Two-site occupancy induced the broad-band emission in the Ba 4- x - y Sr y La 6 O(SiO 4 ) 6 : x Eu 2+ phosphor for white LEDs and anti-counterfeiting.

With the increasing demand for new inorganic functional materials, more and more attention is paid to rare earth ion doped luminescent materials. In this work, an Eu 2+ doped Ba 4 La 6 O(SiO 4 ) 6 phosphor was synthesized by the high temperature solid-phase method. In the phosphor, two Ba 2+ sites could be occupied by Eu 2+ cations to provide two different kinds of coordination environments, resulting in broad emitting bands in the range of 450-630 nm and ultra-wide excitation bands in the range of 250-500 nm. The presence of two different Eu 2+ emitting centers is verified by measuring the photoluminescence spectra and decay curves in Ba 4 La 6 O(SiO 4 ) 6 phosphors. The temperature dependence of emission intensity and full width at half maximum of Eu 2+ in the range of 293-453 K were investigated systematically. The substitution of Ba 2+ by Sr 2+ can adjust the crystal field; thus, the luminous intensity was improved by 2.07 times and T 50 was increased from 380 K to 453 K. Due to the Sr 2+ ion doping, some of the Eu 3+ ions cannot be reduced and remain in the trivalent state. In addition, by integrating the as-prepared Ba 1.42 Sr 2.5 La 6 O(SiO 4 ) 6 :Eu phosphor, commercial blue and red phosphors, and a 385 nm LED chip, a white-LED lamp was made, which realized an applicable color rendering index ( R a = 94.6). For the Ba 0.42 Sr 3.5 La 6 O(SiO 4 ) 6 phosphor, the emission can be shifted from yellow to green and to yellow by excitation wavelength variation from 250 to 360 and 480 nm, which proves that the phosphor is a promising candidate for anti-counterfeiting applications.