Nanocrystalline europium hexaboride: A new type efficient activator enhanced in photoluminescent of CaNb2O6:Eu3+ phosphor
A novel alkaline earth niobates red phosphor CaNb 2 O 6 :Eu 3+ have been prepared through solid-state reaction, using the nanocrystalline EuB 6 as a novel activator. The Rietveld refinement of XRD results reveal that the Eu 3+ ions substitute the lattice site of Ca 2+ ions and the B 2− ions replace the lattice site of O 2− ions, which induces the defect energy levels at the band gap of 5 D n levels and leads to higher luminescence intensity of five times higher than using the Eu 2 O 3 activator. The CIE chromaticity coordinates of Ca 0·88 Nb 2 O 6 :0.12EuB 6 phosphor were calculated to be (0.643, 0.34) and it is quite similar to that of pure red light. Moreover, this phosphor exhibits an excellent luminescence thermal stability. When the ambient temperature rises to 398 K (125 °C) and 423 K (150 °C), the integrated emission intensity remains 90% and 86% of their initial PL intensity at 300 K, respectively. Based on above mentioned, the Ca 1-x Nb 2 O 6 :xEuB 6 as a NUV-excited red phosphor have a potential application for the high-performance white LEDs.
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