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Issue 9, 2003
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Role of interface states associated with transitional nanophase precipitates in the photoluminescence enhancement of SrTiO3∶Pr3+,Al3+

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Abstract

SrTiO3∶Pr3+,Al3+ phosphor samples with varying ratios of Sr/Ti/Al were prepared by the gel-carbonate method and the mechanism of enhancement of the red photoluminescence intensity therein was investigated. The photoluminescence (PL) spectra of SrTiO3∶Pr3+ show both 1D23H4 and 3P03H4 emission in the red and blue spectral regions, respectively, with comparable intensity. The emission intensity of 1D23H4 is drastically enhanced by the incorporation of Al3+ and excess Ti4+ in the compositional range Sr(Ti,Aly)O3+3y/2∶Pr3+ (0.2 ≤ y ≤ 0.4) and SrTi1+xAlyO3+z∶Pr3+ (0.2 ≤ x ≤ 0.5; 0.05 ≤ y ≤ 0.1; z = 2x + 3y/2) with the complete disappearance of the blue band. This cannot be explained by the simple point defect model as the EPR studies do not show any evidence for the presence of electron or hole centers. TEM investigations show the presence of exsolved nanophases of SrAl12O19 and/or TiO2 in the grain boundary region as well as grain interiors as lamellae which, in turn, form the solid-state defects, namely, dislocation networks, stacking faults and crystallographic shear planes whereby the framework of corner shared TiO6 octehedra changes over to edge-sharing TiO5–AlO5 strands as indicated from the 27Al MAS NMR studies. The presence of transitional nanophases and the associated defects modify the excitation–emission processes by way of formation of electronic sub-levels at 3.40 and 4.43 eV, leading to magnetic-dipole related red emission with enhanced intensity. This is evidenced by the fact that SrAl12O19∶Pr3+,Ti4+ shows bright red emission whereas SrAl12O19∶Pr3+ does not show red photoluminescence.

Graphical abstract: Role of interface states associated with transitional nanophase precipitates in the photoluminescence enhancement of SrTiO3∶Pr3+,Al3+

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Publication details

The article was received on 08 May 2003, accepted on 17 Jun 2003 and first published on 04 Jul 2003


Article type: Paper
DOI: 10.1039/B305139K
Citation: J. Mater. Chem., 2003,13, 2271-2278
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    Role of interface states associated with transitional nanophase precipitates in the photoluminescence enhancement of SrTiO3∶Pr3+,Al3+

    T. R. N. Kutty and A. Nag, J. Mater. Chem., 2003, 13, 2271
    DOI: 10.1039/B305139K

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