Solution Of Zr Research Articles

ANTIMICROBIAL, ANTIOXIDANT AND CYTOTOXICITY STUDY OF Cu(II), Zn(II), Ni(II), AND Zr(IV) COMPLEXES CONTAINING O, N DONOR SCHIFF BASE LIGAND

Objective: The aim of the research is to synthesize and characterize Cu(II), Zn(II), Ni(II), and Zr(IV) complexes with a Schiff base ligand, and evaluate their antibacterial and antioxidant properties. Methods: The ligand was synthesized by refluxing salicylaldehyde with o-phenylenediamine in ethanol, forming a yellow-orange product. The complexation reaction involved stirring ethanolic solutions of Zn(II), Cu(II), Ni(II), or Zr(IV) salts with a Schiff base ligand. Thermal decomposition of Zn(II), Cu(II), Ni(II), and Zr(IV) complexes was analyzed under nitrogen, heating at 30 °C/min, measuring weight loss from ambient temperature to 800 °C. The antibacterial activity, antioxidant properties, and cytotoxicity of the synthesized compounds wereexamined using reported methods. Results: Cu(II), Zn(II), Ni(II), and Zr(IV) complexes with a Schiff base ligand were synthesized. Analyzed through Fourier-transform infrared spectroscopy (FTIR), Ultraviolet-visible (UV-vis) and physiochemical tests and confirmed the structures. Magnetic susceptibility and electronic spectra suggested geometries, supported by thermogravimetric data. Antibacterial tests revealed complexes had higher activity than ligands, and also showed antioxidant properties. Conclusion: Cu(II), Zn(II), Ni(II), and Zr(IV) Schiff base complexes were synthesized, showing tetrahedral or square planar geometries. They exhibited thermal stability and strong antibacterial activity, outperforming the ligand alone.

Rare‐earth compositional screening of high‐entropy diborides for improved oxidation resistance

AbstractCompositional screening is an important strategy to improve the oxidation resistance of high‐entropy diborides (HEB2), yet the related studies are limited. Here, we report a rare‐earth (RE) element compositional screening strategy to improve the oxidation resistance of HEB2. To be specific, the single‐phase (Hf0.28Zr0.28Ta0.28RE0.16)B2 (HEB2‐RE) samples with 12 different RE elements are fabricated via ultrafast ultrahigh‐temperature synthesis and spark plasma sintering techniques, and their oxidation resistance is explored by isothermal oxidation tests. The results show that the as‐obtained HEB2‐Sc samples possess the best oxidation resistance among all the as‐fabricated HEB2‐RE samples. Such outstanding oxidation resistance is ascribed to the enhanced viscosity of the generated B2O3 glass originating from the solid solution of (Zr, Me)0.84Sc0.16O2 complex oxides, as confirmed by transmission electron microscope observations and first‐principles calculations.

ZrB2‐based ultrahigh‐temperature ceramic with various SiC particle size: Microstructure, thermodynamical behavior, and mechanical properties

AbstractThis study investigated the influences of WC and HfB2 additives along with SiC reinforcement (with various particle sizes) on densification, microstructure, and mechanical properties of ZrB2–SiC composites. The results showed that WC and HfB2 addition formed a solid solution of (Zr,W,Hf)B2 with a core–shell structure, whereas the remaining WC transformed into WB. Moreover, nano‐sized SiC caused a much better impact on densification compared to micro‐sized SiC. A small fraction of localized phases like ZrC, HfB, and (Hf,Zr)C in the form of solid solution were also formed. The maximum room temperature flexural strength and the fracture toughness of the sample containing 150 nm SiC and 8.9 wt.% WB were measured to be 682 17 MPa and 6.5 .3 MPa m1/2, respectively.

Glass transition of amorphous materials composed of organically modified metal oxo-oligomers

Solutions of Zr(OC3H7n)4, Ti(OC3H7i)4 or Zn(CH3COCHCOCH3)2 containing hexahydrophthalic anhydride, benzoylacetone, succinic anhydride or ethyl benzoylacetate were concentrated and dried into transparent and solidified products. The products had refractive indices of 1.54–1.66, and exhibited glass transition at −30 - 20 °C and softening at 32–50 °C in thermomechanical analysis curves. The product obtained from Zn(CH3COCHCOCH3)2 is regarded as an ordinary metal organic compound glass, while the other products from alkoxides are a new class of glasses in that they are composed of clusters of MOn with M-O-M linkages (M = metal), which are weakly bonded through van der Waals interaction through van der Waals interaction between the surrounding organic ligands. The results demonstrate the potentials of broad metal-ligand combinations in the formation of such new types of glasses, which allows us to expect the creation of innovative glasses with novel properties that arise from clusters of MOn with M-O-M linkages. Their capability of being moulded near at room temperature is also a fascinating character.

Selective Separation of Zr(IV) from Simulated High-Level Liquid Wastes by Zeolites

ABSTRACT Effectively separating Zr(IV) from strong acidic and radioactive solutions is crucial for spent fuel reprocessing plants, but it remains a challenging task. This study investigated the adsorption of Zr(IV) in HNO3 solutions using zeolites as adsorbents. The zeolites were characterized by X-ray diffraction (XRD)，scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The effects of adsorption time, HNO3 concentration, the initial concentration of Zr(IV), zeolites dosage, and temperature on the Zr(IV) adsorption behaviors were investigated. The results demonstrated that HY zeolite had a higher adsorption capacity for Zr(IV) than H-SSZ-13 zeolite. The adsorption capacity of HY zeolite was influenced by its Si/Al ratio, which determined the density of adsorption sites. The optimal HY zeolite (HY-25) exhibited a maximum adsorption capacity of 30.438 mg/g in 3 M HNO3 solution. Furthermore, the adsorption isotherms and kinetics of Zr(IV) adsorption were investigated. The adsorption of Zr(IV) on zeolites was endothermic and spontaneous, in accordance with the Freundlich’s isotherm model and pseudo-second-order kinetic model. In a simulated strong acidic solution of Zr(IV) and 10 co-existing cations (Ag+, Ba2+, Cs+, Ce3+, Eu3+, Fe3+, La3+, Nd3+, Sm3+, Sr2+), HY-25 exhibited good selective adsorption of Zr(IV), indicating its potential application in the treatment of high-level radioactive liquid waste.

Calculation of critical shear stress for binary magnesium alloys: A first-principles study

The selection of alloying elements with the effect of “Solid solution strengthening and ductilizing” (SSDD) is an important way to develop high-performance magnesium (Mg) alloys recently, and the critical shear stress (CRSS) is an intrinsic parameter that characterizes the effect of SSDD. In this study, the CRSS of four slip systems in Mg-X (X = Al, Zn, Ca, Li, Mn, Sn, Bi, Ag Ga, In, Zr), all of which have a solid solubility (>0.5 at%) in Mg, are calculated using a combination of first-principles and the Peierls-Nabarro (P–N) model, and the SSDD effect of the alloying elements is studied systematically and experimentally verified. Calculations indicate that solid solutions of Mn, Ag, and Li can increase the CRSS of basal system and reduce the difference between the three non-basal and basal systems. Solid solutions of Zn, Ca and Zr can narrow the CRSS gap between at least one non-basal slip system and the basal slip system, but other elements have no positive effect. A smaller equilibrium volume and larger charge density around Mn or Ag element than that of Li, which makes CRSS larger. At the same time, the simulation results are validated by experiment. Mg–Ag alloy exhibits improved strength and plasticity, as well as a large number of <c+a> dislocations under TEM, which is consistent with the calculation finding that Ag promotes < c+a> dislocation slip. This study can provide guidance for the selection of solid solution elements for Mg alloys.

KINETICS OF HIGH-TEMPERATURE NITRIDIZATION OF Zr-U-BASED ALLOYS

The kinetic patterns of nitride formation have been established and the sequence of structural transformations characterizing high-temperature (at 1900 °C) nitridation of Zr-U alloys containing 2 and 5 wt.% U in the range from 3.5 to 60 minutes is presented. During high-temperature saturation with nitrogen for each composition, the solid solution (Zr,U) decomposes with the formation of composite structures ZrN-(ZrN1-n/UxEy/U)-ZrN (where E is O, N; n, x, y are stoichiometric coefficients ). During the decomposition of the solid solution, zirconium nitride is formed and a phase of metallic uranium is released, which accumulates impurities contained in the initial solid solution in the central part of the sample. Kinetic curves for a temperature of 1900 °C are approximated by an exponential law and correspond to the nitridation of zirconium. The nitridation rate of the (Zr,U) solid solution increases with increasing uranium content. To complete the formation process of a compact nitride solid solution of (Zr,U)N of stoichiometric composition, it is necessary to increase the temperature and increase the reaction duration.

Preparation and characterization of metastable β-type titanium alloys with favorable properties for orthopedic applications

Titanium (Ti)-based alloys with good mechanical properties are highly desirable for bone implants to achieve long-term clinical success. As non-toxic alloying elements, zirconium (Zr) and molybdenum (Mo) have been employed to improve the mechanical properties of Ti-based alloys. In this work, a series of Ti-Zr-Mo alloys, including Ti-18Zr, Ti-13Mo, and Ti-18Zr-13Mo were prepared and compared for potential orthopedic applications for the first time. The phase composition, microstructure, mechanical properties, corrosion resistance, biocompatibility, and osteointegration performance were systemically investigated. It is found that Ti-18Zr displayed an acicular α′ phase, whereas Ti-13Mo and Ti-18Zr-13Mo exhibited a metastable β phase. Compared with commercially pure Ti (CP-Ti), the prepared Ti-Zr-Mo alloys possessed a higher compressive yield strength and a greater microhardness, because of the solid solution and phase precipitation strengthening of Zr and Mo elements. Furthermore, Ti-18Zr-13Mo and Ti-13Mo demonstrated better corrosion resistance than that of CP-Ti, while Ti-18Zr exhibited an inferior result. The cytocompatibility and osteointegration of prepared alloys were similar to those of CP-Ti. Taken together, the Ti-Zr-Mo alloys investigated in this study present a promising alternative to CP-Ti for orthopedic applications, among which the metastable β-type alloy Ti-18Zr-13Mo is most attractive. Moreover, an appropriate Mo content enhances the mechanical and corrosion resistance properties of Ti-based alloys, whereas a high Zr content may pose an adverse influence on the corrosion resistance, which provides valuable insights into the design and further optimizing of new Ti-Zr-Mo alloys for future biomedical applications.

Design of Titanium Alloys Insensitive to Thermal History for Additive Manufacturing

Powder bed fusion is the most common technology used for 3D printing, where thermal energy is used to selectively melt/sinter granular materials into solid shapes. The build platform is then lowered, more powder is added, and the process is repeated for the next layer to fully print the design. As a result, the built-up part is repeatedly heated. Therefore, materials that are not sensitive to thermal history are preferred for this process. The Ti–Zr system forms a continuous solid solution for both β- and α-phases. The presence of Fe in Ti alloys is inevitable; however, it provides some beneficial effects. The purpose of this work was to prepare Ti–Zr–Fe alloys and investigate their heat treatment behaviour. Ti-xmass%Zr-1mass%Fe alloys (x = 0, 5, 10) were prepared with arc melting. The formation of a solid solution of Zr in Ti was confirmed on the basis of X-ray diffraction peak shifts and hardening effects. A small amount of β-phase precipitation was suggested by the change in electrical resistivity after isothermal ageing at 673 and 773 K. However, no obvious phase or microstructural changes were observed. The laser scanning increased the volume of the precipitates and also coarsened them, but the effect was limited.

Study of Zr addition on the composition, crystallite size, microstructure and properties of high-performance nano Cu alloys prepared by mechanical alloying

Although nanostructured Cu alloys prepared show great advantages in performance, the excellent properties have not been achieved at present primarily due to a single strengthening method or the Fe contamination introduced during mechanical alloying. In the present work, an appropriate amount of Zr was added to adjust the milling process and Fe contamination in the Cu matrix. Then the effects of Zr on the morphologies, crystallite sizes, lattice strain, composition and properties were analyzed. When the added Zr content was 0.1 wt%, it could promote the work hardening of Cu powders, resulting in smaller crystallite sizes, larger internal strain. And a slightly higher Fe content was introduced. However, with the increase of the Zr content, the Fe contamination was reduced obviously and the crystallite size began to increase again. Even so, the average crystallite sizes of nanostructured Cu alloys were still less than 20 nm. The results also showed that MA could increase the solid solubility of Zr in Cu. In a word, the properties of the nanostructured Cu alloys were improved by the refinement strengthening of matrix, solid solution and dispersion strengthening of Fe and Zr. The optimum properties were achieved by Cu-0.1 wt% Zr with electrical conductivity of 75.19% IACS and tensile strength of 526 MPa. The study provided a new route for overcoming Fe contamination in the metal matrix, and further improving the properties of Cu alloys through various strengthening methods.

Microstructure and mechanical properties of Nb[sbnd]16Si alloys with Zr additions

To optimize the microstructure and fracture toughness of NbSi based alloys, the effect of Zr addition on the microstructure and mechanical properties was investigated in Nb16Si alloy. The results show that Zr element promotes the sluggish eutectoid reaction of (Nb, Zr)3Si → Nbss + α-(Nb, Zr)5Si3, and Nb-16Si-8Zr alloy only contains Nbss and α-(Nb, Zr)5Si3 phases. From the energy point of view, as the Zr content reaches 4 at.%, (Nb,X)5Si3 phase is more stable than (Nb, X)3Si phase. With the increase of Zr content, the fracture toughness increases since high Zr content refines eutectic structure and increases the content of primary Nbss. The thickness of primary Nbss has a strong influence on crack propagation. Most of the cracks can destroy primary Nbss phase with the thickness of (20 ± 2) μm and continue to propagate in the original direction. However, it will deflect when it intersects primary Nbss phase with a thickness of about (30 ± 2) μm. The improvement of compressive properties was caused by solid solution of Zr.

Uranium dissolution and uranyl peroxide formation by immersion of simulated fuel debris in aqueous H2O2 solution

ABSTRACT The fuel debris generated in the accident at the Tokyo Electric Power Company’s Fukushima Daiichi Nuclear Power Station has been subject to water and ionizing radiation for years and will be until retrieval. Therefore, we investigated the potential degradation of this fuel debris caused by H2O2, which is the oxidant of major impact from water radiolysis. We performed leaching experiments on different kinds of simulated debris comprising U, Fe, Cr, Ni, and Zr in an aqueous H2O2 solution. Chemical analysis of the leaching solution showed that U dissolution was induced by H2O2. Raman analysis after the leaching revealed that uranyl peroxides were formed on the surface of the simulated debris. The U dissolution and uranyl peroxide formation were observed in most of the simulated debris. These results demonstrate that uranyl peroxides are possible alteration products of fuel debris from H2O2 reaction. However, the sample in which the main U-containing phase was a U-Zr oxide solid solution showed much less U dissolution and no Raman signal of uranyl peroxides. Comparison of these results indicates that formation of an oxide solid solution of Zr with UO2 improves the stability of fuel debris against H2O2 reaction.

Thermodynamic Assessment of the Zr–O Binary System

Abstract Thermodynamic and phase diagram experimental data relevant to the Zr–O binary system have been assessed. A set of Gibbs energy functions describing the phases in this system is presented. The adjustable parameters of the models are obtained by least-squares fit to the experimental data. The liquid phase is described by Hillert’s partially ionic liquid model. The interstitial solid solution model is applied to the metallic zirconium solid solutions bZr and αZr. The ordering αZr is described by a three-sublattice model with Bragg-Williams treatment of ordering. The two modifications of the zirconium dioxide, αZrO2 and bZrO2, are modelled as stoichiometric phases. The modification cZrO2 is described by the Wagner-Schottky model expressed in the compound-energy formalism. The gas phase is treated as an ideal solution of the species Zr, Zr2,O1, O2, O3, ZrO and ZrO2. The calculated phase diagrams and values for the thermodynamic properties are compared with experimental data.

Microstructural characterisation and thermal stability of a metastable Mg-8.6 wt.% Zr alloy produced by physical vapour deposition

Abstract The thermal stability of a Mg-8.6 wt.% Zr alloy processed by physical vapour deposition has been studied using differential scanning calorimetry and transmission electron microscopy. The alloy, in the as-deposited condition, is a solid solution of Zr in the Mg matrix. The microstructure is characterised by elongated grains oriented with their [0001] direction parallel to the growth direction. After DSC experiments, three exothermic transformations have been observed. The first one takes place above the deposition temperature and is related to the recovery phenomena due to stress relaxation generated during the growth process. The second transformation corresponds to the breakdown of the solid solution by the precipitation of Zr in the Mg matrix. This reaction takes place in two stages: (i) Zr plates are formed in the basal plane and (ii) these initial precipitates grow along the [0001] direction. An epitaxial relationship between those Zr precipitates and the Mg matrix of [0001]Zr || [0001]Mg and [1120]Zr || [1120]Mg has been obtained. The third exothermic transformation appears above 720 K and is caused by the strong oxidation of the deposit.

Effect of Cu on microstructure and corrosion behavior in 360°C lithiated aqueous solution of Zr–Cu alloys

AbstractThe effect of Cu on the microstructure and corrosion behavior in 360°C lithiated water was investigated on Zr–xCu alloys (x = 0.05, 0.2, and 1.0, wt%), with remelted pure Zr as reference material. The results revealed that the tetragonal Zr2Cu phase was induced by Cu addition higher than 0.2 wt% and its size and number density were increased with the increase of Cu content. The weight gain and oxide thickness were decreased by Cu addition, but when the Cu content increased to 1.0 wt%, they were both significantly increased and even larger than that of remelted Zr. It was supposed that structural defects, such as pores and microcracks, in the oxide film may result in such degradation in the corrosion property of Zr–1.0Cu alloy.

Effect of Bonding Temperature on Microstructure and Mechanical Properties of 304L/Zircaloy‐4 Diffusion‐Bonded Joints with Ni/Ta Hybrid Interlayer

Diffusion bonding of stainless steel 304 L and zircaloy‐4 (Zr‐4) in solid state is conducted using Ni and Ta as the hybrid interlayer at the bonding temperature of 850−1000 °C for the bonding time of 30 min under the bonding pressure of 6 MPa in vacuum. The effect of the bonding temperature on the microstructure and the mechanical properties of the joints is investigated. The microstructure analysis is conducted by a scanning electron microscope, energy dispersive spectroscopy, and X‐ray diffraction. The mechanical properties of the joints are measured by a shear test and microhardness test. The results show that Ni3Ta intermetallic compounds are formed at the Ni/Ta interface, and the solid solution of Zr and Ta appears at the Ta/Zr‐4 interface. In the meantime, the maximum shear strength reaches 194 MPa and the highest hardness value across the interface of joints is 356 HV in the Ni3Ta layer.

Mechanical Property and Heat Treatment Behaviour of Ti-Zr-Fe Alloys

The element of zirconium (Zr) belongs to the same group 4 as Ti in the periodic table. Therefore it possesses similar chemical properties. The Ti-Zr binary system forms a continuous solid solution for both high temperature β phase with the body centered cubic (BCC) structure and low temperature α phase with the hexagonal close-packed (HCP) structure throughout the entire range of composition. As is well known, on the other hand, the element of iron (Fe) is not only inevitable but also effective element in Ti.By incorporating Fe at the stage of alloy design, off-grade sponge titanium can be employed. Both elements seem to be effective in strengthening the titanium alloys. The purpose of this work was to prepare Ti-Zr-Fe alloys and then mechanical property and heat treatment behaviours were investigated as a fundamental research. Ti-x mass% Zr-1mass% Fe alloys (x=0, 5, 10) were melted in a laboratory-scale arc furnace under a high purity argon atmosphere from the sponge Ti, the sponge Zr and the Fe wire. The resulting ingots were hot forged and rolled at approximately 1120 K to obtain plates of approximately 2 mm in thickness. Well-mixed and homogeneous samples could be obtained, oxygen contaminations were less than 0.09 %. Solid solution of Zr into Ti was confirmed by the XRD peak shift in α phase. Vickers hardness and proof stress increased with Zr content. No remarkable changes could be observed in the microstructures after the solution treatment at 1173 K. However, Young’s modulus increased at x=10 by the treatment.

Insights into the inter-element effects in the EDXRF determination of zirconium in binary aqueous solutions via the calibration method

Calibration of the energy dispersive X-ray fluorescence (EDXRF) spectrometer, using pure elemental standard solutions of Cu, Zr, Nb, Mo, Ta, and U, was carried out and the instrumental sensitivity was derived for each. The effects of the presence of the rest of these elements on the calibration of Zr were evaluated by analyzing the respective binary solutions, separately. All the matrix elements led to a reduction in the Zr- sensitivity of the spectrometer. Intercepts of the calibration curves were found to decrease with Cu, Mo. Nb, Ta, and U led to the elevation of the intercepts. The highest specific changes (per mg of the matrix) in both the slope and intercept were observed upon the addition of Mo. Numerically, these values were -5,917 and -1,187 respectively. Limits of detection for Zr, from the calibration curve, were the best (0.28 μg) in the presence of 7.8 mg Mo and the worst (165.4 μg) in the presence of 53 mg U. The results were validated by multiple standard additions on a sample and analysis of reference standard solution of Zr. Quality control sample analysis re-affirmed the accuracy of the present results. Repeatability was also established for the measurements of solution samples.

Investigation of the formation and distribution of elements in the production of Al-Ti-V-Zr-Nb alloys by the aluminothermic method

The results of testing the method for synthesis of a high-entropy AlNbTiVZr alloy using metallothermic reduction of group IV and V metals from their oxides are presented. At the first stage, a joint aluminothermic recovery of metals in a resistance furnace was performed. Then, to achieve uniformity and remove harmful impurities, the metal was melted in a vacuum furnace with an inert atmosphere. The alloy obtained after the second remelting was subjected to x-ray diffraction and electron microprobe (EMA) analysis. The results of the analysis revealed the presence of a solid solution of Zr (Nb, V) with TiAl inclusions, which confirms the prospects of using metallothermic synthesis to produce a high-entropy alloy with a single-phase structure.

Experimental Modeling of Technetium(VII) Recovery from Raffinates after Extractive Reprocessing of Spent Nuclear Fuel

Experimental justification has been provided for the possibility of extractive isolation of technetium from raffinate of technical process of affinage of uranium–plutonium product resulting from hydrometallurgical reprocessing of spent nuclear fuel (SNF). Technetium (VII) from aqueous solution of Zr(IV) (10 g/L) and 4 mol/L HNO3 with small content of ZrOb+ and $${\text{Z}}{{{\text{r}}}_{{\text{2}}}}{\text{O}}_{{\text{3}}}^{{b + }}$$ oxocations is recovered by 80% in 30% TBP in hydrocarbon diluent over seven stages of counter-current continuous cascade at ratio O : A = 1 : 1. Variation in phase flow ratio for cascade part leads to virtually complete Tc(VII) extraction in organic phase over ten stages. Technetium(VII) is selectively back extracted from loaded organic phase with water virtually completely over eleven stages of counter-current continuous cascade. Technological extraction scheme for technetium isolation from SNF solutions has been proposed.