Discovery of the Persistent Luminescence Mechanism of CdSiO3:Tb3

• Published in: Journal of physical chemistry. C 2012-05, Vol.116 (20), p.11232-11240
• Main Authors: Rodrigues, Lucas C.V, Brito, Hermi F, Hölsä, Jorma, Stefani, Roberval, Felinto, Maria C.F.C, Lastusaari, Mika, Laamanen, Taneli, Nunes, Luiz A.O
• Format: Article
• Language: English
• Subjects: Applied sciences; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Corrosion; Corrosion mechanisms; Exact sciences and technology; Metals. Metallurgy; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of bulk materials and thin films; Photoluminescence; Physics
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/jp212021k

The persistent luminescence of CdSiO3:Tb3+ was investigated with photoluminescence, thermoluminescence (TL), synchrotron radiation X-ray absorption (XANES and EXAFS) and UV-VUV spectroscopies. Only the typical intraconfigurational 4f8–4f8 transitions of the Tb3+ ion were observed with no traces of band emission in either the conventional UV excited or persistent luminescence spectra. The trap structure from TL with three traps from 0.65 to 0.85 eV is ideal for room-temperature persistent luminescence similar to, e.g., Sr2MgSi2O7:Eu2+,R3+. Despite the rather low band gap energy, 5.28 eV, the persistent luminescence from Tb3+ is produced only under UV irradiation due to the inauspicious position of the 7F6 ground level deep in the band gap of CdSiO3. This confirms the role of electrons as the charge carriers in the mechanism of Tb3+ persistent luminescence. The XANES spectra indicated the presence of only the trivalent Tb3+ species, thus excluding the direct Tb3+ → TbIV oxidation during the charging process of persistent luminescence. Eventually, a unique persistent luminescence mechanism for Tb3+ in CdSiO3 was constructed based on the comprehensive experimental data.