1. Photomagnetism and photoluminescence (PL) of (Pb-Fe-e(-)) complex in lead magnesium niobate-lead titanate (PMN-PT) crystals containing beta-PbO nanoclusters.
- Author
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Bairavarasu SR, Edwards ME, Sastry MD, Kochary F, Kommidi P, Reddy BR, Lianos D, and Aggarwal MD
- Subjects
- Argon chemistry, Crystallization, Electromagnetic Fields, Electron Spin Resonance Spectroscopy, Light, Oxygen chemistry, Spectrum Analysis, Raman methods, Iron chemistry, Lead chemistry, Magnetics, Nanoparticles chemistry, Nanotechnology methods, Niobium chemistry, Oxides chemistry, Titanium chemistry
- Abstract
We present electron paramagnetic resonance (EPR)--evidence of photomagnetism under the conditions of in situ green laser illumination (photo-EPR) in lead magnesium niobate-lead titanate, Pb(Mg,Nb)O3-PbTiO3 (PMN-PT), containing nanoparticles/wires of orthorhombic beta-PbO as identified by Raman spectroscopy. Photo-EPR studies of the sample containing beta-PbO, brownish red in color, have shown intense line at g=2.00, and its yield increased when produced in the presence of 7.5 kG external magnetic field suggesting the formation of magnetic polaron. This was identified as due to interaction between Fe3+, photoinduced Pb3+ and unpaired electron trapped at oxygen vacancies. The photoinduced growth and decay of magnetic polaron has shown a non-exponential behavior. Photoluminescence (PL) studies were conducted with excitation at 308 nm (XeCl laser) and also at 454.5, 488 and 514.5 nm using Ar+ laser. The excitation with 308 nm gave broad PL centered at 500 and 710 nm the latter being quite prominent in beta-PbO containing crystals, along with cooperative luminescence at 350 nm involving two emitting centers. The excitation with Ar+ laser lines, close to the electronic absorption in samples containing beta-PbO gave richer and sharp PL emission in red region from the constituents of the magnetic polaron and also intense anti-Stokes emission on excitation with 514.5 nm radiation. This appears to be due to phototransfer optically stimulated luminescence (PT-OSL) involving electron-hole recombination at photoinduced magnetic polaron site.
- Published
- 2008
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