The role of Eu2+ concentration on the phase formation and spectroscopic properties of MZr4(PO4)6 (M2+ = Ca2+, Sr2+).

The electronic structures of M Zr 4 (PO 4 ) 6 ( M 2+ = Ca 2+ , Sr 2+ ) were calculated using the CASTEP and the band gaps for CaZr 4 (PO 4 ) 6 and SrZr 4 (PO 4 ) 6 can reach up to 4.30 and 4.45 eV, respectively. Eu 2+ doped M Zr 4 (PO 4 ) 6 were prepared by solid-state reaction method. The XRD patterns, luminescence, decay curves and thermal quenching properties of the samples were investigated. The Eu 2+ ion can be totally incorporated into M Zr 4 (PO 4 ) 6 forming complete solid solutions. M 1− x Eu x Zr 4 (PO 4 ) 6 (0.01 ≤ x ≤ 1) shows typical broad band emission in energy range from 1.91 to 3.11 eV originating from the 4 f 6 5 d 1 → 4 f 7 5 d 0 transition of Eu 2+ . With increasing Eu 2+ concentration, there is an abnormal blue-shift of the emission for CaZr 4 (PO 4 ) 6 :Eu 2+ due to the decreasing crystal field strength and Stokes shift. However, there is no significant change in the position of the emission spectra in Eu 2+ -activated SrZr 4 (PO 4 ) 6 . M 0.97 Eu 0.03 Zr 4 (PO 4 ) 6 shows the abnormal blue shift with decreasing emission intensity as an increase in temperature. [ABSTRACT FROM AUTHOR]