The luminescence and structural characteristics of Eu3+- doped NaSrB5O9 phosphor

• New red-emitting NaSrB5O9:Eu3+ phosphors were prepared.
• The CTB of Eu-O was observed at ~258 nm for 9 at.%.
• Energy transfer from borates to Eu3+ ions is discussed.
• NaSrB5O9:Eu3+ phosphor exhibited a high color purity of about 99.7%.

A red-emitting phosphor NaSrB5O9:Eu3+ was synthesized by employing a solid-state reaction (SSR) method. The structures of the phosphors were analyzed by X-ray diffraction (XRD), Fourier-transform infrared (FTIR) and Raman studies. The band at ~282 nm in the excitation spectra indicated the charge transfer band (CTB) of B-O in the host, whereas the CTB of Eu-O was observed at ~275 nm for the NaSrB5O9:Eu3+ (Eu3+=1 at.%) phosphor, which was supported by diffuse reflectance spectroscopy (DRS) measurements. The photoluminescence (PL) measurements exhibited a strong red emission band centered at about 616 nm (5D0→7F2) under an excitation wavelength of 394 nm (7F0→5L6). Upon host excitation at 282 nm, the pristine NaSrB5O9 exhibited a broad UV emission centered at ~362 nm. The energy transfer from host to Eu3+ ions was confirmed from luminescence spectra, excited with a 355 nm Nd:YAG laser. In addition, the asymmetric ratios indicate a higher local symmetry around the Eu3+ ion in the host. The calculated CIE (Commission International de l′Eclairage) coordinates displayed excellent color purity efficiencies (around 99.7%) compared to other luminescent materials.

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