Yttria Research Articles

Flexural Strength and Morphological Study of Different Multilayer Zirconia Dental Materials.

Nowadays, yttria (Y3+)-stabilized ZrO2 (Y-TZP) is the most commonly used material in dental prosthetics. Y-TZP dental ceramics are mainly stabilized via the addition of 3 mol% yttrium oxide (Y2O3). These ceramics exhibit excellent mechanical properties, including high flexural strength, fracture toughness, elastic modulus, etc. Some manufacturers have recently introduced a new class of dental materials with multilayer composition with the aim of combining the advantages of adding more or less Y2O3 to the ceramic composition in one Y-TZP material. The flexural strength values of multilayer Y-TZP may vary depending on the dimensions of the specimen, layer distributions, and especially the layer exposed on the maximum tension side, i.e., loading configuration. Although previous studies have examined the flexural strength of separate Y-TZP layers, capturing the flexural strength of multilayer Y-TZP is still challenging. However, one should keep in mind that multilayer flexural strength is important for clinical indications. The objective of this study is to compare the flexural strength of three distinct multilayer translucent Y-TZP materials made up of layers with different Y3+ contents. Rectangular samples (2 mm × 2 mm × 16 mm) were prepared from CAD/CAM discs using the milling machine Programill PM7 (Ivoclar Vivadent AG). Milled bars were tested for flexural strength in a three-point bending test (ISO 6872:2015) using a universal testing machine (Inspekt Duo 5kN; Hegewald & Peschke, Nossen, Germany) at a crosshead speed of 0.5 mm/min. Representative samples of each type of material were selected for quantitative and qualitative analysis of the microstructure. Representative samples of each type of material were selected for structural, mechanical, and microstructural analyses.

Yttrium aluminum garnet analyzed by x-ray photoelectron spectroscopy

Yttrium aluminum garnet (YAG) is a composite crystalline material used as a substrate in various optical applications, especially high-power lasers. It is currently doped with different elements depending on the desired application. This has generated small controversies depending on the fabrication method as well as the doping content. In the present work, a high-purity YAG single crystal was characterized using x-ray photoelectron spectroscopy (XPS) technique. Exploratory spectra, high-resolution spectra for C 1s, O 1s, Y 3d, and Al 2p, and valence band (VB) spectra were acquired. The results showed the presence of yttrium and aluminum oxides with the characteristic stoichiometry of YAG. In addition, the presence of adventitious carbon was detected, without the presence of impurities.

Effect of La2O3 as sintering aid on the structural, mechanical & electrical properties of Y2O3

Yttrium oxide (Y2O3) is a potential material in the development of transparent polycrystalline ceramics (PTCs). PTCs have possible applications in laser-materials, scintillators, Infrared windows, opto-electronic devices, displays etc. To obtain these, the ceramic must have a symmetric crystal structure, high purity and density. Highly dense ceramics require sophisticated sintering procedures as well as optimum sintering additives such as Lanthanum Oxide (La2O3) and Zirconium Oxide (ZrO2). In this manuscript, La2O3 is used as a sintering to embrace the sintering of Y2O3 with the aim to bring down the sintering temperature and systematically study the opto-electrical properties. La2O3 substituted Y2O3 (LaxY2−xO3, where, x = 0, 3, 6 and 9 at.%) ceramics are made, using co-precipitation method were examined for structural, morphological, physico-chemical and electrical properties by using XRD, SEM, TGA-DSC, and dielectric measurements. The obtained results serve as guidelines for the use of Y2O3 as a pathway to new dimensions opto-electronic applications.

Chemical characteristics via quantitative photoelectron analysis of chemical-solution-deposited yttrium oxide thin films for metal-insulator-metal capacitor applications

A cost-effective chemical bath deposition coupled with an annealing methodology is presented for obtaining yttrium oxide (Y2O3) thin films. The resultant thin films are homogeneous, free of pinholes, and show a relatively low surface roughness. The detailed characterization of the as-deposited thin film and the determination of optical, structural, and chemical characteristics of the films upon thermal transformation at 500 °C for 2 h was done with thermogravimetric analysis, X-ray diffraction, UV–Vis spectroscopy, surface topology analysis, and X-ray photoelectron spectroscopy. The results reveal that the as-deposited thin film is composed of an amorphous YOOH compound intrinsic to the synthesis process. However, with annealing, it is crystallized and transformed into a Y2O3 thin film showing a high optical transparency. The characteristics of the film are found to be influenced by the Y‒OH and Y‒O content with direct influence on the shape of the photoelectron spectra of the thin films showing a binding energy downshift of 1.6 eV from the 158.84 eV peak position found for the YOOH sample after annealing. The estimated surface roughness for the as-deposited YOOH and annealed Y2O3 samples resulted in 2.7 and 3.8 nm, respectively. The electrical characteristics and potential performance as a dielectric layer have been assessed in a Metal-Insulator-Metal configuration, where the acceptable values for leakage current in the 6 × 10−4 − 3 × 10−6 A/cm2 range and a capacitance of 218 and 80 nF/cm2 were measured for the YOOH and Y2O3 thin films, respectively. The latter indicates that these films are suitable candidates for gate dielectric transistor applications with the advantage of them being films produced via an economical and technically simple scalable process.

Fluorination of UO2, La2O3, and Y2O3 using ZrF4

Due to its high affinity towards oxygen, zirconium fluoride can fluorinate oxides found in used nuclear fuel while producing zirconium oxide. This study accomplished this using a lithium fluoride, sodium fluoride, zirconium fluoride (26–37–37 mol%) molten salt known as FLiNaZr with a melting point of 709 K. The high concentration of zirconium fluoride in the FLiNaZr molten salt also prevents the formation of oxyfluorides during this process. The maximum reaction rates of FLiNaZr with yttrium oxide, lanthanum oxide, and uranium oxide were studied and analyzed. These rates were normalized by the surface area of the oxide piece exposed to the salt, giving a value that can be easily scaled to larger systems and samples. Tests were run at 773 K, 823 K, 873 K, and 923 K to determine the temperature's impact on the reaction rate.

Stabilizing Phosphorene Nanosheets by Covalent Oxygen-Bridged Yttrium Oxide Nanosheet Bonding for Promoting Interfacial Sodium Storage

Stabilizing Phosphorene Nanosheets by Covalent Oxygen-Bridged Yttrium Oxide Nanosheet Bonding for Promoting Interfacial Sodium Storage

Rapid, selective and sensitive detection of sunset yellow by a novel electrochemical sensor: The impact of europium oxide nanoparticles on a composite of yttrium oxide–carbon nanotubes

Sunset yellow, a widely used azo dye colorant added into food products, can adversely affect humans. Developing a rapid, simple and sensitive method of analysis of food products for the detection of sunset yellow is important in terms of determining the level of risk to human health and thus food safety. The aim of this study was to develop a novel voltammetric method for the accurate detection of sunset yellow content in a widely consumed beverage. This was achieved by modifying a glassy carbon electrode (GCE) with a combination of europium-yttrium oxide (Eu2O3-Y2O3) nanoparticles and carbon nanotubes (CNTs). The voltammetric and electrochemical impedance spectroscopic (EIS) measurements showed that the proposed voltammetric platform (Eu2O3/Y2O3-CNTs/GCE) possessed high electrochemically active surface area and could serve as a promising sensing material. The proposed voltammetric platform exhibited excellent reproducibility, high selectivity and sensitivity for sunset yellow owing to the impact of Eu2O3 on a composite of Y2O3-CNTs. A dynamic working range and detection limit (LOD) for sunset yellow were found to be 4.0 × 10−9–1.3 × 10−6 M and 1.1 × 10−10 M, respectively. This novel method was successfully applied to determine sunset yellow in a nationwide consumed beverage. The results indicated that the proposed method of analysis offered a reliable and accurate determination of sunset yellow.

Comparative study of mesh powder and thin film of yttrium oxide (Y2O3) as saturable absorber

The performance and stability of Y2O3-SA mesh powder and Y2O3-SA thin films prepared using the conventional solution method (SM) have been studied for a passively Q-switched erbium-doped fiber laser (EDFL). The Y2O3-SA thin films prepared using the SM method were introduced into the fiber cavity, the pump power was increased from 43.12 mW to 557.48 mW, the pulse repetition rate increased from 36.4 kHz to 113.3 kHz, and the pulse width decreased from 12.3 μs to 4.3 μs, respectively. In the case of Y2O3 mesh powder as the saturable absorber (SA), as the pump power increased from 30.8 mW to 557.48 mW, the pulse repetition rate increased from 25.5 kHz to 123.48 kHz, and the pulse width decreased from 17.2 μs to 4.3 μs. The pulse energy and peak power of the Y2O3-SA thin film prepared using SM were measured at 1.6 nJ and 4 mW, respectively. The mesh powder of Y2O3-SA exhibited a pulse energy of 1.8 nJ and a peak power of 4.3 mW. It has been noted that the stability of Y2O3-SA mesh powder surpasses that of Y2O3-SA thin films prepared through the conventional solution method (SM).

Photoluminescence and thermoluminescence dosimetry properties of Ag/Y co-doped ZnO nanophosphor for radiation measurements.

This work explores the thermoluminescence (TL) and photoluminescence (PL) properties of Ag/Y co-doped zinc oxide (ZnO) nanophosphor. The proposed dosimeter was prepared by the coprecipitation method and sintered at temperatures from 400°C to 1000°C in an air atmosphere. Raman spectroscopy was studied to investigate the structural features of this composition. The new proposed dosimeter revealed two peaks at 150°C and 175°C with a small shoulder at high temperature (225°C). The PL spectrum showed strong green emissions between 500 to 550 nm. The Raman spectrum showed many bands related to the interaction between ZnO, silver (Ag), and yttrium oxide (Y2 O3 ). The rising sintering temperature enhanced the TL glow curve intensity. The Ag/Y co-doped ZnO nanophosphor showed an excellent linearity index within a dose from 1 to 4Gy. The minimum detectable dose (MDD) of the Ag/Y co-doped ZnO nanopowder (pellets) equaled 0.518 mGy. The main TL properties were achieved in this work as follows: thermal fading (37% after 45 days at 1 and 4Gy), optical fading (53% after 1h and 68% after 6h by exposure to sunlight), effective atomic number (27.6), and energy response (flat behavior from 0.1 to 1.3MeV). Finally, the proposed material shows promising results nominated to be used for radiation measurements.

Effect of yttrium oxide on microstructure and mechanical properties of functionally graded magnesium matrix composites

Over the last decade, there has been a steady increase in the amount of magnesium scrap sourced from manufacturing processes due to the rapidly growing market for magnesium alloys in various industries. As a result, the reuse of magnesium becomes extremely beneficial for cost reduction, natural resource preservation, and environmental protection, as it gives scrap magnesium a new lease on life. The reuse of AZ91 magnesium alloy chips for producing functionally graded composites reinforced with yttrium oxide (Y2O3) to enhance microstructure and mechanical properties was investigated in this paper. The manufacturing method for this study involves: (1) collecting and cleaning magnesium chips, (2) pre-mixing them with Y2O3 particles, (3) melting and blending the compositions using a stir casting method, and (4) finally pouring it into a centrifugal casting to produce the functionally graded composite. The microstructure of the AZ91 matrix was examined, and it indicated a well-distributed gradient of Y2O3 particles with little agglomeration. The estimated concentration of particles (which ranged from 40.35% to 32.1% area) closely matched the experimental data (which ranged from 43% ± 1.5% to 28% ± 1.5% area). The study also revealed that particle concentration had a substantial influence on the mechanical properties, with the outer zone outperforming both the middle and inner zones. In the outer zone, the gradient composite had a hardness of 106.89 ± 1.25 HV, a tensile strength of 197.39 ± 2 MPa, and a compressive strength of 335.29 ± 5 MPa. Furthermore, the findings demonstrated the feasibility of employing chip waste to make graded composites, providing a feasible technique for reusing magnesium chips created during machining procedures. This research sheds new light on the use of magnesium chips as a matrix material in the casting of functionally graded composites.

Enhanced thermoelectric and mechanical properties of Bi0.5Sb1.5Te3 alloy with dispersed yttrium oxide ceramic nanoparticles

Enhanced thermoelectric and mechanical properties of Bi0.5Sb1.5Te3 alloy with dispersed yttrium oxide ceramic nanoparticles

Fabrication of translucent graded dental crown using zirconia-yttrium multi-slurry tape casting 3D printer

This paper aims to fabricate functionally graded dental crown using a multi-slurry tape casting additive manufacturing technology. The different luminescence of the dental crown was obtained with different composition of zirconia and yttria. Zirconia with tunable mechanical properties and translucency are obtained by adding 3, 3.5, 4, 4.5, and 5 mol% of yttrium oxide to zirconia powder. After obtaining the printable slurry with maximum solid loading, the green bodies are prepared using the in-house built high-speed multi-ceramic tape casting technology. They are later sintered with two-stage sintering method. After the successful fabrication, the mechanical properties and translucency of the specimens were evaluated with Vickers hardness, three-point bending and translucency parameter tests. Finally, an FGM tooth crown with five photocurable slurries is proposed to demonstrate the translucent gradient effect of sintered part. The solid loading of 80% zirconia and 20% resin delivered samples without any surface cracks. The shrinkage ratio analysis showed that the sintered sample dimension was reduced by 20%, 20%, and 23% along X, Y, and Z directions. The samples fabricated with 3% yttrium oxide to zirconia delivered excellent hardness (1687 HV) and flexural strength (650.6 MPa). However, the relative luminescence increased with increasing the yttrium oxide for 3–5 mol%. With the optimized process parameters, the proposed dental crown is fabricated and analyzed for their shrinkage ratio, mechanical, and translucency properties. The study proposes the potential of fabricating customized dental crown with gradient translucent appearance.

Spontaneous adsorption effect of graphitic carbon nitride nanosheets to improve sintering behavior of yttria-stabilized zirconia microbeads

Yttria-stabilized zirconia (YSZ) is a ceramic material in which the zirconium dioxide structure is stabilized at room temperature by adding yttrium oxide. However, the YSZ formed by the thick film process on a pre-sintered dense substrate suffers from sintering problems such as different sintering shrinkage rates due to phase transitions and thermal conductivity. This in turn can lead to de-bonding, cracking, delamination, and abnormal growth. We prepared a spherical YSZ green body of approximately 38 μm diameter formed by an organic binder based on a sintered YSZ seed with 15 to 20 μm diameter. In addition, the application of two-dimensional g-C3N4 nanosheets that can be adsorbed on the surface and pores of the green body before the sintering process was evaluated. The YSZ green body with adsorbed surface-modified g-C3N4 nanosheets could be synthesized by stable spontaneous adsorption due to zeta-potential attraction onto the surface of zirconia particles in an aqueous solution. Consequentially, the formation of large grains due to abnormal grain growth was reduced as g-C3N4 was adsorbed. The spontaneous adsorption of nanosheets controls the surface diffusion mechanism by sequentially lowering the energy from a high surface energy in the initial stage of sintering. Uniform grain growth thus can be induced according to the activation energy level of the controlled surface diffusion.

Formation of yttrium oxalate phase filled by carbon clusters on the surface of yttrium oxide films

In the current paper, we report the results of surface modification of cubic Y2O3 films employing carbon-ion implantation. The characterization results demonstrate the formation of a stable yttrium oxalate-based structure with cavities filled with carbon clusters. Theoretical simulations demonstrate that the incorporation of eighteen-atom carbon clusters into the cavities of Y2(C2O4)3 does not lead to valuable changes in the crystal structure of yttrium oxalate. X-ray diffraction and optical measurements demonstrate that the subsurface bulk area of cubic yttrium oxide remains unperturbed. The oxalate “skin” thickness with embedded carbon clusters is estimated to be approximately 10 nm. The prospective employing the method to manage optical properties and increase the biocompatibility of yttria and lanthanide oxides are discussed.

Superlubricity of Nanocomposites of Polyaniline-Functionalized Reduced Graphene Oxide with Yttrium and Vanadium-Codoped Zinc Oxide Nanoparticles

Superlubricity of Nanocomposites of Polyaniline-Functionalized Reduced Graphene Oxide with Yttrium and Vanadium-Codoped Zinc Oxide Nanoparticles

Revealing the quantum nature of the voltage-induced conductance changes in oxygen engineered yttrium oxide-based RRAM devices

In this work, the quasi-analog to discrete transition occurring in the current–voltage characteristic of oxygen engineered yttrium oxide-based resistive random-access memory (RRAM) devices is investigated in detail. In particular, the focus of our research is not on the absolute conductance values of this characteristic but on the magnitude of its conductance changes occurring during the reset process of the device. It is found that the detected changes correspond to conductance values predominantly of the order of the quantum unit of conductance G0 = 2e2/h, where e is the electron charge and h the Planck constant. This feature is observed even at conductance levels far above G0, i.e. where electron transport is seemingly diffusive. It is also observed that such behavior is reproducible across devices comprising yttrium oxide layers with different oxygen concentrations and measured under different voltage sweep rates. While the oxygen deficiency affects the total number of quantized conductance states, the magnitude of the changes in conductance, close to 1 G0, is invariant to the oxygen content of the functional layer.

Synthesis ranges for YBaFe4O7 and its topotactic oxidation in ambient air to YBaFeIII4O8.5

Conditions for YBaFe4O7 synthesis from oxide/carbonate amorphous precursors are investigated versus temperature and partial pressure of oxygen at high-temperature equilibrium with the sample in flowing atmosphere of humidified Ar and H2 gas mixtures. Upon topotactic oxidation in ambient air of the cooled-down product, YBaFeIII4O8.5 forms in a couple of minutes. Neutron powder diffraction suggests that added oxygens enter octahedral holes in the cubic closest packing of O and Ba atoms of YBaFe4O7. Up to two oxygen atoms add to some Fe coordination tetrahedra in the kagome-like layer of YBaFe4O7 in a disordered distribution described as partially occupied crystal-structure sites. The oxidized YBaFeIII4O8.5 is metastable and decomposes at high temperatures into FeIII oxides of barium or yttrium. The synthesized YBaFe4O7 is a powerful room-temperature O2 getter that can be reverted by annealing in the above gas mixture.

Fabrication, sintering behavior and mechanical properties of calcium oxide doped yttrium oxide refractory via aqueous gel casting method

Yttrium oxide is an ideal choice for titanium aluminum alloy melting and casting, its wider use is hindered by sintering challenges and low thermal shock resistance. To address this, we propose a gel casting method for calcium oxide-doped yttrium oxide production. We pretreated yttrium oxide with phosphoric acid to prevented hydrolysis and adjusted the isoelectric point of yttrium oxide to match calcium carbonate's. Anions from calcium carbonate increased slurry solid content (up to 58 vol%) while maintaining low viscosity (57.78 mPa·s at 40 s−1 shear rate). After sintering at 1650 °C for 2 h, the material showed a flexural strength of 78 MPa, with a 90% retention rate after thermal shock test. The introduction of calcium oxide induced lattice distortion, improving mechanical properties by aiding sintering and grain boundary diffusion. XPS and STEM analysis confirmed random replacement of Y3+ by Ca2+ at the C2 position with 1 wt% doping.

Numerical Equivalence of Diabatic and Adiabatic Representations in Diatomic Molecules.

The (time-independent) Schrödinger equation for atomistic systems is solved by using the adiabatic potential energy curves (PECs) and the associated adiabatic approximation. In cases where interactions between electronic states become important, the associated nonadiabatic effects are taken into account via derivative couplings (DDRs), also known as nonadiabatic couplings (NACs). For diatomic molecules, the corresponding PECs in the adiabatic representation are characterized by avoided crossings. The alternative to the adiabatic approach is the diabatic representation obtained via a unitary transformation of the adiabatic states by minimizing the DDRs. For diatomics, the diabatic representation has zero DDR and nondiagonal diabatic couplings ensue. The two representations are fully equivalent and so should be the rovibronic energies and wave functions, which result from the solution of the corresponding Schrödinger equations. We demonstrate (for the first time) the numerical equivalence between the adiabatic and diabatic rovibronic calculations of diatomic molecules using the ab initio curves of yttrium oxide (YO) and carbon monohydride (CH) as examples of two-state systems, where YO is characterized by a strong NAC, while CH has a strong diabatic coupling. Rovibronic energies and wave functions are computed using a new diabatic module implemented in the variational rovibronic code Duo. We show that it is important to include both the diagonal Born-Oppenheimer correction and nondiagonal DDRs. We also show that the convergence of the vibronic energy calculations can strongly depend on the representation of nuclear motion used and that no one representation is best in all cases.

RESEARCH OF INJECTION METHODS FOR Y2O3 NANOPARTICLES INTO NICKEL- FREE STAINLESS STEEL DURING INDUCTION VACUUM REMELTING

Investigation of the possibility of obtaining an oxide-dispersed strengthening steel alloy based on 5 different ways of fine-dispersed strengthening particles Y2O3 injection into the liquid phase of steel Fe-13Cr (wt. %) in a vacuum. For this purpose, were conducted 5 series of experiments with different conditions and regimes. 2 series of 5 melts were carried out to evaluate the possibility of mechanical injection of yttrium oxide in the melt with different entry conditions. 3 series of 5 melts were conducted to evaluate the possibility of oxidation of metallic yttrium in the melt with the formation of yttrium oxide particles. Either melt residence or residual pressure in the furnace chamber was varied in different series. The results of ingot analysis on XRF, ICP-AES, and EDS showed that significant amounts of yttrium oxide were not injected. The method with oxidation of metallic yttrium in the melt from the reduction ofspecially added iron oxide with a concentration of 0.0552 ppm showed the best result.