Synthesis and Optical Properties of Eu2+ and Eu3+ Doped SrBP Phosphors Prepared by Using a Co-precipitation Method for White Light-Emitting Devices

Abstract

The Eu3+ and Eu2+-doped SrBP phosphor powders were synthesized via the co-precipitation method and subsequent reduction of the dopants in N2/H2 gas for application in white light-emitting devices (WLED). The as-prepared powders were annealed at a temperature range of 600°C to 1300°C in air ambient to form Eu3+-doped phosphors with an average particle size in the range of 100 nm to 1 μm. The phosphors were then reduced in the forming gas (90%N2:10%H2) to achieve Eu2+-doped phosphors. It has been found that typical phases of Sr6P5BO20, Sr2P2O7, and Sr3(PO4)2 co-exist in the as-prepared powders. The strong and narrow orange-red emission from 570 nm to 700 nm in the photoluminescence spectra (PL) of the SrBP:Eu3+ phosphors are attributed to the 5D0 → 7Fj transitions of Eu3+ ion (where j gets the value of 1 to 6). In contrast, the broad luminescence band of the SrBP:Eu2+ phosphors in the range of 400 nm to 500 nm are attributed to the 5d–4f transitions of Eu2+ ion in the same host crystal. The Eu3+/Eu2+-doped SrBP phosphors are considered to be promising phosphors for WLED. The co-precipitation method is simple and rapid, but allows for the controlling of particle size and composition with ease.