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Microstructure and properties of WC reinforced Ni-based composite coatings with Y <sub/>2</sub> O <sub/>3</sub> addition on titanium alloy by laser cladding
摘要： In this study, WC reinforced Ni-based composite coatings with Y2O3 addition were deposited on Ti-6Al-4V titanium substrate by laser cladding. The phases, microstructure, microhardness and wear resistance of the composite coatings were studied by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, microhardness tester and wear tester. The results showed that good metallurgical bonding was achieved between the composite coatings and substrate. The phases mainly were γ -Ni, TiC, TiB2, Ni3B, M23C6 and WC. Most of the WC was dissolved in small pieces of WC during the laser cladding process. The microhardness of the composite coatings was about 3 times that of the titanium substrate and the wear resistance of the composite coatings had a significant increase.
关键词： titanium alloy,microstructure,Laser cladding,Y2O3,WC,Ni-based composite coatings
更新于2025-11-28 14:24:20
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Fabrication of fine-grained undoped Y2O3 transparent ceramic using nitrate pyrogenation synthesized nanopowders
摘要： Y2O3 ceramic is a promising optical material for mid-infrared (IR) windows and domes. Improvements in the mechanical and thermal performance of this material have become urgent if it is to perform adequately under extreme conditions. Herein, Y2O3 nanopowders were produced through the nitrate pyrogenation method. The final Y2O3 transparent ceramics were fabricated with a hybrid sintering method combining low temperature presintering and a subsequent hot isostatic pressing (HIP) treatment. The synthesis of nanopowders and the fabrication of the final ceramic products were investigated in detail. The Y2O3 ceramic sample that was presintered at 1350 °C provided the optimum microstructure for HIP treatment and resulted in an average grain size of 0.5 μm. Owing to the reduced grain size, the flexure strength and Vickers hardness of the sample were improved to 180 MPa and 8.4 GPa, respectively. Furthermore, the achieved pure Y2O3 ceramic demonstrated an excellent thermal conductivity at high temperature.
关键词： Nanopowders,Y2O3,Nitrate pyrogenation,Fine-grained transparent ceramic
更新于2025-09-23 15:23:52
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Glass transition and crystallization of ZnO-B2O3-SiO2 glass doped with Y2O3
摘要： The effect of Y2O3 on the glass transition kinetics, crystallization kinetics, phase separation and crystallization behavior of 60ZnO–30B2O3–10SiO2 glass has been investigated by non-isothermal differential thermal analysis, scanning electron microscopy (SEM) and X-ray powder diffraction (XRD). The glass transition activation energies Eg calculated by using both Kissinger and Moynihan model decrease from 668 kJ/mol to 573 kJ/mol for Kissinger model, and 682 kJ/mol to 587 kJ/mol for Moynihan model with the increase of yttrium oxide doping content from 0 to 6 mol%. And the glass crystallization kinetics parameters, crystallization activation energy Ec and Avrami exponent n stands for crystal growth, are also obtained on the basis of several well developed equations. Increase of about 58 kJ/mol in Ec values obtained by different theoretical equations is caused by addition of 6 mol% yttrium oxide into 60ZnO–30B2O3–10SiO2 glass, and the Avrami exponent (n close to 2) suggests that crystal growth in 60ZnO–30B2O3–10SiO2 glass doped with or without yttrium is mainly one-dimensional growth of crystals. The results on the phase separation and crystallization behavior occurred at 893 K and 993 K respectively for base and doped glass, are well consistent with the glass transition and crystallization kinetics results. Hence, addition of yttrium oxide into 60ZnO–30B2O3–10SiO2 glass decrease the glass transition activation energy while increase the crystallization activation energy of glass, thereby the stability of glass structure is improved. Phase separation phenomenon and crystallization behavior occurred at glass surface provide some useful information for preparing glass ceramics with micro- or nano-crystals in surface.
关键词： Thermal properties,Y2O3,Electron microscopy,Glass
更新于2025-09-23 15:22:29
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Optical and magneto-optical properties of Nd0.1La0.1Y1.8O3 transparent ceramics
摘要： Transparent ceramics in the form of yttrium oxide (Y2O3) doped with La and Nd and pure yttrium as a reference material were successfully prepared via modified sol-gel processes and hot isostatic pressure sintering. Their structure and microstructure were examined by means of scanning electron microscopy and X-ray diffraction, which revealed the high density and single-phase character of these materials. Their optical and magneto-optical properties were also analyzed. Emission spectra of Nd0.1La0.1Y1.8O3 after excitation performed with a continuous 808 nm laser beam showed strong and sharp emission lines. The luminescence lifetime was also investigated. The doped material exhibited a high Verdet constant of over 1000 deg/T?m. The figure of merit was calculated in the VIS spectrum. The investigated transparent oxide ceramics can be considered a promising material for application in lasers and magneto-optical devices.
关键词： Y2O3,Verdet constant,Optical properties,Luminescence,Microstructure,Transparent ceramics
更新于2025-09-23 15:22:29
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Highly -sensitive near infrared luminescent nanothermometers based on binary mixture
摘要： We propose a simple strategy to obtain a luminescence intensity ratio nanothermometer operating in the near infrared range (1000 – 1700 nm) by use of binary mixtures of lanthanide doped Y2O3 selected as 1%Ho - Y2O3 + 1%Er - Y2O3 and 1%Ho - Y2O3 + 1%Nd - Y2O3. All nanoparticles were synthetized by citrate complexation method and thermally annealed at 800 °C. The temperature evolution of the emission properties was monitored in the range of 297 – 472 K and analyzed in terms of emission shape, intensity, dynamics, excitation wavelength, acquisition mode and weight ratio of the binary mixture. A maximum relative sensitivity of 1%K-1 at 297 K was recorded for the 3:1 weight ratio Ho – Y2O3 + Er – Y2O3 binary mixture upon excitation at 536.8 nm. For the more appropriate excitation wavelength for bioimaging applications at 649.7 nm, a relative sensitivity of 0.55 - 0.6 % K-1 was recorded in the relevant physiological temperature range (300 -320 K) for the 3:1 weight ratio Ho – Y2O3 + Er – Y2O3 binary mixture. To the best of our knowledge, our study also represents a first report on the near -infrared luminescence (around 1200 nm) lifetime thermometry for a Ho doped nanoparticle. Comparison with the literature demonstrates that our system represents a promising near-infrared thermometer, with a non-sophisticated and reproducible configuration that is open to multiple optimization routes.
关键词： Lifetime thermometry,Binary mixture,lanthanide doped Y2O3,Near infrared luminescence,Self-referenced nanothermometry
更新于2025-09-23 15:22:29
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Fabrication of Laser Grade Yb: Y2O3 Transparent Ceramics with ZrO2 Additive through Hot Isostatic Pressing
摘要： Laser grade 8 at.% Yb: Y2O3 transparent ceramics were fabricated with ZrO2 as a sintering additive by using hot isostatic pressing. The hot isostatic pressed 8 at.% Yb: Y2O3 transparent ceramics have a small average grain size of 3 μm and a high transmittance of 82.8% in the near-infrared light region. Optical homogeneity is compromised slightly in the visible light region likely because of the presence of nano/micro-scaled pores. Laser output at 1076 nm reaches a maximum power of 1.1 W and a slope efficiency of 6.1%, indicating that the hot isostatic pressed 8 at.% Yb: Y2O3 transparent ceramics have a promising optical quality. An unusual laser damage is observed and believed to be related to ZrO2 additive associated defects.
关键词： ZrO2 additive,hot isostatic pressing,laser grade,Yb: Y2O3,transparent ceramics
更新于2025-09-23 15:21:01
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Luminescence of monoclinic Y2O3:Eu nanophosphor produced via laser vaporization
摘要： Europium doped Y2O3spherical nanoparticles with the diameter ~10 nmobtained via cw laser vaporization are shown to crystallize in monoclinic symmetry class (C2/m space group). The size of nanoparticles established via HRTEM coincides with coherent scattering region established by XRD. Luminescence spectrum in the vicinity of ultranarrow transition demonstrates three peaks consistent with three inequivalent positions of Eu3t ion in monoclinic Y2O3 lattice. Hypersensitive transition dominates in the spectrum, admitting the lack of inversion symmetry at Cs sites occupied by Eu3t. The spectrum of hypersensitive transition is expanded to the red part of spectrum due intense transitions terminating at higher-lying components of crystal-field-split 7F2 energy level. Obtaining chromaticity coordinates (0.669, 0.331)and absolute quantum yield (~21%) is possible using red phosphor based on monoclinic Y2O3:Eu3t.
关键词： Laser vaporization,Monoclinic Y2O3:Eu nanophosphor,Photoluminescence of Eu3t
更新于2025-09-23 15:21:01
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Nonradiative energy transfer of electronic excitation between Tm3+ ions in Y2O3:Tm laser ceramics
摘要： The cross relaxation of Tm3t ions (3H4→3F4, 3H6→3F4) in Y2O3:Tm laser ceramics was studied. This process significantly affects the creation of an inverse population between the 3F4 and 3H6 levels of Tm3t ions in two-micron lasers when they are pumped to the 3H4 level by laser diodes with a wavelength of λexc~800 nm. The efficiency of the cross-relaxation process of Tm3t ions (3H4→3F4, 3H6→3F4) was equal to 97% for Y2O3:Tm ceramics with the thulium concentration of 3 at.%. It was revealed that the nonradiative transfer of electron excitation energy by Tm3t ions through cross-relaxation (3H4→3F4, 3H6→3F4) is due to the dipole-dipole mechanism. The interaction microparameter CDA was determined equal to 9.2?10?39 cm6/s.
关键词： Y2O3,Optical properties,Laser ceramics,Spectroscopy
更新于2025-09-23 15:19:57
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Study of energy transfer from Bi3+ to Tb3+ in Y2O3 phosphor and its application for W-LED
摘要： Y2O3 activated with different activators were prepared by co-precipitation method. The prepared phosphors were characterized by XRD, SEM and photoluminescence (PL) techniques. The Tb3+ doped Y2O3 phosphor shows characteristic green emission due to 5D4 to 7Fj transitions of Tb3+ ion. The Bi3+ doped Y2O3 phosphor shows PL emission in blue region due to the transition between excited 3P1 state and ground state 1S0 of Bi3+ ion. The multiple systems of Tb3+emission lines in Y2O3:Tb3+ and two types of excitation and emission spectra of Y2O3:Bi3+ phosphors are due to two Y3+ sites in the host structure with C2 and S6 symmetries. Due to the addition of transition metal ion Bi3+ in Y2O3:Tb3+ lattice, the excitation efficiency is enhanced throughout the spectral range from 300 nm to 400 nm. Bi3+ ions absorb N-UV radiation and, subsequently, the energy is transferred from the sensitizer Bi3+ to activator Tb3+ and emitted via 5D4 to 7Fj transitions of Tb3+ ion. From the spectral properties of Y2O3:Bi3+ and Y2O3:Tb3+, Bi3+, it is established that the prepared phosphors are useful in near UV excited LED (solid state lighting) application.
关键词： Phosphor,Y2O3,W-LED,Energy transfer
更新于2025-09-23 15:19:57
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Spectroscopy and diode-pumped continuous-wave laser operation of Tm:Y2O3 transparent ceramic at cryogenic temperatures
摘要： We present the spectroscopic and laser characteristics of a 3 at.% Tm:Y2O3 transparent ceramic at cryogenic temperatures. An absorption cross section of 4.7 × 10?21 cm2 with a bandwidth of 0.7 nm centered at 793.3 nm and an emission cross section of 29.0 × 10?21 cm2 centered at 1930.9 nm were estimated at 80 K. Continuous-wave laser operation was achieved using broadband and VBG stabilized laser diodes emitting around 793 nm as pump sources. With the VBG pump diode, a maximum output power of 6.4 W was achieved at 80 K corresponding to a slope efficiency of 52.0% with respect to absorbed power.
关键词： cryogenic temperatures,diode-pumped,Tm:Y2O3,spectroscopy,continuous-wave laser,transparent ceramic
更新于2025-09-19 17:13:59