Characterization Of Lanthana-Strengthened Yttria Infrared Transmitting Materials

Abstract

Lanthana-strengthened yttria is of interest for infrared applications because of its high strength, long wavelength cutoff (8 pm), and low emissivity. The optical, thermal, and mechanical properties of the family of La203-strengthened Y203 have been characterized. The properties can be tailored to suit the requirements of specific applications by adjusting composition and processing parameters. The La203 acts as both a densification aid during fabrication and an agent for microstructural control. Since both strength and toughness depend on microstructure, the La203 allows significant strength enhancement, an important factor for window applications. Theoretical parameters have also been calculated to aid in the assessment of relative resistance to thermal shock fracture initiation and propagation. These calculations reveal potential inconsistencies that must be resolved by experimental testing.

Elastic Moduli of Transparent Yttria

“…For four other data points of transparent Y 2 O 3 , only the values of and V l are given for further treatment. Note that for the cases of La 2 O 3 -strengthened materials-sample 116A and the GTE2 sample from Wei et al 12 -‫ס‬ 0.308, which is higher than that of high-purity Y 2 O 3 . In one case, 9 a value of 0.30 was used in the calculation, which might lead to erroneous G and B values.…”

“…Unless otherwise indicated, the Raytheon and GTE1 sample data are from Tropf and Harris,9 whereas the GTE2 sample data are from Wei et al12 ‡ Values in parentheses are calculated from the present study.…”

Sintering of Yb3+:Y2O3 transparent ceramics in hydrogen atmosphere

“…[1][2][3][4] However, it is extremely difficult to grow large-size Y 2 O 3 single crystal with good optical quality because of its very high melting point (≈2430 • C) and structural phase transition at ≈2280 • C. [5][6] By using ceramic fabrication technology, it is possible to get optical transparent Y 2 O 3 ceramics, at same time with big size and complex structure.…”

“…[11][12][13][14][15] Another effective pressureless sintering method is to form a liquid-phase or transition secondary phase by adding some amount of ZrO 2 , Al 2 O 3 , BeO or La 2 O 3 into Y 2 O 3 . 3,[11][12]16 In addition, transparent Y 2 O 3 ceramics can also be prepared by pressureless sintering without any additives but it requires very high temperature. 17 In 2002, by combination of nanocrystalline powder technology and vacuum sintering method, Konoshima Company get great progress in fabricating laser quality transparent YAG ceramics.…”

Final Report: Scintillator Materials for Medical Applications, December 1, 1997 - November 30, 1999

“…Ceramics can be further subdivided into those that are perfectly transparent (the so-called transparent optical ceramics or TOCS), whose constituents are cubic phases [18,19]) or the large majority that are merely translucent. 'The two ceramics listed in Table 2 belong to the second category, with the gadolinia-yttria system doped with Eu featured in GE tomographs, while the ceramic based on Gd oxysulfide doped with Pr is favored by Siemens.…”