brunauer-Emmett-Teller(BET) model for the measurement of the surface area. Finally the samples have been analysed via electron paramagnetic resonance(EPR) for the electronic characterization. Then we tested the new synthetized materials to determine their photocatalytic activity in the reaction of degradation of methylene blue performed under irradiation by diodes(LEDs) emitting exclusively visible light.

Tuning the crystalline and electronic structure of ZrO_(2)via oxygen vacancies and nano-structuring for polysulfides conversion in lithium-sulfur batteries

The recent emergence of tetragonal phases zirconium dioxide(ZrO_(2))with vacancies has generated significant interest as a highly efficient and stable electrocatalyst with potential applications in trapping polysulfides and facilitating rapid conversion in lithium-sulfur batteries(LSBs).However,the reduction of ZrO_(2)is challenging,even under strong reducing atmospheres at high temperatures and pressures.Consequently,the limited presence of oxygen vacancies results in insufficient active sites and reaction interfaces,thereby hindering practical implementation.Herein,we successfully introduced abundant oxygen vacancies into ZrO_(2)at the nanoscale with the help of carbon nanotubes(CNTs-OH)through hydrogen-etching at lower temperatures and pressures.The introduced oxygen vacancies on ZrO_(2-x)/CNTs-OH can effectively rearrange charge distribution,enhance sulfiphilicity and increase active sites,contributing to high ionic and electronic transfer kinetics,strong binding energy and low redox barriers between polysulfides and ZrO_(2-x).These findings have been experimentally validated and supported by theory calculations.As a result,LSBs assembled with the ZrO_(2-x)/CNTs-OH modified separators demonstrate excellent rate performance,superior cycling stability,and ultra-high sulfur utilization.Especially,at high sulfur loading of 6 mg cm^(-2),the area capacity is still up to 6.3 mA h cm^(-2).This work provides valuable insights into the structural and functional optimization of electrocatalysts for batteries.

Effect of composition and sintering temperature on mechanical properties of ZrO_2 particulate-reinforced titanium-matrix composite

The titanium-based composites were synthesized by powder metallurgy method. The effects of composition and sintering temperature on the microstructure and properties of the titanium-based composites were investigated by X-ray diffraction, optical microscopy, scanning electron microscopy and mechanical properties tests. The results demonstrate that adding ZrO2 particles can improve the mechanical properties of powder metallurgy （P/M） titanium-based composites. The Ti composite with 4% （mole fraction） ZrO2 sintered at 1100 °C for 4 h shows an appropriate mechanical property with a relative density of 93.9%, a compressive strength of 1380 MPa （570 MPa higher than pure Ti） and good plasticity （an ultimate strain above 24%）.

Preparation and structure of microarc oxidation ceramic coatings containing ZrO2 grown on LY12 Al alloy

Ceramic coatings containing ZrO2 were prepared in situ on LY12 aluminum alloy by microarc oxidation（MAO） in the mixed solution of zirconate and phosphate solution.The phase composition and morphology of the coatings were studied by XRD and SEM,respectively.The growing mechanism of ceramic coatings was discussed in a preliminary manner.The results show that with an increase in MAO time,the compactness of the coating improved and the thickness increased.From the inner layer to the coating surface,the content of Zr increased,while the content of Al decreased.In addition,the coating was composed of m-ZrO2,t-ZrO2,and a little amount of γ-Al2O3.With an increase in reaction time,the relative content of t-ZrO2 within the coating sharply decreased while the relative content of m-ZrO2 sharply increased,and then both generally kept at a constant level after 60 min.

Fabrication and characterization of 3D printed biocomposite scaffolds based on PCL and zirconia nanoparticles

The application of three-dimensional printed polymer scaffolds in repairing bone defects is a promising strategy.Among them,polycaprolactone(PCL)scaffolds are widely studied due to their good processability and controlled degradation rate.However,as an alternative graft for repairing bone defects,PCL materials have poor hydrophilicity,which is not conducive to cell adhesion and growth.In addition,the poor mechanical properties of PCL materials cannot meet the strength required to repair bone defects.In this paper,nano-zirconium dioxide(ZrO2)powder is embedded in PCL material through a meltmixing process,and a regular grid scaffold is constructed by 3D printing.The embedding of nanometer zirconium dioxide powder improves the hydrophilicity and water absorption of the composite scaffold,which is conducive to cell adhesion,proliferation and growth and is beneficial to the exchange of nutrients.Therefore,the PCL/ZrO2 composite scaffold showed better biological activity in vitro.At the same time,the PCL/ZrO2 composite material system significantly improves the mechanical properties of the scaffold.Among them,compared with the pure PCL scaffold,the Young’s modulus is increased by about 0.4 times,and the compressive strength is increased by about 0.5 times.In addition,the osteogenic differentiation results also showed that the PCL/ZrO2 composite scaffold group showed better ALP activity and more effective bone mineralization than the pure PCL group.We believe that the 3D printed PCL/ZrO2 composite scaffold has certain application prospects in repairing bone defects.

Magnesium alloy AZ63A reinforcement by alloying with gallium and using high-disperse ZrO_(2) particles

The aim of this work was to obtain an experimental magnesium alloy by remelting standard AZ63A alloy with addition of gallium ligatures and ZrO_(2) particles.This allowed reinforcement of alloy and increase its hardness and Young’s modulus.The chemical analysis of this alloy shows two types of structures which are evenly distributed in volume.Thus we can conclude that reinforcing effect is the result of formation of intermetallic phase Mg_(5)-Ga_(2).

Biocompatibility and electrochemical evaluation of ZrO_(2) thin films deposited by reactive magnetron sputtering on MgZnCa alloy

Biodegradable magnesium alloys are promising candidates for temporary fracture fixation devices in orthopedics;nevertheless,its fast degradation rate at the initial stage after implantation remains as one of the main challenges to be resolved.ZrO_(2)-based coatings to reduce the degradation rate of the Mg-implants are an attractive solution since they show high biocompatibility and stability.In this work,the degradation,cytotoxicity,and antibacterial performance of ZrO_(2)thin films deposited by magnetron sputtering on a Mg-Zn-Ca alloy was evaluated.Short-term degradation of ZrO_(2)-coated and uncoated samples was assessed considering electrochemical techniques and H_(2)evolution(gas chromatography).Additionally,long term degradation was assessed by mass-loss measurements.The results showed that a 380 nm ZrO_(2)coating reduces the degradation rate and H_(2)evolution of the alloy during the initial 3 days after immersion but allows the degradation of the bare alloy for the long-term.The ZrO_(2)coating does not compromise the biocompatibility of the alloy and permits better cell adhesion and proliferation of mesenchymal stem cells directly on its surface,in comparison to the bare alloy.Finally,the ZrO_(2)coating prevents the adhesion and biofilm formation of S.aureus.

Thermodynamic analysis and preparation of β-SiC/ZrO_2 composites

A predominance area diagram for the Zr-Si-C-O system at 1773 K was plotted according to correlative thermodynamic data. β-SiC/ZrO2 composites were prepared based on the phase diagram by carbothermal reduction of zircon （ZrSiO4） in argon atmosphere. Zircon and carbon black were mixed according to the C/ZrSiO4 mass ratio of 0.2, and with 0, 1wt% and 2wt% extra addition of La2O3. Phase evolution of the mixture was investigated at 1723-1803 K by X-ray powder diffraction, and the microstructure of the product prepared at 1803 K for 4 h was examined by scanning electronic microscope. The results show that the decomposition of ZrSiO4 and the formation of β-SIC can be promoted by increasing the heating temperature and adding La2O3. The β-SiC/ZrO2 composites can be prepared at 1803 K for 4 h in a mixture of zircon, carbon black and La2O3, and the contents of β-SIC and m-ZrO2 in the product sample with 2wt% La2O3 reach the highest values of 10.8wt% and 89.2wt%, respectively. The crystal size of the products is about 200 nm.

Preparation of Nanocrystalline ZrO_2 by Reverse Precipitation Method

Nanncrystalline ZrO2 particulates with different sizes were prepared by precipitation method using ethanol as dispersive and protective reagent. XRD patterns show that the synthesized ZrO2 is monnclinic in structure with space group P21/a when calcination temperature is in the range of 400- 1000 ℃ . It is found that the smaller the particle, the bigger the crystal lattice distortion, the worse the costal growth, and the lower the diffrnction intensity. TEM images reveal that ZrO2 particles are spherical in shape, and the particle size distribution is in narrow range. The mean sizes of the particles increase with the increase of calcination temperatures . It is first to observe tbe streaks of different crystallographic planes. Thermogravimetric analysis indicates that the crystallization temperature of ZrO2 is 461.32 ℃ . Measurement of ZrO2 relative density shows that the relative density of nanocrystalline ZrO2 powders increases witb the increasing of ZrO2 particle sizes.

Plasma-Chemical Synthesis of Oxide Powders Using Transformer-Coupled Discharge

An experimental investigation of transformer-coupled discharge in an Ar-O2 mixture with the addition of SICl4, TiCl4 and ZrCl4 has been carried out under the atmospheric pressure of plasma-forming gases. Discharge power and discharge heat losses have been determined, and the dispersion and phase composition of reaction products （oxide powders） has been analyzed with SEM and X-ray diffraction analysis. Investigations reveal the formation of ultrafine oxide powders in the case of vaporized chloride （SiCl4 and TiCl4） injecting into the transformer coupled discharge. In the case of fine powder （ZrCl4） injection, full oxidation was not observed and reaction products consisted of a mixture of ZrO2 and ZrOCl2. A conclusion has been made regarding the perspectives of using transformer-coupled discharge to produce ultrafine oxide powders.

Review of Dye-Sensitized Solar Cell (DSSCs) Development

Energy consumption is increasing yearly all over the world due to the increase in population and demand of energy. The world largely depends on a hydroelectric energy supply, thermal electric energy supply which is all non-renewable energy resources. Nevertheless, non-renewable energy resources are rapidly decreasing per year due to increasing rate of energy consumption. The quest for the discovery of another abundant resource of energy has attracted many scientists into development of renewable energy technologies like photovoltaic energy which are the technology that convert solar radiation into electricity. For the past several years, different photovoltaic devices like inorganic, organic, and hybrid solar cells have been invented using different methods for different application purposes. Moreover, high conversion efficiency of silicon solar cells, the high cost of module and complicated production processes involved in the production restricted commercialization of photovoltaic solar cells as a means of electricity supply. Among all organic solar cells, Dye-Sensitized Solar Cells (DSSCs) are the most efficient, low cost and easily implemented technology. This review paper focuses on clarifying the technological meaning of the structure of DSSCs, Various types of DSSCs materials, working electrode and working mechanism of DSSC, transparent and conductive substrate, nanocrystalline semiconductor film electrode, photosensisitizer (dye), electrolyte, carbon layer electrode, zinc oxide (ZnO) layer, zirconium dioxide (ZrO2) layer, benefits of DSSCs and application, the efficiency and challenges for research and development of DSSCs to upgrade the current efficiency.

Analysis of Fracture of Pre⁃sintered Zirconia Material in Neck Milling

With the continuous improvement of the accuracy requirements of clinical base or base tooth and denture,the design of denture neck edge is becoming thinner and thinner,and the presintering zirconia dioxide billet for denture making evacuation and low strength material mechanical characteristics make the certain probability of denture neck edge fragmentation and peeling in the cutting process.Based on this phenomenon,the abnormal wear is the main reason,and a method of high frequency ultrasonic time cleaning to reduce the fracture of the denture neck in actual cutting is proposed.

Silicotungstic acid-derived WO_(3) composited with ZrO_(2) supported on SBA-15 as a highly efficient mesoporous solid acid catalyst for the alkenylation of p-xylene with phenylacetylene

Highly dispersed silicotungstic acid-derived WO_(3) composited with ZrO_(2) supported on SBA-_(15) (WZ/SBA-_(15)) as an ordered mesoporous solid acid catalyst was prepared via a facile incipient wetness impregnation (IWI) method that active ingredients, ZrO_(2) and WO_(3), were impregnated into the channels of SBA-_(15) simultaneously with a subsequent calcination process. The relationship between catalyst nature and performance was explored by high resolution transmission electron microscopy (HRTEM), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), FT-IR, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), N_(2) adsorption-desorption, NH_(3) temperature-programmed desorption (NH_(3)-TPD), and FT-IR of pyridine adsorption (Py-IR) characterization techniques. The catalytic performance of W_(12)Z_(15)/SBA-_(15) is not only greater than that of single component solid acid catalysts, WO_(3)/SBA-_(15) and ZrO_(2)/SBA-_(15), but also W_(12)/Z_(15)/SBA-_(15) prepared by impregnating active ingredients, ZrO_(2) and WO_(3), into SBA-_(15) in sequence. The outstanding performance of W_(12)Z_(15)/SBA-_(15) is derived from the strong interaction between ZrO_(2) and WO_(3), which results in more acid sites, and relatively high specific surface area, large pore volume, and ordered mesoporous structure of SBA-_(15). The characterization and reaction results clearly demonstrate that the synergy of ZrO_(2) and WO_(3) has a clear boost for the alkenylation. The optimized W_(12)Z_(15)/SBA-_(15)-500 achieves a 99.4% conversion of phenylacetylene and a 92.3% selectivity of main product α-arylstyrene for the alkenylation of p-xylene with phenylacetylene, with very low level of oligomers producing at the same time. Moreover, W_(12)Z_(15)/SBA-_(15)-500 shows excellent catalytic stability and regeneration. Therefore, W_(12)Z_(15)/SBA-_(15)-500 is a promising solid acid catalyst for the alkenylation.

N-doped ZrO_(2) nanoparticles embedded in a N-doped carbon matrix as a highly active and durable electrocatalyst for oxygen reduction

Fabricating highly efficient and robust oxygen reduction reaction(ORR)electrocatalysts is challenging but desirable for practical Zn-air batteries.As an early transition-metal oxide,zirconium dioxide(ZrO_(2))has emerged as an interesting catalyst owing to its unique characteristics of high stability,anti-toxicity,good catalytic activity,and small oxygen adsorption enthalpies.However,its intrinsically poor electrical conductivity makes it difficult to serve as an ORR electrocatalyst.Herein,we report ultrafine N-doped ZrO_(2) nanoparticles embedded in an N-doped porous carbon matrix as an ORR electrocatalyst(N-ZrO_(2)/NC).The N-ZrO_(2)/NC catalyst displays four-electron reduction of oxygen in O.1 M KOH,Upon employment in a Zn-air battery,N-ZrO,/NC presented an exellent activity and long-term durability with a half-wave potential(E,v2)of 0.84 V and a selectivity for the intriguing powerdensity of 185.9 mwcm^(-2).anda high secific capacity of 797.9 mA h gzni,exceeding those of commercial Pt/C(122.1 mw cm^(-2) and 782.5 mA h gzn),This excellent performance is mainly ttributed to the ultrafine ZrO_(2) nanoparticles the conductive carbon substrate,and the modifed electronic band structure of ZrO_(2) after N-doping.Density functional theory calculations demonstrated that N-doping can reduce the band-gap of ZrO_(2) from 3.96 eV to 3.33 eV through the hybridization of the p state of the N atom with the 2p state of the oxygen atom;this provides enhanced electrical conductivity and results in faster electron-transfer kinetics.This work provides a new approach for the design of other enhanced semiconductor and insulator materials.

Research of silane film cooperation with ZrO_2 on electrogalvanized steel

The silane composite film formed on electrogalvanized steel sheet by silane film with ZrO2 improve the corrosion resistance. The surface morphology, the structure and composition as well as the corrosion resistance of the prepared silane composite fihn were investigated by SEM, AFM, XPS and electrochemical test. The experimental results showed that the structure of the silane composite film was composed of Si-O-Si three-dimensional network doped with ZrO2 showing excellent corrosion resistance, because the structure of this kind of composite film has much less micropore which improves the uniform and density of the silane film.