CUED Publications database

Investigation of the Young's modulus and thermal expansion of amorphous titania-doped tantala films

Abernathy, MR and Hough, J and Martin, IW and Rowan, S and Oyen, M and Linn, C and Faller, JE (2014) Investigation of the Young's modulus and thermal expansion of amorphous titania-doped tantala films. Applied Optics. pp. 3196-3202. ISSN 1559-128X

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© 2014 Optical Society of America. The current generation of advanced gravitational wave detectors utilize titania-doped tantala/silica multilayer stacks for their mirror coatings. The properties of the low-refractive-index silica are well known; however, in the absence of detailed direct measurements, the material parameters of Young's modulus and coefficient of thermal expansion (CTE) of the high refractive index material, titania-doped tantala, have been assumed to be equal to values measured for pure tantala coatings. In order to ascertain the true values necessary for thermal noise calculations, we have undertaken measurements of Young's modulus and CTE through the use of nanoindentation and thermal-bending measurements. The measurements were designed to assess the effects of titania-doping concentration and post-deposition heat-treatment on the measured values in order to evaluate the possibility of optimizing material parameters to further improve thermal noise in the detector. Young's modulus measurements on pure tantala and 25% and 55% titania-doped tantala show a wide range of values, from 132 to 177 GPa, which are dependent on both titania concentration and heat-treatment. Measurements of CTE give values of (3.9 ± 0.1) × 10 -6 K -1 and (4.9 ± 0.3) × 10 -6 K -1 for 25% and 55% titania-doped tantala, respectively, without dependence on post-deposition heat-treatment.

Item Type: Article
Divisions: Div C > Biomechanics
Depositing User: Cron Job
Date Deposited: 17 Jul 2017 19:34
Last Modified: 24 May 2018 02:06