An AlN phosphor that was coactivated by Ce 3+ and Si 4+ ions was synthesized by gas pressure sintering (GPS) at 2050 °C for 4 h in a 0.92 MPa nitrogen atmosphere. The phosphor emits blue color with the Commission International de l'Eclairage (CIE) chromaticity coordinate of (0.15, 0.07), which is close to the National Television Standard Committee (NTSC) blue coordinate. The crystallization and cell parameters of the samples were investigated by Rietveld refinement and high-resolution transmission electron microscopy (HRTEM). Since the ionic size of Ce 3+ ions are much larger than that of Al 3+ ions, the locations of rare earth (RE) ions in the AlN lattice are unclear. An octahedral interstitial site inside the wurtzite structure is proposed to be the site for RE ions. The effect of Si substitution was verified by energy-dispersive X-ray spectroscopy (EDX) and solid-state nuclear magnetic resonance (ssNMR). Cathodoluminescence (CL) was examined under electron bombardment at different accelerating voltages. Nitride phosphor exhibited high brightness and favorable stability. This study reveals the superior characteristics of nitride compounds in field emission display (FED) applications.
This study investigated the photoluminescent properties of Tb(3+)-Yb(3+)-, Ce(3+)-Tb(3+)-Yb(3+)-, and Eu(2+)-Yb(3+)-doped KSrPO4. The samples were prepared by a solid-state reaction with various doping concentrations. Emission at near-infrared range was focused on the application of luminescent solar concentrator for solar cells. Quantum cutting (QC) energy transfer was confirmed by the lifetimes of the donor. Near-infrared QC involved emission of Yb(3+) ions was achieved by excitation of Ce(3+), Tb(3+), and Eu(2+) ions, where the energy transfer processes occurred from Ce(3+) to Tb(3+) to Yb(3+), Tb(3+) to Yb(3+), and Eu(2+) to Yb(3+), respectively. In addition, the concentration quenching effect of Yb(3+) ions was avoided by low doping concentrations. The overall quantum efficiencies were calculated, and the maximum efficiency reaches 139%. The energy diagrams for divalent and trivalent rare-earth ions in KSrPO4 host lattice were analyzed. Results of this study demonstrate that heat-stable phosphate phosphors are promising candidates for increasing the efficiency of silicon-based solar cells.
In this contribution, steady-state and time-resolved photoluminescence spectra of β-Si 5.9 Al 0.1 O 0.1 N 7.9 /Pr 3+ 0.016 obtained at high hydrostatic pressures up to 260 kbar are presented. At ambient pressure, excitation spectra of the β-SiAlON/Pr 3+ luminescence consist of sharp lines in the spectral region of 20000−22200 cm −1 related to the 3 H 4 → 3 P 0,1,2 transitions and a broad band with two maxima peaking at 30300 and 35700 cm −1 , which are related to the ionization of Pr 3+ ions occupying two different crystallographic sites in the β-SiAlON lattice. In both sites, the luminescence spectra consist of the dominant 1 D 2 red emission and 3 P 0 blue emission of Pr 3+ ions. The intensity of luminescence related to transitions from the 3 P 0 state and the respective decay time gradually decreases when the pressure increases. The intensity of emission from the 1 D 2 state is independent of the pressure and remains strong over the entire pressure range. Weak dependence of the Pr 3+ emission on applied pressure can be related to the covalent and strong Pr−N bonds and specific location of Pr 3+ ions occupying empty lattice points in β-SiAlON.
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