Search

Alumina-yttrium aluminum garnet (YAG)-zirconia composites are often produced by the melt solidification method. In the present study, we investigated the fabrication of α-Al 2 O 3 /Y 3 Al 5 O 12 (YAG)/ZrO 2 composite by Spark Plasma Sintering (SPS) of powders synthesized by Pechini's sol-gel method. The ternary composites with homogenous microstructure and high density were produced by SPS at 1300 °C for 15 min. The addition of ZrO 2 promoted the sintering of composites, resulting in a higher density and, in turn, higher hardness. A change in the indentation fracture behavior as the result of ZrO 2 addition was observed. [ABSTRACT FROM AUTHOR]

Forsterite was synthesized with MgCO 3 and SiO 2 powders using a solid-state method at 1200–1300°C. The ceramic specimen with the highest forsterite phase content was sintered with the ZrO 2 sintering aid at mass fractions of 0.5, 1.0, and 1.5 wt% at 1400°C for 4 h. The dielectric constant and loss tangent were also measured via the waveguide method at 8–12 GHz. The formation of enstatite and cristobalite was minimized through precise synthesis temperature control. Phase measurement by the Rietveld method showed that specimen F28 contained more than 99.8% forsterite. It was found that ZrO 2 reduced the pore volume percent and increased the density even at low mass fractions. A liquid phase on the grain boundaries was demonstrated. The solid ceramic specimen F28-15Z showed a dielectric constant of 6.5 and high quality factor of 189000. [ABSTRACT FROM AUTHOR]

MgO–ZrO 2 refractories were produced by combining MgO refractories (with a CaO/SiO 2 ratio of 2.1) with monoclinic ZrO 2 powder using wet-bag cold isostatic pressing. The phase composition and mechano-physical properties of the MgO–ZrO 2 materials were influenced by the interaction between ZrO 2 and MgO refractories. ZrO 2 enhanced the cold modulus of fracture of MgO refractories but decreased the hot modulus of fracture due to changes in bonding phases. The addition of 1 wt% ZrO 2 transformed Ca 2 SiO 4 into CaMgSiO 4 and CaZrO 3. CaMgSiO 4 with a low melting point deteriorated the hot modulus of fracture of MgO–ZrO 2 refractories from 13.3 to 2.97 MPa. With an increase in ZrO 2 to 3–5 wt.%, CaMgSiO 4 remained while CaZrO 3 gradually transformed into the solid-solution Ca 0.2 Zr 0.8 O 1.8. This transformation occurred because ZrO 2 seized CaO from CaZrO 3 to stabilize itself. Based on thermodynamic equilibrium ZrO 2 preferentially reacts with CaO-containing phases in the MgO matrix in the following order: Ca 3 SiO 5 > Ca 2 SiO 4 > CaZrO 3 > CaMgSiO 4. The thermal shock resistance of MgO–ZrO 2 refractories with less than 5 wt% ZrO 2 was not significantly improved by assessing their strength loss and coefficient of thermal expansion. In conclusion, it is recommended to incorporate ZrO 2 into MgO refractories with low SiO 2 or CaO to develop high-performance MgO–ZrO 2 refractories. [ABSTRACT FROM AUTHOR]

To study the Mg-doped ZrO2, the electronic, thermoelectric, and optical properties were characterized by first principle as well as experimental techniques. For experimental observations, the samples for pure ZrO2 and Mg-doped ZrO2 thin films were prepared. A noticeable difference was observed between the results of electronic, thermoelectric, and optical properties of pure and Mg-doped ZrO2 thin films. The electronic properties extracted from simulations show that Mg-doped ZrO2, Mg-s, Zr-d, and O-p states provide the main contributions. The electrical conductivity and Seebeck coefficient present an increasing trend with doping of Mg content. The absorption coefficient trend shows that the material becomes more absorbing with the increase in Mg content. The refractive index reduces from ∼2.2 to ∼1.8. The content of Mg carries corroborates the substantial variation in optical parameters with varying energy ranges. The comparison is carried out between the results of optical properties deduced through simulations and spectroscopic ellipsometry. [ABSTRACT FROM AUTHOR]

Resistive Random Access Memory (ReRAM) devices are being regarded as very promising choices for the future of non-volatile memory technology. The subject comprises crucial components like as material engineering, device architectural optimization, switching mechanisms, and improvements in reliability. This study examines the resistive switching capabilities of a device made from a ZrO2-CNT nanocomposite. The device was constructed utilizing a trilayer structure consisting of FTO/ZrO2-CNT/Ag, with the ZrO2-CNT film being fabricated by the spray coating technique. Incorporating 1wt% CNT into the ZrO2 matrix reduces the bias voltage needed for resistive switching and approximately doubles the resistance ratio between HRS and LRS. The use of higher weight percentages of carbon nanotubes (CNT) negatively impacts the switching properties. The temperature dependence of resistance of ZrO2 and ZrO2-1wt% CNT devices reveals that in ZrO2, O2 vacancies align to create conducting filaments. On the other hand, in the ZrO2-CNT device, both vacancies of O2 atoms and CNTs contribute to the production of conducting filaments. Inclusion of higher weight percentages of carbon nanotubes (CNT) leads to the formation of permanent conduction paths, which are electrical shorts and results in the loss of the switching capability. [ABSTRACT FROM AUTHOR]

Recent studies have highlighted the ferroelectric potential of ZrO 2 thin films, which offer advantages over HfO 2 -based ferroelectric materials, such as lower thermal budget and greater natural abundance. In this research, pure ZrO 2 ferroelectric thin films were fabricated on Si substrates using chemical solution deposition with all-inorganic precursors. We explored the impacts of film thickness and HfO 2 seed layers on phase transition and ferroelectric properties. Notably, an 11 nm thick ZrO 2 film exhibited ferroelectric behavior with a remanent polarization of 12.6 μC/cm2. Due to the combined effects of tensile stress and surface energy, the increase in thickness to 30 nm led to a phase transition from the orthorhombic phase to the monoclinic phase and a resultant decrease in remanent polarization. Additionally, the introduction of a HfO 2 seed layer facilitated the crystallization of the ferroelectric o-phase, enhancing the remanent polarization to 16.5 μC/cm2 in our ∼8 nm thick ZrO 2 thin film with a ∼2 nm thick HfO 2 seed layer. These findings provide valuable insights into optimizing ferroelectric properties in ZrO 2 thin films through phase transition control. [ABSTRACT FROM AUTHOR]

The effect of ceria doping of (ZrO2)1−x(Sm2O3)x crystals on their phase composition, microhardness and fracture toughness was studied. The (ZrO2)0.995−x(Sm2O3)x(CeO2)0.005 crystals (where x = 0.032, 0.037 and 0.04) were grown using directional melt crystallization in a cold crucible. The mechanical properties, such as microhardness and fracture toughness, were explored using Vickers indentation. It was shown that the (ZrO2)0.995−x(Sm2O3)x(CeO2)0.005 solid-solution crystals contained both Ce4+ and Ce3+ ions. Phase analysis data suggested that CeO2 doping increased the tetragonality degree of the transformable t phase and reduced the tetragonality degree of the non-transformable t' phase as compared to the (ZrO2)1−x(Sm2O3)x crystals. As a result, the t→m phase transition triggered by the indentation-induced stress in the CeO2-doped crystals was more intense and covered greater regions. CeO2 doping of the solid solutions increased the fracture toughness of all the crystals studied, whereas the microhardness of the crystals changed only slightly. CeO2 doping of the (ZrO2)1−x(Sm2O3)x solid solutions in the experimental concentration range did not improve the high-temperature phase stability of the crystals and did not prevent high-temperature degradation of their fracture toughness. [ABSTRACT FROM AUTHOR]

In heterogeneous catalysis, determining the optimal metal particle size is challenging due to the intricate relationship between particle size, electronic structure, and activity. Here, we investigate the size-dependent activity of Pt nanoparticle (PtNP)-based ZrO 2 catalyst for hydrogen evolution reaction (HER) and water-splitting reaction (WSR) using density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulations. By analyzing different Pt nanoparticle sizes (Pt 4 , Pt 7 , Pt 11 , P 15 , Pt 19, and Pt 25) supported on ZrO 2 , we determined their optimized geometries, and electronic structures, and calculated the hydrogen adsorption energies (Δ G H) for HER and activation energies barrier (Δ ‡ G) for WSR. The calculated results demonstrate that Pt 11 is the optimal size for HER, exhibiting the lowest Δ G H (−0.066 eV), while Pt 15 shows the lowest Δ ‡ G (0.24 eV) for WSR. The density of states (DOS) shows that the occupied Pt states fill the gap of ZrO 2 (3.72 eV), significantly reducing the band gap (E g) of the PtNP/ZrO 2 composites. The most favorable configuration of the PtNP on ZrO 2 for HER and WSR is determined to be a three-Pt-layer structure with rooflike edges which corresponds to a nanoparticle size of ∼0.70–1.55 nm for experiments. These findings can be regarded as an effort toward the design and optimization of metal-based oxide catalysts for renewable energy applications. [Display omitted] • Investigations of effect of Pt nanoparticle size on the catalytic activity of ZrO 2 -based catalyst. • The occupied Pt states reduce the band gap of the PtNP/ZrO 2 composites, enabling visible light photocatalytic activity. • Identified Pt 11 and Pt 15 clusters to be optimal size for hydrogen evolution reaction (Pt 11) and water-splitting reactions. • The calculated optimal size corresponds to an approximate nanoparticle size range of 0.70–1.55 nm in experiments. • Three-Pt-layer structure with rooflike edges identified as the most favorable configuration for catalytic performance. [ABSTRACT FROM AUTHOR]

The pursuit of efficient materials for technological applications is essential. Among these materials, zirconia emerges as a promising candidate with potential for several applications, from applications related to mechanical resistance to optoelectronic applications. By introducing dopants into this compound, it becomes feasible to modulate its inherent properties. In this study, ZrO 2 doped with strontium was synthesized for the first time via the sonochemical method at different percentages in mol (1, 2, 4, and 8 mol%). Analysis via X-ray diffraction (XRD) and Raman spectroscopy unveiled the formation of both monoclinic and tetragonal phases, with the latter being stabilized through the incorporation of the dopant element. In addition to observing irregular morphology through scanning electron microscopy (SEM-FEG), a reduction in particle size was also evidenced following the introduction of Sr2+ ions, a phenomenon corroborated via Rietveld refinement. The reflectance spectra of the doped samples exhibited an optical absorption tail characterized by the Urbach energy (E U), indicating an increase in structural disorder in the samples. The photoluminescence (PL) results indicated that the introduction of Sr2+ ions into the ZrO 2 matrix induced modifications in the characteristics of the spectrum profile. The phase transformation observed in XRD was reflected in the changes observed in the photoluminescent behavior of the samples, which emitted light between the blue and green regions. [ABSTRACT FROM AUTHOR]

The surface structure and chemical properties of Y‐stabilized zirconia (YSZ) have been subjects of intense debate over the past three decades. However, a thorough understanding of chemical processes occurring at YSZ powders faces significant challenges due to the absence of reliable reference data acquired for well‐controlled model systems. Here, we present results from polarization‐resolved infrared reflection absorption spectroscopy (IRRAS) obtained for differently oriented, Y‐doped ZrO2 single‐crystal surfaces after exposure to CO and D2O. The IRRAS data reveal that the polar YSZ(100) surface undergoes reconstruction, characterized by an unusual, red‐shifted CO band at 2132 cm−1. Density functional theory calculations allowed to relate this unexpected observation to under‐coordinated Zr4+ cations in the vicinity of doping‐induced O vacancies. This reconstruction leads to a strongly increased chemical reactivity and water spontaneously dissociates on YSZ(100). The latter, which is an important requirement for catalysing the water‐gas‐shift (WGS) reaction, is absent for YSZ(111), where only associative adsorption was observed. Together with a novel analysis Scheme these reference data allowed for an operando characterisation of YSZ powders using DRIFTS (diffuse reflectance infrared Fourier transform spectroscopy). These findings facilitate rational design and tuning of YSZ‐based powder materials for catalytic applications, in particular CO oxidation and the WGS reaction. [ABSTRACT FROM AUTHOR]

Die Oberflächenstruktur und die chemischen Eigenschaften von Yttrium‐stabilisiertem Zirkoniumdioxid (YSZ) waren in den letzten drei Jahrzehnten Gegenstand intensiver Diskussionen. Ein umfassendes Verständnis der chemischen Prozesse, die bei YSZ‐Pulvern ablaufen, ist jedoch aufgrund der fehlenden Erhebung von zuverlässigen Referenzdaten für gut kontrollierte Modellsysteme mit erheblichen Herausforderungen verbunden. Wir stellen hier die Ergebnisse aus der polarisationsaufgelösten Infrarot‐Reflexions‐Absorptions‐Spektroskopie (IRRAS) vor, die für unterschiedlich orientierte, Yttrium‐dotierte ZrO2‐Einkristalloberflächen nach der Adsorption von CO und D2O erhalten wurden. Die IRRAS‐Daten zeigen, dass die polare YSZ(100)‐Oberfläche eine Rekonstruktion erfährt, die durch eine ungewöhnliche rotverschobene CO‐Bande bei 2132 cm−1 gekennzeichnet ist. Berechnungen gemäß der Dichtefunktionaltheorie ermöglichten es, diese unerwartete Beobachtung mit unterkoordinierten Zr4+‐Kationen in der Nähe der durch die Dotierung induzierten O‐Fehlstellen in Verbindung zu bringen. Diese Rekonstruktion führt zu einer stark erhöhten chemischen Reaktivität und zu einer spontanen Dissoziation von Wasser an YSZ(100). Letzteres, eine wichtige Voraussetzung für die Katalyse der Wassergas‐Shift (WGS)‐Reaktion fehlt für YSZ(111), wo lediglich eine assoziative Adsorption beobachtet wurde. Zusammen mit einem neuartigen Analyseschema ermöglichten diese Referenzdaten eine operando‐Charakterisierung von YSZ‐Pulvern mithilfe der DRIFTS (Diffuse‐Reflexions‐Infrarot‐Fourier‐Transform‐Spektroskopie). Diese Erkenntnisse erleichtern das rationale Design und die Abstimmung von YSZ‐basierten Pulvermaterialien für katalytische Anwendungen, insbesondere für die CO‐Oxidation und die WGS‐Reaktion. [ABSTRACT FROM AUTHOR]

Mesoporous zirconium oxides (ZrO2) and cobalt oxides (CoxOy) were prepared by different methods, using vanillin (VAN) as a model compound to explore the catalytic performance of catalysts for the hydrodeoxygenation (HDO) reaction. Various characterization methods were used to test the catalysts' morphology, structure, and chemical composition. Under the optimal conditions, the study found that the yield of catalyzing the HDO of VAN to 2-methoxy-4-methylphenol (MMP) is 99%, with ZrO2 prepared by the precipitation method as the catalyst, isopropanol as the solvent, hydrogen pressure of 5 MPa, reaction time of 24 h, and reaction temperature of 180 °C. A high methylcyclohexanol (MCYL) yield of 99% was obtained for the HDO of VAN, with CoxOy prepared by the precipitation method as the catalyst, isopropanol as the solvent, hydrogen pressure of 4 MPa, reaction time of 24 h, and reaction temperature of 170 °C. [ABSTRACT FROM AUTHOR]

Ti and its alloys have been vastly employed in the manufacturing of biomedical implants for orthopedy and dentistry, especially the Ti-6Al-4V alloy (wt%), which is the most-used Ti alloy worldwide. However, the ion release of Al and V in the long term has been related to harmful effects on the human body. In this scenario, surface modification strategies, such as plasma electrolytic oxidation (PEO), have often been performed in Ti alloys to match the clinical needs. This study evaluated the effect of electrical AC parameters on the surface of the commercial Ti-6Al-4V alloy immersed in ZrO2-rich electrolytic solution regarding the chemical, physical, structural, and topographical aspects. Then, the selected PEO-treated samples surpassed the electrochemical test in saline solution. The results indicated that the electrical AC parameters affect the duration and intensity of the oxidative reactions and plasma micro-discharge steps, resulting in porous and thick oxide layers. PEO treatment promoted bio-camouflage of the surface, enriching it with TiO2, ZrO2, and ZrTiO4 compounds and depleting it of Al and V. After screening the PEO-treated samples and their corrosion behavior, the results indicated that the porous ZrO2–TiO2 ceramic coatings in the Ti-6Al-4V alloy can be a viable alternative for the manufacturing of biomedical implants. [ABSTRACT FROM AUTHOR]

Two experimental ceramic systems, 3Y-TZP/5Y-PSZ (3Y/5Y) and 4Y-PSZ/5Y-PSZ (4Y/5Y), underwent analysis before (3Y/5Yi or 4Y/5Yi) and after hydrothermal aging (3Y/5Ya or 4Y/5Ya) to simulate low-temperature degradation (LTD). The samples were sintered and characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Raman spectroscopy, alongside nanoindentation tests to measure elastic modulus (Em) and hardness (H). Assessments were conducted on the external surfaces and at individual layers on cross-sectioned samples at predetermined regions of interest (ROIs). Degraded superficial regions were observed in the cross-sectional SEM images of the 3Y and 4Y zirconia layers after aging. XRD indicated a tetragonal→monoclinic phase transformation in the aged groups for both 3Y (66 % m-ZrO 2) and 4Y (29 % m-ZrO 2). Raman spectroscopy revealed monoclinic phase amounts of 86 % for 3Y and 62 % for 4Y in the degradation regions observed in the SEM micrographs. Monoclinic phase peaks were virtually no longer detected in either material beyond a depth of 15 μm. Hydrothermal aging significantly diminished the H and Em values for the 3Y and 4Y zirconia surfaces. For the analysis of different zirconia surfaces within the same subgroup, all pairwise comparisons showed statistically significant differences, except for the values of H of 3Y/5Yi and Em for 4Y/5Yi. Regarding the nanoindentation results of cross-sectioned samples, the aging protocol did not affect the H and Em values of the equivalent ROIs (layers), regardless of the bilayered system. However, significant differences in H values were observed among the ROIs (layers) within the same bilayered system. Despite surface changes, nanomechanical properties remained preserved below the surface and at the interfaces of bilayered materials after aging. Nanoscale H values varied among some layers and interfaces, whereas the Em values exhibited differences across certain surfaces. [ABSTRACT FROM AUTHOR]

Composites comprising mechanically stronger ceramic and bioactive alongside resorbable ceramic are a most welcomed choice in load-bearing bone replacement. In this pursuit, the present study aims to investigate the varied levels of cerium additions in the ZrO 2 –CaSiO 3 composite. The influence of cerium concentration on the structural, mechanical, apatite formation, resorbability and in-vitro biological behaviour of the ZrO 2 –CaSiO 3 composite has been undertaken in the current study. Sol-gel synthesis technique has been adopted to yield composite powders and the structural behaviour of the resultant has been performed using various analytical techniques. The results envisaged the crucial role of Ce3+ concentration in accomplishing a phase stable t/c -ZrO 2 - α -CaSiO 3 composite after heat treatment at 1300 °C. XPS analysis revealed the presence of dual oxidation state (+3 and + 4) of cerium in the composite powders and a homogeneous mixture of the composite has been determined from morphological analysis. Mechanical properties determined from nanoindentation indicated better strength displayed by the composite than the natural bone. The immersion tests conducted in simulated body fluids indicated the development of apatite crystals on the composite. Resorbability and biocompatibility tests demonstrated the virtuous appropriateness of the 30 wt% Ce3+/Ce4+ doped t/c -ZrO 2 - α -CaSiO 3 composite for load-bearing bone replacement. [ABSTRACT FROM AUTHOR]

Aqueous Zn batteries, which use metallic Zn as anodes, have gained significant attention due to their affordability and high safety standards. However, these Zn anodes are plagued by issues such as Zn dendritic growth and side reactions, including corrosion and hydrogen evolution. One straightforward yet effective approach to mitigate these issues is to apply protective coatings to the Zn anodes to enhance their reversibility. It is generally believed that these protective layers should have a high affinity for Zn. Contrarily, this study proposes that non‐conductive coatings should form a strong binding with H+ ions while maintaining a weaker interaction with Zn2+ ions, thereby ensuring a higher selectivity for H+ over Zn2+. This concept is illustrated using zirconium dioxide (ZrO2), an ionic conductor that meets these criteria and effectively curbs side reactions and dendritic growth of Zn. Remarkably, Zn anodes coated with ZrO2 layer demonstrate a lifespan exceeding 6000 h at 1 mA cm−2 and 1 mAh cm−2, significantly outperforming uncoated ones, which last <200 h. This discovery introduces a novel design principle for insulating surface coatings, potentially applicable not only for Zn but also for other metal anodes. [ABSTRACT FROM AUTHOR]

Aqueous Zn batteries, which use metallic Zn as anodes, have gained significant attention due to their affordability and high safety standards. However, these Zn anodes are plagued by issues such as Zn dendritic growth and side reactions, including corrosion and hydrogen evolution. One straightforward yet effective approach to mitigate these issues is to apply protective coatings to the Zn anodes to enhance their reversibility. It is generally believed that these protective layers should have a high affinity for Zn. Contrarily, this study proposes that non‐conductive coatings should form a strong binding with H+ ions while maintaining a weaker interaction with Zn2+ ions, thereby ensuring a higher selectivity for H+ over Zn2+. This concept is illustrated using zirconium dioxide (ZrO2), an ionic conductor that meets these criteria and effectively curbs side reactions and dendritic growth of Zn. Remarkably, Zn anodes coated with ZrO2 layer demonstrate a lifespan exceeding 6000 h at 1 mA cm−2 and 1 mAh cm−2, significantly outperforming uncoated ones, which last <200 h. This discovery introduces a novel design principle for insulating surface coatings, potentially applicable not only for Zn but also for other metal anodes. [ABSTRACT FROM AUTHOR]

Lightweight phenolic matrix composites are highly potential in ablative thermal protective materials for future aerospace vehicles, and hybrid modification is considered as one of effective ways to improve the oxidation and ablation resistance of phenolic matrix. Herein, the co-continuous silica zirconium hybrid phenolic resin (SZRx) was synthesized, which can be used to prepare lightweight ablation resistant aerogel composites by the sol-gel method. The SZRx aerogel showed stable porous structure and excellent hydrophobicity, and the silicon zirconium hybrid greatly improved the high temperature carbon residue and oxidation resistance of phenolic resin. The SZRx aerogel composites also possessed excellent integrated characteristics of heat protection and insulation, with a linear ablation rate as low as 0.032 mm/s and a back temperature below 200 °C. The synergistic effect of silicon and zirconium formed the multiphase ceramic layer (C, SiO 2 , SiC and ZrO 2) with the sea-island-like structure on the surface of the composite material, which can effectively resist high-temperature ablation and aerodynamic exfoliation. This can indicate that silicon zirconium dual element hybrid phenolic resin is the highly competitive matrix for lightweight and ablation resistant composite materials. [Display omitted] [ABSTRACT FROM AUTHOR]

Currently, zirconium oxide (ZrO 2 , also called zirconia) is used for restoration or as an implant in dentistry due to its properties and the aesthetics that can be achieved. In the present work, zirconia particles were obtained by the sol-gel method using acid or basic medium to study its influence on the nucleation and growth of the particle size and determine the crystallite size of the high-temperature phase. Also, to control the particle size and improve the solubility and dispersion of the colloidal particles resulting from the hydrolysis-condensation reactions, a mixture of alcohol of different chain lengths were used. The zirconia samples were heat treated at 400, 600, and 800 °C and up to 250 h of holding times to follow the growth of crystallite size of zirconia phases. The results showed tetragonal (ZrO 2 -t) and monoclinic (ZrO 2 -m) zirconia as predominant phases, regardless of the synthesis conditions and heat treatment used. The monoclinic phase is favored at elevated temperatures and prolonged holding times, while the tetragonal ones are favored at low temperatures. The holding time promotes the transformation from the tetragonal to the monoclinic phase in both media (acid and basic). However, this transformation is promoted by the basic catalyst, while the acid medium favors the stability of the tetragonal phase at 400 and 600 °C. The phase transformation, particle size, and crystallite size depend on the synthesis conditions and heat treatment used to obtain the zirconia particles. [ABSTRACT FROM AUTHOR]

Defects engineering is significant for photocatalytic environment remediation. To this end, visible‐light‐driven α‐Fe2O3/ZrO2‐x S‐scheme heterojunction photocatalysts with optimal oxygen vacancy (Ov) defects are successfully synthesized via a two‐step method. Compared with pristine UiO‐66‐NH2‐derived ZrO2‐x and α‐Fe2O3, the heterojunction photocatalysts exhibit a wider range of visible light response and higher efficiency in separating photogenerated electron–hole pairs. Among them, the 5% α‐Fe2O3/ZrO2‐x sample shows the best photocatalytic performance to the degradation of tetracycline (TC) (89.3%), in which the pseudo‐first‐order kinetic rate constants are 8.20 and 16.75 times that of pristine ZrO2‐x and α‐Fe2O3, respectively. The outstanding photocatalytic degradation efficiency can be attributed to both the narrow‐bandgap ZrO2‐x with visible light response and the formation of α‐Fe2O3/ZrO2‐x S‐scheme heterojunctions. During the formation of heterojunctions, the concentration of oxygen vacancies (Ov) at the interface of α‐Fe2O3/ZrO2‐xdecreases monotonically with the increasing loading of α‐Fe2O3, thereby altering the electronic structure of the photocatalyst and forming the heterojunction firmly. In addition, the high stability implies the potential applications in fields of environment. [ABSTRACT FROM AUTHOR]

Cu nanoparticles supported on ZrO2 (CuNPs@ZrO2) were synthesized using a one‐step co-precipitation process, and their application in C–C coupling reactions was investigated. The catalyst was characterized using XRD, XPS, SEM, TEM, and TGA techniques. The prepared catalyst was used for the Sonogashira cross-coupling reactions of aryl bromides with phenyl-acetylene in the presence of K2CO3 in DMF at 110 °C, which resulted in substituted alkynes with good to excellent yields. The protocol was also extended for the Ullmann coupling reactions of aryl iodides under similar reaction conditions, yielding the desired products with good to excellent yields without homo-coupling. Interestingly, unlike other copper catalysts, the present catalyst worked under air and did not require an inert atmosphere to prevent alkyne. This catalytic system is versatile, tolerant, and significantly cheaper than the "traditional" Pd-catalyzed Sonogashira cross-coupling of terminal alkynes with aryl halides. The catalyst could be reused for five catalytic cycles with no significant change in the product yield. All of these characteristics make our prepared CuNPs@ZrO2 catalyst quite suitable for the gram-scale synthesis of biaryls and alkynes, with a simple workup. [ABSTRACT FROM AUTHOR]

Preparing catalysts from cheap metal precursors in a single pot are an appealing method for reducing catalytic preparation costs, minimizing chemical waste, and saving time. With regards to the catalytic conversion of dry reforming of methane, it offers the prospect of significantly reducing the cost of H2 production. Herein, NiO-stabilized metal oxides like Ni/TiO2, Ni/MgO, Ni/ZrO2, and Ni/Al2O3 are prepared at two different calcination temperatures (600 °C and 800 °C). Catalysts are characterized by X-ray diffraction, Raman spectroscopy, surface area-porosity analysis, Temperature program experiments, infrared spectroscopy, and thermogravimetry analysis. The MgO-supported Ni catalyst (Ni/MgO-600), ZrO2-supported Ni catalyst (Ni/ZrO2-600), and Al2O3-supported Ni (Ni/Al2O3-600) catalyst calcined at 600 °C show initial equal H2 yields (~ 55%). The population of CH4 decomposition sites over ZrO2-supported Ni catalyst remains highest, but H2-yield drops to 45% against high coke deposition. The catalytic activity remains constant over the Ni/MgO-600 catalyst due to the enrichment of "surface interacted CO2-species". MgO-supported Ni catalyst calcined at 800 °C undergoes weak interactions of NiO-M′ (M′ = support), serious loss of CH4 decomposition sites and potential consumption of H2 by reverse water gas shift reaction, resulting in inferior H2 yield. H2-yield remains unaffected over an Al2O3-supported Ni catalyst even against the highest coke deposition due to the formation of stable Ni (which exsolves from NiAl2O4) and proper matching between carbon formation and rate of carbon diffusion. [ABSTRACT FROM AUTHOR]

In this study, short carbon fibre (C sf) reinforced ZrB 2 -SiC composites were fabricated via direct ink writing followed by precursor infiltration and pyrolysis. The ablation behaviour of the composites was investigated at heat fluxes of 4–6 MW/m2 under an air plasma flame, which revealed excellent ablation resistance with negative linear ablation rates of − 0.1 to − 0.5 µm/s. The results showed that ZrO 2 -SiO 2 oxide layer was formed on the ablation surface after ablation, which provided effective protection to the internal materials. With an increase in heat flux, ZrO 2 precipitated from the SiO 2 melt first in the form of nano-tetragonal ZrO 2 (t -ZrO 2), owing to the vaporisation of SiO 2. During cooling, the nano t -ZrO 2 particles were retained, and some of them reacted with SiO 2 to form ZrSiO 4 , thus improving the thermal stability of the SiO 2 -ZrO 2 oxide layer. In contrast, t -ZrO 2 agglomerated and grew owing to capillary force and finally transformed into monoclinic ZrO 2 (m -ZrO 2). Moreover, a higher heat flux led to the size of precipitation ZrO 2 increases, meanwhile increasing the content of t -ZrO 2 and ZrSiO 4 in the oxide layer. • Short carbon fibers reinforced C sf /ZrB 2 -SiC composites were fabricated by direct ink writing, followed by precursor impregnation and pyrolysis. • During cooling, the nano t -ZrO 2 particles were retained, and some of them reacted with SiO 2 to form ZrSiO 4 , thus improving the thermal stability of the SiO 2 -ZrO 2 oxide layer. • The capillary force leads to the nano crystals gradually agglomerate and form dendritic structure. • From 4 to 6 MW/m2, the size of the dendritic structure ZrO 2 increased. [ABSTRACT FROM AUTHOR]

The Solar cell efficiency is crucial, and optical losses can hinder it significantly. Anti-reflective coatings are effective in minimizing these losses. In our study, we used Fresnel equations to calculate reflectance values for single-layer SiO2, ZrO2, a SiO2-ZrO2 mixture, and a double-layer SiO2/ZrO2 configuration. We then assessed their impact on crystalline silicon solar cells using the SCAPS program. The reflectance values of single-layer SiO2, ZrO2 and 10%SiO2-90%ZrO2 mixture were calculated as 19.17%, 13.09% and 13.01%, respectively. Notably, the double-layer SiO2/ZrO2 coating showed a low reflectance of 7.58%, a significant improvement compared to uncoated silicon at 37.45%. Efficiency values for crystalline silicon solar cells were calculated for single layer as 18,95% (SiO2), 20.39% (ZrO2), 20,40% (mixed coating) respectively and 21.68% for the double-layer SiO2/ZrO2 configuration. [ABSTRACT FROM AUTHOR]

Tailoring the properties of microfabricated ceramics through doping can unlock new avenues for the additive manufacturing (AM) of advanced 3D architectures. The first step to achieving optical functionality is to control material morphology, crystallinity, and defects associated with the composition of the produced AM architecture and dopants. For this purpose, AM of zinc‐doped zirconia (ZrO2:Zn) 3D microarchitectures is proposed using two‐photon lithography and tailor‐made resin. It is found that Zn doping modulates ZrO2:Zn architecture crystallinity and optical properties. The modification of optical properties through Zn doping is confirmed by micro‐photoluminescence, where higher energy photon emission is observed due to the promotion of oxygen vacancies and surface defects. It is also shown that Zn 2.5% and 5 wt% stabilizes the monoclinic ZrO2 at a lower temperature than in the case of undoped ZrO2. Furthermore, there is evidence that Zn tends to form ZnO wurtzite, which is later sublimated. The findings provide a promising route to understand the role of defects ZrO2:Zn optically upon annealing. [ABSTRACT FROM AUTHOR]

A series of MOF-derived ZrO2-supported Pd-Ni bimetallic catalysts (PdNi/UiO-67-CTAB(n)-A500) were prepared by co-impregnation and pyrolysis at 500 °C under air atmosphere using UiO-67-CTAB(n) (CTAB: cetyltrimethylammonium bromide; n: the concentration of CTAB; n = 0, 3, 8, 13, 18) as a sacrificial template. The catalytic activity of PdNi/UiO-66-CTAB(n)-A500 in 1,3-butadiene hydrogenation was found to be dependent on the crystal morphology of the UiO-67 template. The highest activity was observed over the PdNi/UiO-67-CTAB(3)-A500 catalyst which was synthesized using UiO-67-CTAB(3) with uniform octahedral morphology as the template for the 1,3-butadiene selective hydrogenation. The 1,3-butadiene conversion and total butene selectivity were 98.4% and 44.8% at 40 °C within 1 h for the PdNi/UiO-67-CTAB(3)-A500 catalyst, respectively. The catalyst of PdNi/UiO-67-CTAB(3)-A500 can be regenerated in flowing N2 at 200 °C. Carbon deposited on the surface of the catalyst was the main reason for its deactivation. This work is valuable for the high-efficiency bimetallic catalyst's development on the selective hydrogenation of 1,3-butadiene. [ABSTRACT FROM AUTHOR]

This article explores the intricacies of micro-grinding parameter control for hard and brittle materials, with a specific focus on Zirconia ceramics (ZrO2) and Optical Glass (BK7). Given the increasing demand and application of these materials in various high-precision industries, this study aims to provide a comprehensive kinematic analysis of material removal during the micro-grinding process. According to the grinding parameters selected to be analyzed in this study, the ac-max values are between (9.55 nm ~ 67.58 nm). Theoretical modeling of the grinding force considering the brittle and ductile removal phase, frictional effects, the possibility of grit to cut materials, and grinding conditions is very important in order to control and optimize the surface grinding process. This research introduces novel models for predicting and optimizing micro-grinding forces effectively. The primary objective is to establish a micro-grinding force model that facilitates the easy manipulation of micro-grinding parameters, thereby optimizing the machining process for these challenging materials. Through experimental investigations conducted on Zirconia ceramics, the paper evaluates a mathematical model of the grinding force, highlighting its significance in predicting and controlling the forces involved in micro-grinding. The suggested model underwent thorough testing to assess its validity, revealing an accuracy with average variances of 6.616% for the normal force and 5.752% for the tangential force. Additionally, the study delves into the coefficient of friction within the grinding process, suggesting a novel frictional force model. This model is assessed through a series of experiments on Optical Glass BK7, aiming to accurately characterize the frictional forces at play during grinding. The empirical results obtained from both sets of experiments—on Zirconia ceramics and Optical Glass BK7—substantiate the efficacy of the proposed models. These findings confirm the models' capability to accurately describe the force dynamics in the micro-grinding of hard and brittle materials. The research not only contributes to the theoretical understanding of micro-grinding processes but also offers practical insights for enhancing the efficiency and effectiveness of machining operations involving hard and brittle materials. [ABSTRACT FROM AUTHOR]

Chromium (Cr) coating is a potential candidate material for improving the oxidation resistance and extending rail service life of zirconium (Zr) alloys used in nuclear fuel cladding materials. This study investigates the effect of temperature on the effectiveness of Cr coating on Zr-4 alloy deposited using arc ion plating, revealing the microstructure evolution mechanism of Cr coating in high temperature steam environments. The research results indicate that the oxidation of the Cr coating is slow at 900-1000 °C and that the surface oxide layer, to some extent, hinders the diffusion of oxygen from the outside to the inside. However, at higher temperatures, the oxidation rate of the Cr coating is accelerated, and large bubbles and voids are formed at the interface between the Cr 2 O 3 layer and the residual Cr layer, resulting in the fracture of the oxide layer. At this time, the protective performance of the Cr coating is completely lost. Note that the simultaneous inward diffusion of oxygen and outward diffusion of Zr trigger the occurrence of redox reactions, generating a ZrO 2 network. Changes in steam temperature significantly affect the oxidation behavior of Cr coating. As a driving force, temperature accelerates the diffusion of oxygen to the substrate. Conversely, the formed zirconia network also promotes the failure of the Cr coating. [Display omitted] • The effect of temperature on microstructure of Cr coating in high-temperature steam environment was investigated. • Different sizes of ZrO 2 products were found above the Cr oxide layer. • Cr coated Zr-4 alloy exhibits parabolic oxidation kinetics and significant weight increase. • ZrO 2 network structure accelerates the degradation and failure of Cr coating. • The invasion of hydrogen promotes the initiation and development of cracks. [ABSTRACT FROM AUTHOR]

The slow dissolution process of zirconium oxide (ZrO 2) limits the efficient and energy-saving production of zirconium-rich basalt fibers with excellent alkali resistance for fiber-reinforced concrete. Therefore, it is necessary to investigate the optimum homogenization conditions to produce high-performance zirconium-rich basalt fibers. In this study, quenched zirconium-rich glasses and zirconium-rich fibers with the addition of 7 wt% ZrO 2 at different homogenization temperatures and time were prepared. The quenched melt structure was characterized by XRD and FTIR, and followed information about the melt structure obtained by Gaussian curve fitting of the FTIR spectra. The results indicated that obvious ZrO 2 crystals appeared in the melts and fibers with homogenization temperature below 1500 °C and time below 4 h. The degree of polymerization of zirconium-rich basalt melt was found to increase with increasing homogenization temperature and time. Meanwhile, the tensile strength and production stability of zirconium-rich fibers increased with increasing the degree of polymerization. The optimum homogenization temperature and time for zirconium-rich basalt fibers were concluded to be 1580 °C and 10 h, and the corresponding tensile strength is 1799 MPa and 1761 MPa, respectively. By diffusion experiment of ZrO 2 in basalt melt with altered major component content, it was found that the Ca, Mg, Na, and Fe significantly facilitated the melting of ZrO 2 into basalt melt by XRD and EDS. It was mainly attributed to the charge-compensating effect of metal cations on the [ZrO 6 ] octahedra, which promoted the homogenization of ZrO 2 in basalt melt. [ABSTRACT FROM AUTHOR]

Propylene is an important resource for large petrochemicals production. Propane dehydrogenation (PDH), which directly produces propylene while producing hydrogen as a by-product, has attracted extensive attention in recent years. Among various PDH catalysts, Zn-based catalyst has great potentials in industrial implementation because of its low cost and eco-friendly. Herein, we synthesized Zn– O –Zr active center via atom trapping strategy for effectively catalyzing PDH reaction. The ability of phase transition upon Zn deposition is supposed to be a possible indicator to assess active degree of ZrO 2 , which is directly related to the proportion of surface absorbed oxygen species (SAOS) on ZrO 2. We demonstrate that SAOS concentration can be promoted through stabilizing tetragonal-phase and doping Hf, results in more Zn–O–Zr species, lower active energy, and easier phase transition. This study reveals the electronic effect on atom trapping process used in Zn–ZrO 2 system and provides guidance to design and prepare high-performance Zn-based PDH catalysts. [Display omitted] • An efficient Zn–O–Zr structure was prepared by atom trapping method. • The interaction between metals is quantified by binding energy shifting. • Periodic phase transition of support during the reaction. • The surface defect degree of Zn species was regulated by crystal phase. [ABSTRACT FROM AUTHOR]

In orthopedic applications the use of metal matrix composites is essential for potential replacement to the traditional metal scaffolding in bio implant application. Magnesium (Mg) based alloys are more suitable material for the orthopedic applications as it mimics that of human bone. In this research a hybrid reinforcements such as seashell powder (SSP) and zirconium dioxide (ZrO 2) are added with AZ31 Mg alloy and examined their suitability and adoptability in bioenvironmental. The composites are fabricated through stir casting route. The effect of adding different proportions (0, 5 and 10 wt%) of ZrO 2 and fixed proportion (2 wt%) of SSP in AZ31 matrix composites on morphological, mechanical, corrosion and biodegradability behavior are analyzed. Morphological studies are analyzed in scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS). The mechanical properties such as tensile, compression, impact strength and hardness are studied. The biodegradability of the material is calculated by mass loss corrosion test and degradability test in simulated body fluid (SBF) environment. The cell culture and MTT assay test are carried out to find the cytotoxicity and cell viability of the proposed composite samples. The results reveal that the addition of ZrO 2 and SSP particles drastically improved the mechanical and corrosion resistance behavior of AZ31 Mg alloy. From the mechanical, corrosion and bio studies confirmed that the 10 wt% of ZrO 2 and 2 wt% of SSP reinforced AZ31 Mg composite has the potential replacement to the traditional metal scaffoldings in orthopedics. [ABSTRACT FROM AUTHOR]

This paper investigates the sliding friction and erosion resistance of untreated and heat-treated electroless Ni–B coatings, reinforced with ZrO 2 and (3 mol%) YSZ nanoparticles. A ball-on-flat system was used for the sliding friction wear test, and an air jet carries solid particles for the erosion wear test. The wear scars were studied with a 3D profilometer. Further, a scanning electron microscope (SEM) for morphological and energy-dispersive spectroscopy (EDS) was used to examine the chemical properties of the worn surfaces. These scars correlate with properties of hardness, Young's modulus, and fracture toughness has been studied with microhardness and nanoindentation tests. X-ray diffraction (XRD) analyzed the coating phase structure and synthesis. The wear tests revealed that Ni–B–ZrO 2 and Ni–B-YSZ coatings had lower friction coefficients at heat-treated conditions (with an average value of μ = 0.3) than Ni–B, HT, which had a 14 % higher coefficient. Consequently, the Ni–B-YSZ demonstrates the lowest specific wear rates (2.4 x10−6 mm3/N-m) and erosion resistance which is more promising for use in indented gun barrel applications. [ABSTRACT FROM AUTHOR]

The catalytic isomerization of glucose to fructose plays a pivotal role in the application of biomass as a feedstock for chemicals. Herein, we propose a facile solid-state-grinding strategy to construct ZrO2/MgO mixed oxides, which offered an excellent fructose yield of over 34.55% and a high selectivity of 80.52% (80 °C, 2 h). The co-mingling of amphiphilic ZrO2 with MgO improved the unfavorable moderate/strongly basic site distribution on MgO, which can prohibit the side reactions during the reaction and enhance the fructose selectivity. Based on the catalyst characterizations, MgO was deposited on the ZrO2 surface by plugging the pores, and the addition of ZrO2 lessened the quantity of strongly basic sites of MgO. Additionally, the presence of ZrO2 largely enhanced the catalyst stability in comparison with pure MgO by recycling experiments. [ABSTRACT FROM AUTHOR]

Radiation shielding plays a crucial role in safeguarding human health, and ongoing research is exploring alternative materials for this vital purpose. Herein, physical and radiation-shielding features of the manufactured glasses via melt-quenching technique doped with ZrO2 within a glassy system, (100-x-y)[SrTiO3]-x[2B2O3·SiO2]-y(ZrO2), (39 ≤ x ≤ 40, and 0 ≤ y ≤ 4 mol % ZrO2) were studied. The density (ρ) and field-strength (Fs) values of the synthesized glasses were found to be in an increasing order of 2.6068–3.0720 g/cm3 and 5.2401–14.2399 Å−2 respectively. The study also encompassed an exploration of the radiation shielding properties such as mass attenuation coefficient (MAC), linear attenuation coefficient (LAC), half value length, tenth value length, mean free path, effective atomic number (Zeff), and effective electron-density (Neff) of the synthesized glasses, employing the freely available 'Phy-X/PSD' software within the energy range of 0.015–15 MeV. The highest values of MAC, LAC, and Neff at 0.02 MeV were found to be 25.275 cm2/g, 77.644 cm−1, and 8.42 × 1023 electrons/g for SrTZ4 (x = 39 and y = 4) glass respectively. Notably, among all the fabricated glasses, SrTZ4 emerged as the standout performer, demonstrating superior gamma-radiation protecting abilities along with effective physical properties. Thus, the fabricated SrTZ4 glass with its remarkable radiation shielding properties holds promising applications for the development of radiation protection equipment. [ABSTRACT FROM AUTHOR]

Unveiling the mechanisms and process of the interfacial reaction between transition metal oxides and metals have far-reaching implications for their superior application. Herein, the interfacial reaction between ZrO 2 and metals was comparatively studied, and the interfacial reactions between three types of ZrO 2 and Zr were systematically investigated by MD simulations. Comparative experiments show that the c -ZrO 2 reacts more vigorously with the active metal than the m -ZrO 2 under the same conditions, and modified c -ZrO 2 nanoparticles have core-shell structures due to the resulting oxygen concentration gradient. The MD simulations reveal that the crystal structure of ZrO 2 has a great influence on its oxygen loss rate (5.14 %–6.46 %) and oxygen distribution induced by the ZrO 2 /metal interface reaction. Meanwhile, the differences in ZrO 2 properties lead to two modes of ZrO 2 /metal interfacial reactions, which are distinguished by the characteristics of the oxygen distribution in the modified ZrO 2. One is that there is no obvious oxygen concentration gradient inside the ZrO 2 during the interfacial reaction, and the crystal defects in the modified ZrO 2 are uniformly distributed, such as c -ZrO 2 and t-ZrO 2. Another reaction mode is that only the region immediately adjacent to the interface in ZrO 2 undergoes diffusion of oxygen ions to the metal, and the interfacial reaction process proceeds layer by layer, such as m -ZrO 2. In addition, when the oxygen density and V O density of ZrO 2 are both low while the oxygen conductivity is high, the ZrO 2 /metal interfacial reaction tends to proceed according to mode A, resulting in modified ZrO 2 with uniformly distributed defects. [ABSTRACT FROM AUTHOR]

In this research, a straightforward sample treatment for multiresidue pesticide evaluation of onion samples was developed using the solid-phase extraction/quick, easy, cheap, effective, rugged, and secure (SPE/QuEChERS) method. The suggested technique is based on acetonitrile liquid-liquid partitioning, then follows dispersive solid-phase extraction with ZrO2 particles for extract purification. ZrO2 is synthesized via co precipitation and analyzed via XRD, FTIR, and SEM. ZrO2 has been demonstrated to be more effective than normal graphitized carbon black at eliminating pigment. Thirty-five pesticides from various chemical classes were examined using gas chromatography and tandem mass spectrometry (GC-MS/MS) to assess the outlined technique. Most analytes had recoveries in the range of 74–105%, with relative standard deviations of less than 14%. The linearity, precision, and accuracy of GC-MS/MS were adequate. The validated technique was applied effectively to onion samples from the farmer's field. [ABSTRACT FROM AUTHOR]

The present study aimed to analyze the mechanism underlying the color alteration of dental zirconia ceramics stabilized with 3 and 5 mol% yttria (3YZ and 5YZ, respectively) caused by 254-nm ultraviolet (UV) irradiation. Fully sintered specimens of 3YZ (Zpex, Tosoh) and 5YZ (Zpex Smile, Tosoh) were irradiated with 254-nm UV at 4 mW/cm2 (up to 60 min). Color alteration (ΔE) was analyzed using the CIE L*a*b* colorimetric system. The UV-induced excitation of oxygen vacancies, which capture two electrons in zirconia (i.e., F center) was analyzed using photoluminescence (PL) and electron spin resonance (ESR) spectroscopy. Furthermore, the spontaneous change in ΔE after cessation of UV irradiation was evaluated. UV irradiation increased ΔE to 13.4 in 3YZ and 10.3 in 5YZ within the initial 10 min of irradiation, and then, ΔE reached a plateau. A PL peak was observed at 435 nm, which decreased with UV irradiation. In addition, UV irradiation generated an ESR signal attributed to the F+ centers formed via one-electron detachment from F centers. The signal intensities of both 3YZ and 5YZ increased with irradiation time; however, the signal intensity was higher in 3YZ than that in 5YZ. After cessation of UV irradiation, ΔE gradually decreased to approximately 2, which took a few weeks. The discoloration of 3YZ and 5YZ caused by UV irradiation was due to the excitation of F centers. Although the specimens spontaneously reverted to their original color over time, clinical procedures involving UV irradiation, such as photo-functionalization, should be performed with caution to avoid damaging the esthetics of dental zirconia restorations. [ABSTRACT FROM AUTHOR]

The optimization of the sintering process for ceramic stereolithography-based additive manufacturing is attracting high interest important due to its correlation with the final properties of the fabricated parts. In this work, a photosensitive zirconia suspension with low viscosity and high solid loading (48 vol%) was prepared using surface-modified zirconia ceramic powders, resulting in an improvement in long-term stability. The correlations between the sintering temperature (1400–1520 °C) and mechanical properties were investigated. The results showed that and the as-sintered zirconia parts exhibited a relatively high density of 99.5 ± 0.1 % and three-point flexural strength of 821 ± 65 MPa as well as excellent fracture toughness (4.37 ± 0.22 MPa m1/2) sintering at 1480 °C, which was attributed to the highly homogeneous microstructure without obvious pores or crack. The obtained insights regarding the correlation between sintering temperature, relative density, and flexural strength can provide practical guidance for the future applications of zirconia ceramics. [ABSTRACT FROM AUTHOR]

The utilization of a zirconium oxide (ZrO2) thin film as the insulator in a metal–insulator–semiconductor (MIS) capacitor to enhance the characteristics of thin‐film transistors is investigated. Although the high crystallinity of ZrO2 is favorable to achieving higher capacitance density in metal–insulator–metal capacitors with ZrO2 thin films, it decreases the capacitance with increasing applied bias in Mo/ZrO2/InGaZnO (IGZO)‐structured MIS capacitors. Through comprehensive physical, chemical, and electrical characterizations, this study investigated the mechanism underlying the decreasing capacitance with increasing the applied bias in the accumulation state of the Mo/ZrO2/IGZO‐structured MIS capacitor depending on the crystallinity of ZrO2. Furthermore, the investigation identifies the optimal crystal structure of ZrO2 thin films for IGZO‐based MIS capacitors, highlighting the importance of forming meso‐crystalline structures in high dielectric constant (k) materials to enhance the k value and mitigating the decrease in capacitance caused by the accumulated carrier loss through grain boundaries of ZrO2. [ABSTRACT FROM AUTHOR]

In this study, structural parameters and optical constants of size dependent zirconium dioxide (ZrCh) nanostructures were calculated. The effect of particle size was investigated on the calculated structural and optical parameters/constants. ZrCh nanostructures were produced by chemical route. To change the grain size of the ZrCh nanostructures, different annealing temperatures (450-550 °C) were applied. The x-ray diffraction (XRD), scanning electron microscope (SEM), and ultraviolet/visible region (UV-Vis) spectroscopy measurement results were used to calculate the structural and optical parameters/constants. The results of XRD measurement showed the ZrCh nanostructures were crystallized in single tetragonal (cubic) ZrCh phase. SEM results exhibited dense and homogeneous surfaces and enhanced surface grains with increased annealing temperature. The compositional formation of ZrCh nanostructures were proved by electron dissipated x-ray and mapping analysis. Optical measurements were strongly changed dependent on the grain size (Gs). The calculated structural parameters such as crystallite size, lattice parameter (a), microstrain, and dislocation density were showed that the powerful variation according to the Gs. The computed optical constants such as refractive index, extinction coefficient, reel and imaginer dielectric constants of the ZrO2 samples were highly varied upon the Gs. The variant in these calculated parameters/constant were extremely promising for the optic and dielectric applications. [ABSTRACT FROM AUTHOR]

Copyright of Gazi Journal of Engineering Sciences (GJES) / Gazi Mühendislik Bilimleri Dergisi is the property of Gazi Journal of Engineering Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This work proposed a strategy of indirectly inducing uniform microarc discharge by controlling the content and distribution of β-Mg17Al12 phase in AZ91D Mg alloy. Two kinds of nano-particles (ZrO2 and TiO2) were designed to be added into the substrate of Mg alloy by friction stir processing (FSP). Then, Mg alloy sample designed with different precipitated morphology of β-Mg17Al12 phase was treated by microarc oxidation (MAO) in Na3PO4/Na2SiO3 electrolyte. The characteristics and performance of the MAO coating was analyzed using scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), contact angle meter, and potentiodynamic polarization. It was found that the coarse α-Mg grains in extruded AZ91D Mg alloy were refined by FSP, and the β-Mg17Al12 phase with reticular structure was broken and dispersed. The nano-ZrO2 particles were pinned at the grain boundary by FSP, which refined the α-Mg grain and promoted the precipitation of β-Mg17Al12 phase in grains. It effectively inhibited the "cascade" phenomenon of microarcs, which induced the uniform distribution of discharge pores. The MAO coating on Zr-FSP sample had good wettability and corrosion resistance. However, TiO2 particles were hardly detected in the coating on Ti-FSP sample. [ABSTRACT FROM AUTHOR]

Aluminum Hybrid Metal Matrix Composites (Al-HMMCs) are contemporary materials that blend aluminum with additional reinforcing elements to enhance their mechanical, thermal, and other properties. These materials find applications across various sectors including the aerospace industry, automotive sector, military and defence, marine industry, as well as manufacturing industries. In this research, AA6061, zirconium dioxide (ZrO2) and boron carbide (B4C) have been selected as the matrix and reinforcement materials. AA6061/ZrO2/B4C (Al-HMMCs) is manufactured using Ultrasonic-assisted stir casting. The process parameters of ultrasonic assisted stir casting were optimized with the help of Taguchi optimization technique. The melting temperature (700, 750 and 800 ºC), stirring speed (10, 15 and 20 minutes) and AA6061/xwt.%B4C/xwt.%ZrO2 ( 6, 8 and 10) are selected as input parameters for optimization. The reinforcements ZrO2 and B4C are weighed by equally sharing by wt.% The micro hardness was selected as response parameter and it was determined by using Vickers micro hardness tester. The L9 Orthogonal Array (OA) was employed for optimization of input parameters of ultrasonic assisted stir casting. Taguchi results showed that medium level of melting temperature (750 ºC), higher level of stirring speed (300 rpm), lower level of stirring duration (10 minutes) and medium level of wt.% of ZrO2 and B4C (8wt.%) were the optimized combination of input process parameters of ultrasonic assisted stir casting for fabricating AA6061 HMMC. The AA6061/xwt.%B4C/xwt.%ZrO2 (x = 0,4,6,8 and 10) HMMCs were manufactured by utilizing optimized process parameters. The micro hardness of AA6061/xwt.%B4C/xwt.%ZrO2 (x = 0,4,6,8 and 10) was determined. . From the obtained hardness tests, it was observed that the hardness of AA6061 HMMCs was enhanced up to addition of 8wt. % of B4C and ZrO2 and decreased the hardness while adding 10wt.% of B4C and ZrO2. The better AA6061/8wt.%ZrO2/8wt.%B4C HMMC undergone X-ray Diffraction Analysis (XRD) and Scanning Electron Microscope (SEM) testing to identify elements and examine the microstructure. The high peak of ZrO2, B4C and Al was obtained in 71.4, 35.68 and 37.81 2 theta values respectively. The SEM image of ultrasonic aided stir cast AA6061 based composite was confirmed the uniform distribution of zirconium di oxide and boron carbide reinforcements. There was no oxide formation on the surface of the stir casted AA6061 composites due to the execution of casting process in the inert environment. The casted AA6061/8wt.%ZrO2/8wt.%B4C surface of the composite exhibits no porosity occurrence due to the impact of usage of ultrasonic vibrator to prevent the formation of holes due to escape of unwanted gases. Subsequently, corrosion tests were conducted on the AA6061 HMMC in various corrosive environments such as NaOH, HCl, H2SO4, and NaCl to evaluate its electrochemical behavior. The surfaces of corroded specimens were analyzed using SEM and Energy Dispersive Spectroscopy (EDS). The research findings indicate that AA6061 composites exhibit the highest corrosion resistance when immersed in a NaCl medium. This enhanced resistance was attributed to the medium's lower corrosion potential, stronger charge transfer resistance (Rct), and lower double-layer capacitance (Cdl) compared to alternative environments. Additionally, SEM analysis illustrated that the incorporation of B4C and ZrO2 ceramics results in the formation of protective barrier layers, further enhanced their corrosion resistance. ZrO2 particles were attracted and neutralized the corrosive ions and electrons, thereby reducing corrosive activity on the AA6061 aluminium matrix.

The wettability behavior and characteristics of the high chromium cast iron (HCCI)/zirconium dioxide system were studied using the sessile drop method. A complete and uniform layer of titanium was prepared on the surface of ZrO2 ceramics using the salt bath coating method. The introduction of titanium reduced the contact angle of the HCCI/ZrO2 system abruptly from 110° to approximately 13°, at the solid/liquid interface, no complete layer of reaction products was detected, XRD results indicated that TiO, ZrO, and non-stoichiometric ZrO2-x were primarily formed at the interface; thereby the spreading of HCCI on the Ti-coated ZrO2 ceramic plate was primarily dominated by the adsorption of titanium elements at the interface with generation of non-stoichiometric ZrO2-x, and the diffusion of Fe and Cr elements into the interior of the ceramics. Meanwhile, the introduction of titanium elements at the interface between HCCI and ZrO2 benefits the preparation of metallurgical well-bonded composite interfaces.

The magnesium alloy composite is a vital material for automotive applications due to its features like high stiffness, superior damping resistance, high strength, and lightweight. Here, the motto of research is to establish the AZ91 alloy nanocomposite with the exposures of 0, 1, 3, and 5 volume percentages (vol%) of nano zirconium dioxide (ZrO2) particles (50nm) through fluid stir metallurgy route associated with 1x105 Pa vacuum die cast process. Exposures on structural morphology, hardness, and impact toughness of composite are analyzed and identified as the nano AZ91 alloy composite enclosed with 5vol% is homogenous particle dispersion, enhanced hardness (97.6HV), and optimum toughness of 21.2J/mm2. However, composite faces machining difficulties due to the hard abrasive particles with higher hardness, resulting in tool wear. This experiment predicts the optimum mill parameters during the end mill operation of magnesium alloy nanocomposite (AZ91/5vol%) by using a tungsten carbide coated end mill cutter to attain the maximum metal removal rate with low surface roughness and tool wear analyzed via the general linear model (GLM) ANOVA approach. The input conditions for end milling operation vary, like feed rate (0.1 -0.4mm/rev), depth of cut (0.05 -0.2mm), and spindle speed (250-1000rpm). During the ANOVA GLM approach, the L16 design experiment is fixed for further interaction analysis. The results predicted by the depth to cut and feed rate were dominant and played a major role in deciding the tool wear, surface roughness, and MRR.

Extracellular vesicles (EVs) are pivotal in intercellular communication, disease mechanisms. Despite numerous methods for EVs isolation, challenges persist in yield, purity, reproducibility, cost, time, and automation. We introduce a EVs isolation technique using Fe3O4@ZrO2 beads, leveraging ZrO2-phosphate interaction. The results indicated that EVs were efficiently separated from large volumes of samples in 30 minutes without preconcentration. Our method demonstrated capture efficiency (74%–78%) compared to ultracentrifugation, purity (97%), and reproducibility (0.3%–0.5%), with excellent linearity (R2 > 0.99). EVs from urine samples showed altered expression of miRNAs. The logistic regression model achieved an AUC of 0.961, sensitivity of 0.92, and specificity of 0.94. With potential for automation, this magnetic bead-based method holds promise for clinical applications, offering an efficient and reliable tool for EVs research and clinical studies.

Y2O3 transparent ceramics with different amounts of ZrO2 were obtained by reactive vacuum sintering at a relatively low temperature of 1735 °C for 22 h. The influence of ZrO2 concentration within the 0–15 mol.% range on the microstructure, phase composition, microhardness, and optical properties of ceramics in the visible and IR ranges was investigated. SEM and XRD results indicate the absence of secondary phases in the studied concentration range, indicating the formation of single-phase solid solutions. It was shown that doping by ZrO2 considerably decreases the average grain size of ceramics, while microhardness has the opposite behaviour. 15 mol.% ZrO2-doped Y2O3 ceramics demonstrated the highest transmittance in the visible wavelength range. On the other hand, 5 and 7 mol.% ZrO2-doped Y2O3 could be considered promising materials for the first atmospheric window (3–5 μm).