Intense White Luminescence from Combustion Synthesized Ca12Al14O33: Yb3+/Yb2+ Single Phase Phosphor

Abstract

The Ca(12)Al(14)O(33):Yb(3+)/Yb(2+) single phase nano-phosphor has been synthesized through combustion route and its luminescence and lifetime studies have been carried out up to 20 K using 976 and 266 nm excitations. The samples heated in open atmosphere have shown the presence of Yb in Yb(3+) and Yb(2+) states. The 976 nm excitation results a cooperative upconversion emission at 486 nm due to the Yb(3+) state and a broad band in the blue region and has been assigned to arise from the defect centers. The 266 nm excitation on the other hand results a broad emission band even from as-synthesized phosphor without doping of Yb, the width of which increases in presence of Yb due to the emission from Yb(2+) ions formed in heated samples. The white emission covers almost whole visible region with bandwidth 190 nm. The ions in Yb(2+) state has been found to increase with the increase in heating temperature up to 1,273 K. A back conversion of Yb(2+) to Yb(3+) has been observed for higher temperatures. Effect of boric and phosphoric acids as flux on the emission properties of Yb(3+) and Yb(2+) states have been examined and discussed. Quantum yield of emission has also been determined for different samples.

Photoluminescence of an Yb3+/Al3+-codoped microstructured optical fibre

“…The waveform within 400 nm-600 nm is the same as that reported in Ref. [6]. Xu et al [4] have suggested that the blue emission band of 486 nm can result from the cooperative process corresponding to the simultaneous radiation relaxation of a pair of excited Yb 3+ ions.…”

“…[4] Investigations into Yb 3+ -doped materials have revealed that Yb 3+ ions can produce not only laser emission in the near infrared region from 900 nm to 1200 nm but also narrow and bright visible emission around 486 nm due to cooperative upconversion emission. [5,6] Cooperative upconversion luminescence is a special type of upconversion luminescence. [7] In the Yb 3+ system, two interacting ions in the excited state can emit one photon when they return to the ground state simultaneously, while the energy of the output photon is twice the energy of the single ion transition.…”

Efficient sensitization of Mn2+ emission by Eu2+ in Ca12Al14O33Cl2 host under UV excitation

“…2 shows. 17,19 The two different [AlO 4 ], Al(1) and Al (2), in the ratio of 4 : 3, which are connected by a common corner and forms boat-shaped eight-member rings. The Al(1) atom is surrounded to one O(2) atom and three O(1) atoms.…”

Change in structural morphology on addition of ZnO and its effect on fluorescence of Yb3+/Er3+ doped Y2O3

“…An interesting feature of Yb 3+ ion is that though no band is usually seen at 488 nm in its absorption spectrum, an emission at this wavelength is seen with appreciable intensity. This has been explained as due to cooperative emission [19,20]. Though, the process responsible for this emission is not very well understood it has been invoked in many upconversion studies [21].…”