Synthesis and characterization of red emission phosphor NaY(WO4)2:Eu3+ with La3+-doped

A series of novel red-emitting Na(LaxEuyY1-x-y)(WO4)(2) phosphors were successfully synthesized using the high-temperature solid-state method. The crystal structure and morphology of the phosphor were characterized by XRD, SEM and infrared absorption spectroscopy. Because of the larger ionic radius and stronger polarizability of La3+, the W-O bond length is changed and the lattice is enlarged. The energy band structure of the phosphor was calculated and estimated by using the Density functional theory. The band gap energy of NaLa(WO4)(2) host is 4.51 eV, which is greater than the 4.44 eV of NaY (WO4)(2) host. The excitation spectra and emission spectrum of the sample were tested, which confirmed that the introduction of La3+ ions changed the energy transfer mechanism of the phosphor. The D-5(0) level radiative transition lifetime and CIE chromaticity coordinates of the samples were calculated. The experimental results show that La3+ doping can change the energy transfer process of Eu3+, and then realize the regulation of red emission.