Yttria, or yttrium sesquioxide (Y2O3), has been considered for use in nuclear applications and has gained interest relatively recently for use in infrared optics. Single crystals of yttria have been grown successfully at the NASA Glenn Research Center using a laser-heated float zone technique in a fiber and rod. Such samples allow measurement of the single-crystal elastic properties, and these measurements provide useful property data for the design of components using single crystals. They also yield information as to what degree the elastic properties of yttria ceramics are a result of the intrinsic properties of the yttria crystal in comparison to characteristics that may depend on processing, such as microstructure and intergranular phases, which are common in sintered yttria. The single-crystal elastic moduli are valuable for designing such optical components. In particular, the temperature derivatives of elastic moduli allow the dimensional changes due to heating under physical constraints, as well as acoustic excitation, to be determined.
The single-crystal elastic moduli of yttria were measured by Brillouin spectroscopy up to 1200 °C. The room-temperature values obtained were C 11 = 223.6 + 0.6 GPa, C 44 = 74.6 + 0.5 GPa, and C 12 = 112.4 + 1.0 GPa. The resulting bulk and (Voigt-Reuss-Hill) shear moduli were K = 149.5 + 1.0 GPa and GVRH = 66.3 + 0.8 GPa, respectively. Linear least-squares regressions to the variation of bulk and shear moduli with temperature resulted in derivatives of dK / dT = -17 + 2 MPa/°C and dGVRH / dT = -8 + 2 MPa/°C. Elastic anisotropy was found to remain essentially constant over the temperature range studied.
Top: Room-temperature velocities in the {100} plane of yttria. Bottom: Single-crystal elastic moduli at high temperatures. (Copyright James Palko, University of Michigan,
Ann Arbor; used with permission.)
Long description
| Bulk modulus, K , GPa |
Shear modulus, G , GPa |
Young's modulus, E , GPa |
Poisson's ratio, n |
|---|---|---|---|
| ----------- | 65.6 ± 0.8 | 172 ± 2 | 0.305 ± 0.003 |
| 149.5 ± 1.0 | 66.3 ± 0.8 | 173 ± 2 | 0.307 ± 0.003 |
| ----------- | 67.0 ± 0.8 | 175 ± 2 | 0.309 ± 0.003 |
| ----------- | 56.4 | 158.3 | 0.3426 |
| 167.7 | 57.7 | 155.2 | 0.3457 |
| ----------- | 59.0 | 152.1 | 0.3488 |
| 148.9 ± 3.0 | 69.2 ± 2.0 | 179.8 ± 4.8 | 0.299 ± 0.004 |
| 145 | 67 | 173 | 0.30 |
| 146.2 | 69.42 | 179.8 | 0.2951 |
Palko, James W., et al.: Elastic Constants of Yttria (Y2O3) Monocrystals to High Temperatures. J. Appl. Physics, vol. 89, issue 12, 2001, pp. 7791-7796.
Case Western Reserve University contact:
Dr. Ali Sayir, 216-433-6254,
Ali.Sayir@grc.nasa.gov
Glenn contact:
Dr. Serene C. Farmer, 216-433-3289,
Serene.C.Farmer@grc.nasa.gov
Authors: James W. Palko, Waltraud M. Kriven, Sergey V. Sinogeikin, Jay D. Bass, and Dr. Ali Sayir
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Last updated: June 2002
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