Preparation, band-structure and luminescence of double perovskite Ba2MgMoO6:Eu3+ orange-red phosphor for white LEDs

Abstract Novel Eu3+-doped double perovskite Ba2MgMoO6 orange-red phosphors were successfully prepared using EDTA-citric acid complexing method at low calcination temperature for the first time. The XRD, FTIR, SEM, UV–VIS diffuse reflectance and photo-fluorescence spectroscopy were employed to study the structure and luminescence of powders. The first-principle calculations of state density and structure refinement were also performed to get the energy-band structure and structure information. At the low calcination temperature of 1000 °C, ions doped double perovskite powder with homogenous ordering of B-site was obtained. Its structure was an orthogonal perovskite in which BO6 octahedrons were periodically arranged and the space group with small tilting was P21/n. The strong and wide absorption in near-UV region was due to the charge transfer from the O 2p orbital to the Mo 4d orbital in the MoO6 octahedron. The orange-red (593 nm) resulted from the unforbidden magnetic dipole transition dominated the emission. However, the red light (615 nm) resulted from the electric dipole transition was dominated under the excitation of blue light (464 nm) due to the partial release of parity inhibition. With the increase of calcination temperature, the grain size, order degree of B site and particle size of the powder were all increased, and the powder calcined at 1200 °C exhibited the highest luminescence intensity.