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Effect of interface states associated with transitional nanophase precipitates in the enhancement of red emission from $SrAl_{12}O_{19}:Pr^{3+}$ by $Ti^{4+}$ incorporation

Nag, Abanti and Kutty, TRN (2005) Effect of interface states associated with transitional nanophase precipitates in the enhancement of red emission from $SrAl_{12}O_{19}:Pr^{3+}$ by $Ti^{4+}$ incorporation. In: Journal of Physics and Chemistry of Solids, 66 (1). pp. 191-199.

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Abstract

$SrAl_{12}O_{19}:Pr^{3+}, Ti^{4+}$ phosphor suitable for field emission displays is prepared by the wet chemical gel-carbonate method and the mechanism of enhancement in red photoluminescence (PL) intensity with $Ti^{4+}$ therein has been investigated. The PL spectra of $Pr^{3+}$ show both $^1D_2-^3H_4$ and $^3P_0-^3H_6$ emission in the red region with very weak intensity when excited at 355 nm. The emission intensity has increased by about 100 times at room temperature in the compositional range $SrAl_{12-x}Ti_xO_{19+x/2}:Pr^{3+}$, with $0.1 \leq x \leq 0.3$ in comparison to Ti-free $SrAl_{12}O_{19}:Pr^{3+}$. TEM investigations show the presence of exsolved nanophase of $SrAl_8Ti_3O_{19}$, the precipitation of which is preceded by the presence of defect centers at the interfacial regions between the semicoherent transient phase and the parent $SrAl_{12}O_{19}$ matrix. The presence of transitional nanophase and the associated defects modify the excitation–emission process by way of formation of electronic sub-levels at lower energy (3.5 eV) than the band gap of $SrAl_{12}O_{19} (\sim 7 eV)$ followed by non-resonance energy transfer to $Pr^{3+}$ level, leading to magnetic-dipole related red emission with enhanced intensity. The PL intensity of $Pr^{3+}$ decreases at high $Ti^{4+}$ concentrations $(x>0.3)$ due to higher extent of segregation of non- emissive $SrAl_8Ti_3O_{19}:Pr^{3+}$ phase.

Item Type: Journal Article
Additional Information: The Copyright belongs to Elsevier.
Keywords: A. Inorganic compounds;C. Electron microscopy;D. Defects;D. Electron paramagnetic resonance (EPR);D. Luminescence
Department/Centre: Division of Chemical Sciences > Materials Research Centre
Date Deposited: 28 Mar 2006
Last Modified: 19 Sep 2010 04:24
URI: http://eprints.iisc.ernet.in/id/eprint/5850

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