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Ultrafine WC-Co cemented carbide has superior performance of high strength and high hardness, which is widely used in industrial fields. In the traditional process, high temperature carburization method is used to prepare tungsten carbide, and solid-phase mechanical milling method is used to mix grain growth inhibitor (Cr 3 C 2) and tungsten carbide, which easily lead to large WC particle size and uneven WC grain size distribution in WC-Co cemented carbide, thus affecting mechanical properties of the alloy. In the new process, based on the genetic relationship between the particle size of ammonium paratungstate and tungsten carbide, ultrafine ammonium paratungstate uniformly doped with yttrium was firstly obtained by adding a certain amount of ammonia and yttrium oxide into the ammonium metatungstate solution. Then the ammonium paratungstate was calcined to obtain yttrium-doped tungsten trioxide, which was then converted into yttrium-doped ultrafine tungsten carbide powders by introducing carbon monoxide at a low temperature. Finally, the ultrafine WC-Co cemented carbide was prepared by pressure sintering. During the neutralization and crystallization process of ammonium metatungstate solution, the yttrium-doped ultrafine ammonium paratungstate (Fischer particle size 8.4 μm) with narrow particle size distribution and regular morphology was prepared. The yttrium-doped ammonium paratungstate was calcined at 500 °C for 90 min in air atmosphere to obtain yttrium-doped tungsten trioxide powder with a Fischer particle size of 4.5 μm and narrow size distribution. Then the yttrium-doped tungsten trioxide and carbon monoxide gas were reacted at 920 °C for 3h to obtain yttrium-doped ultrafine tungsten carbide powder with a Fischer particle size of 0.32 μm and a specific surface area of 4.44 m2/g, and ultrafine WC-Co cemented carbide with tungsten carbide grain size of 0.28 μm was obtained by pressure sintering. The yttrium uniform distributed effectively inhibited the abnormal growth of tungsten carbide grains. Compared with the WC-Co cemented carbide prepared by solid-phase mechanically mixing tungsten carbide powder and chromium carbide, the yttrium-doped WC-Co cemented carbide had a smaller average tungsten carbide grain size and a more homogeneous microstructure. The prepared yttrium-doped WC-Co cemented carbide had a hardness (HRA) of 94.6, a bending strength of 4841 M, and a coercive force of 42.3 KA/c. [ABSTRACT FROM AUTHOR]

In the semiconductor industry, the long "seasoning" time required after the installation of new ceramic components in etching equipment restricts the wafer production efficiency. This study proposes a novel and practical method for the fabrication of pre-seasoned ceramics through surface modification of Y 2 O 3 ceramics. Fluorine-containing reactive vapors were produced by utilizing NH 4 F as the source. Further, the formation of yttrium oxyfluoride layers on the surfaces of Y 2 O 3 ceramics was demonstrated. The modified surface comprises a single-crystalline phase near the interface with the Y 2 O 3 substrate. The change in the composition, crystalline nature of the modified layer, and orientation relationship with the substrate were examined via transmission electron microscopy. The kinetics of the surface modification were studied for the sintered Y 2 O 3 bulk as well as for practical coatings such as plasma-sprayed or PVD coatings. The proposed surface modification approach can be used to fabricate pre-seasoned Y 2 O 3 coatings, which can significantly benefit the semiconductor industry. [ABSTRACT FROM AUTHOR]

Yttrium-containing ceramics exhibit excellent resistance to water-oxygen corrosion, making them an attractive choice as the modified matrix for SiC f /SiC composites. However, the oxidation products of yttrium-containing ceramics are complex and vary widely in performance. In this study, YSOC ceramics, which are composed of yttrium silicate, SiO 2 , and SiC, were prepared using Y 2 O 3 , SiO 2 , SiC, and Li 2 CO 3. This research investigated the effects of high temperatures, air oxidation, and water-oxygen corrosion on the phase compositions of YSOC ceramics. The influence of environmental factors on the synthesis and decomposition of yttrium silicate was analyzed. Moreover, the study explored the compatibility of different oxidation products with SiC. The results suggest that Y 2 SiO 5 and Y 2 Si 2 O 7 are formed through the low eutectic of SiO 2 , Y 2 O 3 , and Li 2 CO 3. The high SiO 2 content likely contributes to the relatively low formation temperature of Y 2 Si 2 O 7. In the oxidizing environment, Y 2 SiO 5 reacts with SiO 2 to produce Y 2 Si 2 O 7. Conversely, in the water vapor-containing atmosphere, Y 2 Si 2 O 7 undergoes hydrolysis to form Y 2 SiO 5. Y 2 Si 2 O 7 displays a reduced elastic modulus in comparison to SiC fibers and exhibits favorable physical and chemical compatibility with SiC fibers. However, the hydrolysis of Y 2 Si 2 O 7 may potentially affect the water-oxygen corrosion resistance of the ceramics. These findings will significantly advance research and enhance understanding of the water-oxygen corrosion behaviors of yttrium-containing matrix-modified composites. [ABSTRACT FROM AUTHOR]

For successful 3D printing based on stereolithography technologies, one of the most important factors influencing the success of printing is the dynamic viscosity of the prepared suspension. For the purposes of viscosity prediction at different volume fillings, two ZrO 2 powders with different yttrium content (CY3Z-RS and CY8Z-RS) with volume filling 0–40 % in two different dispersing mediums at two temperatures were investigated in this paper. The dependence of relative viscosity on volumetric filling was fitted by existing models and a new semi-empirical model based on experimental data was proposed and successfully plotted. Fitted data for all zirconia photosensitive suspensions showed a high correlation to the proposed model (R 2 from 97.02 % to 99.61 %). The model in addition to the possibilities of mathematical generalization of his prescription, introduces a fitting parameter C , which is thought to be thermodynamically influenceable and predictable. Furthermore, another key characteristic that is often neglected in rheological characterization, the stability of prepared ceramic suspensions, was verified either by rheological measurements but also by employing prospective technology based on analytical centrifuge. It was confirmed that all prepared suspensions were highly stable, and all instability indexes reached values less than 0.05. [ABSTRACT FROM AUTHOR]

This study investigated the influence of carbon source on the microstructure and water–oxygen corrosion behavior of Si–Y alloy modified SiC/SiC composites. The results indicated that incorporating a small-sized and diffusely distributed carbon source within the matrix not only facilitates the preparation of a highly dense matrix, but also enables a uniform dispersion of the reaction-generated SiC. Furthermore, with the assistance of residual Si–Y alloy, the dispersed SiC enhanced the matrix strength, leading to a stepwise fracture behavior of the composites. Yttrium silicate with a gradient structure formed around the dispersed SiC could effectively exert its water–oxygen corrosion resistance. After 100 h of water–oxygen corrosion test at 1300 °C, the flexural strength of the composites with this structure reached 416 MPa, with a retention rate of 85 %. Both bending strength and retention were found to be at a high level in the current research on matrix modification. [ABSTRACT FROM AUTHOR]

The solid solution Ba 5 In 2– x Y x Al 2 ZrO 13 (0 ≤ х ≤0.50) with hexagonal structure (space group P 6 3 / mmc) was prepared by the solid-state reaction method. The effects of isovalent Y3+-substitution on the structure, hydration, bandgap and transport properties have been investigated. The introduction of yttrium was accompanied by lattice expansion, which led to an increase in the concentration of protons during hydration. The doping did not lead to a significant increase in oxygen-ion conductivity since there was no change in oxygen stoichiometry. At the same time, doping led to an increase in ionic transport numbers due to a decrease in hole conductivity. Proton conductivity contribution and the values of proton conductivity increase with the increase in yttrium concentration. The phases with yttrium content x > 0.2 were predominant proton conductors at the temperature below 600°С under wet air. [ABSTRACT FROM AUTHOR]

Fine powders of yttrium orthoniobate activated by Eu, Sm, Tb, Er have been synthesized by the sol-gel. The synthesized powders have been calcined at different temperatures (1000, 1100 and 1180 °C). Luminescent ceramics (Y 0.96 Еu 0.01 Sm 0.01 Tb 0.01 Er 0.01)NbO 4 were prepared from fine powders by uniaxial hot pressing (UHP) via various technological modes. For the first time, the crystal structure, microstructure, spectral composition, photoluminescence properties of (Y 0.96 Еu 0.01 Sm 0.01 Tb 0.01 Er 0.01)NbO 4 ceramics have been studied depending on the temperature conditions of the synthesis of powders and UHP conditions during sintering of ceramics. The mechanical properties of these ceramics (Young's modulus, microhardness and critical stress intensity factor for the mode I K IC) have been evaluated. [ABSTRACT FROM AUTHOR]

This study systematically investigated the influence of varying yttrium(Y) additions on the interfacial reaction mechanism between the DD5 superalloy melt and Al 2 O 3 -based ceramic molds during directional solidification. The analysis revealed the formation of a complex multilayer reaction layer at the alloy-ceramic interface. The interfacial products changed from CaO·6Al 2 O 3 to a mixture of various yttrium oxides after Y was added. As the reaction time increased, the sequence of interfacial reaction products observed on the surface of Y-containing alloys progressed as follows: Y 2 O 3 , Y 4 Al 2 O 9 , YAlO 3 , and ultimately Y 3 Al 5 O 12. Increasing the Y additions promoted the formation of a reaction layer with a higher atomic percentage of Y. The interfacial reaction process between the DD5 superalloy and Al 2 O 3 -based ceramic molds involved ceramic decomposition and diffusion, Y element diffusion and displacement reactions, Al 2 O 3 dissolution and further diffusion of the Al element. This process resulted in the formation of different yttrium-aluminum oxides and related to the bidirectional erosion of the Y 2 O 3. These interfacial reactions significantly contributed to the consumption of Y element within the alloy. • Components of multilayer interfacial reaction layer varied with the Y additions. • The phases and microstructures of Y 2 O 3 , Y 4 Al 2 O 9 , YAlO 3 , and Y 3 Al 5 O 12 , were determined. • Four oxidation reaction products formed sequentially with extended reaction time. • The reaction involved dissolution, diffusion, displacement and dual erosion. [ABSTRACT FROM AUTHOR]

Yttrium orthovanadate (YVO 4), a wide-bandgap photocatalyst was tuned into a visible responsive material by anchoring an organic framework on the surface of YVO 4 nanoparticles using polyethyleneimine (PEI). The surface organic framework was identified as the decomposed PEI derivatives with the carbonyl and carboxylic acid functional groups by the FTIR and XPS analyses. The top of the valence band (VB) was raised and the bottom of the conduction band was moved down; hence, the band gap of YVO 4 was reduced to absorb the light in the visible region for all three synthesized samples, which was confirmed by DRS UV–Vis analysis. The functional groups facilitated more water molecules on the YVO 4 surface via hydrogen bonding; hence, the YVO 4 surface acquired superhydrophilicity. Among the three YI, YII, and YIII samples synthesized with three different calcination temperatures of 80, 260 and 400 °C respectively, YII showed many advantageous photocatalytic properties. The optimum loading of organic compounds obtained on YII surface at 260 °C, which improved the surface area, visible light absorption, hydrophilicity, and exciton's life. Hence, YII showed a better performance of 3.75 mmol h−1g−1 cat H 2 production than YI and YII. This work interestingly revealed the influence of calcination temperature on surface functionalization and the performance of catalytic materials. [Display omitted] [ABSTRACT FROM AUTHOR]

Micro-wave assisted combustion synthesis technique was adopted to synthesize the dysprosium-doped yttrium calcium borate xDy3+: Y (2-x) CaB 10 O 19 (Dy:YCB) polycrystalline phosphor materials with varying concentrations (x = 1, 3, 5, 7 and 9 mol %) for the first time. The formation of phase, crystal structure was analyzed by x-ray diffraction study and was affirmed to be formed pertaining to the monoclinic crystal structure (a = 11.475 Å, b = 6.345 Å, c = 9.223 Å and α = γ = 90°, β = 91.83°) with C2 space group. The absorption capability of the prepared samples was investigated by UV-DRS spectroscopy and the optical band gap was found to be 5.28 eV. FTIR study validated the presence of functional groups and their molecular vibrations. The excitation wavelength of the synthesized samples was found to be 350 nm from photoluminescence excitation (PLE) spectra. The PL emission spectra were recorded to authenticate the emission wavelengths and found to possess two emission peaks at 480 nm (blue) and 577 nm (yellow) contributed by the Dy3+ ions. The optimized dopant concentration of dysprosium ion was fixed at x = 0.07 to avoid the concentration quenching effect. The chromaticity co-ordinate of optimized sample was determined to be x = 0.3188, y = 0.3233 which are closer to ideal white light co-ordinate. The color temperature was determined to be 6209 K, which occurs in the cool white light region. Luminous efficacy of radiation (LER) was determined to be 269.31 l m/W opt for the optimal phosphor. The luminous efficiency for the optimal phosphor was determined to be 40%. Color rendering index (CRI) of the optimal sample was evaluated to be 77. Internal quantum yield (IQE) of the optimal sample was determined to be 50.58 %. The phosphor materials have excellent thermal stability as validated from the temperature dependent PL measurements. [ABSTRACT FROM AUTHOR]

The commercialization of ternary layered cathode materials with a relative nickel content of more than 90 % faces serious challenges. Among them, it is urgent to address the issues of rapid capacity degradation and structural degradation. Herein, we provide a simple process for doping yttrium at the precursor preparation stage. The feasibility of yttrium doping in the precursor and the positive effects of yttrium ions on the crystal structure and properties of the cathode materials are scientifically explained by a variety of characterization and testing methods, such as Eh-pH, Particle Size Analyzer, ICP, SEM, EDS, XRD, XPS, HRTEM, dQ/dV, CV, EIS and DFT. Yttrium-doped NCMY cathode materials have more stable lattice oxygen and significantly less irreversible phase transition. Furthermore, the electrochemical performance of the NCMY cathode material is significantly improved, with a capacity retention rate of 82.71 % after 150 cycles at a current density of 1C, which is much higher than 65.39 % for NCM. The NCMY cathode material significantly improves the lithium ion diffusion ability, especially at the high rate of 10C, the discharge specific capacity is still as high as 177.05 mAh g−1. [ABSTRACT FROM AUTHOR]

Though phase-change materials (PCMs) are regarded as constituent part of next-generation phase-change memory and other unfolding optoelectronic applications, the kinetics study of glass transition and crystallization, significant property in switching remains obscure in high-temperature region. Hence, this paper reports the investigation of glass transition and crystallization kinetics of Te (1-x) (GeSe 0.5)Y x (TGSY) chalcogenide glass using differential scanning calorimetry (DSC) at heating rates 5, 10, 15, 20 °C/min. The effect of increasing Y quantity has been described by connecting structural relaxation kinematics during glass transition phenomena and devitrification while crystallization in chalcogenide glasses with their varied physicochemical characteristics. The inclusion of Y causes a discernible rise in the crystallization rate. The system is compatible with a strong glass-forming liquid, according to the Te (1-x) (GeSe 0.5) Y x material fragility index. According to the average values of the kinetic exponent factors, there is heterogeneous nucleation for the investigated composition, which is subsequently followed by a two- or three-dimensional crystal growth phenomenon. Different glass stability criteria have been discussed based on the relationship between the characteristic temperatures. The C ZW and C LX criteria were found to be inappropriate for discussing glass stability (GS) for the studied compositions based on the heating rate and composition dependencies of all criteria. The C YL criteria of Yuan et al. is the finest and it demonstrates the optimal ability for evaluating the GS, according to the data that was extracted from several GS criteria and their relative change parameters. By adding Y, thermal stability parameter and enthalpy emitted during the transition of glass and crystalline phases have been found to have an inverse relationship. All studied properties can conclude the application of studied material in phase-change material devices. [ABSTRACT FROM AUTHOR]

Yttrium-doped barium cerate (BCY) is one of the best proton-conducting ceramics to be used in fuel cells/electrolyzers at intermediate temperatures, due to its high hydration enthalpy and high conductivity. Nonetheless, it has commonly been discarded for these applications due to its instability in the presence of carbonaceous and humidified atmospheres. A recent work has addressed this issue, by suggesting the use of this material in very low water vapor partial pressures (p H2O ∼ 10−4 atm) [ Electrochimica Acta 334 (2020) 135625 ] and at low temperatures (T ≤ 400 °C). Under these conditions, BCY can still offer pure protonic conductivity while also offering suitable stability. In the current work, we provide a comprehensive analysis of the effects of the acceptor dopant concentration (Y 2 O 3) in the structural, microstructural, and electrical properties in a wide compositional series of BaCe 1- x Y x O 3- δ (x = 0.05, 0.10, 0.20 and 0.30) at low levels of humidity in the low temperature range (100–400 °C). The results show that BaCe 0.9 Y 0.1 O 3- δ (BCY10) offers the highest bulk conductivity in these conditions, while further increase in dopant concentration leads to impairment due to " proton trapping " effects. In contrast, the specific grain boundary conductivity increases with increasing dopant concentration due to a reduction of Schottky barrier height at the space-charge layer. We demonstrate that, by operating at very low temperatures (e.g. , below 400 °C), the peak performing, BCY10 material can still operate at very low levels of water vapor partial pressure (p H2O ∼ 10−4 atm), where its stability can be maintained. This work paves the way for the optimization of this material, with a focus on utilizing low humidity levels and low temperatures, where it can offer a competitive advantage over that of the majority of other proton-conducting perovskites for potential applications operating under these conditions. [ABSTRACT FROM AUTHOR]

Yttrium vanadate (YVO 4) nanocrystals are synthesized by a modified sol-gel route followed by coupling with 4.0–16.0 wt% of cobalt ferrite (CoFe 2 O 4) nanoparticles. The synthesized heterostructures were laboured for photocatalytic H 2 generation in a water/glycerol system below visible light in the presence of platinum cocatalyst traces. The addition of CoFe 2 O 4 nanoparticles has improved the physicochemical characteristics of YVO 4 in terms of light harvesting and photoinduced charge separation. The 12.0 wt% CoFe 2 O 4 /YVO 4 indicates the narrowest bandgap of 2.5 eV and the highest visible-light activity with a slight reduction of its surface area from 185 to 168 m2 g−1. Moreover, the H 2 evolution rate has augmented utilizing this photocatalyst at 2.557 mmol g−1h−1 compared to 0.044 mmol g−1h−1 over the pure YVO 4. Furthermore, the dose optimization of 12% CoFe 2 O 4 /YVO 4 at 2.0 gL−1 has endorsed the photocatalytic generation of H 2 to 3.389 mmol g−1h−1 with recyclability of 97% after the fifth cycle. [Display omitted] [ABSTRACT FROM AUTHOR]

Hematite has the advantages of a suitable band gap, high stability, low cost, and environmental protection, and is considered as one of the most ideal photocatalytic semiconductors in the field of iron-based. In this experiment, pure α-Fe 2 O 3 and Fe 2 O 3 nanoparticles doped with yttrium ion (xY-Fe 2 O 3 , x = 0.1, 0.4, 0.7, 1.0, and 1.3%) alone were prepared by a simple and environmentally friendly hydrothermal method to investigate the photocatalytic degradation efficiency of pure and different concentrations of doped α-Fe 2 O 3 for MB dyes. The synthesized products were further confirmed and the photocatalytic performances of pure and single-doped specimens were assessed by XRD, SEM, XPS, FT-IR, UV–vis, and PL. The prepared nanospheres were found to be around 100 nm by SEM test. With the increase of yttrium concentration, the band gap of the specimens reduced from 2.09 to 2.07 eV, and the degradation rate added from 53.8% to 74.1%. The doping of 1.0% yttrium ions significantly affected the photocatalytic performance of α-Fe 2 O 3. This is due to the result that the doping of yttrium ions generates additional impurity energy levels, decreases the band gap, and causes a significant decrease in the complexation rate of α-Fe 2 O 3 photogenerated electron-hole pairs, improving the carrier generation and transport. In addition to this, the probable mechanism for the improved photocatalytic properties is discussed and analyzed. [ABSTRACT FROM AUTHOR]

As the rate of application of multilayer ceramic capacitors (MLCCs) in small electronic devices increases, the use of the raw material barium titanate (BaTiO 3) with a small particle size and excellent dielectric properties becomes needed. Due to the size effect, small-sized BaTiO 3 generally has a cubic phase structure with a low dielectric constant, which limits its use in MLCCs. We report the preparation of small cubic phase Y-doped BaTiO 3 (BYT) nanoparticles by a hydrothermal method and the preparation of highly dielectric tetragonal phase BYT ceramics based on this method. XRD and Raman analysis showed that the BYT nanoparticles are in substable cubic phases. The particle size of the BYT nanoparticles, measured by TEM, XRD, and BET, was approximately 35 nm. The dielectric properties of the BYT ceramics were tested by an impedance analyzer, and the dielectric constant of the BYT ceramics was 7547 when the Y3+ doping amount was 0.5 mol%. In addition, the substitution mechanism of Y3+ doping in BaTiO 3 crystals was proposed from XPS and EPR analysis. The results demonstrate for the first time that the 50 nm cubic phase BaTiO 3 powder can meet the needs of next-generation high-capacity MLCCs. This work provides a reference for small cubic phase BaTiO 3 as a dielectric material for high-capacity MLCCs. • Y-doped BaTiO 3 nanoparticles with different yttrium concentrations are prepared by a one-step hydrothermal method. • Y ion doping can accelerate the transformation of BYT ceramics from the cubic phase to the tetragonal phase. • The dielectric constant of BYT ceramics is comparable to that of BYT ceramics prepared by the solid-phase method. [ABSTRACT FROM AUTHOR]

In this study, self-healing and failure behavior of yttrium silicate (YS)-coated silicon carbide fibers-reinforced silicon carbide matrix (SiC f /SiC) composites were systematically investigated at temperatures ranging from 1000 to 1400 °C for 100 h in air. The self-healing mechanism involves the filling of cracks with SiO 2 glass and Y 2 Si 2 O 7 (oxidation product). The three-point bending strength of samples before and after oxidation was determined in order to clarify the self-healing performance. The strength and strength retention of YS-coated SiC f /SiC composites after oxidation were consistently higher than those of the oxidized SiC f /SiC composites. The strength retention rate of YS-coated SiC f /SiC composites was found to be 110% at 1100 °C, while the corresponding value for SiC f /SiC composites was only 68%. According to the Deal and Grove oxidation kinetic model, the oxidation activation energy of YS-coated SiC f /SiC composites was ∼377 kJ mol−1, which is higher than that of SiC f /SiC composites (306 kJ mol−1). These results indicate that the YS coating can protect SiC f /SiC composites in oxidizing environments. Moreover, the degradation mechanisms of YS-coated SiC f /SiC composites were expounded by finite element analysis. [ABSTRACT FROM AUTHOR]

The polished surfaces of yttrium aluminium garnet (YAG) polycrystalline ceramics were scratched at different depths to study the material-removal mechanism. The results showed that the material-removal mode was divided into three stages at increasing scratch depths. First, at shallow depths, the etching groove was completely plastic, the surface was uniform and smooth, and no cracks occurred, indicating the ductile removal. Second, with an increase in the scratch depth, the material-removal mode not only peeled off on the edge of the scratch groove but also produced a smooth groove surface with a tear, causing a radial crack at an angle of 30°. A brittle morphology began to form at this angle and plastic brittleness occurred. Finally, in the third stage, the range of brittleness phenomena including notch fracture, radial crack propagation, transverse crack interweave, scratch groove twist and tear, large-scale scaly spalling, and brittle fracture were gradually revealed due to the orange-peel effect unique to polycrystalline materials. Ultimately, by combining the fracture on the grooved surface, crack propagation form, and scratching force, the critical removal depth of the YAG polycrystalline ceramic material was obtained. YAG polycrystalline ceramic materials with high surface quality and ductility removal were achieved, thereby providing a theoretical basis for determining the process parameters of ultra-precision grinding. [ABSTRACT FROM AUTHOR]

The present work proposes a new method for fabrication partially stabilized porous zirconia ceramics using monoclinic zirconia as raw material, yttrium nitrate and magnesium compounds as pore-forming agents and stabilizers. Effects of different pore-forming agents, firing temperatures and firing time on properties of samples were investigated. Thermal decomposition of yttrium nitrate and magnesium compounds creates a large number of pores, and thus porous zirconia ceramics were fabricated. ZrO 2 can be partially stabilized by Y 2 O 3 and MgO derived from the precursors. The porous ZrO 2 ceramics obtained by using Y(NO 3) 3 ·6H 2 O and 4MgCO 3 ·Mg(OH) 2 ·6H 2 O as pore-forming agents had relatively high stabilization ratio, uniform pores and high strength. The optimum firing temperature and firing time are 1400 °C and 3 h, and the samples have the stabilization ratio of 45.7%, high cold crushing strength (26 MPa), uniform pores, and apparent porosity is about 40%. [ABSTRACT FROM AUTHOR]

Vacuum induction melting is a potential process for the preparation of TiAl alloys with good homogeneity and low cost. But the crucial problem is a selection of high stability refractory. In this study, a BaZrO 3 /Y 2 O 3 dual-phase refractory was prepared and its performance for melting TiAl alloys was studied and compared with that of a Y 2 O 3 refractory. The results showed the dual-phase refractory consisted of BaZr 1- x Y x O 3-δ and Y 2 O 3 (ZrO 2), exhibited a thinner interaction layer (30 μm) than the Y 2 O 3 refractory (90 μm) after melting the TiAl alloy. Although the TiAl alloys melted in the dual-phase and Y 2 O 3 refractory exhibited similar oxygen contamination (<0.1 wt%), the alloy melted in the dual-phase refractory had smaller Y 2 O 3 inclusion content and size than that in the Y 2 O 3 refractory, indicating that the dual-phase refractory exhibited a better melting performance than the Y 2 O 3 refractory. This study provides insights into the process of designing highly stable refractory for melting TiAl alloys. [ABSTRACT FROM AUTHOR]

Co 0.5 Cu 0.25 Zn 0.25 Y x Fe 2-x O 4 ; (0≤x≤0.1; step 0.02) (CCZY) spinel ferrites were prepared by citrate technique. The prepared CCZY samples have crystallite sizes ranging from 21 to 34 nm. The nanoscale nature of the samples was, also, established by HRTEM micrographs. Even though the substitution route here involves the replacement of magnetic ions Fe3+ by a non-magnetic one Y3, the magnetization of CCZY nanoparticles did not show a continual decrease as expected. The nanoferrite Co 0.5 Cu 0.25 Zn 0.25 Y 0.06 Fe 1.94 O 4 , has a moderate value of saturation magnetization 63.45 emu/g (decreased with 11.55% than the pristine sample) and higher coercivity 416.44 Oe (increased with 21.83% than the pristine sample), which may be a suitable candidate for data storage applications. All CCZY nanoferrite have direct optical band gap within the range 1.57 eV–1.50 eV; which doesn't introduce a regular behavior with Y/Fe substitution process. Distinctively, the MB dye removal shows an optimum value with the nanoferrite CCZY (0.1), which gives a degradation efficiency of 95% after 60 min only. The outstanding increase in catalytic performance of the nanoferrite CCZY (0.1) was correlated with the size factor and saturation magnetization. The desirability function approach enabled to distinguish the optimal material (CCZY (0.1)) with the superior catalytic performance; the smallest size and convenient magnetic properties. Hence, the nanoferrite Co 0.5 Cu 0.25 Zn 0.25 Y 0.1 Fe 1.9 O 4 can be utilized efficaciously for water treatment, via the safe photocatalytic process; without sabotaging the environment. [ABSTRACT FROM AUTHOR]

The current study reports the fabrication of (1- x) Y 3 Al 5 O 12 / x LaPO 4 (x = 0, 0.1, 0.2, 0.3, 0.4) composites and their evaluation against molten V 2 O 5 corrosion at 900 °C and 1000 °C for 20 h. The phase compositions and microstructures of the samples were analysed using X-ray diffraction (XRD) spectroscopy, as well as scanning electron microscopy (SEM), both before and after the corrosion tests. The yttrium aluminium garnet (Y 3 Al 5 O 12 , YAG) was easily corroded by molten V 2 O 5 , with the primary product being YVO 4. While LaPO 4 exhibited perfect resistance to the molten V 2 O 5 corrosion, it was ineffective at improving the corrosion resistance of the YAG/LaPO 4 composite materials. However, the LaPO 4 /YAG double layers materials prepared with LaPO 4 coated on the surface of YAG exhibit excellent resistance to molten V 2 O 5 , owing to the formation of the P diffusion layer at the interface between the LaPO 4 and YAG, which acts as a sealing layer, preventing the molten V 2 O 5 from penetrating. [ABSTRACT FROM AUTHOR]

Understanding and optimization the rheological properties characterization of zirconia (ZrO 2) based ceramics inks is critical for optimizing the production of Direct Ink Writing (DIW) components to achieve complex structures with similar properties as those obtained by using the traditional processing routes. In this work, ZrO 2 based ceramic materials with different yttrium contents (3 and 8 mol %) were designed and produced by DIW to determine the most suitable ceramic ink composition in terms of the rheological properties (e.g. flow curves, viscosity, loss modulus G′, storage modulus G″, etc.) to design new components. Different ceramic inks with charges up to 75 wt % were prepared and characterized. A systematic study of the feedstock, as well as the different ceramic inks, was performed to determine the optimal ceramic charge. This characterization evidences that rheological properties of zirconia based ceramic inks are influenced by the particle size and amount of ceramic content. Furthermore, the rheological study highlights that the ZrO 2 inks present a Non-Newtonian behavior depending on the ceramic content. Results revealed that the yttrium content affects the flow properties of ZrO 2 suspensions in such a way that, higher shear rate was required to make the suspensions flow at increasing the amount of powder. It was also found that the best rheological properties corresponded to 73 and 70% for the 3Y- and 8Y–ZrO 2 of ceramic charge, respectively. [ABSTRACT FROM AUTHOR]

Yttrium aluminium garnet (YAG) is a promising topcoat material for thermal barrier coatings due to its high temperature stability and better CMAS (calcium-magnesium-alumino-silicate) resistance. YAG topcoats were deposited by suspension and solution precursor high-velocity oxy-fuel (HVOF) thermal spray. The relationships between processing, microstructure and final properties were studied through a range of characterization techniques and thermal cycling tests. The microstructure of the as-sprayed YAG topcoat from stoichiometric solution precursor (SP-YAG) had distributed pores and inter-splat boundaries, while the as-sprayed topcoat produced from suspension (S-YAG) had vertical and branched micro cracks, pores, and inter-splat boundaries. Both as-sprayed coatings were composed of amorphous phase, hexagonal yttrium aluminium perovskite (YAP) and cubic YAG. In thermal cycling tests, 20% of SP-YAG failure was reached after the 10th cycle; whereas, S-YAG reached the failure criteria between the 60th and 70th cycle. The failure of both the SP-YAG and the S-YAG topcoats occurred due to thermal stresses during the thermal cycling. [ABSTRACT FROM AUTHOR]

The internal gelation process without cooling at room temperature is a significant challenge for the preparation of yttria-stabilized zirconia (YSZ) ceramic microspheres. In this work, a high-throughput and instant-mixing droplet microfluidic system that can prepare monodisperse YSZ ceramic microspheres was constructed. It mixed two stable solutions at room temperature in an active micromixer at a flow rate of mL/min, and then the mixed unstable precursor solution was quickly dispersed into sol droplets through a coaxial microfluidic device, and the droplets solidified into gel microspheres. The washed and dried gel microspheres could be sintered to obtain ceramic microspheres. Compared with no-micromixing and T-junction micromixers, the system had the best mixing performance and Y and Zr elements in the prepared ceramic microspheres were evenly distributed. Therefore, the system overcame the problem of precursor solution solidification and clogging of the device, and provided a new approach for the internal gelation process without cooling at room temperature. [Display omitted] • A new high-throughput and instant-mixing droplet microfluidic system for the preparation of monodisperse ceramic microspheres is proposed. • The system can work continuously at a flow rate of mL/min for more than 15 h without clogging for preparation of yttrium stabilized zirconia microspheres. • Compared with no-micromixing and T-junction micromixer, the system has the best mixing performance. • The system provides a new idea for preparing ceramic microspheres by the internal gelation process at room temperature. [ABSTRACT FROM AUTHOR]

This work aims to fully analyze the luminescence spectra and time response properties of LYSO:Ce (Lu 2-2x Y 2x SiO 5 :Ce) scintillation crystals with different Y contents. The photoluminescence excitation (PLE) and emission (PL) spectra of Ce1 and Ce2 luminescence centers in LYSO:Ce crystals with different Y contents have been systematically examined. The shape of photoluminescence emission spectra and the contribution of the energy transfer process between Ce1 and Ce2 have been varied with the yttrium content in the crystal. Based on the photoluminescence and scintillation decay time measurements, a table has been shown to provide the relationship between the decay time and Y content in the crystal. Meanwhile, the afterglow measurements demonstrate the relationship between long-lived delay recombination processes and the free carrier traps existing in the bandgap, and the source of afterglow has been analyzed. [ABSTRACT FROM AUTHOR]

New substitutional, limited solid solution of the formula Y 8-y Yb y V 2 O 17 where 0 < y ≤ 2.0 was synthesized by the high-temperature reaction in the air from mixtures of α-Y 8 V 2 O 17 with Yb 8 V 2 O 17. The new Y 8-y Yb y V 2 O 17 were characterized by powder XRD, DTA–TGA, IR, UV–vis-DRS and SEM methods. The structure, thermal stability, unit cell volume, band gap energies as well as the position of the IR absorption bands in the spectrum of Y 8-y Yb y V 2 O 17 were determined. The solid solution was established to have the same structure as β-Y 8 V 2 O 17 and it was found that with increasing concentration of Yb3+ ions in its crystal lattice the volume of its unit cell decreases along with its energy gap decreasing to 2.4 eV (for y = 2.0), while the IR absorption bands are shifted towards higher wavenumbers. The morphologies of the high temperature polymorph of Y 8 V 2 O 17 and solid solution were analyzed. [ABSTRACT FROM AUTHOR]

Yttrium stabilized zirconia (YSZ) used as the state-of-the-art electrolyte for solid oxide fuel cells (SOFCs) requires high temperature (over 800 °C) to realize sufficient oxygen ion conductivity. Thus, the high operational temperature is the main restriction for the commercial process of YSZ-based SOFCs. To obtain decent ionic conductivity at intermediate-low temperatures, Sr-free cathode LaNiO 3 is introduced into YSZ to construct a novel LaNiO 3 -YSZ composite electrolyte, which is sandwiched by two Ni 0.8 Co 0.15 Al 0.05 LiO 2-δ (NCAL) electrodes to assemble systematical fuel cells. This device presents an excellent peak output of 1045 mW cm-2 at 600 °C and even 399 mW cm-2 at 450 °C. A series of characterizations indicates that the oxygen ion conductivity of the LaNiO 3 -YSZ composite is significantly promoted in comparison with that of pure YSZ, and the LaNiO 3 component has certain proton conductivity after hydrogenation. Both of the two factors contributes to the superior performance of such devices at intermediate-low temperatures. Furthermore, the sharp decrease in electronic conductivity for LaNiO 3 in hydrogen atmosphere combined with Schottky junction at the anode-electrolyte interface eliminates the short-circuiting problem. Our work demonstrates that incorporating Sr-free cathode LaNiO 3 into the YSZ electrolyte is an efficient strategy to boost the performance and reduce the operational temperature of YSZ-based SOFCs. [ABSTRACT FROM AUTHOR]

The effects of Yttrium-doped Barium Zirconate (BZY) synthesis steps by solid-state reaction and the number of starting reactants (2 or 3) on the characteristics of the synthesized ceramic powders were investigated. The slow diffusion rate associated with this synthesis route and the calcination steps used in this work lead to an incomplete synthesis reaction. This condition proved to be useful to improve densification during sintering for undoped samples by emulating the reactive sintering technique with transient reactions originating from the residual BaCO 3 reactant. The effects of a low concentration (1 mol%) of ZnO as sintering aid on microstructure and electrical conductivity were also investigated and used for comparison to undoped samples. Electrical properties were analyzed and correlated with microstructural and compositional characteristics. Dense undoped BZY samples (99% of relative density) with high proton conductivity (2.4 × 10 − 2 S/cm at 600 °C) were obtained by sintering at 1500 °C, while ZnO-doped samples achieved high relative density (97%) at only 1300 °C, but with lower electrical conductivity (7.8 × 10 − 3 S/cm at 600 °C). Image 1 • BZY was synthesized by solid-state reaction route using 2 or 3 reactants: BaCO 3 and 10YSZ or BaCO 3 , ZrO 2 , and Y 2 O 3. • Solid-state reactive sintering was achieved without sintering aids due to the presence of residual BaCO3 reactant. • Undoped BZY samples achieved high densities (99% of relative density) by traditional sintering at 1500 °C. • Characteristics of undoped samples were compared to samples with ZnO as sintering aid. • Undoped BZY samples presented high proton conductivity at 600 °C (2.4 × 10 − 2 S / c m). [ABSTRACT FROM AUTHOR]

Polymer-derived Silicon oxycarbide (SiOC) and yttrium-containing silicon oxycarbide (SiYOC) ceramics were obtained in the present work. To investigate their high temperature behaviors in low pressure atmosphere, these ceramics were further annealed at 1200 °C, 1300 °C, 1400 °C, and 1500 °C. The structure evolutions of SiOC and SiYOC ceramics through heat-treatment were studied. It was found that the carbothermal reductions of SiOC ceramics were activated at 1400 °C and almost finished at 1500 °C. The introduction of Y element played a major role on high temperature stability by influencing the structure evolution of SiOC and hindering the carbothermal reductions. The results show that introducing yttrium to modify the SiOC structure should be an effective way to enhance the thermal stability of SiOC ceramics. [ABSTRACT FROM AUTHOR]

Based on the minimum Gibbs free energy principle, thermodynamic calculations of the Y 2 O 3 –CH 3 SiCl 3 –CO 2 –H 2 -Ar system are carried out using FactSage software. Moreover, the influences of deposition temperature, total pressure, the H 2 dilution ratio, and the molar ratio of reactants on thermodynamic phase diagrams and product yield diagrams of the Y 2 O 3 –CH 3 SiCl 3 –CO 2 –H 2 -Ar system have been systematically investigated. Subsequently, based on the calculation results, the X1-Y 2 SiO 5 and β-Y 2 Si 2 O 7 phases are successfully deposited at a lower deposition temperature of 1100 °C, system pressure of 2 kPa, CH 3 SiCl 3 flow rate of 39 mL/min, H 2 dilution ratio of 9, and n (CO 2)/ n (H 2) ratio of 3:10. In addition, NMR results revealed the molecular structure of the as-deposited yttrium silicate coating, and scanning electron microscopy, which was used for morphological analysis, confirmed the dispersion of yttrium silicate particles in the SiC layer. [ABSTRACT FROM AUTHOR]

Ceramic pigments based on chromium-doped yttrium aluminate (YAl 1-X Cr X O 3 ; x = 0.01; 0.03 and 0.05 mol%) were obtained by using chemical combustion method. Chemical processes with and without the use of mineralizers were employed. The modifications in the structure, morphology, optical and thermal properties caused by the inserted agents in the aluminate network were investigated by means of the following techniques: X-ray diffraction (XRD), Rietveld refinement, diffuse reflectance spectroscopy in the ultraviolet–visible region (UV–Vis), Fourier-transform infrared (FTIR) spectroscopy, field emission gun scanning electron microscopy (FEG-SEM), and CIELab colorimetric coordinates. The pigments were applied to ceramic pieces and the color stability was evaluated. XRD patterns results coupled with Rietveld refinement analyses showed a pronounced phase evolution for the samples containing mineralizers. This confirmed the effectiveness of these constituents for the formation of yttrium aluminate perovskite phase. The UV–Vis spectra showed greater reflectance in samples without mineralizers, while FTIR spectroscopy Analysis showed bands of vibration related to Al3+ coordinated octahedrally for both systems. Samples with the presence of mineralizer agents showed morphology similar to a cube with the presence of primary aggregated particles as revealed by FEG-SEM. The colorimetric pigments data showed values of the a* coordinate, which is related to red color components. This value was higher for the powder in the system with mineralizers as well as in the pigments that were employed on the ceramic pieces. [ABSTRACT FROM AUTHOR]

The associated impurity phases derived from the introduction of vanadium ions in yttrium gallium garnet (YGG) were investigated in detail. The XRPD data indicate that β -Ga 2 O 3 is contained in all synthesized samples and YVO 4 can be identified when the V-doped concentration above 0.5 at. %. The existence of β -Ga 2 O 3 is related to the antisite defects usually contained in the garnet host, and the generation of YVO 4 is mainly derived from its lower formation temperature in comparison to the garnet phase. The micro-area composition analysis further verifies the existence of impurity phases, and the X-ray computed tomography survey provides a more visualized spatial distribution of the YVO 4 phase. Moreover, the fluorescence analysis manifests a more sensitive phase identification than the XRPD technique, and the YVO 4 impurity phase can be detected even if the V-doped content is reduced to 0.2 at. %. Additionally, the evaluated V/(V + Y + Ga) ratios from structure refinement coincide well with the theoretical value in the low-doping section, and the slight deviation in the high doping part is mainly attributed to the volatilization of vanadium oxides. What discussed in this study offers a comprehensive analysis strategy for the detection of impurity phases originating from ion doping. [ABSTRACT FROM AUTHOR]

YBCO fabrics composed of nanowires, produced by solution blow spinning (SBS) are so brittle that the Lorentz force produced by induced currents can be strong enough to damage them. On the other hand, it is known that silver addition improves the mechanical and flux pinning properties of ceramic superconductors. Thus, in this work, we show how we successfully obtained a polymeric precursor solution containing YBCO + Ag salts, which can be spun by the SBS route to produce ceramic samples. Yttrium, barium, copper, and silver metal acetates, and polyvinylpyrrolidone (PVP) (in a ratio of 5:1 wt [PVP:acetates]) were dissolved in a solution with 61.5 wt% of methanol, 12 wt% of propionic acid, and 26.5 wt% of ammonium hydroxide, together with 6 wt% of PVP in solution. Three different amounts of silver (10 wt%, 20 wt%, and 30 wt%) were used in YBa 2 Cu 3 O 7− x. The TGA characterizations revealed a lowering of crystallization and partial melting temperatures by about 30 °C. SEM images show that after burning out the polymer, a fabric composed of nanowires of diameters up to 380 nm is produced. However, after the sintering process at 925 °C for 1 h, the nanowires shrink into a porous-like sample. [ABSTRACT FROM AUTHOR]

Resistive RAM (ReRAM), which uses the anion-based resistive switching characteristic of transition metal oxide, is one of the strong candidates for next-generation non-volatile memory. The resistance switching characteristics depend on oxygen defects and their electrochemical migration. This study systematically investigated the Y3+ doping effect in CeO 2 resistive switching behavior to control oxygen vacancy. The resistive switching devices of Ce 1-x Y x O 2-y (CYO) (x = 0, 0.05, 0.1, 0.15, and 0.2) were fabricated by the photochemical metal-organic deposition method, which could successfully obtain directly patterned CYO films. The XRD pattern and Raman spectrum confirmed that the lattice shrink and structural distortion was induced and increased gradually by increasing the oxygen vacancy concentration with yttrium content. All the CYO devices showed bipolar filament-type resistive switching, and both resistance of the pristine state and forming voltage decreased with increasing Y content from an increase in oxygen vacancy concentration. And the on/off ratio decreased with increasing Y content because of reduced HRS resistance, even after the recovered insulation oxide region by HRS switching, due to fixed defect sites with trapped electrons formed by yttrium. And with a SPEM experiment, we found that ceria loses 24% oxygen for LRS resistive switching, which induced a resistance change of about five orders of magnitude. [ABSTRACT FROM AUTHOR]

The 10 nm thick yttrium doped hafnium oxide (Y:HfO 2) thin films, prepared by chemical solution deposition which using all-inorganic aqueous salt reagents, were fabricated on Si (100) substrates. The crystalline structure, chemical composition and ferroelectric properties of thin films, annealed in protection atmosphere of Air, Ar and N 2 , were examined. Result showed that the crystalline structure and ferroelectric properties of films exhibited a strong annealing protection atmosphere dependence. When compared to annealing protection atmosphere of Air and Ar, the films with the N 2 exhibited lowest m-phase fraction of 19.4%, and the highest oxygen vacancy percentage content of 3.06%, accompanied with the highest relative permittivity of 50.9 and the remanent polarization of 14.6 μC/cm2. These excellent ferroelectric properties were correlated with asymmetric orthorhombic phase and the concentration of oxygen vacancy introduced from the nitrogen doping concentration. [ABSTRACT FROM AUTHOR]

The yttrium substituted cadmium ferrites having composition Cd 1-x Y x Fe 2 O 4 (X = 0.00, 0.125, 0.250, 0.375, 0.500) were synthesized by the co-precipitation method and sintered at 1100 °C for 6 h. Structural, morphological, electrical, optical and dielectric characteristics were explored by XRD, SEM, EDS, FTIR, I–V two probes, UV–Vis and LCR techniques.XRD results confirmed the cubic structure of spinel ferrites. A decrease in lattice constants of the prepared samples was observed with the substitution of Y ions and was attributed to the difference in ionic radii of Y3+ (0.95 Å) and Cd2+ (0.97 Å) ions. Cationic distributions, ionic radii of both tetrahedral and octahedral sites, tolerance factor, oxygen positional parameters, bond lengths, interatomic distances, positional parameters and bond length angles were calculated from XRD data. The morphology of the prepared ferrites was studied using SEM and results ratified the XRD results. EDS confirmed the presence of all inserted elements in Cd 1-x Y x Fe 2 O 4 composition. DC resistivity and drift mobility of soft-ferrites were found to be increased from 1.047 × 108–4.822 × 1010 Ω-cm and 5.87 × 10−12 – 1.045 × 10−14 cm2V−1s−1, respectively, at 523 K with yttrium content confirming the behavior of semiconductor materials. The optical band gap energy calculated from the UV–Vis pattern of the Cd 1-x Y x Fe 2 O 4 system was decreased from 3.6011 to 2.8153 eV. DC resistivity and optical band gaps exposed inverse relation. FTIR results revealed lower and upper-frequency absorption bands in the ranges of 419.31–417.01 cm−1 and 540.95–565.70 cm−1, respectively. Dielectric constant and dielectric losses were in decreasing order, while ac conductivity revealed rising behavior with increasing frequency. Results showed the potential of yttrium doped Cd nanoferrites for applications in high-frequency microwave absorbing devices. [ABSTRACT FROM AUTHOR]

Y 2 O 3 -Al 2 O 3 -SiO 2 (Y-Al-Si-O, YAS) glass is a highly promising material offering resistance against calcium magnesium aluminosilicate (Ca-Mg-Al-Si-O, CMAS) corrosion, and it is an excellent candidate for environmental barrier coating (EBC). In this study, influence of composition on YAS glass properties and CMAS corrosion resistance at 1300 °C was investigated, and the result indicated that most sets of YAS glass possessed the superior CMAS resistance than yttrium disilicate. The increase of Y 2 O 3 content and decrease of Al/Si ratio both resulted in a higher nucleation rate during heating. Moreover, when YAS was subjected to the molten CMAS corrosion, two types of corrosion restraining behaviors were observed. One is the generation of anorthite layer on YAS with high-optical basicity, and the recession depth becomes less than that of yttrium disilicate. Stacking of anorthite grains obstructs the diffusion of Y to the corrosion front, which inhibits the corrosion. The other mechanism involves the generation of calcium yttrium cyclosilicate layer at ~1270 °C first on YAS with low-optical basicity. Next, with the increase in the temperature, the reaction changes to generate an amorphous phase. Moreover, the layer acts as a barrier to restrain the corrosion. Furthermore, the difference between the two corrosion behaviors was explained based on the optical basicity (OB) theory calculation, and a YAS composition region with excellent resistance toward CMAS corrosion was predicted. The region with an OB higher than that of CMAS shows superior CMAS resistance, in particular, for the portion with a lower difference in values of OB between the two substances. [ABSTRACT FROM AUTHOR]

Porous anodic aluminum oxide templates with average pore size of approximately 100 nm were synthesized by two step anodization processes. Pure and Yttrium substituted BiFeO3 nano-structures with different concentrations were hydrothermally grown on anodic aluminum oxide templates to explore its various physical properties. X-ray diffraction was employed to extract the crystallographic information revealed the formation of rhombohedral geometry with R-3c space group. Field emission scanning electron microscopy displayed the filling up of pores with growth of distorted diamond and flakes like BiFeO 3 and Yttria enriched nanostructures, respectively. Energy dispersive X-ray spectroscopy was confirmed the presence of expected elemental contents in each template. UV–Vis spectrophotometry recorded a significant increment in optical absorption of AAO template with growth of nanostructures. The value of optical band gap was found to decrease from 2.49 eV to 2.02 eV with incorporation of metallic yttrium content. Dielectric permittivity was found to increase substantially from 19 to 159 in Yttria containing nano-flakes with comparatively low loss factor of 0.84 disclosed these templates as prominent candidate for energy storage applications. [ABSTRACT FROM AUTHOR]

In order to obtain high-quality superalloy castings, the wettability and interactions between superalloy melts with various Y contents and SiO 2 -based ceramic cores were investigated at 1823 K. The results indicated that the wettability and interface reactions were affected by the content of Y in the alloy. For the alloys with Y content less than 0.011 wt%, no Y-oxide was found at the interface, but HfO 2 , Al 2 O 3 and ZrO 2 phases were formed, and the wetting angle dropped slightly. However, different Y-oxides precipitated at the alloy-ceramic interface for the alloys with Y content more than 0.017 wt%, and the wetting angle dropped sharply. When the content of Y was 0.017 and 0.025 wt%, Al 2 O 3 , Y 3 Al 2 (AlO 4) 3 , HfO 2 and ZrO 2 phases were formed at the interface. When the content of Y was 0.1 wt%, YAlO 3 , Y 3 Al 5 O 12 , Y 4 Al 2 O 9 , HfO 2 and ZrO 2 phases were formed. The formation of different reaction products was mainly caused by the change of Y activity (a Y) in the alloy. The reaction between Y and SiO 2 could improve the wettability of the system apparently. [ABSTRACT FROM AUTHOR]

Yttrium silicate powders were synthesised through acid catalysed sol-gel route using Y(NO 3) 3.6H 2 O and tetra ethyl ortho silicate (TEOS) as precursors. The crystallographic phases evolved from the prepared gel on calcination at 1100°C were correlated with the experimental parameters used for synthesis. The optimised experimental condition resulted in well defined and crystallised phases of Yttrium disilicate (YDS), yttrium monosilicate (YMS) and biphasic mixture (YDS + YMS) powders on calcinations to 1100°C to 1500°C for 2 h. Surface morphology and structure of the final powders were investigated by XRD, SEM, particle size analysis, FTIR and Raman spectroscopy. The powders show particle size in the range 0.8 μm to 10μm. The YDS, YMS and YDS + YMS powders were pelletised and sintered at 1400°C for 2 h leading to 83 ± 1% dense products. [ABSTRACT FROM AUTHOR]

In this paper, an experimental study has been performed on failure analysis of cermet coatings thermally sprayed on X2CrNiMo-17-12-2 stainless steel using a high-velocity oxy-fuel (HVOF) technique. A comparative study was carried out to investigate the microstructural, mechanical and tribological properties of pure and ceramic-reinforced WC–10Co4Cr cermet coatings. Two different feedstocks i.e. Yttrium-III (Yttria) and Zirconium-IV (Zirconia) were used to develop two different ceramic-reinforced WC–10Co4Cr powders. Tribological properties were tested with the help of laboratory scale pot tester. Coal ashes (i.e., fly ash and bottom ash) were used as the erodents. Different parameters like velocity, time, concentration of particles, and impact angle were varied during the tribological experiments. The microstructural analysis reveals the interlocked lamellae splats, pores and unmelted particles on the as-sprayed surfaces. Yttria reinforced WC–10Co4Cr coating exhibit superior tribo-resistance and mechanical properties. The zirconia reinforced WC–10Co4Cr coating has shown good wear resistance in fly ash slurry which possesses a weak acidic nature (pH = 6.32–6.09 for concentration range of 30–60 wt%). Microhardness of WC–10Co4Cr cermet was also improved with the addition of Yttria. The erosion mechanisms were analyzed by using backscattered X-ray scanning electron microscope (SEM), interactive 3D surface plots, and 2D pseudo-images. [ABSTRACT FROM AUTHOR]

FeAl coatings with yttrium (Y) doping were prepared at 600 °C on pure iron. The anti-flaking properties of Al 2 O 3 -oxide films at 1000 °C oxidation was improved significantly by Y doping in FeAl coatings. The spallation was 0.47 mg/cm2 for 200 h of oxidation and only ~1/6 of that without Y. The first principle calculation results demonstrate that the interfacial bond strength were enhanced with Y doping, that is because Y substituted primarily in the Al 1 and Al 2 position at the Al 2 O 3 /FeAl interfacial zone as the most negative interfacial cohesive energy of −13.94 eV and −12.72 eV. Remarkably, it is found that the maximum tensile strength of Y–FeAl/Al 2 O 3 reaches to 20.48 GPa on uniaxial tensile strain, which is 1.33 times than that of FeAl/Al 2 O 3 interface (15.36 GPa). Meanwhile, compared with a pure interface, Y doping would change ductile fracture on the Al 2 O 3 /FeAl interface as the strain was enhanced significantly by 49.12%. The bond length of the Al 1 –Y showed little change under external stress, which resulted in an increase in bonding strength of the Al 2 O 3 /FeAl interface and the inhibition of the generation and propagation of micro-cracks. The formation of a YAlO 3 layer induced a release of thermal stress at the Al 2 O 3 /FeAl interface. Due to the improvement of interfacial strength, the enhancement of interfacial toughness and the formation of a YAlO 3 stress-release layer between the Al 2 O 3 film and FeAl coating, therefore, Y doping can significantly improve the anti-flaking performance of the Al 2 O 3 -oxide films in high temperature oxidation. [ABSTRACT FROM AUTHOR]

Activation energies of nickel ferrite samples containing different amounts of yttrium (Y) were experimentally determined. In order to understand the influence of Y ions to selected properties of nickel ferrite, a computational analysis based on density functional theory (DFT) calculations has been performed. DFT calculations provided deeper understanding of the structural effects introduced by the presence of Y ions and contributed to the explanations of conductivity. In order to track the changes in magnetic properties, spin polarized formalism was adopted, which enabled us to assess to what extent Y doping might influence the magnetic properties of nickel ferrite. Band structure calculations have been performed in order to obtain information about band gaps, while analysis of total and partial density of states (TDOS and PDOS, respectively) have indicated the overall contribution of different states and Y ion. Image 1 [ABSTRACT FROM AUTHOR]

Trivalent rare-earth cation (R3+) and Y3+ co-doped BaCeO 3 materials show an enhanced proton conductivity than single Y doped BaCeO 3 material. For the same purpose, Sm3+ and Y3+ as paired ions are incorporated into BaZrO 3 perovskite structure. The crystal structure, electrical conductivity and sinterability of Sm3+ and Y3+ co-doped BaZr 0.8 Y 0.2-x Sm x O 3-δ (BZYS, x = 0, 0.05, 0.1, 0.15, 0.2) materials are investigated for the potential electrolyte application of protonic ceramic fuel cells. Powder XRD diffraction shows BZYS with the cubic perovskite structure and a decrease of lattice constants with increasing Sm3+ content indicates Sm3+ doped into perovskite B site. Although the sinterability enhances by Sm3+ introduction, the grain interior conductivity, specific grain boundary conductivity and total conductivity all cannot be improved. This proves that, unlike BaCeO 3 proton conductors, Sm3+ and Y3+ co-doping strategy cannot improve the charge transport properties of BaZrO 3 proton conductors, which is the main contribution of this paper. Through comprehensively considering sinterability and electrical conductivity, the BZYS5 (BaZr 0.8 Y 0.15 Sm 0.05 O 3-δ) is considered as the potential electrolyte material and the corresponding protonic ceramic fuel cell shows the peak power density of 180 mW cm−2 at 700 °C. [ABSTRACT FROM AUTHOR]

In the conventional fiber drawing process, the waveguide parameters (fiber core diameter, refractive index profile, numerical aperture) of the optical fiber are decided (with very limited perturbation range) once the optical and geometric properties of the preform are determined. In comparison, yttrium aluminosilicate (YAS) fibers prepared by "molten core method" (also termed as "melt-in-tube" method) reveal a unique fiber formation process. Although the previous works have shown that the element diffusion plays a significant role in the formation of YAS fiber, the description of this formation process is still vague and the properties of YAS fibers obtained by this method show low controllability in practice, which cannot be explained by elemental diffusion alone. Here, a new model for the formation mechanism of YAS fibers is proposed based on the experimental data, which involves the consideration of interfacial stress during the formation of YAS fibers. The relationship between the refractive index and the element distribution in the YAS fibers was studied. Structural simulation based on the molecular dynamics was also performed to demonstrate the formation mechanism of glassy YAS fiber core. [ABSTRACT FROM AUTHOR]

In this study, Nascent Lanthanum Phosphate (LaPO 4) and LaPO 4 with 20% reinforced Yttria (Y 2 O 3) precursor ceramic powder was synthesized through aqueous Sol-gel route, where theLaPO 4 and LaPO 4 /Y 2 O 3 powder was sourced from Lanthanum chloride (LaCl 3) and orthophosphoric acid (H 3 PO 4). By sintering the precursor powder at 1400 °C for 2 h, a relatively high-density composite material of LaPO 4 (97.4%) and LaPO 4 /Y 2 O 3 (98.4%) were fabricated. Through X-ray powder diffraction (XRD) experiment, the results revealed that LaPO 4 and LaPO 4 /Y 2 O 3 electrolyte samples sintered at 1400 °C for 2 h is impurity free and thereby elemental composition of the powders is also verified. Further, a small quantity of LaP 2 and La 2 O 3 elements formed during the synthesis of LaPO 4 was found to contribute more on corrosion resistance and high withstanding capacity of the material. 26% of YPO 4 formed due to a chemical reaction between Yttrium and Lanthanum made this composite a suitable candidate material for high-temperature applications. Various mechanical characterization tests such as micro-hardness, flexural strength, and compression capacity were studied, where the microscopic analysis provided comprehensive information about both transgranular and intergranular types of failure on the fractured regions of LaPO 4 and LaPO 4 /Y 2 O 3 material. The MicroVicker'shardness of LaPO 4 and composite was found to be 5 GPa and 5.2 GPa, respectively. When compared with the nascent sample, on an average, 22% reduction in flexural strength and a 1.05% increase in Young's modulus are observed for the high-density composite. [ABSTRACT FROM AUTHOR]

In this study, the effects of the addition of carbonyl nickel powder on the density, microstructure, and mechanical properties of sintered yttria-stabilized zirconia (3YSZ) were investigated. Sintering at 1300 °C resulted in the optimum comprehensive mechanical properties. The addition of 5 vol% carbonyl Ni increased the fracture toughness and flexural strength from 9.51 MPa m1/2 to 14.5 MPa m1/2 and from 747 MPa to 873 MPa, respectively. The addition of carbonyl nickel showed greater improvement than did the addition of spherical Ni powder. The dendritic morphology improved the interface bonding between the ceramic and the metal, enabling a bridging mechanism of the ductile phase. However, further Ni addition decreased the mechanical properties. X-ray diffraction results showed that the amounts of the monoclinic phase (M) and cubic phase (C) of 3YSZ increased, whereas the amount of the tetragonal phase (T) decreased. The Y segregation near the Ni particles, which was confirmed by an energy dispersive spectrometer (EDS), caused the phase changes. The segregation of Y occurred during the cooling stage, rather than the holding stage, of sintering. During the cooling stage, the heat mismatch between Ni and ZrO 2 resulted in strong elastic strain energy, which promoted Y segregation. [ABSTRACT FROM AUTHOR]

Abstract New yttrium substituted manganese ferrite (MnY x Fe 2- x O 4) nanoparticles (NPs) were prepared by low cost reverse micelle micro-emulsion method by utilizing cheap raw materials like Paraffin, Triton X-100, and 1-butanol and corresponding metal salts. The Y3+content (x) range was kept 0 ≤ x ≤ 0.16. Thermogravimetric analysis (TGA) of un-annealed precipitates was carried out to probe the phase formation temperature. The annealing of precipitates of all compositions of MnY x Fe 2- x O 4 nanoparticles was carried at 400 °C for 4 h (h). The annealing was carried out under vacuum to control the oxidation of manganese. The effect of Y3+ cations on structural, spectral and dielectric properties was investigated by X-ray diffraction (XRD), Fourier Transform Infra-Red (FTIR) spectroscopy and impedance analyzer measurements at room temperature. XRD patterns confirmed the formation of MnFe 2 O 4 and its derivatives with yttrium. Site radii and bond lengths were calculated from XRD data. FTIR spectra confirmed the tetrahedral (A) and octahedral (B) sites in all compositions of MnY x Fe 2- x O 4 nanoparticles, which is characteristic of spinel ferrites having FCC (face centered cubic) structure. Scanning electron microscopic (SEM) analysis confirmed the spherical morphology of ferrite particles. Dielectric parameters analysis in the frequency range from 1 × 106 Hz to 3 × 109 Hz suggested that these ferrite particles may find their potential applications in high frequency devices fabrication. [ABSTRACT FROM AUTHOR]

Abstract In this work the reactivity in solid BaCe 0.9 Y 0.1 O 3-δ - liquid V 2 O 5 system was investigated in order to evaluate the possibility of composite formation in this system. Impregnation of melted vanadium(V) oxide into solid Y-doped BaCeO 3 was performed in various temperature and time conditions. Due to the relatively high reactivity of components in this system an analysis of the synthesized materials was divided into discussion of the properties of the reactive layer and the inner part. As was shown, decomposition of Y-doped BaCeO 3 in contact with melted vanadium(V) oxide occurs already at temperature 700 °C and results in formation of CeVO 4 as one of the main phases. Moreover, the presence of Ba 8 V 7 O 22 as the intermediate phase was observed. The extension of reaction time and increase of temperature resulted in significant changes in the microstructure and chemical composition of the reactive layer. The incorporation of vanadium into yttrium doped BaCeO 3 structure for inner parts of the synthesized materials was postulated based on the modification of the materials electrical properties and chemical stability towards CO 2 and H 2 O. Also, the presence of additional phase in the intergranular voids of doped-BaCeO 3 was suggested. [ABSTRACT FROM AUTHOR]