Fig. 3. Visible appearances of the (a) as-sprayed (off-white) and (b) monolithic (pink) Cr-doped aluminas indicate differences in optical absorption that may be correlated to changes in crystallographic structure upon heat treatment (1973 K, 4 h in air). SEM of the (a) mixed-phase (i.e., ?α- and ?η-alumina), as-sprayed Cr-doped alumina coating and the (d) Cr-doped ?α-alumina monolith shows that grain growth, an emergence of crystal faceting and a generation of intragranular optical scatterers (pores), is associated with the transformation of ?η-phase to the ?α-alumina host.
Portions of Dr. Michael Brupbacher’s recently defended dissertation have been published in Applied Optics, a journal of the Optical Society of America. The article, titled “Temperature-dependent diffuse reflectance spectroscopy of plasma-sprayed Cr-doped α-alumina using supercontinuum laser illumination and CO2 laser heating“, was selected as an “Editor’s Pick” which connotates that the work in an excellent representation of the scientific research taking place in the field. Dr. Brupbacher’s work was a collaboration with the John’s Hopkins Applied Physics Laboratory and supported by a JHU APL Research Assistantship.