RESUMO
Discovering multifunctional luminescent materials to meet the demands of modern spectroscopy is of great significance. However, it is a standing challenge to enable multiple luminescence properties in a single material system via single metal ion doping. Here, we report the inherently Bi3+/Bi2+ codoped Ca3Ga2Ge3O12 persistent phosphor where Bi3+ is in situ reduced to Bi2+. This phosphor can act as an efficient multimodal luminescence material, which simultaneously exhibits long-lasting (>12 h) ultraviolet-B (UVB) and near-infrared (NIR) dual-band persistent luminescence after irradiation by 254 nm ultraviolet (UV) light. UVB and NIR afterglow are ascribed to the distinct Bi3+ and Bi2+ emitters, respectively, proven by comprehensive spectroscopic investigations including X-ray absorption near-edge structure spectra and X-ray photoelectron spectroscopy. Besides, this phosphor also exhibits exceptional photochromic features, accompanied by a rapid body color transformation from white to brown in response to 254 nm UV light within 60 s and excellent recovery capacity upon thermal or blue/white light stimulation. The combination of UVB persistent luminescence of Bi3+ and NIR afterglow of Bi2+ coupled with reversible white-to-brown photochromism phenomenon offers one type of promising multifunctional luminescence material, showing potential to be used for optical storage and anti-counterfeiting applications.
RESUMO
Narrowband ultraviolet-B (NB-UVB) luminescent materials are characterized by high photon energy, narrow spectral width, and visible-blind emission, thus holding great promise for photochemistry and photomedicine. However, most NB-UVB phosphors developed so far are photoluminescent, where continuous external excitation is needed. Herein, we realize NB-UVB persistent luminescence (PersL) in an indoor-lighting environment by exploiting the interaction between self-trapped/defect-trapped excitons and Gd3+ emitters in ScPO4. The phosphor shows a self-luminescing feature with a peak maximum at 313 nm with a time duration of >24 h after ceasing X-ray irradiation, which can be clearly imaged by an UVB camera in a bright environment. Spectroscopic and theoretical approaches reveal that thermo- and photo-stimulations of energies trapped at intrinsic lattice defects followed by energy transfer to Gd3+ emitters account for the emergence of the afterglow. The present results can initiate more exploration of NB-UVB PersL phosphors for emerging applications in secret optical tagging and phototherapy.
RESUMO
Based on the homology principle in advanced pharmaceutical chemistry, a new high efficiency and low toxicity collector, O-butyl S-(1-chloroethyl)carbonodithioate, was designed. By using molecular simulation technology, MS (Materials Studio) was used to build the molecular model of the collector. The molecular structure was relaxed and optimized. The process of interaction between reagent and mineral surface was simulated and the interaction energy of reagent and mineral surface was calculated by density functional theory (DFT). The interaction process of the new collector and butyl xanthate on the mineral surface and the interaction energy of these two reagents and mineral surface were compared. The molecular structure of the new collector was designed from the perspective of the difference of the interaction energy between the reagents and the mineral surface. According to the results of molecular design and modelling, the new collector was synthesized. The flotation tests of pure minerals and real ores were carried out to verify the new collector. The experimental results showed that the collector has the characteristics of low toxicity, high selectivity, moderate collecting ability and low cost, and it is more suitable for flotation of the complex and refractory copper sulfide with low grade and fine dissemination.
