UV and Visible Luminescence of Pr 3+ Doped Oxides: New Materials
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1111-D08-07
UV and visible luminescence of Pr3+ doped oxides: new materials Fabio Piccinelli1, Adolfo Speghini2, Konstantin Ivanovskikh3, Andries Meijerink3, Cees Ronda3,4,5 and Marco Bettinelli1 1 Department of Science and Technology, University of Verona, and INSTM, UdR Verona, Strada Le Grazie 15, 37134 Verona, Italy. 2 DiSTeMeV, University of Verona, and INSTM, UdR Verona, Via della Pieve 70, 37029 S. Floriano (VR), Italy 3 CMI, Debye Institute for Nanomaterials Science, Utrecht University, P. O. Box 80 000, 3508 TA Utrecht, The Netherlands 4 Philips Research Europe-Aachen, Weisshausstr. 2, D-52066 Aachen, Germany 5 Zhejiang University, Centre for Optical and Electromagnetic Research, Hangzhou 310058, China ABSTRACT The garnet Ca3Sc2Si3O12 (CSSO) and the silico-carnotite Ca3Y2Si3O12 (CYSO) and Ca3Lu2Si3O12 (CLSO) materials, both undoped and doped with Pr3+, have been synthesized by solid state reaction at high temperature. The luminescence spectroscopy and the excited state dynamics of the materials have been studied upon VUV and X-ray excitation using synchrotron radiation. All doped samples have shown efficient 5d-4f emission upon direct VUV excitation of 5d levels, but only CSSO:Pr3+ shows luminescence upon interband VUV or X-ray excitation. The VUV excited emission spectra of CYSO:Pr3+ and CLSO:Pr3+ show features attributed to emission from two distinct sites accommodating the Pr3+ dopant. The decay kinetics of the Pr3+ 5d-4f emission in CSSO:Pr3+ upon VUV excitation across the conduction band are characterized by decay times in the range 25-28 ns with no significant rise after the excitation pulse. They appear to be faster upon X-ray irradiation than for VUV excitation. Weak afterglow components are attributed to defect luminescence. INTRODUCTION Luminescent inorganic materials doped with trivalent lanthanide ions and showing 4fn-15d→4fn (5d-4f) electric dipole allowed transitions find numerous applications in important technological fields. These applications concern the development of tunable lasers in the UV and visible regions, and of scintillators which can convert ionizing radiation (X- and γ-rays) to UV and visible emission. Moreover, there is a number of important applications that are presently being developed in medicine and high energy physics. The search for faster luminescence, allowing for higher count rates and superior spatial resolution, has led to investigations concerning the possible use of the Pr3+ ion as a suitable activator of inorganic hosts. In fact, this ion gives rise to 5d-4f luminescence located at shorter wavelengths than Ce3+ one, and characterized by shorter decay times (shorter than 30 ns). In this contribution we present some recent results obtained in our laboratories and concerning the 5d-4f luminescence of the Pr3+ ion in crystalline oxide materials. Special attention is given to promising hosts that are transparent in the UV region, such as garnets and complex
silicates. In particular, data pertinent to the silicate hosts Ca3Sc2Si3O12 (CSSO), Ca3Y2Si3O12 (CYSO) and C
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