Doped Zirconia Research Articles

Effects of Zr substitution on structure and thermoelectric properties of Bi2O2Se

In this study, the facile synthesis method of Bi2−xZrxO2Se (x = 0, 0.02, 0.04, and 0.06) ceramics using a combining the high-energy ball milling and cold pressing was reported. The effects of zirconium (Zr) doping on the microstructure and thermoelectric properties of Bi2O2Se were systematically investigated. The results indicate that the powder samples were synthesized as a single phase with no impurities. With increasing Zr content, conductivity increased from 13.49 S to 34.91 S cm−1 at 773 K. The thermal conductivity of Bi1.98Zr0.02O2Se was also reduced to 0.51 W m−1 K−1. The maximum power factor (PF) value of the Bi1.96Zr0.04O2Se sample was 186 μW m−1 K−2 at 773 K. A peak ZT of around 0.27 was achieved for the Bi1.96Zr0.04O2Se sample, which is approximately 2.4 times greater than that of un-doped one (∼0.11). The results indicate that Zr-doping significantly improves the thermoelectric properties of the Bi2O2Se system.

Natural Diatomite Supported Zirconium-Doped TiO2 with Tailoring Band Structure for Enhanced Visible-Light Photocatalytic Properties.

The development of economically applicable, highly efficient and low cost photocatalytic materials has always been a challenge. In this work, we report a zirconium doped TiO/diatomite (ZrTD) composite with enhanced visible light-induced photocatalytic activity. The as-prepared samples were characterized by X-ray diffraction, scanning electron microscopy, UV–VIS diffused reflectance spectroscopy, high-performance liquid chromatography-mass spectrometry, photoluminescence and X-ray photoelectron spectroscopy, respectively. The optimal doping ratio of zirconium into TiO was obtained at 3% (3%ZrTD composite), and the degradation rate constant of which tetracycline (TC) is up to around 8.65 times higher that of zirconium doped TiO. In addition, zirconium doping introduces the impurity levels of Zr 3d and oxygen vacancies into the lattice of TiO, resulting in broadening the light absorption range, reducing the band gap, and improving the separation efficiency of photogenerated electron-hole pairs, thus endowing with visible light photocatalytic properties. Moreover, both the photogenerated holes (h) and superoxide (•O) radicals are responsible for the degradation process of TC, and a possible degradation pathway and the corresponding intermediate products of TC by ZrTD composite are also proposed in detail.

Sintesis Metal-Doped Carbon Nitride Nanosheets sebagai Pengurai Limbah Pewarna secara Fotokatalisis

<p><em>Batik dye waste pollutes the Bengawan Solo River in high levels. One of the effective efforts to overcome pollution in the aquatic environment is through a degradation process using photocatalysts with UV-rays. In this research, carbon nitride nanosheets as photocatalyst with zirconium and cobalt doping was used. The addition of doping on g-C3N4 nanosheets was able to improve the photocatalytic performance. The purpose of this study was to determine the effect of various types of doping on the photoremediation performance of carbon nitride nanosheets. Synthesize Co-doped g-C3N4 nanosheets and Zr-doped g-C3N4 nanosheets was carried out by synthesizing pure g-C3N4 nanosheets using melamine and ammonium sulfate that calcined at 600°C. Afterwards, the mixture was impregnated by Zr and Co-doped using a vacuum evaporator. The effectiveness of the photocatalyst to degrading rhodamine-B was analyzed using X-Ray Diffraction (XRD) and UV-Visible Spectrophotometer. The result shows that photodegradation performance of Co and Zr-doped g-C3N4 nanosheets has increased. Based on the absorbance data of photocatalysts, the Zr-doped g-C3N4 nanosheets photocatalyst give the most optimal results in degrading rhodamine-B with the final rhodamine-B concentration close to zero.</em></p>

Stresses within rare-earth doped yttria-stabilized zirconia thermal barrier coatings from in-situ synchrotron X-ray diffraction at high temperatures

There is a growing interest for smart coatings that can be integrated into turbine engines for in-situ temperature measurements or health monitoring. The addition of rare-earth dopants into standard thermal barrier ceramic top coat materials is used to obtain luminescent coatings that enable spectral measurements, for real-time temperature or health monitoring. The thermomechanical performance and durability of such novel coating compositions in extreme environments still remains to be evaluated. Consequently, the ability to manufacture sensor coatings which present suitable thermal properties needs to be demonstrated. For this study, highly luminescent erbium and europium doped yttria-stabilized zirconia and state-of-the-art yttria-stabilized zirconia coatings manufactured by air plasma spray were characterized to determine the effects of the embedded rare-earth dopants on coating internal strain and stress and to quantify and compare their high temperature response using synchrotron X-ray diffraction. In-situ depth-resolved strain measurements were performed at 15 μm intervals along the depth of the coatings to evaluate materials response at key locations, specifically at layer interfaces. In-plane stress was calculated for the coatings and a finite element model was implemented to supplement the results and enable further predictions. The results show that the sensor coatings that were manufactured in this work revealed only minor variations in the strain response of sensor coatings under a typical thermal cycle and especially at temperatures closer to that of gas turbine operating conditions, compared to state-of-the-art coatings. This work demonstrates the viability of manufacturing rare-earth doped yttria-stabilized zirconia coatings that provide beneficial spectroscopic monitoring capabilities while having minimal impact on the thermomechanical response of the thermal barrier coatings.

Fabrications of hybrid Polyurethane-Pd doped ZrO2 smart carriers for self-healing high corrosion protective coatings

The work demonstrates the effective utilization of hybrid Polyurethane - palladium doped zirconium oxide (Pd–ZrO2) as innovative carriers for corrosion protection coatings on steel materials. ZrO2 and Pd–ZrO2 nanoparticles were successfully synthesized using Photodeposition followed by the hydrothermal synthesis method. The synthesized nanoparticles were then incorporated into the polyurethane matrix and characterized using Fourier-transform infrared spectroscopy and scanning electron microscopy (SEM). The FTIR and SEM confirm the presence of ZrO2 and Pd–ZrO2 nanoparticles and their morphologies in polyurethane composites material. The thermogravimetric analysis (TGA) results indicated that the polyurethane matrix remained stable up to 250 °C. At 800 °C, >50% of residues are observed for Pd–ZrO2 – polyurethane in the TGA analysis, which confirms that the primer and nanoparticles addition enhances the thermal stability of the composite. The water contact angle measurement explains the hydrophobic behavior of nanocomposite modified coatings on a mild steel substrate. It indicates that Pd–ZrO2 and primer significantly increase the hydrophobicity of polyurethane. The major advantages of developing water-repellent or hydrophobic surfaces open up a world of possibilities for metals and alloys in terms of corrosion prevention. Electrochemical impedance spectroscopy (EIS) and a salt spray test were used to determine the anti-corrosion behavior of the prepared polymer nanocomposites. The polymer nanocomposite coatings have better anti-corrosive capabilities when compared to pure polyurethane. The corrosion protection efficiency increased from 76.63% to 97.57% upon incorporating 2 wt % of Pd–ZrO2 in the polyurethane matrix. The results confirmed that the modifications on the polyurethane enhanced the hydrophobicity and anti-corrosion properties of the polymer nanocomposite coatings.

A novel yttria-doped ZrO2 based conductometric sensor for hydrogen leak monitoring

Pure and (8%)Y 2 O 3 -doped zirconium oxide commercial samples were investigated for developing a high performance conductometric hydrogen sensor. The morphological, microstructural, optical, and electrical characteristics of the samples were studied and compared. Conductometric sensors based on these samples were fabricated using a planar platform in alumina provided with interdigitated electrodes, and sensing tests were carried at different operating temperatures and hydrogen concentrations. Sensing tests revealed that the fabricated sensor based on the tetragonal ZrO 2 –Y 2 O 3 (8%) showed the best performances in terms of sensor response (R 0 /R H2 = 7.3@10000 ppm of hydrogen), response and recovery time (5 and 10 s, respectively), and low operating temperature (150 °C). These characteristics have been exploited for developing the first hydrogen leak conductometric sensor based on ZrO 2 so far reported. • A low-cost H 2 sensor was developed with commercial ZrO 2 doped with 8 mol% Yttria. • The 8% Y 2 O 3 -doped ZrO 2 sensor showed very good response, selectivity, repeatability and stability for H 2 monitoring. • The sensor showed further both a rapid response (5 s) and recovery (7 s), helpful for monitoring H 2 leaks.

The Electronic and Ferroelectric Properties in Strontium and Zirconium Doped BaTiO3 from First-Principles Calculations

The structure, electronic and ferroelectric properties of BSZT were investigated based on first-principles calculations. The result of relaxation structure and two-dimensional charge density indicates that the tetragonal crystalline structure is distorted after Sr and Zr doping. The double-well curve fits well with the phenomenological Landau-Devonshire theory. Moreover, the smaller Zr ion displacement leads to a lower spontaneous polarization of BSZT than the original BaTiO3. The hybridization between the 3d states of Ti and the 2p states of O, and the hybridization between the 4d states of Zr and the 2p states of O are observed in the density of states, which is the reason for the ferroelectricity of BSZT materials.

Ferroelectric Polarization Enhancement in Hafnium-Based Oxides Through Capping Layer Engineering

In this work, we investigate that the capping layer (CL) engineering of aluminum oxide (AlOx) on the dopant-free hafnium oxide (HfOx) and the hafnium zirconium oxide (HfZrOx) ferroelectric metal-ferroelectric-metal (MFM) capacitors. The AlOx CL featuring large bandgap and excellent thermal stability offers a stable interface favorable for ferroelectric phase transition. Therefore, the ferroelectric polarization and high-temperature leakage current of HfZrOx MFM capacitor can be largely improved due to the combination of zirconium doping and AlOx capping effect. From the analysis of interface thermodynamic stability and leakage current mechanism, the AlOx CL effectively alleviates interface defect traps between electrode and ferroelectric HfZrOx, which lowers high-temperature leakage current, reduces ferroelectric domains pinning, enhances ferroelectric polarization, and stabilizes the long-term endurance cycling.

Catalytic Transfer Hydrogenation of Biomass-Derived Furfural into Furfuryl Alcohol Over Zirconium Doped Nanofiber

Catalytic Transfer Hydrogenation of Biomass-Derived Furfural into Furfuryl Alcohol Over Zirconium Doped Nanofiber

Strontium doped zirconia for enhanced anti-microbial activity

Doping of group 2 elements in zirconia is a crucial way to modulate structural properties of ZrO2 nanoparticles. In this study, pristine and strontium doped zirconium oxide nanoparticles of different molar ratios were successfully prepared by simple co-precipitation method. Obtained adsorbents were characterized by X-ray diffraction analysis. XRD pattern reveal that the pristine zirconia is highly crystalline with pure tetragonal phase and there is a co-existence of tetragonal and monoclic phases occurs while increasing dopant concentration. Doping is an essential way to normalize and regulate the interaction of zirconia nanoparticles with bacteria and fungus. Strontium doped zirconia has well behaved anti-bacterial activity for both gram positive and gram negative and anti- fungal activities than that of pristine zirconia.

Antimicrobial and photocatalytic activities of strontium doped zirconium oxide nanoparticles

An alkaline earth metal (Strontium-Sr) doped Zirconium Oxide (Zr1-xSr xO2 : x = 0, 0.04, 0.08 and 0.12) nanoparticles were synthesized using Co-precipitation method. X-Ray diffraction pattern of ZrO2 shows the pure tetragonal phase and Sr doped ZrO2 shows the mixture of tetragonal and monoclinic phases with high crystalline structure. SEM images depicts the rod shaped morphology for pure ZrO2, flake and polygon shaped morphology for Sr doped ZrO2 nanoparticles. Optical properties were studied using UV–Vis spectrometer and obtained band gap range between 4.6 and 4.25 eV. The obtained nanoparticles were used as a photocatalyst for the degradation of Methylene Blue (MB) dye and the results shows that the Sr doped ZrO2 enhanced the degradation with 92% efficiency within 35 min. Strontium doped zirconia has well behaved anti-bacterial activity for both gram positive and gram negative and anti- fungal activities than that of pristine zirconia.

Photocatalytic reductive applications of C-doped ZrO2/PANI composite towards Cr(VI)

Carbon doped zirconium oxide polyaniline, C-ZrO2/PANI was synthesised for application in the photocatalytic reduction of Cr(VI) under visible light irradiation. The carbon doping agent applied was carboxymethyl cellulose. C-ZrO2 was obtained via the precipitation method. Coupling of the polyaniline to the C-ZrO2 occurred by in situ oxidative polymerization to obtain the C-ZrO2/PANI composite. XPS and EDS showed presence of C, Zr, O, N in the C-ZrO2/PANI sample. The physiochemical characteristics of the photocatalyst such as a large surface area of 31,47 m2/g, good charge separation were important aspects in the adsorption and subsequent Cr(VI) reduction. Band edge positions for the C-ZrO2/PANI deduced from UV–Vis DRS and Mott-Schottky plot showed that the lowest unoccupied molecular orbital (LUMO) of PANI was below the C-ZrO2 conduction band (CB). Further, photogenerated electrons from LUMO were transferred to C-ZrO2 CB and were involved in the generation of superoxide radicals, •O2−, which were critical in Cr(VI) reduction to Cr(III). Comparably the photocatalyst, C-ZrO2/PANISDS, prepared in the presence of surfactant sodium dodecyl sulfate (SDS) indicated diminished photocatalytic reduction of Cr(VI). From the photocatalytic results, performances of the photocatalysts were in the order C-ZrO2/PANI > PANI > C-ZrO2/PANISDS. Photocatalytic results revealed that 100% of 20 mg/L Cr(VI) was reduced by C-ZrO2/PANI within 70 mins at pH 2. The first order reaction rate constant was 0.0309 min−1. The photocatalyst can be reused for 4 cycles without excessive loss of efficiency and with maintained stability.

Twofold Effects of Zirconium Doping into TiN on Durability and Oxygen Reduction Reactivity in an Acidic Environment

Twofold Effects of Zirconium Doping into TiN on Durability and Oxygen Reduction Reactivity in an Acidic Environment

Oxygen Sensors for Industrial Application

The present work aimed to study a family of solid ceramic electrolytes based on magnesium oxide doped zirconium oxide, usually identified as Mg-PSZ (zirconia partially stabilized with magnesia), used in the manufacture of oxygen sensors for molten metals. A set of electrolytes was prepared by mechanical (milling) and thermal (sintering) processing, varying the composition in magnesia and the cooling rate from the sintering temperature. These two parameters are essential in terms of phase composition and microstructure of Mg-PSZ, determining the behavior of these materials. The structural and microstructural characterization was done by means of X-ray diffraction (XRD). The electrical properties were analyzed by impedance spectroscopy in air. In general, the results obtained from various concentrations of dopant, different cooling rates and the same sintering step condition showed an increased conductivity for samples with predominance of high temperature stable phases (tetragonal and cubic).

Synthesis, Thermoluminescence and Photoluminescence Study of Gd3+ Doped La2Zr2O7 Phosphor

Thermoluminescence (TL) and photoluminescence (PL) properties of the Gd3+ doped lanthanum zirconium phosphor (La2Zr2O7:Gd3+) are reported in this work. Gd3+ doped La2Zr2O7 (LZO) phosphor has been prepared via a high temperature solid state reaction method and it was prepared by using H3BO3 (as flux) and the preliminary materials were La2O3, ZrO2 and Gd2O3. The results of the XRD study shows that La2Zr2O7:Gd3+ phosphor has the cubic structure with 51.68 nm average crystallite size. The TL studies were carried out for the prepared phosphors using UV radiation (UV 254 nm), and a single glow peak was found in this study. Herein to extract the information about the positions of the TL emission at this work the peak shape methods are usage and the maximum peak exhibit the general order kinetics. In TL study the effect of UV exposure was investigated, it was found that it showed linearity with dose, which is helpful in TL dosimeters. The PL emission peaks of Gd -doped LZO phosphors were found to be in the region 450-650 nm, which was due to the 4f-4f transitions of Gd3+. More intense peaks at 468, 539, 589 and 627 nm were found at room temperature under excitation at 276 nm. Here the afterglow and photoluminescence behaviour of the Gd doped LZO phosphor is also reported.

Material properties of IR-to-IR down-converting Er and Nd-Doped ZrO2 nanopowders

Specially tuned luminescent lanthanide-doped IR-to-IR down-converting nanopowders are utilized as taggants to tag and track explosives and valuables. Zirconia (ZrO 2 )-based oxides doped with an Er or Nd dopant offer a cheaper alternative to fluoride taggants. Maximum IR-to-IR down-conversion intensity was achieved with low concentrations (1 mol%) of Er or Nd dopant. Er-doped ZrO 2 powders possessed strong emission bands from 1444 nm to 1600 nm. Nd-doped ZrO 2 powders possessed strong emission bands from 1055 nm to 1151 nm as well as 1323 nm–1473 nm. No visible light emission was detected for any of the doped compositions. For all doped compositions, increasing the phase fraction of monoclinic structure substantially increased the luminescent intensities and is hypothesized to be a result of decreased lattice symmetry and oxygen vacancy concentration decreasing the number of non-radiative pathways for energy transfer. Our results suggest that Er and Nd-doped ZrO 2 represents an excellent candidate for an IR-IR taggant system because it possesses a wide array of unique emission spectra which may be tailored by controlling dopant chemistry, dopant concentration, and annealing temperature. •Rare-earth doped zirconia nanopowders were fabricated using aqueous precursors •Lower symmetry crystal systems had the highest tested luminescence response •The lowest dopant concentrations resulted in the highest luminescence intensity •Each nanopowder tested displayed a unique emission spectrum implying a high tunability

Synthesis of Fe3O4@mZrO2-Re (Re = Y/La/Ce) by Using Uniform Design, Surface Response Methodology, and Orthogonal Design & Its Application for As3+ and As5+ Removal.

In this study, iron oxide (Fe3O4) was coated with ZrO2, and doped with three rare earth elements((Y/La/Ce), and a multi-staged rare earth doped zirconia adsorbent was prepared by using uniform design U14, Response Surface methodology, and orthogonal design, to remove As3+ and As5+ from the aqueous solution. Based on the results of TEM, EDS, XRD, FTIR, and N2-adsorption desorption test, the best molar ratio of Fe3O4:TMAOH:Zirconium butoxide:Y:La:Ce was selected as 1:12:11:1:0.02:0.08. The specific surface area and porosity was 263 m2/g, and 0.156 cm3/g, respectively. The isothermal curves and fitting equation parameters show that Langmuir model, and Redlich Peterson model fitted well. As per calculations of the Langmuir model, the highest adsorption capacities for As3+ and As5+ ions were recorded as 68.33 mg/g, 84.23 mg/g, respectively. The fitting curves and equations of the kinetic models favors the quasi second order kinetic model. Material regeneration was very effective, and even in the last cycle the regeneration capacities of both As3+ and As5+ were 75.15%, and 77.59%, respectively. Adsorption and regeneration results suggest that adsorbent has easy synthesis method, and reusable, so it can be used as a potential adsorbent for the removal of arsenic from aqueous solution.

Cs2HfCl6 doped with Zr: Influence of tetravalent substitution on scintillation properties

Homeland security is an emerging application field for inorganic scintillators. Detection and identification of radioactive materials in both individual and cargo transport requires scintillators with excellent energy resolution and high light output. On the other hand, the time characteristics of the scintillation are less crucial. Furthermore, price is a key parameter due to the large volume of the detectors. State-of-the-art halide scintillators e.g. SrI2:Eu or LaBr3:Ce can satisfy the requirements for light yield and energy resolution, but the production costs are very high due to complicated crystal growth and the high prices of rare earth metals. Cesium hafnium chloride (Cs2HfCl6) is a promising intrinsic scintillator with high light yield and excellent resolution. Moreover, its low hygroscopicity and cubic crystal structure could allow lower production costs compared to SrI2 or LaBr3. Intrinsic luminescence of Cs2HfCl6 is commonly attributed to self-trapped excitons. However, the luminescence of Cs2HfCl6 shows complex structure and temperature dependence. This might be explained by the presence of zirconium which is a common impurity in hafnium compounds. We present a study of the influence of zirconium doping on the scintillation properties of Cs2HfCl6. Single crystals of Cs2HfCl6 with zirconium doping from 0 to 1 mol% were grown by the vertical Bridgman method. Their phase purity, radioluminescence, scintillation decay, light yield, and afterglow were evaluated. Results show that zirconium doping can affect the scintillation properties of Cs2HfCl6 even at concentrations comparable to impurity levels of zirconium in hafnium compounds.

Comparative studies of tungsten and zirconium doping on single crystal cobalt-free cathode material

Comparative studies of tungsten and zirconium doping on single crystal cobalt-free cathode material

Study of synthesis and photocatalytic performance of the monoclinic/cubic heterophase junction of rare earth doped zirconia

Eu and Y co-doped ZrO2 is fabricated by solid state reaction method. ZrO2/Eu/Y products evolve from the monoclinic phase to the monoclinic/cubic phase in structure as the Eu ion content increases. Monoclinic/cubic heterophase junction is obtained during structural evolution, which develops a new route to fabricate ZrO2 heterophase junction. Photocatalytic property measurement is carried out for ZrO2/Eu/Y materials. The ZrO2/Eu0.1/Y monoclinic/cubic heterophase junction promotes photogenerated electron-hole separation effectively and hence exhibits better photocatalytic performance.