Eu3+-doped ZnLaB5O10: A suitable candidate for near ultraviolet LED pumped red phosphor.

It is important to develop red phosphors which can be efficiently excited by near ultraviolet (NUV) irradiation, matching the wavelength of commercial LED chips. ZnLaB 5 O 10 possesses a significantly distorted coordination of La3+ and suitable for the Eu3+ incorporation, whose parity-forbidden law could be suppressed in such a coordination and be efficiently excited by f - f transitions in the NUV range. ZnLa 1- x Eu x B 5 O 10 (0 ≤ x ≤ 1.0) were prepared by high temperature solid state reactions. Excitation and emission spectra prove that the concentration saturation occurs at a high Eu3+ concentration (∼60 atm%). All the phosphors emit the bright red light with a high red-to-orange ratio (2.7–3.1) and CIE coordinate (0.64, 0.36). In-situ high temperature photoluminescence spectra of ZnLa 0.4 Eu 0.6 B 5 O 10 prove its high thermal stability, i.e. the emission intensity at 150 °C remains 90% of the value at room temperature, thus being a suitable candidate for NUV-LED pumped red phosphor. ZnLa 1- x Eu x B 5 O 10 (0 ≤ x ≤ 1.0) were prepared by solid state reactions and the photoluminescence property was investigated systematically. Eu3+ locates at a 10-fold coordination environment with C 1 symmetry, thus the f - f transition at 393 nm is substantially intense and the emission quenching occurs at a high Eu3+ concentration (>60 atm%). The optimal sample ZnLa 0.4 Eu 0.6 B 5 O 10 together with commercial blue and green phosphors were combined with the 390 nm LED chip to emit a warm white light. Image 1 • ZnLa 1- x Eu x B 5 O 10 (0 ≤ x ≤ 1.0) were prepared by typical solid state reactions. • The concentration saturation occurs at a high Eu3+ concentration (∼60 atm%). • All samples emit the bright red light with a high red-to-orange ratio (2.7–3.1). • The emission intensity of ZnLa 0.4 Eu 0.6 B 5 O 10 at 150 °C remains 90%. • ZnLa 0.4 Eu 0.6 B 5 O 10 phosphor can be efficiently pumped by a 395 nm LED chip. [ABSTRACT FROM AUTHOR]