Effects of Eu3+ doping on the luminescence properties of novel Sr2CaLa(VO4)3 from partial substitution of Sr2+ by Ca2+ in Sr3La(VO4)3

Abstract

Eu 3+ -activated Sr 3 −x Ca x La(VO 4 ) 3 phosphors were fabricated via citric-acid-assisted sol combustion. Characterization of the Sr 3 −x Ca x La(VO 4 ) 3 :Eu 3+ samples with different concentrations of Ca 2+ revealed a hexagonal crystal structure belonging to the R -3 m space group. The amount of Ca 2+ added ( x ) was controlled within 0 ≤ x ≤ 2 to yield high-purity phosphors. Scanning electron microscopy results showed that an increase in Ca 2+ concentration resulted in a decrease in the particle size of Sr 3 −x Ca x La(VO 4 ) 3 :Eu 3+ , with the shape gradually changing from nearly equiaxed to lath-shaped. The Sr 2 CaLa(VO 4 ) 3 :Eu 3+ phosphor (denoted as SCLVO:Eu 3+ ) exhibited the strongest photoluminescence (PL) intensity at 618 nm among the samples under excitation of 394-nm near-UV (NUV) light. The study of Eu 3+ doping concentration confirmed that Eu 3+ could enter the lattice of the SCLVO matrix without altering its crystal structure. SCLVO:Eu 3+ was found to strongly absorb 394 nm NUV light and 464 nm blue light. The optimal concentration of the Eu 3+ dopant in the SCLVO host was 0.11, which resulted in the phosphor achieving an excellent PL intensity and a color purity of 98.68%. Tunable luminescence from the orange area (0.5280, 0.4522) of Commission Internationale de l'éclairage (CIE) to the red area (0.6313, 0.3650) was achieved by adjusting the concentration of Eu 3+ . Under 394 nm excitation, SCLVO:0.11Eu 3+ phosphor has a quantum yield (QY) of 28.2% and excellent thermal stability with 0.383 eV activation energy. Consequently, White-light-emitting diode (WLED) based on SCLVO:0.11Eu 3+ phosphor yielded a high color rendering index (CRI), low correlated color temperature (CCT), and CIE coordinates of 91.8, 5196 K, and (0.3407, 0.3612), respectively, under the 20 mA driven current. These results indicated the tremendous potential of SCLVO:0.11Eu 3+ phosphors for application in WLEDs excited by NUV or blue light.