Fabrication and Upconversion Luminescence of Highly Transparent Er:YAG Ceramics

2012 ◽  
Vol 185 ◽  
pp. 55-59 ◽  
Author(s):  
Xian Peng Qin ◽  
Jian Zhang ◽  
Hao Yang ◽  
De Wei Luo ◽  
Jan Ma ◽  
...  
Keyword(s):  
Grain Size ◽  
Optical Properties ◽  
Solid State ◽  
Grain Boundary ◽  
Upconversion Luminescence ◽  
Secondary Phase ◽  
Transparent Ceramics ◽  
Vacuum Sintering ◽  
Average Grain Size ◽  
Sintering Method

Highly transparent Er:YAG ceramics with different Er concentration were fabricated by a solid-state reaction and vacuum sintering method. The optical properties, the microstructure and the upconversion luminescence of the Er:YAG ceramics were investigated. For 3 mm thick samples, the in-line transmittances of the as-fabricated Er:YAG ceramics at the wavelength of 1100 nm and 400 nm were about 84% and 82%, respectively, which was very close to the theoretical transmittance of YAG ceramics. The micrograph of the Er:YAG transparent ceramics exhibited a pore-free structure and the average grain size was about 10 μm. The grain boundary of the ceramics was clean and no secondary phase was detected. When pumped by a 980 nm LD, the strong green and red upconversion luminescences in the Er:YAG ceramics were observed. The different upconversion mechanisms depending on Er concentration in the Er:YAG ceramics were also discussed.

Fabrication and Properties of High Quality Transparent Ho:YAG Ceramics

2012 ◽  
Vol 185 ◽  
pp. 51-54
Author(s):  
Hao Yang ◽  
Jian Zhang ◽  
Xian Peng Qin ◽  
De Wei Luo ◽  
Jan Ma ◽  
...  
Keyword(s):  
Cross Section ◽  
Yttrium Aluminum Garnet ◽  
Transparent Ceramics ◽  
Reactive Sintering ◽  
Photoluminescence Spectra ◽  
Vacuum Sintering ◽  
High Quality ◽  
Average Grain Size ◽  
Yttrium Aluminum ◽  
Sintering Method

High quality holmium doped Yttrium Aluminum Garnet (YAG) transparent ceramics were fabricated by a reactive sintering method under vacuum. Fully dense Ho:YAG ceramics with the average grain size of ~ 10 μm were obtained after vacuum sintering at 1780 for 8 h. The optical properties, microstructures and photoluminescence spectra of the fabricated Ho:YAG ceramics were investigated. The transmittances of Ho:YAG ceramic are higher than 82% at 400 nm and 84% at 2400 nm. The absorption coefficient was 1.32 cm-1 for 1.5 at.% Ho:YAG at 1907 nm. And the absorption cross section of the Ho:YAG ceramic is 0.645×10-20 cm2.

Effect of MgO on the Microstructure of Polycrystalline Nd:YAG Ceramics and its Action Mechanism

2012 ◽  
Vol 535-537 ◽  
pp. 836-839 ◽  
Author(s):  
Bo Wang ◽  
Quan Xi Cao
Keyword(s):  
Grain Size ◽  
Electron Microscope ◽  
Solid State ◽  
Scanning Electron Microscope ◽  
Optical Transmittance ◽  
Action Mechanism ◽  
Vacuum Sintering ◽  
Polycrystalline Ceramics ◽  
Sintering Method ◽  
Scanning Electron

1.0at% Nd:YAG polycrystalline ceramics were fabricated with different sintering adds by solid-state reaction and vacuum sintering method. The optical transmittance spectra of the samples were measured using V-570 UV spectrophotometer. The microstructure and the grain size of the samples were characterized by Scanning electron microscope. It is found that the sample with 0.5wt% SiO2and 0.5wt% MgO had the best transmittance, the most densification and uniform grain size, and the grain size decreased with the increasing MgO. Effects of MgO on the microstructure of YAG and its action mechanism have been investigated.

Influences of Excess PbO on Optical Properties and Microstructures of La Modified 0.75Pb (Mg1/3Nb2/3)O3-0.25PbTiO3 Electro-Optic Transparent Ceramics

2013 ◽  
Vol 745-746 ◽  
pp. 555-559 ◽  
Author(s):  
Wen Long Ji ◽  
Xi Yun He ◽  
Wen Xiu Cheng ◽  
Ping Sun Qiu ◽  
Xin Sen Zheng
Keyword(s):  
Grain Size ◽  
Optical Properties ◽  
Phase Structure ◽  
Perovskite Structure ◽  
Second Phase ◽  
Transparent Ceramics ◽  
Precursor Method ◽  
Electro Optic ◽  
Average Grain Size ◽  
Columbite Precursor

La-modified 0.75Pb (Mg1/3Nb2/3)O3-0.25PbTiO3(PLMNT) electro-optic (EO) transparent ceramics were synthesized through a columbite precursor method. Excess PbO (10, 15 and 20 mol %) was added to study the effect on the transparency, electro-optic effect, and microstructures of PLMNT transparent ceramics. The phase structure of different samples can be identified as single perovskite structure with no second phase detected. The average grain size increased as the concentration of excess PbO increased from 10 mol% to 20 mol%. On the contrary, the transparency decreased with the increase of the concentration of excess PbO. When the concentration of excess PbO was 10 mol%, the transmittance was about 62% at 632.8nm. The EO coefficient was calculated through measuring the birefringence as a function of electric field. The EO coefficient increased with the increase of the concentration of excess PbO and the maximum EO coefficient reached 40.6×10-16(m/V)2 when the excess PbO was 20 mol%.

scholarly journals Fabrication and microstructures of YAG transparent ceramics

2008 ◽  
Vol 40 (3) ◽  
pp. 311-317 ◽  
Author(s):  
M. Liu ◽  
S.W. Wang ◽  
D.Y. Tang ◽  
L.D. Chen ◽  
J. Ma
Keyword(s):  
Grain Size ◽  
Refractive Index ◽  
Solid State ◽  
Grain Boundary ◽  
High Purity ◽  
Solid State Reaction ◽  
Optical Scattering ◽  
Transparent Ceramics ◽  
Scattering Loss

YAG transparent ceramics with different microstructures were fabricated via solid-state reaction of high-purity powders. Influences of grain size, grain-boundary phases on the transmittance of the fabricated YAG ceramics were experimentally investigated. Our results confirm that the optical scattering loss in YAG ceramics is mainly caused by pores. Grain size did not influence the transmittance, and the grain-boundary phases with similar refractive index to the host only affected slightly the transmittance of the YAG transparent ceramics.

scholarly journals Effect of starting materials and sintering temperature on microstructure and optical properties of Y2O3:Yb3+ 5 at% transparent ceramics

2020 ◽  
Author(s):  
R. P. Yavetskiy ◽  
A. E. Balabanov ◽  
S. V. Parkhomenko ◽  
O. S. Kryzhanovska ◽  
A. G. Doroshenko ◽  
...  
Keyword(s):  
Grain Size ◽  
Optical Properties ◽  
Sintering Temperature ◽  
Raw Materials ◽  
High Energy ◽  
Reactive Sintering ◽  
Average Grain Size ◽  
Median Particle ◽  
Energy Ball ◽  
Sintering Method

Abstract Y2O3:Yb3+ 5 at% ceramics have been synthesized by the reactive sintering method using different commercial yttria powders (Alfa-Micro, Alfa-Nano, and ITO-V) as raw materials. It has been shown that all Y2O3 starting powders consist from agglomerates up to 5–7 µm in size which are formed from 25–60 nm primary particles. High-energy ball milling allows to significantly decreasing the median particle size D50 below 500 nm regardless of the commercial powders used. Sintering experiments indicate that powder mixtures fabricated from Alfa-Nano yttria powders have the highest sintering activity, while (Y0.86La0.09Yb0.05)2O3 ceramics sintered at 1750 °C for 10 h are characterized by the highest transmittance of about 45%. Y2O3:Yb3+ ceramics have been obtained by the reactive sintering at 1750–1825°C using Alfa-Nano Y2O3 powders and La2O3+ZrO2 as a complex sintering aid. The effects of the sintering temperature on densification processes, microstructure, and optical properties of Y2O3:Yb3+ 5 at% ceramics have been studied. It has been shown that Zr4+ ions decrease the grain growth of Y2O3:Yb3+ ceramics for sintering temperatures 1750–1775 °C. Further increasing the sintering temperature was accompanied by a sharp increase of the average grain size of ceramics referred to changes of structure and chemical composition of grain boundaries, as well as their mobility. It has been determined that the optimal sintering temperature to produce high-dense yttria ceramics with transmittance of 79%–83% and average grain size of 8 µm is 1800 °C. Finally, laser emission at ∼1030.7 nm with a slope efficiency of 10% was obtained with the most transparent Y2O3:Yb3+ 5 at% ceramics sintered.

Fabrication and Effects of Different Average Grain Sizes on Thermal Conductivity of Nd:YAG Ceramics

2012 ◽  
Vol 535-537 ◽  
pp. 801-804
Author(s):  
Sen Tian ◽  
Quan Xi Cao ◽  
Bo Wang ◽  
Fu Min Xu
Keyword(s):  
Thermal Conductivity ◽  
Grain Size ◽  
Thermal Diffusivity ◽  
Solid State ◽  
Laser Flash ◽  
Flash Method ◽  
Vacuum Sintering ◽  
High Quality ◽  
Grain Sizes ◽  
Average Grain Size

High quality, transparent 1.0at% Nd:YAG ceramics were fabricated successfully by a solid-state reaction and vacuum sintering, and the characteristics were also identified in different methods. The lowest transmittance is 44.85% and the highest is 71.98%. 9 samples were used for thermal diffusivity detecting using laser flash method. Thermal diffusivity decreases as temperature increases, and The diffusivity increases as average grain size grows. However, when average grain size is smaller than 8μm, the diffusivity decreases much faster. Mechanical advantages be ensured, the average grain size should be above 8μm.

scholarly journals Dislocations in Grain Boundary Regions: The Origin of Heterogeneous Microstrains in Nanocrystalline Materials

2019 ◽  
Vol 51 (1) ◽  
pp. 513-530 ◽  
Author(s):  
Zhenbo Zhang ◽  
Éva Ódor ◽  
Diana Farkas ◽  
Bertalan Jóni ◽  
Gábor Ribárik ◽  
...  
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Nanocrystalline Materials ◽  
Md Simulation ◽  
High Pressure Torsion ◽  
Md Simulations ◽  
Line Profile Analysis ◽  
Misfit Dislocations ◽  
X Ray ◽  
Average Grain Size

Abstract Nanocrystalline materials reveal excellent mechanical properties but the mechanism by which they deform is still debated. X-ray line broadening indicates the presence of large heterogeneous strains even when the average grain size is smaller than 10 nm. Although the primary sources of heterogeneous strains are dislocations, their direct observation in nanocrystalline materials is challenging. In order to identify the source of heterogeneous strains in nanocrystalline materials, we prepared Pd-10 pct Au specimens by inert gas condensation and applied high-pressure torsion (HPT) up to γ ≅ 21. High-resolution transmission electron microscopy (HRTEM) and molecular dynamic (MD) simulations are used to investigate the dislocation structure in the grain interiors and in the grain boundary (GB) regions in the as-prepared and HPT-deformed specimens. Our results show that most of the GBs contain lattice dislocations with high densities. The average dislocation densities determined by HRTEM and MD simulation are in good correlation with the values provided by X-ray line profile analysis. Strain distribution determined by MD simulation is shown to follow the Krivoglaz–Wilkens strain function of dislocations. Experiments, MD simulations, and theoretical analysis all prove that the sources of strain broadening in X-ray diffraction of nanocrystalline materials are lattice dislocations in the GB region. The results are discussed in terms of misfit dislocations emanating in the GB regions reducing elastic strain compatibility. The results provide fundamental new insight for understanding the role of GBs in plastic deformation in both nanograin and coarse grain materials of any grain size.

Vacuum sintering and optical properties of Gd2-xNdxZr2O7 transparent ceramics using combustion synthesized nanopowders

2020 ◽  
Vol 100 ◽  
pp. 109622 ◽  
Author(s):  
Weiwei Li ◽  
Kuibao Zhang ◽  
Wenwen Zhao ◽  
Dayan Xie ◽  
Baozhu Luo ◽  
...  
Keyword(s):  
Optical Properties ◽  
Transparent Ceramics ◽  
Vacuum Sintering

Influence of Annealing on the Microstructure and Mechanical Properties of Electrodeposited Nanocrystalline Nickel

2011 ◽  
Vol 683 ◽  
pp. 103-112 ◽  
Author(s):  
B. Yang
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Elastic Modulus ◽  
Grain Boundary ◽  
Boundary Structure ◽  
Boundary State ◽  
Microstructure And Mechanical Properties ◽  
Grain Boundary Structure ◽  
Average Grain Size ◽  
Different Grain Size

The evolution of the microstructure and mechanical properties of electrodeposited nanocrystalline Ni with different annealing procedures was studied systematically. For the annealed specimens hardness decreases with increasing average grain size but the dependence changes at different grain size ranges. The specimens annealed at a low temperature show higher hardness compared to the as-deposited nanocrystalline Ni, despite an increased measured average grain size. In association with this hardening an increase in elastic modulus and a decrease in microstrain was observed after annealing. With increasing annealing temperature both the tensile strength and the fracture strain were observed to decrease, this is companied with a transition from ductile to brittle in the fracture surfaces. These results indicated that the mechanical behaviour of nanocrystalline Ni depends not only on the average grain size but also on the grain boundary structure. A change in the grain boundary state arising from annealing may be responsible for the observed increase in hardness and elastic modulus as well as the deterioration of tensile properties.

Optical Properties and Microstructure of Mn: MgAl2O4 Transparent Ceramic after HIP Treatment

2008 ◽  
Vol 368-372 ◽  
pp. 417-419
Author(s):  
Yue Feng Sun ◽  
Tie Cheng Lu ◽  
Xue Jun Wang ◽  
Mu Yun Lei ◽  
Cun Xin Huang
Keyword(s):  
Optical Properties ◽  
Hot Isostatic Pressing ◽  
Wavelength Region ◽  
Optical Transmittance ◽  
Light Transmittance ◽  
Transparent Ceramics ◽  
Light Wavelength ◽  
Vacuum Sintering ◽  
Two Samples ◽  
Mn Doped

5.0at% and 10.0at% Mn-doped MgAl2O4 transparent ceramics have been prepared through vacuum sintering (1750°C /2h) and subsequent hot isostatic pressing (HIP) (1650°C /2h). The effect of microstructure on the light transmittance of the sintered MgAl2O4 is discussed. Results showed that the grains became dense and grain boundary became clear and most of pores inside and between grains were removed, so the transmittance of two samples increased. The optical transmittance of the 5.0at% specimens was increased by one times in the visible light wavelength region. HIP treatment has a great effect on improving the transparency of samples with low doping concentrations.

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