An efficient blue phosphor with high thermal stability for lighting and optical pressure sensor applications

Abstract

For exploring new and efficient luminescent materials, we developed an efficient narrow-band blue-emitting phosphor Eu²⁺ doped Na₃CsMg₇(PO₄)₆. Under near-ultraviolet light excitation, the phosphor can emit bright blue light with a narrow FWHM of about 53 nm peaked at 463 nm with a high quantum yield of about 88.1%. And it has a broad excitation spectrum from 250 nm to 435 nm, and the strongest absorption is located between 350 and 410 nm, which can be efficiently excited by near-ultraviolet LED chips. Due to the energy transfer from the defect level to 5d–4f of Eu²⁺, the samples possess excellent thermal stability, even up to 200 °C, and the emission integrated intensity still retains more than 110% of that at room temperature. The fabricated white LED device using the as-prepared sample demonstrates great potential to be used as a blue phosphor for w-LEDs. Furthermore, the luminescence properties under various pressures were investigated, and the emission color can be changed from 451 nm to 488 nm by changing the pressure and dλ/dP is 2.13 nm GPa⁻¹. At a pressure of 13.3 GPa, the sample exhibits a narrow blue emission with a FWHM of about 31 nm. The visual color variation, high pressure sensitivity and high pressure upper limit of the phosphor indicate that it could be applied as an optical pressure sensor.