Fabrication and properties of La2O3-doped transparent yttria ceramics by hot-pressing sintering

Transparent La 0.1 Nd 0.1 Y 1.8 O 3 ceramics were prepared by use of the ethylenediaminetetraacetic acid gel process followed by sintering by hot isostatic pressing. The structure and morphology of the powders and bulk samples and the optical properties of bulk samples were investigated by use of x-ray diffraction (XRD), scanning electron microscopy, visible and near-infrared reflectance spectroscopy, and study of magneto-optic (Faraday) effects. The powders consisted of many agglomerates of fine, oval particles. XRD studies of the powder and bulk sample confirmed their single-phase composition, and spectrophotometric and magneto-optical studies in the range 500-1000 nm revealed their potential for application as an optical materials.

Optical Materials, 2013

Y 3−3x Nd 3x Sc 1 Al 4 O 12 (x = 0, 0.01, and 0.02) ceramics were fabricated by sintering at high temperature under vacuum. Unit cell parameter refinement and chemical analysis have been performed. The morphological characterization shows micrograins with no visible defects. The thermal analysis of these ceramics is presented, by measuring the specific heat in the temperature range from 300 to 500 K. Their values at room temperature are in the range 0.81−0.90 J g 1− K −1 . The thermal conductivity has been determined by two methods: by the experimental measurement of the thermal diffusivity by the photopyroelectric method, and by spectroscopy, evaluating the thermal load. The thermal conductivities are in the range 9.7−6.5 W K −1 m −1 in the temperature interval from 300 to 500 K. The thermooptic coefficients were measured at 632 nm by the dark mode method using a prism coupler, and the obtained values are in the range 12.8−13.3 × 10 −6 K −1 . The nonlinear refractive index values at 795 nm have been evaluated to calibrate the nonlinear optical response of these materials.

Optical Materials, 2010

a b s t r a c t (Yb 0.05 Y 0.95 ) 2 O 3 transparent ceramics were fabricated by vacuum sintering technique using high purity Y 2 O 3 powder as starting material and ZrO 2 as additive. The results indicated that the introduce of ZrO 2 can improve the transmittance of yttria ceramics greatly and the mechanism was also analyzed. 3.0 at.% ZrO 2 doped (Yb 0.05 Y 0.95 ) 2 O 3 transparent ceramics sintered at 1800°C for 20 h had the optimum transmittance. The microstructure is uniform and no secondary phase is observed in the ceramics with the average grain size of 15 lm. The relative density is 99.68% and the transmittance in near-infrared band is as high as 83.7% (up to 98.5% of theoretical value). The spectroscopic properties of 3.0 at.% ZrO 2 doped (Yb 0.05 Y 0.95 ) 2 O 3 ceramics were also investigated. The absorption, emission cross-section and fluorescence lifetime have been estimated as 1.175 Â 10 À20 , 1.767 Â 10 À20 cm 2 and 0.93 ms, respectively. All the results indicate that Yb 3+ doped Y 2 O 3 transparent ceramic is promising laser material.

Modern Electronic Materials, 2022

The aim of this work was to study the effect of vacuum sintering conditions and cerium concentration on the optical, luminescent and thermal properties of yttrium-aluminum garnet based ceramics doped with Се 3+ cations. Series of ceramic powders were synthesized and samples of luminescent ceramics having the composition Y 3-х Се х Al 5 O 12 were synthesized where x was in the range 0.01 to 0.025 f.u. We show that the phase composition and grain size distribution of the ceramic powders do not depend on cerium concentration. Without sintering additives, an increase in vacuum sintering temperature from 1675 to 1800 °C leads to an increase in the optical transmittance of luminescent ceramic specimens from 5 to 55% at a 540 nm wavelength and an increase in the thermal conductivity of the samples from 8.4 to 9.5 W/(m • K). It was found that an increase in cerium concentration leads to a shift of the luminescent band peak from 535 to 545 nm where as the width of the luminescent band decreases with an increase in vacuum sintering temperature from 1675 to 1725 °C.

Journal of The European Ceramic Society, 2017

To evaluate the effectiveness of dry ball-milling, yttria powders were ball-milled, and the optimal sample was spark plasma sintered to fabricated transparent yttria ceramics. The characterization of the powders and pellets were analyzed using XRD, FESEM, UV/VIS/NIR and FTIR spectrometer throughout the whole experimental process. The results indicated that ball-milling can significantly decrease yttria particle size and enhance the specifice surface area. The best duration is 20 h ball-milling with average particle size and specifice surface area of 64 nm and 20.4 m 2 /g, respectively. Transparent yttria ceramic was made up of grains in the size range of approximately 0.67 m and the relative density was 99.8%. The in-line transmittance of the SPS-sintered yttria ceramic (2.5 mm thick) reached 83% in the infrared region, which is very close to the theoretical value of yttria.

Ceramics International, 2014

Transparent ceramics of zinc oxide (ZnO) and 10% Yb 3+ doped Lu 2 O 3 (YLO) were fabricated by spark plasma sintering. The major sintering parameters to obtain transparent ceramics and their interdependency on each other are explained for cubic and non-cubic crystal structured transparent ceramics. Highly densified YLO and ZnO ceramics were obtained at 1250 1C and 850 1C, respectively. Postannealing of sintered YLO and ZnO ceramics at 1200 1C and 700 1C respectively removes discoloration and improves transparency. The 2 mm thick YLO ceramics prepared at 1700 1C with dwell time of 5 min and heating rate at 50 1C/min shows the maximum transmittance of 55% at a wavelength of 2 μm and the 2 mm thick ZnO transparent ceramics prepared at 1100 1C with dwell time of 20 min and heating rate of 10 1C/min shows maximum transmittance in the visible region with nearly 60% transmittance.

Journal of The American Ceramic Society, 2010

(Tm0.01Y0.99)2O3 transparent ceramics have been fabricated in a vacuum condition using high-purity Y2O3 and Tm2O3 powders as raw materials, and ZrO2 and tetraethyl orthosilicate (TEOS) as additives. Effects of ZrO2 and TEOS on controlling the growth of grain size were investigated to obtain high-optical-quality transparent ceramics. Self-compensation of ZrO2 at high temperature offers vacancies, which promote the diffusion and densification rate. Meanwhile, the solid solution formed by substitution and interstice mechanism improves the optical quality of transparent ceramics significantly. The growth of grain size under different criteria was observed by field-emission scanning electron microscopy. The spectroscopic properties were also investigated. The result indicates that ZrO2 is necessary for the sintering of yttrium-transparent ceramics, but TEOS fails to contribute in the yttrium system.

Ceramics International, 2020

Via a facile solid reactive method, transparent Ln 0.1 La 0.9 GdZr 2 O 7 (Ln = Nd, Yb) ceramics were successfully fabricated for the first time. The highest in-line transmittances of Nd:LaGdZr 2 O 7 and Yb:LaGdZr 2 O 7 ceramics reached 68% and 69%, respectively, at 1100 nm. The microstructure and crystal structure of Ln 0.1 La 0.9 GdZr 2 O 7 transparent ceramics were fully investigated, indicating that the solid reactive technique is a good method of industrially fabricating Ln 0.1 La 0.9 GdZr 2 O 7 transparent ceramics. The PL spectra demonstrated that Ln 0.1 La 0.9 GdZr 2 O 7 ceramics can effectively be excited at 808 nm and 976 nm, which correlates with the widely applied output wavelengths of AlGaAs and InGaAs laser diodes. The luminescence decay curves were also studied, showing that the average fluorescence lifetimes of Nd 0.1 La 0.9 GdZr 2 O 7 and Yb 0.1 La 0.9 GdZr 2 O 7 transparent ceramics was 355 μs and 663 μs, respectively. Combined with its high temperature resistance and good mechanical strength, Ln 0.1 La 0.9 GdZr 2 O 7 (Ln = Nd, Yb) transparent ceramics can have potential applications in Nd/ Yb solid-state laser construction.

Materials Letters, 2004

Yttria nanopowders were synthesized using a chemical precipitation method. pH value at the end of the precipitation process has a significant effect on the size and morphology of the precursor and the yttria powders. Under the same calcination condition, the yttria powders made from the precursor obtained at a pH of 8 are smaller in mean particle size and narrower in size distribution than those made from the precursor obtained at a pH of 10. It was found that the optimum calcination temperature is 1000 jC, and the yttria powder obtained is fine (30 nm) and well dispersed. Using the yttria powder, transparent yttria ceramics was produced by vacuum sintering at 1700 jC for 4 h without any additives.

Optics Express, 2008

Ce 3+ :(Lu 0.7 Y 0.25 La 0.05 ) 2 O 3 transparent ceramics were fabricated with nanopowders and sintered in H 2 atmosphere. The spectral properties of Ce 3+ :(Lu 0.7 Y 0.25 La 0.05 ) 2 O 3 transparent ceramics were investigated and the luminescence of Ce 3+ in the solid solution of Lu 2 O 3 , Y 2 O 3 and La 2 O 3 has been found. The ceramics has high density of 8.10g/cm 3 and short fluorescence lifetimes of 7.15 ns and 26.92 ns. It is expected to be a good fast response high temperature inorganic scintillating materials.

Optical Materials, 2015

Highly transparent Yb 3+ doped Y 2 O 3 (Yb 3+ : Y 2 O 3) ceramics was fabricated by a solid-state reaction method using ZrO 2 and La 2 O 3 as additives. The morphology of the prepared powder was investigated and the phase of the sintered Yb 3+ : Y 2 O 3 ceramics sample was identified. The microstructure, transmittance spectrum, Vickers hardness and fracture toughness for the as-sintered Yb 3+ : Y 2 O 3 ceramics were measured. The average grain size was about 9.11 lm and the transmittance at the wavelength of 2000 nm was about 82.0%, which was 99% of the theoretical value. ZrO 2 and La 2 O 3 were useful additives for highly transparent Yb 3+ : Y 2 O 3 ceramics fabrication and mechanical properties improvement.

Journal of Alloys and Compounds, 2010

Neodymium doped YAG transparent ceramics were fabricated by vacuum reactive sintering method using commercial ␣-Al 2 O 3 , Y 2 O 3 and Nd 2 O 3 powders as the starting materials with both tetraethyl orthosilicate (TEOS) and MgO as sintering aids. The morphologies and microstructure of the powders and Nd:YAG transparent ceramics were investigated. Fully dense Nd:YAG ceramics with average grain size of ∼10 m were obtained by vacuum sintering at 1780 • C for 8 h. No pores and grain-boundary phases were observed. The in-line transmittance of the ceramic was 83.8% at 1064 nm.

Optical Materials, 2009

The results of investigations of mechanical, optical and laser characteristics of ceramics made from neodymium-activated yttrium oxide are presented. The ceramics were fabricated with the use of a new technology including Laser synthesis of nanopowders and their magnetic pulsed compaction (LSN&MPC). The fracture toughness (R IC = 0.9-1.4 MPa m 1/2 ) and microhardness (H V = 11.8 GPa) of the ceramics have been determined. It has been found that ceramic samples sintered in the temperature range from 1550 to 2050°C have (1-150) vol. ppm porosity and optical loss coefficient in the range from 0.03 to 2.1 cm À1 . It has been shown that pore content in this range did not influence on the optical loss coefficient. Laser generation at k g % 1.079 lm with a slope efficiency of 15% under laser diode pumping has been obtained in 1.1 mm thickness sample with a 1.07 lm = 0.03 cm À1 .

The Journal of Physical Chemistry C, 2014

Y 3-3x Nd 3x Sc 1 Al 4 O 12 (x = 0, 0.01, and 0.02) ceramics were fabricated by sintering at high temperature under vacuum. Unit cell parameter refinement and chemical analysis have been performed. The morphological characterization shows micrograins with no visible defects. The thermal analysis of these ceramics is presented, by measuring the specific heat in the temperature range from 300 to 500 K. Their values at room temperature are in the range 0.81-0.90 J g 1-K -1 . The thermal conductivity has been determined by two methods: by the experimental measurement of the thermal diffusivity by the photopyroelectric method, and by spectroscopy, evaluating the thermal load. The thermal conductivities are in the range 9.7-6.5 W K -1 m -1 in the temperature interval from 300 to 500 K. The thermooptic coefficients were measured at 632 nm by the dark mode method using a prism coupler, and the obtained values are in the range 12.8-13.3 × 10 -6 K -1 . The nonlinear refractive index values at 795 nm have been evaluated to calibrate the nonlinear optical response of these materials.

Atomic and Molecular Pulsed Lasers VII, 2007

The results of investigations of mechanical, optical and laser characteristics of ceramics made from neodymiumactivated yttrium oxide are presented. The ceramics was fabricated with the use of a new technology including Laser synthesis of nanopowders and their magnetic pulsed compaction (LSN&MPC). The fracture toughness (К IC = 0,9 -1,4 MPa⋅m 1/2 ) and microhardness (Н V = 11,8 GPa) of the ceramics have been determined. It has been found that ceramic samples sintered in the temperature range from 1550 to 2050°С have (1 -150) vol. ppm porosity and optical loss coefficient α 1,07 µm = 0,03 -2,1 cm -1 . It has been shown that pore content in this range did not influence on the optical loss coefficient. Laser generation at λ g ≈ 1,08 µm with a slope efficiency of 15 % at laser diode pumping has been obtained in 1.1 mm thickness sample with α 1,07 µm = 0,03 cm -1 .