Energy transfer rate and electron-phonon coupling properties in Eu³⁺ -doped nanophosphors

A series of controllable emissions SrWO₄ :Eu³⁺ and charge-compensated SrWO₄ : Eum3+ (m = 0.01 or 0.20) phosphors was successfully prepared via a simple co-precipitation method. The energy transfer mechanism was studied based on the Huang's theory. A low magnitude of Huang-Rhys factor (10^-2 ) was calculated using phonon sideband spectra. The Judd-Ofelt parameters Ω_λ (λ = 2, 4 and 6) of Eu³⁺ -activated SrWO₄ doped with charge compensation were obtained. The calculated Commission Internationale de l'Eclairage chromaticity coordinates were found to be about (0.67, 0.33) for SrWO₄ : Eu0.203+ and charge-compensated SrWO₄ : Eu0.203+ phosphors, which coincided with the National Television Standard Committee system standard values for red. A white light emission was obtained under 362 nm excitation. The correlated color temperature was computed by a simple equation to characterize light sources. Thus, warm white light-emitting diodes with higher Ra can be constructed by combining as-prepared high efficiency, low correlated color temperature and high color purity phosphor.