Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1233904 | Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy | 2008 | 7 Pages |
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 β-PbO as identified by Raman spectroscopy. Photo-EPR studies of the sample containing β-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 β-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 β-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.
Related Topics
Physical Sciences and Engineering
Chemistry
Analytical Chemistry
Authors
Sundar R. Bairavarasu, Matthew E. Edwards, Medury D. Sastry, Faris Kochary, Praveena Kommidi, B. Rami Reddy, Dimitrios Lianos, Manmohan D. Aggarwal,