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This paper focuses on the use of [Zn2+–Ge4+] to co-replace [Ga3+–Ga3+], which redshifts the near-infrared emission of Cr3+ in Ga2O3, and broadens the full width at half maximum.

The introduction of K+ into a RbNa3(Li3SiO4)4:Eu2+ phosphor to partially or completely replace Rb+ allows the emission spectrum to be modulated from blue (λ = 473 nm, FWHM = 22.5 nm) to a narrow cyan band (λ = 485 nm, FWHM = 21.1 nm).

Through engineering the interfacial layer in cubic SrYF5:YbEr@CaF2@SrYbF5:Nd core/shell/shell NCs, the maximum Sr of 10.01% K−1 and minimum Sr of 2.56% K−1 under 980 nm laser excitation are achieved.

Polychromatic emission can be achieved by controlling the distribution of the rare earth activator in multi-cation lattices, which can be used in the fields of white light LED and fluorescence temperature sensing.

Here, a "chemical unit co-substitution" method is used to improve the near-infrared (NIR) emission of phosphors, using [Zn

A series of BaGd2O4:Bi3+,Eu3+ phosphors with dual-emitting centers were prepared by high-temperature solid-state method. X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), fluorescence spectroscopy, lifetime decay curve and variable temperature emission spectroscopy were used to systematically study the structure, luminescence performance and temperature characteristics. Under ultraviolet (UV) excitation, the BaGd2O4:Bi3+,Eu3+ phosphor showed a broad-band emission in the blue region corresponding to transitions of Bi3+ ions and the sharp red light emission corresponding to Eu3+ ions. The Bi3+ and Eu3+ ion emission peaks were well-separated, which meets a prerequisite for efficient temperature signal resolution measurement. The fluorescence intensity ratio (FIR) technique was used to measure the different temperature response characteristics between Bi3+ blue emission and Eu3+ red emission. When the temperature varies from 293 K to 473 K, the relative temperature sensitivity (Sr) of BaGd2O4:Bi3+,Eu3+ phosphors is obtained, was determined as 1.0182%K−1. In addition to calculating the relative sensitivity by FIR technology, we can also obtain the value of Sr through experiments and formulas related to the decay life, and found to be 1.0651%K−1. Therefore, BaGd2O4: Bi3+,Eu3+ phosphor is an excellent non-contact optical temperature measurement material.

A series of Rb

Realizing multicolored luminescence in two-dimensional (2D) nanomaterials would afford potential for a range of next-generation nanoscale optoelectronic devices. Moreover, combining fine structured spectral line emission and detection may further enrich the studies and applications of functional nanomaterials. Herein, a lanthanide doping strategy has been utilized for the synthesis of 2D ZnSe:Er

Rare earth doped luminescence glasses have been noteworthy recently in the fields of near-middle-infrared applications. In this work, serious Er3+ doped new kind of germanosilicate-zinc glasses have been investigated aiming to obtain efficient infrared and mid-infrared luminescence performance. The drastically reduced OH− content in present host support the enhanced 2.7 and 1.5 μm emissions corresponding to the 4I11/2 → 4I13/2 and 4I13/2 → 4I15/2 transitions owing to the decreased energy loss between OH− and active ions. Meanwhile, the energy transfer mechanism has been discussed based on both the infrared and visible spectra together with the measured decay curves. Hence, the large absorption and emission cross-sections indicate that this kind of germanosilicate-zinc glasses may provide high gain as a good medium for efficient infrared laser system.

A system of zinc fluoride glasses were synthesized to analyse the sensitization mechanism between doped Ln3+ ions under 808 or 980 nm excitation. Differential scanning calorimetry (DSC) curve and Raman spectra indicate the favourable thermal stability and a low maximum phonon energy of the host. Judd-Ofelt (J-O) theory together with the absorption spectra were utilized to compute the Ωt for predicting radiative features of each sample which coincide with the later measured emission spectra. Broadband emission ranging from 2400 to 3300 nm with a half-width of 361 nm in Er3+/Dy3+ codoped zinc fluoride glasses under 980 nm pumping has been investigated, which may be applicated in mid-infrared fiber amplifier and broadband tunable lasers field. On the other hand, the efficient sensitization effect mechanism between Er3+ and Dy3+ around 3 μm band with an extremely high energy transfer efficiency Ƞ (96.1%) of Er3+:4I13/2→Dy:6H11/2 has been researched under 808 nm excitation. Hence, Er3+ and Dy3+ doped zinc fluoride glasses may be potential optical candidates of great development foreground in the fields of mid-infrared applications.

Efficient NIR–MIR luminescence conversion materials are urgently required for numerous applications in the fields of medicine, remote sensing, and optical communications. The control of the chemica...

Fluorescence intensity ratio-based temperature sensing with a self-referencing characteristic is highly demanded for reliable and accurate sensing. Although enormous efforts have been devoted to explore high-performance luminescent temperature probes, it remains a daunting challenge to achieve highly relative sensitivity which determines temperature resolution. Herein, we employ a novel strategy to achieve temperature probes with ultrahigh relative sensitivity through integrating both positive and negative thermal quenching effect into a hydrogel. Specifically, Er3+ ions show evidently a positive thermal quenching effect in Yb/Er:NaYF4@NaYF4 nanocrystals while Nd3+ and Tm3+ ions in a Yb2W3O12 bulk exhibit prominently a negative thermal quenching effect. With elevating temperature from 313 to 553 K, the fluorescence intensity ratio of Er (540 nm) to Nd (799 nm) and Tm (796 nm) to Er (540 nm) is significantly decreased about 1654 times and increased about 14,422 times, respectively. The maximum relative sensitivity of 15.3% K-1 at 553 K and 23.84% K-1 at 380 K are achieved. The strategy developed in this work sheds light on highly sensitive probes using lanthanide ion-doped materials.

International audience; Fluorescence of negative-charged nitrogen-vacancy centers in nanodiamond allows applications in quantum metrology, nanoscale sensor, and bioimaging, of utmost relevance to domains from nanotechnologies to biosensing. However, the low color center content and collection efficiency of photons are crucial issues. Although, several studies about coupling nanodiamond into optical waveguides have already been proposed, the search for the most appropriate substance and simplest, most effective method are of keys. In this study, we present a novel nontraditional way to incorporate nanodiamond with increased negative-charged nitrogen-vacancy content to 75.48% into tellurite germanate glass. The hybrid glass is stable in structure with predominant TeO4 trigonal bipyramid. Moreover, the fluorescence intensity is enhanced in composite. Such robust nanodiamond in tellurite germanate glass optical system has the potential to be used for nanoparticle sensing and quantum metrology.

International audience; Lanthanide-doped up-conversion (UC) materials with color tunable property show promising application in many fields, such as biological imaging, optical multiplexing, and information security. Although great efforts have been devoted to regulate UC emission color via modifying chemical composition, crystal structure, or external stimuli condition, it is remain a daunting challenge to develop a general strategy that probably suitable for various lanthanide-doped nano-systems. Herein, we verify the cross-relaxation possibility between sensitizer Yb3+ and activator Er3+ as well as Er3+- Er3+ pairs can be well modified by engineering the crystal lattice distortion of matrix, leading to the evident UC emission color variations. Specifically, with incorporating Al3+ or Ca2+ ions into the Yb/Er co-doped BaF2 nanocrystals (NCs) contained glass ceramics (GCs), the contraction of the crystal lattice lead to the change of UC emission color from green to red. On the contrary, the high laser excitation power results in the lattice expansion of the Al3+-doped BaF2:Yb/Er GCs at different Yb3+ concentration as well as Al3+ doped CaF2 GCs, which leads to the greatly increased green-to-red ratio. These multi-color UC GCs show potential application in anti-counterfeiting filed. Our results open up a general avenue for the control of UC emission color via engineering crystal lattice distortion.

Surface-enhanced Raman scattering (SERS) has attracted much attention with its powerful trace detection and analysis capabilities, especially biological and environmental molecules. However, building a protein SERS detection platform based on semiconductor devices is a huge challenge. Herein, through the synergy of NH3 and nickel foam, a large-sized semiconductor tungsten oxide hydrate platform (WOHP) was synthesized. The crystal plane of a single WOHP particle is larger than the excitation spot. As a SERS substrate, WOHP can make full use of the excitation light without destroying the structure during the protein molecules detection process. Through the synergy of WOHP and Au NPs, the enhancement factor is 1.5 × 104. Raman peaks of WOHP can be used as references for the detection of typical protein cytochrome C (Cyt C). As the Cyt C concentration decreases, the ICyt C/IWOHP ratio decreases, and the signal can still be obtained when the concentration is as low as 5 × 10−9 mol L−1. More importantly, the method does not affect the catalytic activity of Cyt C and can be applied to the detection of Cyt C concentration in serum.

A series of the BaGd2O4:Bi3+, Sm3+ phosphors with dual emission centers were prepared by high-temperature solid-phase method. X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, fluorescence spectroscopy, lifetime decay curve, and variable temperature emission spectroscopy were used to systematically study the structure, luminescence performance, and temperature characteristics of the samples. At ultraviolet stimulation, BaGd2O4:Bi3+, Sm3+ phosphors exhibit broad band blue emission, corresponding to the transition of Bi3+ from 3P1 level to 1S0 level, and sharp red characteristic emission, corresponding to the Sm3+ ions’ energy level transition from 4G5/2 to 6Hm/2(m=5,7,9). In addition, the Bi3+ and Sm3+ ions’ emission positions in BaGd2O4 host are ideally separated. Based on the property, FIR can be employed to test the difference of temperature in response to performances between Bi3+ blue light emission and Sm3+ red light emission. For the Bi3+/Sm3+ co-doped system, it is found that their relative sensitivity gradually decreases with the increase of the Sm3+ ion concentration, the value of maximum can reach 1.105%K-1, which makes it possible to synthesize temperature sensing materials with adjustable sensitivity. The relative sensitivity can also be calculated by experiments related to the decay lifetime, and the value of maximum obtained was 1.662%K-1. Thus, BaGd2O4:Bi3+, Sm3+ systems are superior non-contact optical pyrometer materials with ultrahigh temperature sensitivity and superhigh signal discriminability.

As a leader of long persistent luminescence (LPL) materials, the optical properties of aluminate phosphor have remained unsurpassed for many years. As a powder material, its practical application will always be limited to the field of security signs. In this paper, the SrAl 2 O 4 : Eu 2 + , Dy 3 + inorganic solid material with comparable LPL properties to powder materials was obtained. The crystallization mechanism and crystallite micro-morphology of inorganic glass materials have been studied, and a new opinion is put forward that the large-size SrAl 2 O 4 crystallites in the glass matrix are stacked by rod-shaped crystals arranged in a regular direction. In addition, the SrAl 2 O 4 : Eu 2 + , Dy 3 + glass obtained cannot only collect high-energy photons but also is sensitive to low-energy sunlight. The results show that the material exhibits superior performance in LPL, thermoluminescence, and photostimulable luminescence. Based on this property, a new application of this material in the field of information storage was explored. This paper has a certain reference value for the development and application of aluminate LPL materials in the field of smart optical information storage.

Diode-pumped solid-state 2 μm lasers have seen rapid development for their efficient operation, compact size, and stable performance. In this work, doped germanosilicate (SiO2-GeO2-Ga2O3-Lu2O3) glasses with varying Tm3+/Ho3+ concentrations exhibiting excellent physical and optical characteristics were successfully prepared. Thermal and structural properties were analyzed by the measured DSC and Raman spectra. An evident efficient wide absorption band near 770–830 nm demonstrated the feasible energy transfer between Tm3+: 3F4 → 3H6 and Ho3+: 5I7 → 5I8 transitions. Meanwhile, combining with Judd-Ofelt theory, super predicted spontaneous emission probabilities were obtained, which are beneficial to obtain fine laser action for solid-state lasers. This is a first study to demonstrate that a tunable fluorescence peak (1.8–2.05 μm) can be obtained by modulating the combined effects between two luminous activation centers. Therefore, the results indicate a promising rare-earth doped glass host for solid-state 2 μm lasers.

The fluorescence properties in IR region of fluorotellurite glass with high Er3+ concentration up to 13 mol% are investigated and optimum concentration of 2.7 µm emission is 11 mol%, followed by a decrease in fluorescence intensity. The thermal characteristic parameter (ΔT = 98 °C) based on DSC curve shows a good thermal stability. The FWHM corresponding to 1.5 µm broadens as Er3+ increases and reaches a maximum of 110 nm (13 mol%) which shows superior bandwidth properties. The high amplifier gain value(σemi × τmea) of 11.87 × 10–21 cm2 ms, along with longer lifetime (1.72 ms), which benefits from the low phonon energy (612 cm−1) and hydroxyl content (0.03 cm−1), indicates the ideal 2.7 µm laser characteristics. Hopefully, the glass studied here may be find potential applications in the fields of fiber amplifier and MIR microchip lasers.

We report a detailed spectroscopic investigation of a series of fluorotellurite glasses with different Er3+ ions concentration in system 50TeO2-27BaF2-9ZnF2-8YF3-3MgF2-3NaF-xErF3-1HoF3(x = 1,2,3 mol%). Intense 2 μm emission and 2.75 μm emission with high absorption and emission cross-section were observed under 980 nm LD pumping, and the maximum gain coefficient around 2750 nm was as high as 2.41 cm−1, suggesting the prepared glasses are a competitive candidate for mid-infrared laser materials. Besides, it was found that the trend of 2 μm and 2.75 μm emission intensity varied with Er3+ ions concentration was different. Energy transfer process was discussed subsequently to explain this phenomenon. Furthermore, we quantitatively investigate the energy transfer efficiency from Er3+: 4I13/2 level to Ho3+: 5I7 level.

2.85 μm fluorescence of Ho3+ was firstly obtained in Yb3+/Ho3+ co-doped silica-germanate glass. The combination of low OH− concentration and high mid-infrared transmittance were beneficial to the realization of mid-infrared emissions. A large calculated spontaneous radiative transition probability (30.27 s−1) corresponding to the Ho3+:5I6 → 5I7 transition was beneficial for high gain and more opportunity to achieve laser action. Besides, enhanced green (548 nm) and red (662 nm) emissions were obtained due to the energy transfer between Yb3+ and Ho3+. Moreover, the measured lifetime of Ho3+:5I6 reached as high as 283 μs in Yb3+/Ho3+ co-doped silica-germanate glass, which also possesses a large emission cross section (8.05 × 10−21 cm2). All results reveal that Yb3+/Ho3+ co-doped silica-germanate glass might provide a new choice for 2.85 μm laser applications.

Non-rare-earth Bi was firstly used as sensitizer on Ho3+: 2.0 μm emission for its mid-infrared applications in successfully prepared germanosilicate glass under 808 nm excitation. Sensitization mechanism has been analyzed theoretically through matched energy transfer processes based on the measured absorption, fluorescence spectra and calculated luminous parameters. Meanwhile, typical broadband near-infrared (NIR) emission band of Bi ions has also been obtained in present germanosilicate glass, which shifts to a longer wavelength with Ho3+ co-doped owing to the different of Bi-related active centers. X-ray Photoelectron Spectroscopy demonstrated that the addition of Ho3+ lead to the part valence conversion among the mixed-valence state of Bi. All results reveal that Bi/Ho co-doped germanosilicate glass might provide a new choice for 2.0 μm laser applications.

A series of Ca2-xSrxMgSi2O7: Ce3+, Eu2+ (x = 0, 0.5, 1, 1.5, 2) phosphors were synthesized on the basis of high temperature solid-state reaction strategy. Its phase composition, optical spectral properties, fluorescence lifetime and temperature sensitivity were investigated in detail. Under excitation at 342 nm, the emission spectra of Ca2MgSi2O7: Ce3+, Eu2+ exhibit a purple emission band (Ce3+ ions) and a green emission band (Eu2+ ions). The emission band of Ce3+ overlaps with the excitation band of Eu2+, indicating that there may be energy transfer (ET) between the two ions. The decreasing fluorescence lifetime of Ce3+ with increasing Eu2+ concentration further proves the existent of ET process in Ca2MgSi2O7: Ce3+, Eu2+ phosphor. In addition, Ca2-xSrxMgSi2O7: Ce3+, Eu2+ solid solution was designed and synthesized by Sr2+ substituting Ca2+. As Sr2+ gradually replaced Ca2+, the blue-shift of Ce3+ and Eu2+emission band were caused by the change of crystal field. With the increase of temperature, the fluorescence intensity of Ce3+ and Eu2+ emission bands decreased slowly and rapidly, respectively. Hence, in the Ce3+/Eu2+ co-activated Ca2-xSrxMgSi2O7 phosphor, Ce3+ ions and Eu2+ ions can be used as fluorescence intensity ratio (FIR) signals. The maximum relative sensitivity can reach 2.43% K−1 (at 293 K) under 342 nm excitation. The above results indicate that Ca2-xSrxMgSi2O7: Ce3+, Eu2+ phosphors are potential candidates for optical thermometer materials.

In order to study the optical temperature sensing characteristics of phosphors with dual emission centers, a series of La2MgGeO6: Bi3+, Mn4+ phosphors were prepared by solid phase method at high temperature. Due to the different thermal responses of Bi3+ and Mn4+ ions, the fluorescence intensity ratio between the double emission centers is expected to be an effective method for temperature sensing. The structural phase and luminescence properties of the samples were characterized by X-ray powder diffraction, field emission scanning electron microscopy, ultraviolet spectrophotometer and fluorescence spectrometer. According to the structure of La2MgGeO6 host, it can be seen that Bi3+ ion can replace La3+ ion and Mn4+ ion can replace Ge4+ ion because the valence state of ions are the same and the ion radius is close. Through the excitation of ultraviolet light, La2MgGeO6: Bi3+, Mn4+ present two emission bands, which correspond to the Bi3+ ions 3P1 → 1S0 transition (emitting blue light) and Mn4+ ions 2Eg → 4A2g transition (emitting red light) respectively. Moreover, there is energy transfer from Bi3+ ions to Mn4+ ions. Based on the different temperature responses of Bi3+ blue emission and Mn4+ red emission, their fluorescence intensity ratio was used to discuss the temperature measurement characteristics. The absolute sensitivity and relative sensitivity of La2MgGeO6: Bi3+, Mn4+ phosphors reached the maximum value of 1.419% K−1 at 473 K and 3.027% K−1 at 383 K in the temperature range of 293–473 K. Therefore, La2MgGeO6: Bi3+, Mn4+ phosphors are excellent materials for optical temperature measurement.

White light-emitting diodes (LEDs), as a fourth-generation green lighting source, have been widely used in various fields. At present, most white LEDs have based on a mixture of silicone with poor heat resistance and phosphors as luminescent components, which prevent them from adapting to high-temperature environments and limit their applications of high-power lighting. To improve the optical properties and reliability of white LEDs, phosphor solid is proposed as a new alternative, which not only has the strong stability of glass, but also completely retains the luminescent properties of phosphor. Therefore, in this study, tellurite glass was used as the matrix of phosphor solids to improve the luminescence performance by optimizing the composition of the matrix glass. In addition, rare earth ions were introduced into the tellurium glass matrix, and the dissolution ability of the matrix to rare earth ions was explored to improve the luminous quality of white LEDs.

International audience; Changes in glass structure and crystallization behaviour from oxyfluoride silicate glass to oxyfluoride germanate glass were studied by modifying the ratio of Si/Ge in oxyfluoride germanosilicate glass ceramics, and transparent glass ceramic with low light scattering and efficient mid-infrared emissions were obtained. The NaYF4 nanocrystals crystallization ability of oxyfluoride glass was decreased with the increase in Ge content, which can be attributed to the weakened oxide and fluoride phase separation in GeO2-rich glass. Upconversion and down-conversion emission spectra together with Ho3+: 5I6 energy level fluorescent decay curves have been discussed for SiO2-rich glass ceramics and GeO2-rich glass ceramics, in which the fluoride crystallization induced the decrease of multi-phonon non-radiative decay rates plays the main role in the energy transfer processes. The influence of Si/Ge ratio on 2 μm and 3 μm fluorescent emissions in glasses and glass ceramics, and its link with glass network structural changes were discussed. The optimized Yb/Ho codoped oxyfluoride germanosilicate glass ceramic with low light scattering, high peak emission cross section(11.18 × 10−21cm2) and maximum gain coefficient (1.387 cm−1) at 2888 nm provides a potential application in the development of new 3 μm laser devices based on transparent oxyfluoride glass ceramic materials.

The excessive accumulation Cu2+ ions in human body may lead to kinds of harmful neurodegenerative diseases. Although kinds of PL probes have been widely utilized for the detection of Cu2+ ions, the detection limit is still required to be improved. Herein, a photoluminescent probe of NaGdF4@NaYF4:Ce/Tb inert-core/active-shell nanoparticles is employed for the selective and ultra-sensitive detection of Cu2+ ions in aqueous solution. The hydrophilic PAA is chosen to replace the original hydrophobic OA ligand, and their morphologies as well as core/shell architecture have been systematically studied. With confining sensitizer/activator (Ce/Tb) in a thin shell layer (~3.7 nm), the interaction between Ce/Tb and Cu2+ ions is greatly strengthened, benefiting the improvement of Cu2+ ions sensing performance. In our case, the Cu2+ ions detection limit is measured to be as low as 3.5*10−10 M. The decreased energy transfer possibility from Ce3+ to Tb3+ after the adsorption of Cu2+ ions activates the sensing capability.

In this paper, Ca2MgSi2O7: Bi3+, Eu3+ thermometric phosphors with dual-emitting centers were favorably designed. Phosphors were created by the approach of solid phase in high temperature condition. The inner phase structure and photoluminescence characteristics were investigated. The approaches of characterization including X-ray diffractometry, SEM, EDS mapping, ultraviolet–visible diffuse reflectance spectroscopy, as well as fluorescence spectrometry were applied. The influence of temperature on the photoluminescence characteristics of Ca2MgSi2O7: Bi3+, Eu3+ phosphors was systematically researched. The intensity ratio of 3P1→1S0 purple luminescence of Bi3+ and 5D0→7F2 red luminescence of Eu3+ is dependent on the temperature, which provides a method of optical sensing thermometry. Under the UV excitation of 287 nm, the maximum relative sensitivity (Sr) of this Ca2MgSi2O7: Bi3+, Eu3+ phosphor is 0.66%K−1 (at 533 K) and absolute sensitivity (Sa) gets to 0.0086 K−1 (at 573 K). The experimental phenomena were explained by the thermal-quenching mechanism. The garnered results provide an idea for the future development of luminescence intensity ratio (LIR) technology sensing materials on the basis of Ca2MgSi2O7.

A series of β-Sr1.98-yMgySiO4-1.5xNx: 0.02Eu2+ (x = 0, 0.3, 0.6, 0.9, 1.2 and 4/3, 0 ≤ y ≤ 0.5, β-S(M)SON: Eu2+) phosphors were synthesized by a conventional solid state reaction method. The coordination environments of Eu2+ are modified effectively via the introduction of N3- and Mg2+ using different concentration, which is confirmed by XRD refinement results and PL spectra. Both fourier transform infrared (FT-IR) spectra and energy dispersive spectroscopy (EDS) analysis qualitatively confirm that the existence of N3-. The crystal structures of β-Sr2SiO4-1.5xNx (β-SSON): Eu2+ and β-Sr2-yMgySi(O,N)4: Eu2+ (β-SMSON, x = 4/3, y = 0.1) have been determined effectively. Rietveld refinement indicates that N3- dopants most likely partly substitute O22− site. With the increase of N content, the unit cell volume and partial Si O and Sr N bond lengths gradually decrease, which are coincided each other. With the introduction of N3-, the emission of Eu(I) (∼465 nm) hardly change but that of Eu(II) (∼540 nm) splits into two emission bands as Eu(II) (∼540 nm) and Eu(II)′ (∼616 nm). According to the analysis of XRD data, unit cell volume, FT-IR spectra, photoluminescence (PL) and reflectance spectra of β-SMSON: Eu2+, it can be concluded that the incorporation of Mg2+ into the host leads to interstitial sites rather than substitutional ones. Mg2+ doping couldn't change the dominant peak wavelengths (DPWs) of Eu(I), Eu(II) and Eu(II)′ sites but only affects the PL intensity of title phosphors and could offset the nitridation effects. The concentration quenching mechanism and thermal activation energy of β-SSON: Eu2+ phosphors are determined effectively. The β-S(M)SON: 0.02Eu2+ phosphor have the feature that it can achieve color-tunable white light-emitting combined with blue light emitting diodes (LEDs) with single activator doped and single-phase host, which enables these materials to be enormous possibilities used in white light emitting diodes.

Rare-earth-doped optical functional glasses have attracted great interest for their excellent luminous performance in the applications of optical communications and biomedical systems. To the best of our knowledge, it is demonstrated for the first time that more than seven times' enhancement of luminescence performance in the mid-infrared region (MIR) has been obtained in germanosilicate glasses controlled by ZnF

Two-dimensional transition metal dichalcogenides (2D TMDs) have drawn considerable attention due to their promising applications in biomedical and optoelectronic areas. However, the emission of 2D TMDs materials and devices is mostly limited from visible to the edge of near-infrared (NIR), which restricts their wide applications. Herein, we develop Er doped WSe2 nanosheets through cation exchange and ultrasonication-assisted liquid-phase exfoliation. Thanks to the Er ions, the luminescence of 2D nanosheets can be extended to NIR II window. The emission at NIR II range can effectively penetrate several centimeters thick biological tissue. Furthermore, a series of photothermal experiments is also performed with 808 nm laser. The photothermal conversion efficiency of as-produced nanosheets is determined to be as high as 35.2%, which is greatly higher than many previous reports. It suggests that as-prepared nanosheets combining NIR II emission and highly effective photothermal conversion property may be promising as a bifunctional agent for bioimaging and photothermal therapy.

International audience; Lanthanide-doped luminescent materials have been widely used in the field of information security and optical sensing, owing to their unique optical properties. However, conventional luminescent materials usually exhibit unicolor and single-peak emission, which leads to a decrease in the application efficiency of anti-counterfeiting and optical temperature sensing. In this work, we have successfully developed a series of novel multi-mode stimulation luminescent materials in the Ca2Nb2O7 system via the solid phase reaction. This luminescent material is synthesized by doping dual lanthanide ions to realize adjustable multi-mode luminescence, which simultaneously create luminescent centers and carrier traps in the host lattice. The multi-colored emission can be realized under different excitation wavelengths. Meanwhile, it has a combination of fluorescent phenomenon by upconversion, down-shifting and thermal stimulation. In addition, the fluorescence intensity ratio of lanthanide ions shows significant temperature dependence, and the maximum Sr is 0.0072 K−1 at 293 K. Hence, we have fabricated a novel material that can be used for multi-mode anti-counterfeiting and optical temperature sensing. © 2020 Elsevier B.V.

Novel blue LED excitable Ce3+-doped alkaline-earth sulfide nanocrystals are exploited for selective and sensitive Fe3+ ions sensing in this work. The detection limit is calculated to be as low as 92.5 nM, which is better than most previous ultra-violet light excited fluorescence probes. The decreased radiative probability of the Ce3+: 5d by the NC surface environmental variation activates the sensing capability.

In this study, a multi-color and multi-mode luminescence material has been developed for anti-counterfeiting and temperature sensing. The rare earth ions Er 3 + are selected as the luminescent center to be doped in the piezoelectric material ZnS. The prepared samples can generate multi-color (orange–yellow–green) and multi-mode (upconversion/down-shifting/energy transfer) emission through the energy transitions of lanthanide ions in the ZnS host. When the excitation wavelength or the temperature is selected to be different, the luminous color is obviously different due to different mode emission. Therefore, multiple anti-counterfeiting of a single compound can be realized, the security degree of the anti-counterfeiting can be improved and overcome the defect of the general fluorescent material in a single light-emitting mode. The work will establish experimental basis for the design and development of a new high-integration functional luminescence material, and is expected to use the developed materials in the fields of optical anti-counterfeiting and information encryption.

A group of novel multi-component fluoride glasses simultaneously activated using two mid-infrared (MIR) luminescence centers Er3+ and Ho3+ with different ratios were synthesized to systematically investigate their radiation and energy transfer processes and explore their potential MIR applications. Differential thermal analysis and transmission curve indicate that this new component glass has good thermodynamic properties and high MIR transmission. Fluorescence spectra show that Ho3+ has a strong quenching effect on the lower energy level of the 2.7 µm Er3+ emissions, whereas the quenching effect on the upper energy level is weak, suggesting that Ho3+ can be used as sensitizing ions in a 2.7 µm Er3+ laser operation. For the MIR band, the effective linewidth of co-doped Er3+/Ho3+ sample increases with the Er3+ concentration, which has potential application for use in MIR fiber amplifiers and pulsed laser generation. The fluorescence decay curves show that in this multi-component fluoride glass matrix the lifetime of each band is longer than that of the other substrates. The lifetime (5.95 ms) of the 2.7 µm Er3+ obtained in this experiment is noticeably the longest among other reported glass systems. Moreover, the radiation and energy transfer mechanisms are given based on the fluorescence spectra and fluorescence decay curves.