Effect of symmetry reduction on the electronic transitions in polytypic GdAl3(BO3)4:Eu:Tb crystals |
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| Affiliation: | 1. Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, Budapest, Hungary;2. Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Wrocław, Poland;1. State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China;2. School of Information Engineering, Nanchang Hangkong University, Nanchang 330063, China;3. Key Laboratory of Nondestructive Test (Ministry of Education), School of Measuring and Optical Engineering, Nanchang Hangkong University, Nanchang 330063, China;1. Laboratoire de Physico Chimie de l''Atmosphère, EA 4493 Université du Littoral Côte d''Opale, 59140 Dunkerque, France;2. Institut des Sciences Chimiques de Rennes, Eq. Verres et Céramiques, UMR CNRS 6226, Université de Rennes 1, 35042 Rennes Cedex, France;1. Department of Inorganic Chemistry, Institute of Chemical Technology, Technická 5, Prague 6 166 28, Czech Republic;2. Institute of Physics, the Academy of Sciences of the Czech Republic, Cukrovarnická 10, Prague 6 162 00, Czech Republic;1. Department of Chemistry, University of Florida, Gainesville, FL 32611-7200, USA;2. Department of Science and Mathematics, Texas A&M University-Central Texas, Killeen, TX 76549, USA;3. CNRS and Université Grenoble Alpes, Institut Néel, 38042 Grenoble, France |
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| Abstract: | The existence of a recently described monoclinic phase (C2/c, Z = 8) (Beregi et al., 2012) in addition to the well-known Huntite type rhombohedral (R32) polytypic modification of the GdAl3(BO3)4 (GAB) crystal at room temperature provides a unique possibility to investigate the incorporation of rare earth dopants into slightly modified crystal lattice by spectroscopic methods. In these characteristic GAB structures the dopant ions, e.g. Tb3+ or Eu3+, possess slightly different neighbor geometries and local symmetries. The Tb3+: 7F6 → 5D4 and Eu3+: 7F0,1,2 → 5D0,1,2 electronic transitions were successfully identified in the absorption spectra using polarization, concentration and temperature dependent measurements in both polytypic modifications. The positions of the investigated Tb lines are shifted by up to 10 cm−1 due to symmetry changes. In addition, some of the Eu lines show splittings of about 4–30 cm−1 as a consequence of the change of the local environment. From the room temperature absorption measurements some of the low energy crystal field levels of 7F and 5D states of the Eu3+ ions were successfully determined for both modifications. |
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| Keywords: | Electronic transition Absorption Polytypism Europium |
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