Multifunctional praseodymium-doped composite silica glasses for UV shielding and photonic applications
P J Gracie, D. Geetha, I. K. Battisha
Abstract
Abstract Silica phosphate glasses strengthened with a calcium oxide modifier and doped with different concentrations (0%, 0.5%, 1%, 1.5 mol%) of praseodymium (Pr 3+ ) were synthesized by a sol–gel method. The absence of sharp peaks in the X-ray diffraction spectra confirms the noncrystallinity of the glasses. Higher doping indicates increasing optical bandgaps due to Burstein–Moss shift, which also reflects on structural disorders at the absorption tails, as validated by Urbach’s rule. The density increases with a subsequent decrease in oxygen-packing density, proving the mechanical and chemical stability of the glasses. The composite glasses are multifunctional with marked absorption at 280 nm predicting their purpose as UV shielding films. Luminescence corresponding to the intra 4f transition, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:msub> <mml:mn>1</mml:mn> <mml:mrow> <mml:mtext>D</mml:mtext> </mml:mrow> </mml:msub> </mml:mrow> <mml:mn>2</mml:mn> </mml:msub> <mml:mo stretchy="false">→</mml:mo> <mml:msub> <mml:mrow> <mml:msub> <mml:mn>1</mml:mn> <mml:mrow> <mml:mtext>G</mml:mtext> </mml:mrow> </mml:msub> </mml:mrow> <mml:mn>4</mml:mn> </mml:msub> </mml:math> in the infrared region, with high transmission and low reflection losses suggests the use of the synthesized glass material for S-band telecommunications, while the radiative process involving <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:msub> <mml:mn>3</mml:mn> <mml:mrow> <mml:mtext>P</mml:mtext> </mml:mrow> </mml:msub> </mml:mrow> <mml:mn>0</mml:mn> </mml:msub> <mml:mo stretchy="false">→</mml:mo> <mml:msub> <mml:mrow> <mml:msub> <mml:mn>3</mml:mn> <mml:mrow> <mml:mtext>F</mml:mtext> </mml:mrow> </mml:msub> </mml:mrow> <mml:mn>2</mml:mn> </mml:msub> </mml:math> yields a predominant red laser source. Commission International de l’Eclairage color coordinates observe warmer red emission corresponding to a correlated color temperature of 3200 K. The composite silica phosphate glass systems evidence the effective role of Pr 3+ for photonic applications.