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The rare earth luminescent nanoparticles are regarded as one of the most ideal fluorescent probes. In order to solve the problem of insufficient luminescence intensity of rare earth luminescent imaging materials, a new core–shell-structured CuS@YF3:Eu with strong luminescent nanoparticles was successfully prepared. The nanoparticles possessed stronger luminescent property than individually dispersed YF3:Eu nanoparticles that it is attributed to the plasmon-enhanced localized electric fields effect of the interface of CuS and YF3:Eu nanoparticles. This work provides insight on the development of nonmetallic plasmon-sensitized optical materials and to promote their application in the diagnosis and treatment of cancer. [ABSTRACT FROM AUTHOR]

Eu3+-doped germanate based red emitting phosphors SrGe4O9: xEu3+ (0 ≤ x ≤ 0.5 mol%) were prepared by high-temperature solid-state procedure. Moreover, the Density Functional Theory (DFT) calculation, X-ray diffraction (XRD) Rietveld refinement, scanning electron microscopy (SEM), and photoluminescence (PL) measurement were discussed in detail to fully investigate the crystal structure and PL properties of SrGe4O9: xEu3+. Furthermore, the Judd–Ofelt (J–O) analysis demonstrated that the Eu3+ ions in the SrGe4O9 host possessed lower sites symmetry. In addition, the phosphor SrGe4O9: 0.35%Eu3+ displayed superior thermal stability with PL intensity at 423 K is around 90% of its initial value at 298 K. As a result, the white light emitting diodes (WLED) device based on SrGe4O9: 0.35%Eu3+ achieved an expected result of a correlated color temperature (CCT) of 4573 K and a color rendering index (CRI) of 80.8 under a voltage of 3 V and a driven current of 20 mA. [ABSTRACT FROM AUTHOR]

Near-infrared (NIR) phosphor-converted light-emitting diodes (pc-LEDs) have exhibited tremendous potential in spectroscopic technology, promoting the demand of developing novel NIR materials with excellent properties. In this paper, a series of germanate based NIR phosphors Sr 3 ZnGe 5 O 14 : xCr3+ (0 ≤ x ≤ 0.05) were synthesized by high temperature solid state reaction. The X-ray diffraction (XRD), scanning electron microscopy (SEM), Ultraviolet diffuse reflection, photoluminescence spectra and PL decay were measured to analyze the crystal structure, morphology properties and elements composition, PL emission properties and lifetimes of these NIR phosphors. Results demonstrated that phosphors Sr 3 ZnGe 5 O 14 : xCr3+ (0 ≤ x ≤ 0.05) crystallized in a trigonal with a space group of P 321(150) with a broad band gap (E g) of 4.70–4.59 eV. Sample Sr 3 ZnGe 5 O 14 : 0.03Cr3+ with the best PL emission properties showed a good thermal stability with the PL emission intensity remains 69 % of its initial value at 420 K. It's worth noting that the NIR device based on Sr 3 ZnGe 5 O 14 : 0.03Cr3+ displays an impressive electroluminescent emission stability, for example, the electroluminescent emission intensity is still about 92.3 % of its initial value when the NIR pc-LED light up for 18 h. These research results provided an important guidance for developing novel Cr3+ doped germanate based NIR phosphors with excellent thermal and electroluminescent emission stability. [ABSTRACT FROM AUTHOR]

The photoluminescence and temperature sensitivities of Ca 3 Y 2 Si 3 O 12 :Pr3+ thermo-phosphors with silico-carnotite structure obtained by solid state reaction method were investigated. Pr3+ ions were accommodated in the A sites having coordination number of 9 in AB 2 C 2 (SiO 4) 3 to replace Y3+ ions. The typical sample consisted of microcrystals with an irregular structure and the surface of particles was smooth, which could enhance the luminescence due to reducing the scattering and non-radiation produced by rough surfaces. The band gap value of typical sample was about 4.01 eV. Dipole-dipole interaction could account for concentration quenching. The two thermometry strategies including normalized intensities from 3P 0 →3H 4 transition and Fluorescence intensity ration (FIR) of 3P 0 →3H 4 /3P 1 →3H 5 transitions were employed for temperature sensing in 298–573 K. The results revealed that Ca 3 Y 2 Si 3 O 12 :Pr3+ thermo-phosphors had good temperature sensitivity performance with maximum S r of 0.59% K−1@573 K and 0.762% K−1@298 K in the above two methods, respectively. Hence, Ca 3 Y 2 Si 3 O 12 :Pr3+ would be a promising candidate in the field of optical thermometry. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel M O O 3-x @YF 3 :Yb3+,Er3+with enhanced up-conversion/NIRII luminescent was prepared. • Novel M O O 3-x @YF 3 :Yb3+,Er3+carriers with strong drug loading capacity was prepared. • The luminescent properties of carriers was enhanced through LSPR effect. • Novel M O O 3-x @Yb3+,Er3+carriers with strong drug release effect was prepared. • The cytotoxicity was obviously related to the concentration of carriers. A new rod-shaped MoO 3-x @YF 3 :Yb3+,Er3+ integrated carrier for the NIR-II fluorescence imaging and chemotherapy has been successfully prepared by introducing the local surface plasmon resonance (LSPR) effect and regulating the morphology and surface state. The analysis methods such as XRD, SEM, EDX, TEM, UV–Vis-NIR, PL and IR are used to study the structure, morphology, composition and properties. XRD, SEM and TEM analysis shows that the surface of MoO 3-x is successfully coated with YF 3 :Yb3+, Er3+ nanocrystals of well-crystallized orthogonality, and the carrier obtained has a unique rod-like morphology. XPS analysis shows that Mo element exists in two valence states: Mo (VI) and Mo (V). Furthermore, PL analysis shows that the carrier has stronger luminescence intensity of up-conversion and the near-infrared second region (NIR II) under the excitation of 980 nm and 1540 nm, respectively. The drug delivery capacity and release effect of carrier are studied by using doxorubicin (DOX) as an anti-tumor template drug. The results shows that the carrier with unmodified polyethylene glycol (PEG) has strong drug loading capacity and release effect. The cytotoxicity of the carrier is performed using Hela cells. The result show that the cytotoxicity was obviously related to the concentration of MoO 3-x @YF 3 :Yb3+,Er3+ nanoparticles. This work will solve the bottleneck of fluorescence imaging of visual drug delivery carriers, tumor penetration rate and efficient drug delivery. [ABSTRACT FROM AUTHOR]

Up-converting luminescent nanoparticles (UCNPs) have been arousing increasing attention in biomedical imaging because of their long-life emission and concomitant benefits (e.g., zero-autofluorescence background, low toxicity). However, the further development on the application has been limited by the low luminescence efficiency and intensity of UCNPs. Herein we report the design principle, synthesis route, and luminescence properties of core-shell structured Cu 2-x S@YF 3 :Yb–Er nanoparticles with strong luminescent property (red emission). The design principle leverages on the plasmon-enhanced localized electric fields effect of the interface of Cu 2-x S and YF 3 :Yb–Er nanoparticles and photo-thermal effect of Cu 2-x S. This strategy could enhanced luminescence properties of YF 3 :Yb–Er nanoparticles. The as-prepared Cu 2-x S@YF 3 :Yb–Er nanoparticles possessed stronger luminescent property (red emission) than individually dispersed YF 3 :Yb–Er nanoparticles. And the nanoparticles presented a dramatic red-shift that was due to the growth of YF 3 :Yb–Er on the Cu 2-x S surface. The research supplies an insight on the development of nonmetallic plasmon-sensitized luminescent materials, and hopefully it could promote them application in the diagnosis and treatment of cancer. [ABSTRACT FROM AUTHOR]

SrSnO 3 : Pr3+ phosphors with red long afterglow (LAG)and temperature sensing were prepared by albumin assisted sol-gel method. The typical sample had cubic structure. The mean particle size was about 2.02 μm. The band gap values of samples were in the range of about 4.06–4.09 eV. The luminescent properties and LAG behaviors of SrSnO 3 : Pr3+ phosphors were investigated and the luminescence mechanism of red LAG was discussed. Albumin assisted SrSnO 3 : Pr3+ phosphor with a red long afterglow had an average decay time of 74.25 s. Pr3+ ions not only act as an activator, emitting red long afterglow, but also act as a trap provider. Moreover, the temperature sensing property was studied based on the non-thermal coupling FIR of TE and 3P 0 →3H 4 transition emission. The relative sensitivity was as high as 3580.89/T2. The absolute sensitivity (S a) and relative sensitivity (S r) of SrSnO 3 : 0.5%Pr3+ were 0.0374 K-1 and 4.03% K−1, respectively. Its optical thermometry performance is better than that of most phosphors. It has the potential to be applied in the field of temperature sensing. [Display omitted] • Albumin assisted SrSnO 3 : Pr3+ phosphors with red long afterglow (LAG)and temperature sensing were prepared. • Pr3+ ions not only act as an activator, but also act as a trap provider, emitting red long afterglow. • The relative sensitivity was as high as 3580.89/T2. • It has the potential to be applied in the field of temperature sensing. [ABSTRACT FROM AUTHOR]

CaSnO 3 : Pr3+ phosphor for new application in temperature sensing was investigated. CaSnO 3 : 0.3%Pr3+ had distorted orthorhombic perovskite structure and Pr3+ occupied Ca2+ sites due to their similar ionic radii. CaSnO 3 : 0.3%Pr3+ had spherical particles with mean size of 0.816 μm. The electric dipole−dipole interaction could explain the concentration quenching mechanism. The chromaticity coordinates were (0.1324, 0.3847), located in greenish-blue region and the average afterglow decay time was 60.2 s for CaSnO 3 : 0.15%Pr3+, which had potential applications for LED and emergency lighting. CaSnO 3 : 0.3%Pr3+ had the activated energy of 0.380 eV. The maximum relative temperature sensitivity for CaSnO 3 : 0.3%Pr3+ was 7.57% K−1 at 298 K and relative sensitivity was as high as 6722.76/T2 K−1, which was better than that of most Pr3+ doped phosphors and had potential application in temperature sensing. Moreover, the possible luminescence and long afterglow mechanisms and thermal quenching process of 3P 0 level through IVCT state were proposed. Unlabelled Image • Pr3+ doped CaSnO 3 phosphor for new application in temperature sensing. • S r value of 6722.7557/T2 K−1 was better than that of most Pr3+ doped phosphors. • CaSnO 3 : 0.3%Pr3+ had spherical particles with mean particle size of 0.816 μm. • τ avg is 60.2 s for CaSnO 3 : 0.15%Pr3+, potential application in emergency lighting. • Possible luminescence and long afterglow mechanisms were proposed. [ABSTRACT FROM AUTHOR]

Two series of Eu3+ ions activated high performance red-emitting phosphors Ba 2(1-x) AGe 2 O 7 : 2xEu3+ (A = Mg, Zn, 0 ≤ x ≤ 0.2) were synthesized by high-temperature solid-state procedure. The research results showed that the host lattice Ba 2 MgGe 2 O 7 possess higher band gap than that of Ba 2 ZnGe 2 O 7 , and all the Ba 2(1-x) MgGe 2 O 7 : 2xEu3+ (BMGO: 2 xEu3+, 0 ≤ x ≤ 0.2) and Ba 2(1-x) ZnGe 2 O 7 : 2xEu3+ (BZGO: 2 xEu3+, 0 ≤ x ≤ 0.2) phosphors crystallized in a tetragonal unit cell with the space group of P 421 m (113). Compared with other phosphors in the same series, the samples BMGO: 0.30 Eu3+ and BZGO: 0.25 Eu3+ presented the highest absorption intensity when monitoring at 616 nm under 395 nm excited, respectively. Moreover, the samples BMGO: 0.30 Eu3+ and BZGO: 0.25 Eu3+ not only exhibited high color purity of 90% and 90.3%, respectively, but also possess excellent thermal stability. Unsurprisingly, the WLED devices based on BMGO: 0.30 Eu3+ and BZGO: 0.25 Eu3+ as the red-emitting components displayed good luminescence properties, especially the color rendering index (CRI, R a) R 9 represented the saturation of colour of illuminated objects exhibited a high value of 89.6 and 82.3, respectively. In contrast, the WLED device based on BMGO: 0.30 Eu3+ as red-emitting phosphors presented better electroluminescence performances than those of BZGO: 0.25 Eu3+ on account of its much favorable crystal structure, PL performance and thermal stability. Image 1 • Ba 2 AGe 2 O 7 : Eu3+ were synthesized as red-emitting phosphors. • BMGO:0.3Eu3+ and BZGO:0.25Eu3+ exhibit excellent color purity and thermal stability. • BMGO:0.3Eu3+ and BZGO:0.25Eu3+ based WLED present excellent luminescence properties. [ABSTRACT FROM AUTHOR]