65616 20200221144243.0 doi 10.1016/j.solmat.2015.09.053 sideral 92311 ART-2016-92311 eng (orcid)0000-0003-3480-398X Oliete, P. B. Universidad de Zaragoza Directionally solidified Al2O3-Yb3Al5O12 eutectics for selective emitters 2016 Access copy available to the general public Unrestricted Al2O3-Yb3Al5O12 eutectic rods were directionally solidified using the laser floating zone method at rates between 25 and 750 mm/h. The microstructure consisted of an interpenetrated network of both eutectic phases for all the growth rates. The size of the phases was strongly dependent on the growth rate, the eutectic interspacing decreasing from 4.5 µm at the lowest growth rate to 600 nm at 750 mm/h. The optical transmission of the sample with coarser microstructure was measured and compared with that of an Yb3Al5O12 single crystal grown "ad hoc" using the same method. The apparent "oscillator strength" of the single 2F7/2¿2F5/2 Yb3+ absorption band was larger in the eutectic sample than in the single crystal, which was attributed to the increase in the light path caused by multiple refractions at the eutectic interphases. The thermal emission of the eutectic rod was studied between 1000 °C and 1500 °C. An intense and relatively narrow emission band at about 1 µm corresponding to the 2F5/2¿2F7/2 Yb3+ electronic transition was observed in the whole temperature range. The intensity of the band increased with the temperature up to about 1300 °C. At higher temperatures a saturation of the selective emission was observed which was attributed to the competition between the increase in the thermal population of the excited state and the enhancement of the non-radiative de-excitation channels with the temperature. info:eu-repo/grantAgreement/ES/MINECO/MAT2013-41045-R info:eu-repo/grantAgreement/ES/UZ/CUD2014-TEC-11 info:eu-repo/semantics/openAccess by-nc-nd http://creativecommons.org/licenses/by-nc-nd/3.0/es/ 4.784 2016 ENERGY & FUELS 13 / 92 = 0.141 2016 Q1 T1 PHYSICS, APPLIED 22 / 147 = 0.15 2016 Q1 T1 MATERIALS SCIENCE, MULTIDISCIPLINARY 40 / 275 = 0.145 2016 Q1 T1 1.599 2016 Electronic, Optical and Magnetic Materials 2016 Q1 Surfaces, Coatings and Films 2016 Q1 Renewable Energy, Sustainability and the Environment 2016 Q1 info:eu-repo/semantics/article info:eu-repo/semantics/acceptedVersion Mesa, M. C. (orcid)0000-0003-0747-405X Merino, R. I. Universidad de Zaragoza (orcid)0000-0001-9690-9064 Orera, V. M. Universidad de Zaragoza 5001 065 Universidad de Zaragoza Dpto. Ciencia Tecnol.Mater.Fl. Área Cienc.Mater. Ingen.Metal. 2003 395 Universidad de Zaragoza Dpto. Física Materia Condensa. Área Física Materia Condensada 144 (2016), 405-410 Sol. energy mater. sol. cells SOLAR ENERGY MATERIALS AND SOLAR CELLS 0927-0248 304475 http://zaguan.unizar.es/record/65616/files/texto_completo.pdf Postprint 50532 http://zaguan.unizar.es/record/65616/files/texto_completo.jpg?subformat=icon icon Postprint oai:zaguan.unizar.es:65616 articulos driver 2020-02-21-13:22:41 ARTICLE