Luminescence and decay times Eu(III) and Nd(III) in polymer electrolytes
- PDF / 145,751 Bytes
- 5 Pages / 612 x 792 pts (letter) Page_size
- 31 Downloads / 184 Views
MATERIALS RESEARCH
Welcome
Comments
Help
Luminescence and decay times Eu(III) and Nd(III) in polymer electrolytes L. D. Carlosa) and M. Assunc¸a˜ o Departamento de F´ısica, Universidade de Aveiro, 3800 Aveiro, Portugal (Received 20 October 1995; accepted 15 January 1996)
Time-resolved spectroscopy of poly(ethylene) oxide (PEO) and poly(propylene) oxide (PPO) electrolytes containing different concentrations of Eu31 and Nd31 ions is reported. A description of the main luminescence features of the Nd31 electrolytes is also presented. Lifetimes regarding the main transitions of the luminescence spectra (5 D0 ! 7 F1,2 and 4 D3/2 ! 4 I11/2 for Eu31 and Nd31 , respectively) are determined and are presented as a function of temperature in the range of 13 to 310 K. The order of magnitude of the values obtained at room temperature (0.2–0.6 ms and ø0.7 ms for Eu31 and Nd31 , respectively) is a further indication of the technological potential of these new polymeric materials. For the Eu31 ion the thermally activated quenching of the 5 D0 ! 7 F2 luminescence is discussed in terms of the observed energy superposition between the 5 D0,1 levels and the ligands-to-metal charge-transfer states.
I. INTRODUCTION
In spite of the recent interest in the luminescence features of solid polymer electrolytes based on poly(ethylene oxide), PEO, and poly(propylene oxide), PPO, containing trivalent salts, only a limited amount of work has been reported on these new polymer electrolytes.1–12 This interest arises mainly from their promising optical features, in particular, their strong luminescence from 13 K up to room temperature, and from the possibility, namely in Eu31 -based electrolytes, of gaining some insight on the characterization of the local environment surrounding the cation.5,6,8 The efforts toward technological potential applications of these new luminescence polymeric materials require a deeper study of their photoluminescence properties. For instance, very little is known about their time-resolved spectroscopy behavior. Following previous preliminary work,4,11 this paper reports the first detailed description of the time-resolved spectroscopy of PEO and PPO containing either EuBr3 or NdCl3 –PEOn MX3 and PPOn MX3 , where M sands for the cation, X for the halides ion, and n for the number of ether oxygen atoms in the polymeric chain per M31 cation. In the case of the Eu31 ion, we also present a theoretical interpretation of our experimental data which contributes to the understanding of the energy transfer processes between the metal ion and its ligands environment. The temperature dependence of the lifetimes determined for the europium electrolytes (Table I) indicates the presence of a thermally activated nonradiative mechanism. This mechanism is discussed a)
Address all correspondence to this author.
2104
http://journals.cambridge.org
J. Mater. Res., Vol. 11, No. 8, Aug 1996
Downloaded: 20 Mar 2015
in terms of the Mott–Seitz model and is related to the energy superposition between the 5 D0,1 levels and the ligands-to
Data Loading...
