Mechanical, Thermal, And Optical Properties Of Yttria And Lanthana-Doped Yttria

Tropf, William J.; Harris, Daniel C.

doi:10.1117/12.960758

Cited by 21 publications

(28 citation statements)

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“…1. The shift in peaks towards lower 2θ values was also reported in the literature in Y 2 O 3 /La 2 O 3 system with increase in calcination temperature due to the expansion of Y 2 O 3 lattice along with the lanthanum ion penetration [13,29]. Both materials have 16 formula units per unit cell, allowing calculation of theoretical density [29].…”

Section: Resultssupporting

confidence: 73%

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Influence of La3+ ion in the yttria matrix in improving the microhardness of infrared transparent nano LaxY2-xO3 sintered via hybrid heating

et al. 2017

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Abstract:In the present work, hybrid sintering technique which couples the resistive heating and microwave heating is employed to sinter infrared transparent La 0.15 Y 1.85 O 3 to 99.2% of the theoretical density for the first time to the best of our knowledge. The presence of La 3+ in the yttria matrix improves the hardness properties to a greater extent without affecting the transmittance properties, but there is a deterioration in the thermal properties of the sample. So we have limited our studies to La 0.15 Y 1.85 O 3 which shows better optical, thermal, and hardness properties. The pellets fabricated from the ultra-fine nano powder with average particle size of ~12 nm synthesized by combustion technique and sintered at 1430 ℃ with an average grain size of 0.22 µm show ~80.1% transmittance in the UV-visible region and 81% in mid infrared region. For a comparative study of the optical, mechanical, and thermal properties, two other variants of sintering strategies namely conventional sintering and microwave sintering are also employed. A comprehensive analysis on the hardness reveals that the hardness of the pellets sintered via hybrid heating is 9.73 GPa and is superior to the pellets sintered using the other two techniques. The thermal conductivity of the sample is also analyzed in detail. The results clearly indicate that the La 0.15 Y 1.85 O 3 ultra-fine nano powder synthesised by the single-step combustion method and sintered via microwave hybrid heating shows better transmittance properties without compromising the mechanical properties, and can be used very effectively for the fabrication of infrared transparent windows and domes.

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Section: Resultssupporting

confidence: 73%

“…The cubic structure of yttria is maintained at least for 12 mol% addition. The phase change for 9 mol% lanthanum doped yttria occurs only after 2325 K [29]. It is found that in the present work, lattice constant changes from 10.613 to 10.658 Å as the La 3+ concentration changes from 1 to 5 mol%.…”

Section: Resultssupporting

confidence: 48%

Influence of La3+ ion in the yttria matrix in improving the microhardness of infrared transparent nano LaxY2-xO3 sintered via hybrid heating

et al. 2017

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“…(16) degrades to Eq. (9). Therefore, the soundwave velocity increases only because of the increase in the elastic modulus, and an increase in the elastic modulus has a more overwhelming effect on soundwave velocity than does an increase in density.…”

Section: (4) Use Of Longitudinal Soundwave Velocity As a Predictor Ofmentioning

confidence: 95%

Elastic Moduli of Transparent Yttria

Yeheskel¹,

Tevet²

1999

Journal of the American Ceramic Society

108

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The elastic moduli of yttria (Y 2 O 3 ) samples that were made from powders with various particle morphologies were studied by means of ultrasonic measurements. The soundwave velocities in the longitudinal and transverse modes were measured. The elastic moduli were calculated from the sound velocities and density. For the high-purity, highdensity (>5000 kg/m 3 ) Y 2 O 3 that was prepared in the present study, the average density and elastic moduli (and their standard deviations) were as follows: density () of 5020 ± 18 kg/m 3 , Young's modulus (E) of 179.8 ± 4.8 GPa, shear modulus (G) of 69.2 ± 2.0 GPa, bulk modulus (B) of 148.9 ± 3.0 GPa, and Poisson's ratio () of 0.299 ± 0.004. The average longitudinal and transverse soundwave velocities (V l and V t , respectively) were 6931 ± 65 and 3712 ± 49 m/s, respectively. The elastic moduli of lanthana-strengthened yttria (LSY) were ∼6% lower than those of high-purity Y 2 O 3 , and the value for LSY was ∼0.304. It has been argued that soundwave velocity is better than density, in regard to predicting the elastic moduli of fully dense and slightly porous materials. A linear equation that describes the change of the elastic moduli with soundwave velocity alone has been suggested. This equation was applicable to a relative elastic moduli range of 0.75-1.02.

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“…However, La 2 O 3 rapidly absorbs moisture and carbon dioxide from air to form hydroxides and hydroxycarbonates [11,12], which makes it more difficult to maintain an exact weight during the weighing process. The absorption of H 2 O and CO 2 leads to a weight increase and composition variation, resulting in the fluctuation of the sintering behavior and refractive index, among others [4]. In order to insulate against H 2 O and CO 2 absorption, such procedures have to be carried out under N 2 , which increases the production cost, especially in the case of industrial production [11].…”

Section: Introductionmentioning

confidence: 99%

“…Owing to their low infrared emissivity at both ambient and elevated temperatures, Y 2 O 3 ceramics are considered as a candidate material for use in hypersonic guided-missile windows and domes [4][5][6][7]. The use of La 2 O 3 permits the attainment of ceramics with high optical quality and good mechanical properties by eliminating pores and inhibiting grain growth during the Y 2 O 3 ceramic sintering process [8][9][10].…”

Section: Introductionmentioning

confidence: 99%