Search

This paper investigates the influence of various sintering temperatures on the microstructure and photoluminescence properties of KSr 0.99 PO 4 :Eu 0.01 3+ phosphors prepared by microwave-assisted sintering. The package properties of KSr 0.99 PO 4 :Eu 0.01 3+ phosphors combined with a n-UV InGaN chip are also investigated. To achieve maximum luminescence, the optimum sintering temperature for KSr 0.99 PO 4 :Eu 0.01 3+ phosphors prepared by microwave assisted-sintering is 1200 °C due to the pure phase and uniform and large particles (as identified by XRD and SEM). The results of the package properties showed that KSr 1−x PO 4 :xEu 3+ (x = 0.01) phosphor sintered at 1200 °C by microwave-assisted sintering could emit orange-red light via the n-UV InGaN chip.

LiBaPO 4 :Dy 3+ phosphors were synthesized by microwave-assisted and conventional sintering. XRD analysis confirmed the phase formation of all the LiBaPO 4 :Dy 3+ phosphors. PL results showed that the optimum concentration of Dy 3+ for LiBaPO 4 :Dy 3+ prepared by microwave-assisted sintering is 7 mol%. The phosphors were efficiently excited by the UV–vis light region from 300 to 400 nm, and exhibited blue (483 nm), yellow (576 nm) and red (671 nm) emission corresponding to 4 F 9/2 → 6 H 15/2 , 6 H 13/2 , and 6 H 11/2 transitions, respectively. The microwave-assisted sintering improves the sintering behavior and provides a more uniform particle morphology of LiBa 0.03 PO 4 :0.07Dy 3+ phosphors so as to obtain a luminescence intensity greater than that obtained by conventional sintering even at the same sintering temperature. Moreover, all the chromaticity ( x , y ) of the LiBa 0.03 PO 4 :0.07Dy 3+ phosphors are located in the white region (0.33, 0.37) even on using microwave-assisted sintering as the heat treatment did not influence the purity of LiBa 0.03 PO 4 :0.07Dy 3+ phosphors.

Zn 2 SiO 4 : x Eu 3+ phosphors were synthesized with different concentrations of Eu 3+ ions ( x = 0.001, 0.003, 0.005, 0.007 and 0.01) by using tetraethylorthosilicate (TEOS) solution as silicate source. The samples were sintered at 1200 °C for 2 h in air using solid-state sintering. The XRD results showed the prepared Zn 2 SiO 4 :Eu 3+ phosphors have a small impurity phase of SiO 2 when the Eu 3+ concentration is less than x = 0.005. However, the SEM results showed the prepared particles of Zn 2− x SiO 4 : x Eu 3+ phosphor have spherical shape, and fine size powder morphologies. The PL results showed the intensity of the emission spectra of Zn 2− x SiO 4 : x Eu 3+ phosphor increased first and reached a maximum value at x = 0.005, and then decrease due to concentration quenching effect. Moreover, the intensity of the emission spectra of Zn 2− x SiO 4 : x Eu 3+ ( x = 0.005) phosphor via TEOS solution as silicate source is stronger than that using SiO 2 powder as silicate sources, which may be attributed to the uniform particle size distribution. Moreover, all the chromaticity ( x , y ) of Zn 2− x SiO 4 : x Eu 3+ phosphors are located in the red region (0.63, 0.36) even if adopted TEOS solution as silicate source that would not influence the purity of Zn 2− x SiO 4 : x Eu 3+ phosphor.