New aspects of the luminescence of magnesiumtitanate part II: Activation with manganese

Ab Initio-Aided Sensitizer Design for Mn4+-Activated Mg2TiO4 as an Ultrabright Fluoride-Free Red-Emitting Phosphor

“…Furthermore, the EXAFS was obtained in order to investigate the coordination environment of Nb in the Mg 2 TiO 4 matrix. As shown in Table 1, the bond lengths between Nb and the nearest-neighboring O (32e) and Mg (8a) are very close to those of Ti and Mn in the same MTO matrix 9 (see the detailed fitting process in the Supporting Information). This demonstrates that the crystal site of Nb is very similar to that of Ti and Mn.…”

“…Additionally, the internal quantum efficiency of MTO:Mn,Nb is estimated to be 44.8% (see the details in the Supporting Information), which is 160% of the undoped MTO:Mn. To the best of our knowledge, this is the brightest MTO-based red-emitting phosphor reported. , However, when the Nb doping level exceeds 0.5 at. %, the PL intensity drastically drops.…”

“…To the best of our knowledge, this is the brightest MTO-based red-emitting phosphor reported. 8,9 However, when the Nb doping level exceeds 0.5 at. %, the PL intensity drastically drops.…”

“…Red-emitting phosphor materials are an essential component in white-light LED devices; they are usually (oxy)­nitride compounds with rare-earth (RE, e.g., Eu 2+ and Eu 3+ ) dopants. − However, RE dopants are expensive and highly hazardous to the environment during mining and production processes . Recently, tetravalent manganese (Mn 4+ ) has been identified as an environmentally friendly luminescence alternative to substitute the conventional hazardous RE dopants in red phosphor. − Unfortunately, the fluoride compounds that are required as a matrix for Mn 4+ will result in high pollution because concentrated hydrofluoric acid is used in the fabrication process. − Mg 2 TiO 4 (MTO), with a Mn 4+ luminescent center (MTO:Mn), is an ecofriendly “RE-free” and “fluoride-free” red-light material. − However, the intrinsic excitation properties of MTO:Mn are less efficient in the blue than in the ultraviolet region, limiting its applications as a red-light component in blue LEDs for white-light emission . A proper sensitizer can enhance the efficiency of phosphor materials by transferring energy to the luminescent centers; for instance, the Bi 3+ ion was recently proposed as a sensitizer for MTO:Mn .…”

Rare earth-free high color rendering white light-emitting diodes using CsVO3 with highest quantum efficiency for vanadate phosphors

“…We focused on a Mn 4+ emission color center to tune the luminescence color of CsVO 3 . We prepared red phosphor Mn 4+ -doped Mg 2 TiO 4 (Mg 2 TiO 4 :Mn 4+ ), 35,36 and fabricated a high color rendering WLED consisting of CsVO 3 and Mg 2 TiO 4 :Mn 4+ , and an excitation near-ultraviolet (NUV) LED.…”