Presence Of Zirconium Research Articles

Microstructure and mechanical properties of a porous ceramic composite with needle‐like mullite and zirconia

AbstractPorous mullite ceramics have good properties for high‐temperature applications, but porosity gives place to ceramics with low mechanical strength, which restricts the service life in their potential applications. Therefore, performing modifications at the microscale to increase the mechanical strength has become a current challenge to expand its application fields. This work describes the properties of a porous mullite–zirconia composite produced by ceramic processing, using industrial kaolin and stabilized zirconia as raw materials. The growth of mullite needle‐like grains to reinforce the ceramic was promoted by the addition of a molybdenum oxide precursor. The effect of zirconia on the composite was analyzed through an experimental multi‐technique approach and considering a pure mullite sample, identically processed, as a reference. The novel composite has a porosity of about 50%, and presents a homogeneous microstructure, with interlocked mullite needle‐like grains and dispersed rounded zirconia grains. This morphology restricts the mullite tendency to shrink during sintering, giving the material a higher stiffness. In particular, the presence of zirconia in the composite improves both the flexural strength and the apparent Young modulus of the material (about 20% and up to 600%, respectively). These results encourage further investigations to establish this composite for different technological applications.

Unleashing the electrochemical performance of zirconia nanoparticles on valve-regulated lead acid battery

The electrochemical act of valve-regulated lead acid batteries can be enhanced by conductive materials like metal oxides. This work aims to examine the preparation and influence of zirconia on poly(vinyl alcohol) based gel valve-regulated lead acid battery. Characterizations like Fourier transform infrared spectroscopy, ionic conductivity, water retention study, cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge-discharge techniques were done. The optimized gel system exhibited a discharge capacity of 198.45 μAh cm−2 at the current density of 0.6 mA cm−2. The battery cell with an optimized gel matrix displayed a maximum discharge capacity of 22.5 μAh at a current of 20 μA. After 500 continuous cycles, the battery attained a discharge capacity retention of 91 %. The presence of zirconia will increase the electrochemical performance of gel valve-regulated lead acid batteries.

Study of the leaching process for dust chamber sublimates followed by the extraction of niobium and zirconium into solution

The material composition of the sublimates from dust chambers in titanium chlorinators has been studied by chemical, X-ray and microprobe analysis methods. Studies of the phase composition of dust chamber sublimates have shown that the object consists of aqueous and anhydrous chloride phases to a greater extent. Two forms of niobium present, such as oxychloride and oxide niobium were found. The presence of zirconium in sublimates has a chloride and oxychloride nature. Experiments for the aqueous leaching of dust chamber sublimates were conducted to determine the optimal process conditions: S:L ratio = 1:8, leaching time = 1 hour, temperature = 25℃. Studies were conducted to choose an acidic reagent for cake leaching followed by the conversion of niobium and zirconium into a solution. A solution consisting of HF+H2SO4 was selected as an acidic reagent for cake leaching. Optimal conditions for the extraction of niobium and zirconium into solution were established, such as 25% [18M HF] +75% [7M H2SO4], S:L ratio = 1:3, temperature = 90 °C, duration of the leaching process = 120 minutes. Under these leaching conditions, the extraction of niobium, zirconium, and titanium into solution was 94.06%, 84.95% and 32.35%, respectively. The elemental and phase composition of the residue from acid leaching of cake were determined.

Elimination of the Interfacial Crud in the Extraction of Simulated High-Level Liquid Waste After Denitration in the TRPO Process

ABSTRACT Denitration is a proven technique that can reduce the nitric acid concentration of high-level liquid waste (HLLW) to meet the aqueous acidity requirement of the TRPO (TriAlkyl Phosphine Oxide) process. However, interfacial crud is generated in the TRPO extraction of the HLLW after denitration. In this work, the interfacial crud was characterized by Fourier-transform infrared spectroscopy and dynamic light scattering. The extraction distribution ratio of zirconium by 30% TRPO in kerosene decreases dramatically after the simulated HLLW is denitrated, and we proposed that the presence of zirconium in the simulated HLLW after denitration is responsible for the generation of interfacial crud. Using ammonium molybdate as a precipitant, the concentration of zirconium in the simulated HLLW was successfully reduced without essentially changing the concentration of other metal ions. The effects of reaction time, temperature, and amount of ammonium molybdate added on the zirconium removal process were investigated and the precipitates formed in the removal of zirconium were characterized by scanning electron microscope, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. Finally, after reducing the concentration of zirconium in the simulated HLLW to below 10 mg/L by using ammonium molybdate, the extraction experiment was performed again and no interfacial crud was observed.

Comparative evaluation of gingival fibroblast growth on 3D-printed and milled zirconia: An in vitro study.

The purpose of this study was to analyze the fibroblast growth and proliferation on 3D-printed zirconia in presence and absence of porosities. A total of 40 bars (8×4×3) were included in this study. Thirty 3D-printed and 10 milled zirconia samples were prepared. The 3D-printed samples had different porosities, 0% (PZ0), 20% (PZ20), and 40% (PZ40) with 10 specimens in each group. Milled zirconia samples were used as the control (MZ). Rat gingival fibroblasts were cultured for 48h, and the proliferation of fibroblasts on each sample in each group (n=10) was determined by MTT assays. The differences among the four groups were compared by one-way ANOVA. To test the significance of the observed differences between two groups, an unpaired Student's t-test was applied. The significance level was set at p<0.05. Qualitative analysis for the cell culture was performed using scanning electron microscopy. One-way ANOVA showed that the numbers of the fibroblasts among the four groups had a statistical difference. Post hoc Bonferroni test revealed that there was no significant difference between PZ0 and MZ; however, all other groups and among groups were significantly different. Fibroblasts had a better affinity toward the MZ and PZ0 in a short period of cell culture time.

The influence of the main alloying elements on the formation of the initial grain structure, on phase transformations and on structural changes that occur during superplastic deformation of alloys Al - 4.1 wt.% Mg - 0.5 wt.% Zr, 1420T, 1421, 1423

The article presents the results of research aimed at revealing the influence of the main alloying elements on the formation of the initial grain structure, on phase transformations and on structural changes that occur during superplastic deformation of several aluminum alloys. It was possible to form a homogeneous ultrafine-grained structure in samples of alloys Al - 4.1 wt.% Mg - 0.5 wt.% Zr and 1423 due to dynamic recrystallization during their superplastic deformation. It is revealed that the initial microstructure of the 1420T alloy samples is bimodal. The average grain size is approximately 5 μm, in some areas of the working part of the samples there are large elongated grains, the average size of which is approximately equal to 25 μm. The initial structure of alloy 1421 samples is fine-grained, and the initial structure of alloy 1423 samples is multi-grained and coarse-grained. Metallographic studies showed that the grain structure of samples of alloys 1420T, 1421 and 1423 increases slightly during superplastic deformation at high homologous temperatures. Cavitation accumulates in the samples and structural changes occur, which are probably associated with local melting at grain boundaries and at interphase boundaries. It was established that the presence of zirconium and scandium additions in the composition of the samples ensures the formation of an ultrafine-grained structure in them and counteracts the grain growth during superplastic flow. Magnesium and lithium, which are included in the samples of the studied alloys 1420T, 1421 and 1423, form several intermetallic phases with aluminum. These phases are part of mixtures of crystals of peritectic origin, which are localized in the form of layers between some grains. The occurrence of peritectic reactions at high homologous temperatures can be one of the reasons for the partial melting of samples of alloys 1420T, 1421, and 1423 during their superplastic deformation. Partial melting of samples of alloys 1420T, 1421 and 1423 can probably be carried out due to the presence of segregations of magnesium and lithium at the grain boundaries, which lower the melting temperature of the aluminum-based solid solution. Partial melting of samples of alloys 1420T, 1421, and 1423 during their superplastic deformation, which is performed at high homologous temperatures, leads to the formation of cells of a metastable liquid-solid phase at the grain boundaries, the viscous flow of which leads to the formation of fibrous structures due to the development of grain boundary sliding.

Synthesis of Zirconia in Cement (Zir-Cem) and Study of Adsorption of EDTA on Zir-Cem

The important problem to address in nuclear industries involves mitigation of the radioactive and corrosion products of nuclear reactor components. Even though physical and chemical methods lend a helping hand in solving this problem, the dominant method is by carrying out chemical cleaning. But this process results in the metal ions in complex state, not viable for treatment. To render the metal ions in the free state advanced oxidation process using oxidizing agents like ozone, Hydrogen peroxide, electro flotation, supercritical oxidation etc can be resorted . The decontaminating agents used are picolinic acid, EDTA, ascorbic acid, NTA etc. EDTA complex the metal ions but generate secondary waste with them. In our work, treatment of generated decontaminated waste using EDTA as decontaminant has been dealt with. From the literature, we understand that attempts have been made to degrade ethylene diamine tetraacetic acid using Fenton’s reagent in the presence of light [1]. This will facilitate the release of free radioactive ions for further treatment. In addition to chemical oxidation of EDTA, photochemical oxidation in presence of Zirconia and titania which generates electrons and positive ions for further oxidation has been reported [2]. In this paper, we have made an attempt to absorb the EDTA on zirconia loaded on white cement, study the adsorption characteristics which is the first step for photodegradation using UV light. Zirconium oxide was synthesized by the sol-gel method using Zirconium isopropoxide to water ratio 1:2 which resulted in powder by this process. This Powder was characterized for physical and chemical parameters before immobilizing with cement for adsorption. The system containing cement bonded to Zirconia (Zir-Cem) was subjected to removal of EDTA by adsorption. Since the zirconia powder as generated was found to have a high surface area compared to heat-treated (470oC and 720oC resulting in monoclinic and tetragonal crystalline forms) the as prepared zirconia was found to be the best candidate for efficient adsorption.

Enhancement Properties of Zr Modified Porous Clay Heterostructures for Adsorption of Basic-Blue 41 Dye: Equilibrium, Regeneration, and Single Batch Design Adsorber.

Zirconium porous clay heterostructures (Zr-PCH) were synthesized using intercalated clay minerals by zirconium species with different contents of zirconium. The presence of zirconium and silica species was confirmed by X-ray diffraction, X-ray fluorescence, and magic-angle spinning nuclear magnetic resonance. The insertion of zirconium improved the thermal stability, the specific surface area with a maximum of 950 m2/g, and the acidity concentration of 0.993 mol of protons per g of solid. These materials were used to adsorb the basic blue-41 from aqueous solution. The adsorption efficiency was examined at different conditions, with a maximum adsorbed amount of 346 mg/g as estimated from Langmuir model. This value was dependent on zirconium content in the PCHs. The adsorption process was found to be favorable and spontaneous. The efficiency of the spent materials was maintained after five reuse cycles with a decrease by 15% of the original value for a particular Zr-PCH material with a Zr content of 6.82%. Single stage batch adsorber was suggested using the mass balance equation and Langmuir isotherm model. The amount of PCH materials required depended on the target percentage of adsorption at specific volume and initial concentration of the basic-blue-41 dye solution.

Defect-induced asymmetrical mechanical behavior in shape memory zirconia: A phase-field investigation

An elastoplastic phase-field model is used to investigate the deformation mechanisms of yttria stabilized tetragonal zirconia in presence of defects. A remarkable tension-compression asymmetry is detected. A higher strength and a lower degree of transformation are observed in compression than in tension. Also, deformation mechanism is asymmetric depending on the crystal orientation. For some cases (other cases), phase transformation is absent in tension (in compression), while both transformation and plasticity are present in compression (in tension). Such tension-compression asymmetry is attributed to activation of different monoclinic variants with different Eigen strain tensors in tension versus compression. Results also reveal a higher degree of transformation and plasticity with lower onset stresses as the void size increases. Elliptic voids exhibit a directional effect with a maximum stress intensity factor of 5.6 MPa m1/2 when the long semi-axis is diagonally oriented with respect to the loading direction, and this prediction is comparable to experiments.

Effect of milled and lithography-based additively manufactured zirconia (3Y-TZP) on the biological properties of human osteoblasts

Statement of problemLithography-based additively manufactured (AM) zirconia has been used to fabricate dental implants and custom barriers for guided bone regeneration procedures. However, studies on the effect of AM zirconia on the biological properties of human osteoblasts are lacking. PurposeThe purpose of this in vitro study was to compare the effect of milled and lithography-based AM zirconia on the biological properties of normal human osteoblasts (NHOsts), as well as to compare the chemical composition between the milled and lithography-based AM 3 mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) zirconia. Material and methodsThree mol percentage yttria-stabilized tetragonal zirconia polycrystal disks (Ø6×2-mm) were fabricated using subtractive milling (Priti multidisc ZrO2 monochrome) (M group) and lithography-based additive manufacturing methods (LithaCon 3Y 210) (AM group) (n=10). NHOsts were exposed to different material extracts (1:1, 1:2, and 1:4) and cytotoxicity, cell migration, cell morphology, and cell attachment biological tests were completed. Additionally, for morphological and chemical analysis, a scanning electronic microscopy with energy-dispersive X-ray analysis (SEM/EDX) evaluation was completed. Data were analyzed by using 1-way ANOVA and the Dunnett test (α=.05). ResultsSubstantial cell attachment and spreading were observed in both material surfaces. The presence of zirconium was evident in both groups, although the percentage of zirconium in the AM group (64.7%) was slightly higher than in the M group (52.6%). When NHOsts were cultured in the presence of the different material eluates, the M and AM groups exhibited similar NHOst viability and migration rates when compared with untreated cells; no significant differences were found (P>.05). ConclusionsThe lithography-based AM zirconia tested showed adequate cytocompatibility without differences when compared with the milled zirconia (M group) specimens. Slight chemical element composition differences were found between milled and lithography-based AM zirconia.

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.

On the role of boron, carbon and zirconium on hot cracking and creep resistance of an additively manufactured polycrystalline superalloy

We investigate the hot cracking susceptibility and creep resistance of a nickel-based superalloy with three different contents of boron, carbon and zirconium fabricated by laser powder bed fusion. Crack-free and creep resistant components are achieved for the alloy version with boron, carbon and no zirconium. We then rationalize this result by evaluating how boron, carbon and zirconium are distributed at grain boundaries in the as-built and heat-treated microstructures of an alloy containing all these elements. Observations are conducted by scanning and transmission electron microscopy, and atom probe tomography. In the as-built microstructure, boron, carbon and zirconium segregate at high-angle grain boundaries as a result of solute partitioning to the liquid and limited solid-state diffusion during solidification and cooling. After heat-treatment, the amount of boron and carbon segregating at grain boundaries increases significantly. In contrast, zirconium is not found at grain boundaries but it partitions at the γ' precipitates formed during the heat treatment. The presence of zirconium at grain boundaries in the as-built condition is known to be susceptible to enhance hot cracking, while its absence in the heat-treated microstructure strongly suggests that this element has no major effect on the creep resistance. Based on our observations, we propose alloy design guidelines to at the same time avoid hot cracking during fabrication and achieve the required creep performance after heat-treatment.

Investigation of Microstructure and Corrosion of TiNbTaZrMo High-Entropy Alloy in the Simulated Body Fluid

Microstructures and corrosion of TiNbTaZrMo (Ti20Nb20Ta20Zr20Mo20) High-Entropy Alloy (HEA) were investigated in the Simulated Body Fluid (SBF). Microstructure of this alloy was investigated by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) techniques. Our observations confirmed the presence of two bcc phases as the major matrix as well as another minor phase in the microstructure of the alloy. Concentration of some elements, such as tantalum, niobium, and molybdenum in the dendritic branches and the presence of zirconium and titanium in the inter-dendritic branches were clearly evidenced by Energy Dispersive X-ray (EDX) analysis. Given importance of corrosion of implant alloys in the human’s body, electrochemical impedance and cyclic polarization tests were performed on the alloy in SBF. Through the corrosion tests, corrosion potential, current, and resistance were obtained as Ecorr = −0.42 V, icorr = 0.34 eA·cm−2, and Rp = 27.44 k ohm·cm2, respectively. The results revealed that the rate of corrosion in TiNbTaZrMo HEA is about 26 times better than that of Ti6Al4V alloy. Also, both alloys had no pitting corrosion in the SBF solution.

Hydrogels Based on Poly(Ether-Ester)s as Highly Controlled 5-Fluorouracil Delivery Systems-Synthesis and Characterization.

A novel and promising hydrogel drug delivery system (DDS) capable of releasing 5‑fluorouracil (5-FU) in a prolonged and controlled manner was obtained using ε‑caprolactone‑poly(ethylene glycol) (CL-PEG) or rac‑lactide-poly(ethylene glycol) (rac‑LA-PEG) copolymers. Copolymers were synthesized via the ring-opening polymerization (ROP) process of cyclic monomers, ε‑caprolactone (CL) or rac-lactide (rac-LA), in the presence of zirconium(IV) octoate (Zr(Oct)4) and poly(ethylene glycol) 200 (PEG 200) as catalyst and initiator, respectively. Obtained triblock copolymers were characterized by nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC) techniques; the structure and tacticity of the macromolecules were determined. The relationship between the copolymer structure and the reaction conditions was evaluated. The optimal conditions were specified as 140 °C and 24 h. In the next step, CL-PEG and rac-LA-PEG copolymers were chemically crosslinked using hexamethylene diisocyanate (HDI). Selected hydrogels were subjected to in vitro antitumor drug release studies, and the release data were analyzed using zero-order, first-order, and Korsmeyer-Peppas mathematical models. Controlled and prolonged (up to 432 h) 5-FU release profiles were observed for all examined hydrogels with first-order or zero-order kinetics. The drug release mechanism was generally denoted as non-Fickian transport.

Structural, magnetic, and impedance properties of Co1-xZrxFe2O4 nanocrystallites by PEG-assisted sol-gel route

This work presents the Zr4+-substituted CoFe2O4 nanocrystallites at lower concentrations prepared via sol-gel method in order to investigate their structural and magnetic properties along with their impedance properties. XRD patterns confirm the inverse spinel phase of CoFe2O4 and the presence of zirconium (Zr) nanoparticles in the spinel network. The crystallite size was found to decrease after Zr substitution. CoFe2O4 nanocrystallites of 34-nm size and lattice parameter slightly increase with Zr4+ substitution into cobalt ferrite as observed from the XRD pattern. The presence of all functional groups involved in the present synthesis was determined from FTIR spectroscopy. Characteristic peaks of cubic spinel structured cobalt ferrites are observed in the Raman spectrum of each ferrite composition. The HRSEM images revealed the spherical morphology and nanosize of the Zr4+-doped CoFe2O4 nanocrystallites. EDX analysis confirmed that the applied process for the fabrication of Co1-xZrxFe2O4 nanoparticles is a proper process for the synthesis of spinel cobalt ferrites with homogeneity in composition. The TEM images evidently exposed formation of well-shaped nanoparticles and the fringes are uniform with 0.44-nm width and the selected area electron diffraction pattern exposed periodic arrangements. The results of magnetic hysteresis revealed that the zirconium-substituted cobalt ferrite nanoparticles increase the saturation magnetization and coercivity with increasing zirconium content. Impedance increased when Zr4+ was substituted, but for higher concentration it was reduced.

Tribological Behaviour of Ti or Ti Alloy vs. Zirconia in Presence of Artificial Saliva

Abutment is the transmucosal component in a dental implant system and its eventual appearance has a major impact on aesthetics: use of zirconia abutments can be greatly advantageous in avoiding this problem. Both in the case of one and two-piece zirconia abutments, a critical issue is severe wear between the zirconia and titanium components. High friction at this interface can induce loosening of the abutment connection, production of titanium wear debris, and finally, peri-implant gingivitis, gingival discoloration, or marginal bone adsorption can occur. As in vivo wear measurements are highly complex and time-consuming, wear analysis is usually performed in simulators in the presence of artificial saliva. Different commercial products and recipes for artificial saliva are available and the effects of the different mixtures on the tribological behaviour is not widely explored. The specific purpose of this research was to compare two types of artificial saliva as a lubricant in titanium–zirconia contact by using the ball on disc test as a standard tribological test for materials characterisation. Moreover, a new methodology is suggested by using electrokinetic zeta potential titration and contact angle measurements to investigate the chemical stability at the titanium–lubricant interface. This investigation is of relevance both in the case of using zirconia abutments and artificial saliva against chronic dry mouth. Results suggest that an artificial saliva containing organic corrosion inhibitors is able to be firmly mechanically and chemically adsorb on the surface of the Ti c.p. or Ti6Al4V alloy and form a protective film with high wettability. This type of artificial saliva can significantly reduce the friction coefficient and wear of both the titanium and zirconia surfaces. The use of this type of artificial saliva in standard wear tests has to be carefully considered because the wear resistance of the materials can be overestimated while it can be useful in some specific clinical applications. When saliva is free from organic corrosion inhibitors, wear occurs with a galling mechanism. The occurrence of a super-hydrophilic saliva film that is not firmly adsorbed on the surface is not efficient in order to reduce wear. The results give both suggestions about the experimental conditions for lab testing and in vivo performance of components of dental implants when artificial saliva is used.

Toward Novel Biocomposites from Unavoidable Food Supply Chain Wastes and Zirconia

The synthesis and characterization of novel biocomposites, herein termed bioboards, derived from agricultural residues (wheat straw and barley straw) and aqueous biosilicate solutions, as binder, are reported. The addition of a small amount of protein significantly enhances board strength. The internal bond strength (IBS) increases from 0.0498 to 0.0688 N mm–2. Prior to adhesion, the agricultural residues were dewaxed (ethanol), making them more amenable to aqueous wetting. The aqueous biosilicate binder was obtained via KOH-assisted hydrothermal leaching of spent ashes derived from the combustion of wheat straw. The concentration of biosilicate was determined by ATR-IR spectroscopy and compared with commercial silicate solution (K120). Zirconia powders were introduced to increase the fireproof ability of bioboards. The presence of zirconia was evidenced by powder X-ray diffraction studies. Thus, the bioboards reported represent “greener” alternatives to conventional, commercial particle and medium density fiber boards because they are wood-free, use waste as a renewable resource (agricultural straws), and, importantly do not use any harmful phenol-formaldehyde and isocyanate binders.

Impact of sintering conditions and zirconia addition on flexural strength and ion conductivity of Na-β”-alumina ceramics

Na-β”-alumina ceramics are applied as electrolytes in high-temperature Na/NiCl2 and Na/S batteries. Although featuring excellent sodium-ion conductivity in the order of 0.2 S cm−1 at 300 °C, the brittleness associated with ceramic materials makes Na-β”-alumina electrolytes vulnerable to mechanical stresses, e.g. during battery operation. In this study, the impact of grain size and density on the flexural strength of Na-β”-alumina ceramics is investigated. For constant composition but largely varying grain sizes, we report a constant flexural strength of 163 ± 10 MPa for sintering temperatures between 1560 °C and 1620 °C and dwell times ≤ 30 min. Addition of 5 vol % zirconia improves the flexural strength by 30 %, but reduces the conductivity by 15 %. Furthermore, we show that the addition of zirconia reduces the onset temperature of the liquid phase formation during sintering. These findings show promise for using lower sintering temperatures in the presence of zirconia, which is beneficial on an industrial level.

Hydrothermal Synthesis and Electrochemical Characterization of Hexagonal Zr-CuS Nanocomposite and its Charge Storage Capacity

Hexagonal zirconia doped CuS nanaocomposites were successfully synthesized through a simple mild hydrothermal synthesis. The higher dopent concentration of zirconia produces increased mesoporous homogeneous nanostructures. The structure and nature of the resulting product (Zr-CuS) were characterized by XRD, XPS, SEM/EDS and TEM techniques. The results show that zirconia is homogeneously dispersed on CuS and well separated from one another. Electrochemical studies show that the final product (Zr-CuS) possesses high specific surface area. An increase in zirconia concentration might increase the mesopore volume and a widening of microporosity. Zirconia doped CuS composite exhibits high electrochemical performance with a high capacitance of 949.47 F g-1. The presence of zirconia in CuS improves the capacitive behaviour of samples. Therefore, Zr-CuS could be promising nanocomposite for energy storage device.

Observation of multiply charged states ions in a high-power pulsed reflex discharge

Time-resolved optical emission spectroscopy studies have been made to investigate the elemental/charge composition of the plasma ionic component at pulsed reflex discharge. The discharge plasma has are registered spectral lines neutral atoms and ions of the working gas Ar, Ar1+, Ar2+, and also of the cathode material: Zr, Zr1+, Zr2+, Zr3+. The presence of zirconium in the spectrum attests to the entry of cathode material into the plasma and its subsequent ionization. The variation of spectral line intensity with time in the early stage of the discharge and in the stage of dense plasma existence (time interval from the onset of the discharge up to 4 ms) correlates with the dynamics of plasma parameters. Characteristic times of appearance of excited atoms and ions in the plasma have been determined. The time of appearance of excited Zr* atoms is by the order of magnitude longer than that of Ar*. The stage of high-voltage mode exhibits the lines of excited Ar*, Zr* atoms and Ar+*, Zr+* ions, with the intensity of which sharply increasing during the transition to the high-current mode. The excited Ar2+*, Zr2+*, Zr3+* ions appear later, when the discharge has already gone into the high-current mode.