Search

The phosphor-converted light emitting diode (pc-LED) is an efficient light source to adjust growth rhythm and raise yield of plant. Blue and red light play the dominant role in the process of plant growth, thus it is meaningful to search the blue-red dual emission phosphors with high quantum field and better thermal stability for developing plant growth LED. Herein, the blue-red dual emission phosphors were synthesized by co-doping Sb3+ and Ho3+ into the Cs 2 NaLuCl 6 , which emitted blue (454 nm) to red (657 nm) light with increasing the content of Ho3+ to 25% and their relative intensity could be tuned through adjusting the concentration of Ho3+ due to the efficient energy transfer from Sb3+ to Ho3+. The intensity of blue emission from Sb3+ and red emission from Ho3+ could maintain 78.4 and 75.8% of the room temperature at 150 °C, respectively. Furthermore, the spectra of fabricated blue and red LEDs match well with the absorption of carotenoid, Phytochrome and Chlorophyll b , implying the samples possess great application potential in plant growth LED. Blue-red double color emitting phosphor Cs 2 NaLuCl 6 :Sb3+, Ho3+. [Display omitted] [ABSTRACT FROM AUTHOR]

• Cs 2 NaScCl 6 : Yb3+, Er3+ was prepared through solvothermal method. • UC and DC properties of sample were investigated. • Potential application in anti-counterfeiting was evaluated. At present, most fluorescent anti-counterfeiting technologies on the market are based on single-mode luminescence, which generally have poor anti-counterfeiting capabilities. Thus, developing multi-mode luminescent anti-counterfeiting materials that combine dynamic and static luminescence is a particularly urgent task. In this study, Cs 2 NaScCl 6 : Yb3+, Er3+phosphors were successfully prepared using the solvothermal method. These materials can emit bright green light under 980- or 1550-nm infrared laser irradiation and red light under 365-nm ultraviolet lamp illumination. In addition, by increasing the 980-nm laser power density from 20 to 309 mW/cm2, the luminescence colour can be adjusted from green to yellow, which equips this sample with an outstanding potential for dynamic anti-counterfeiting. Finally, screen printing technology was used to assess the sample's anti-counterfeiting capacity, and the sample was found to be an excellent anti-counterfeiting luminescent material. Stimulus-mode dependent multi-color emitting phosphor Cs 2 NaScCl 6 : Yb3+, Er3+exhibits green emission with the irradiation of 1550 and 980 nm laser and red emission under excitation of 365 nm UV lamp, but yellow emission with the increase of 980 nm laser power density, which present great potential application in anti-counterfeiting field. [Display omitted] [ABSTRACT FROM AUTHOR]

Obtaining phosphors with white-light emission is a promising and economical approach for phosphor-conversion light emitting diodes (pc-LEDs), but traditional single-phase white light emission phosphors are inefficient. Here a white-light-emission phosphor was prepared via a co-precipitation method by doping Sb3+ into lead-free and vacancy-ordered double perovskite Cs 2 ZrCl 6. X-ray diffraction, X-ray photoelectron spectroscopy, and formation energy calculations confirmed that Sb3+ ions replaced the Zr4+sites in the [ZrCl 6 ]2− octahedron. The optical properties of Cs 2 ZrCl 6 :Sb3+ were investigated and compared with those of blank Cs 2 ZrCl 6. The origination of the emission bands was determined according to their fluorescence spectra and decay-time at an approximate temperature of 4 K Sb3+-doped Cs 2 ZrCl 6 exhibited white-light emission with double emission bands at 495 and 622 nm due to the 1P 1 → 1S 0 and 3P 2, 1, 0 → 1S 0 transitions of Sb3+, respectively. The intensity ratios of cyan light (495 nm) and the red light emission bands (622 nm) were tunable by adjusting the Sb3+concentration. The red component increased with increasing Sb3+ concentration in the present experimental range. Moreover, 10% Sb3+-doped Cs 2 ZrCl 6 showed the strongest emission with a photoluminescence quantum yield of approximately 78% under excitation of 333-nm light White LED devices with different correlated color temperatures were achieved by combining 1% or 10% Sb3+-doped Cs 2 ZrCl 6 with a 310-nm ultraviolet chip, suggesting that the synthesized samples have potential applications in white-illumination LEDs. Single-phased white emitting phosphor Cs 2 ZrCl 6 : Sb3+ and corresponding LEDs. [Display omitted] [ABSTRACT FROM AUTHOR]

As a new generation of near-infrared (NIR) light source, phosphor-converted NIR light emitting diodes (NIR pc-LEDs) have broad application prospects in biological tissue imaging, night vision and chemical composition analysis. However, most NIR emitting phosphors are still limited to short-wavelength, narrow-band emission and low efficiency. Here, based on the multi-site occupation strategy, the NIR phosphor Mg 2 LaTaO 6 :Cr3+ (MLT:Cr3+) achieves an efficient broadband NIR emission with the full width at half maximum (FWHM) of 203 nm in the range of 600–1300 nm under the excitation of 468 nm blue light. The phosphor MLT:0.01Cr3+ not only exhibits an excellent internal quantum efficiency (IQE) of 85.6 %, but also has good thermal stability and remains about 64.2 % photoluminescence (PL) intensity of room temperature at 423 K. Furthermore, the MLT:0.01Cr3+ phosphor was combined with a blue LED chip to fabricate the NIR pc-LED device, and its potential applications were successfully realized in information encryption, bioimaging and the qualitative or quantitative analysis of mixture of ethanol and water. NIR LED fabricated with broadband emitting phosphor Mg 2 LaTaO 6 :Cr3+ together with its potential application. [Display omitted] [ABSTRACT FROM AUTHOR]

As a new generation of near-infrared (NIR) light source, phosphor-converted NIR light emitting diodes (NIR pc-LEDs) have broad application prospects in biological tissue imaging, night vision and chemical composition analysis. However, most NIR emitting phosphors are still limited to short-wavelength, narrow-band emission and low efficiency. Here, based on the multi-site occupation strategy, the NIR phosphor Mg 2 LaTaO 6 :Cr3+ (MLT:Cr3+) achieves an efficient broadband NIR emission with the full width at half maximum (FWHM) of 203 nm in the range of 600–1300 nm under the excitation of 468 nm blue light. The phosphor MLT:0.01Cr3+ not only exhibits an excellent internal quantum efficiency (IQE) of 85.6 %, but also has good thermal stability and remains about 64.2 % photoluminescence (PL) intensity of room temperature at 423 K. Furthermore, the MLT:0.01Cr3+ phosphor was combined with a blue LED chip to fabricate the NIR pc-LED device, and its potential applications were successfully realized in information encryption, bioimaging and the qualitative or quantitative analysis of mixture of ethanol and water. NIR LED fabricated with broadband emitting phosphor Mg 2 LaTaO 6 :Cr3+ together with its potential application. [Display omitted] [ABSTRACT FROM AUTHOR]

In this study, temperature and salinity profiles from Argo floats are assimilated into a coupled ice–ocean model over the North Atlantic Ocean and Arctic using an ensemble optimal interpolation (EnOI) scheme, with the aim of improving the thermohaline structure of the Labrador Sea estimated by the model. Data assimilation experiments are carried out from September 2014 to April 2015 both with and without a one-step bias correction method from the literature. It is found that assimilation of the Argo profiles reduces the errors in the model temperature and salinity when verification is done against both withheld Argo profiles and sea surface temperature from satellite data. The assimilation also leads to deeper mixed layer depth in the Labrador Sea, closer to observations shown in other studies, in particular when bias correction is used. We hypothesize that this is because the bias field leads to vertical density profiles that are less stratified, and hence requiring less energy for mixing, than when bias correction is not used. [ABSTRACT FROM AUTHOR]

The ZnO films is a common candidate for photodetectors. However, the performance of photodetectors based on ZnO films fabricated by traditional sol-gel spin coating method is restricted to narrow absorption range and persistent photoconductance caused by defects. Herein, the carbon quantum dots (CDs) prepared by hydrothermal method are hybridized with the ZnO film to fabricate the ZnO/CDs hybrid photodetector. The transmission electron microscope (TEM) measurement confirmed that the existence of ZnO and CDs as well as the fabrication of ZnO/CDs hybrid structure. Owing to the wide absorption range of CDs, the ZnO/CDs photodetector demonstrated broadband photoresponse from UV (300–360 nm) to visible range (400–600 nm) compared with the ZnO photodetector. Meanwhile, the ZnO/CDs photodetector possesses the faster response that the rise time decreased from 180.93 to 5.94 s and the decay time reduced from 329.05 to 0.77 s. This work provides a useful approach to improve the optoelectronic performance of ZnO films photodetectors fabricated by sol-gel spin coating method. [Display omitted] • A broadband photodetector was achieved by incorporating the ZnO films and carbon dots. • The ZnO/carbon dots hybrid photodetector showed a great potential for UV and visible photodetector. • The ZnO/carbon dots hybrid photodetector possessed a faster response than the ZnO films photodetector. • The mechanism of the enhanced photodetection performance was investigated. • This work provided a new perspective for improving the performance of ZnO film photodetectors. [ABSTRACT FROM AUTHOR]

This study explores the relationship between coherent eddies and zonally elongated striations. The investigation involves an analysis of two baroclinic quasigeostrophic models of a zonal and double-gyre flow and a set of altimetry sea level anomaly data in the North Pacific. Striations are defined by either spatiotemporal filtering or empirical orthogonal functions (EOFs), with both approaches leading to consistent results. Coherent eddies, identified here by the modified Okubo-Weiss parameter, tend to propagate along well-defined paths, thus forming 'eddy trains' that coincide with striations. The striations and eddy trains tend to drift away from the intergyre boundary at the same speed in both the model and observations. The EOF analysis further confirms that these striations in model simulations and altimetry are not an artifact of temporal averaging of random, spatially uncorrelated vortices. This study suggests instead that eddies organize into eddy trains, which manifest themselves as striations in low-pass filtered data and EOF modes. [ABSTRACT FROM AUTHOR]

Emission wavelength or color and excitation mode of luminescent materials play the decisive role in their applications of information hiding and anti-counterfeiting. Conventional luminescent anti-counterfeiting materials generally exhibit monochromatic emissions under the excitation of ultraviolet or near-infrared light, which are easily to be imitated or substituted. The development of multicolor and multimodal excitation in one single-phased host was regarded as effective strategy and significant challenges for luminescent anti-counterfeiting materials. As typical lead-free halide double perovskite material Cs2NaBiCl6 not only offers excellent stability and facile synthesis but also provides greater tolerance to rare earth and transitional ions, thus Er3+, Yb3+ and Mn2+ tri-doped Cs 2 NaBiCl 6 was synthesized by co-precipitation method at room temperature in this paper. The efficient green up- and strong orange red down-conversion (UC and DC) emissions were realized through irradiation of 980/1550 nm infrared light and 365 nm near ultraviolet light. The possible UC mechanisms and energy transfer from Er3+ to Mn2+ were also investigated, and some fluorescent security patterns were also designed to demonstrate the potential applications of the present samples in anti-counterfeiting and concealing important information. CNBC: 10% Er3+, 15% Yb3+, 15% Mn2+ exhibits brilliant green and orange emission under the excitation of 980, 1550 and 365 nm light, which present great potential for application in multi-mode anti-counterfeiting. [Display omitted] • The UC phosphor Cs 2 NaBiCl 6 was investigated. • The UC and DC emission color of Cs 2 NaBiCl 6 : Yb3+, Er3+, Mn2+ were discussed. • Potential application as anti-counterfeiting materials was evaluated. [ABSTRACT FROM AUTHOR]

This study describes a nonlocal mechanism for the generation of oceanic alternating jets by topographic ridges. The dynamics of these jets is examined using a baroclinic quasigeostrophic model configured with an isolated meridional ridge. The zonal topographic slopes of the ridge lead to the formation of a system of currents, consisting of mesoscale eddies, meridional currents over the ridge, and multiple zonal jets in the far field. Dynamical analysis shows that transient eddies are vital in sustaining the deep meridional currents over the ridge, which in turn play a key role in the upper-layer potential vorticity (PV) balance. The zonal jets in the rest of the domain owe their existence to the eddy forcing over the ridge but are maintained by the local Reynolds and form stress eddy forcing. The analysis further shows that a broad stable current that either becomes locally nonzonal or encounters a topographic ridge tends to become unstable. This instability provides a vorticity source and generates multiple zonal jets in the far field through a nonlocal mechanism. [ABSTRACT FROM AUTHOR]

The importance of bottom topography in the linear baroclinic instability of zonal flows on the β plane is examined by using analytical calculations and a quasigeostrophic eddy-resolving numerical model. The particular focus is on the effects of a zonal topographic slope, compared with the effects of a meridional slope. A zonal slope always destabilizes background zonal flows that are otherwise stable in the absence of topography regardless of the slope magnitude, whereas the meridional slopes stabilize/destabilize zonal flows only through changing the lower-level background potential vorticity gradient beyond a known critical value. Growth rates, phase speeds, and vertical structure of the growing solutions strongly depend on the slope magnitude. In the numerical simulations configured with an isolated meridional ridge, unstable modes develop on both sides of the ridge and propagate eastward of the ridge, in agreement with analytical results. [ABSTRACT FROM AUTHOR]

An accurate deep-tissue thermometer with excellent photothermal conversion efficiency is desired for effective photo-thermal therapy (PTT), which will minimize collateral damages to normal cells from overheating or ineffective treatment from insufficient heat. Herein, a nano-thermometer with Nd3+/Yb3+/Ho3+ tri-doped Na 3 InF 6 was designed by hydrothermal method to real-time monitor tissue temperature, and its luminescent performance and temperature sensing behavior based on the luminescence intensity ratio (LIR) technology in the visible and near infrared regions were analyzed under 808 nm excitation. The advantage of temperature probes located in the near infrared (NIR) biological window region was demonstrated by the penetration depth in simulating biological tissue agar. Furthermore, the feasibility of the sample as a self-monitoring photothermal platform was verified by in vitro bactericidal experiments, which expressed excellent photothermal conversion performance and sterilizing rates reached 59.8 % (E. coli) and 53.6 % (S. aureus), respectively. Results demonstrated that the present single-phased Na 3 InF 6 :Nd3+/Yb3+/Ho3+ nanophosphor could serve as a bifunctional photothermal agent with internal tissue temperature measurement and photothermal conversion. Na 3 InF 6 : Nd3+, Yb3+, Ho3+ UC nanoparticles with multimode temperature detection and photothermal conversion functions. [Display omitted] [ABSTRACT FROM AUTHOR]

Non-invasive photo-thermal therapy (PTT) has been proposed as a powerful method for cancer treatment, in which accurate temperature monitoring is necessary to prevent ineffective therapy or damage to normal cells during the process of PTT. This promotes the design and development of photothermal agents (PTAs) with real-time temperature control and excellent photothermal conversion. Here, the designed dual-function photothermal agents YVO 4 : Nd3+, Yb3+@IR-780 were obtained, while the temperature detection behavior based on the fluorescence intensity ratio (FIR) of Nd3+ (4F 3/2 → 4I 11/2) to Yb3+ (2F 5/2 → 2F 7/2) and the temperature-dependent Yb3+ lifetime were investigated in detail. The advantages of fluorescence lifetime thermometry in the biological field were confirmed by the internal temperature detection of pork tissue through comparison with fluorescence intensity ratio technology. The photo-thermal conversion efficiency of samples YVO 4 : Nd3+, Yb3+@IR-780 reached about 34.3% and its potential application was also evaluated by the sterilization of E. coli and S. aureus, which shows that IR-780 coated nano-materials have excellent photo-thermal conversion performance. Results illuminated that the present photothermal agents with temperature self-monitoring had a bright future in the process of photothermal therapy. The NIR-Multifunctional photo-thermal therapeutic nanoplatform YVO 4 : Nd3+, Yb3+@IR-780 under 808 was developed, which offers the functions of temperature sensing and photo-thermal ablation. [Display omitted] [ABSTRACT FROM AUTHOR]

Cr3+ activated near‐infrared (NIR) phosphors are getting unprecedented attention to fabricate the broad band NIR light emitting diodes (NIR‐LEDs) for nondestructive detection, bio‐imaging, and night vision. However, it remains a major challenge to obtain ultrabroadband NIR emitting phosphor with excellent quantum yield (QY). Here, a broadband NIR emitting phosphor Mg7Ga2GeO12:Cr3+ (MGGO: Cr3+) ranging from 600 to 1300 nm with an outstanding QY (93%) and large full width of half maximum (FWHM = 226 nm) is developed, in which the site occupancy tendency of Cr3+ in MGGO host is discussed in detail through combining the structure optimization and the first‐principles theory calculation with luminescent properties at low temperature. After that, the emission intensity of MGGO:Cr3+ is improved through partial substitution of Mg2+ by alkaline‐earth ions Ca2+, Sr2+, or Ba2+, and the luminescence enhancement mechanism is also investigated. Furthermore, the NIR pc‐LED device is fabricated by combining 450 nm blue LED chip with the brightest phosphor MGGO:Cr3+/Ba2+, and its potential applications are evaluated in the field of nondestructive detection, night vision, and bio‐imaging. [ABSTRACT FROM AUTHOR]

Excellent heterojunction photocatalysts constructed through combining g-C 3 N 4 with enhanced ferroelectric or piezoelectric materials Cr3+-Nb5+ pairs co-doped Bi 4 Ti 3 O 12. [Display omitted] • Cr3+-Nb5+ pairs doping enhanced piezoelectric potential and absorption of Bi 4 Ti 3 O 12. • Heterojunction BTCNO-0.1/5%-CN exhibited optimal photocatalytic performance. • Improved carrier separation due to piezoelectric potential and Z-scheme mechanism. Polarizations within ferroelectric or pizeoelectric materials are conducive to improve photocatalytic activity by promoting interior photogenerated carriers separation. However, the photocatalytic activity of pristine ferroelectric or pizeoelectric semiconductor is generally limited by its insufficient polarization and spectral absorption. Herein, Bi 4 Ti 3-2 n Cr n Nb n O 12 / x -g-C 3 N 4 (BTCNO- n / x -CN) heterojunctions was prepared by loading ultrathin g-C 3 N 4 on ferroelectric BTCNO synthesized by co-doping Cr3+-Nb5+ pairs into Bi 4 Ti 3 O 12 (BTO). The Cr3+-Nb5+ pairs co-doping not only endows the heterojunctions stronger pizeoelectric performance but also further promotes the spectral absorption, which were confirmed through the hysteresis loop, piezoelectric potential, density functional theory calculations and UV–vis diffuse reflectance spectra (DRS). The piezo-photocatalytic performance of BTCNO- n / x -CN was investigated in detail by RhB degradation and H 2 evolution under light and ultrasound. According to these results, the optimal loading content of g-C 3 N 4 and doping concentration of Cr3+-Nb5+ pairs were determined as n = 0.1 and x = 5 %, and BTCNO-0.1/5%-CN showed an optimal photocatalytic activity for 98.7 % RhB removal ratio after 45 min, and 696 µmol·g−1·h−1 of H 2 production rates. The possible Z-scheme charge transfer mechanism in BTCNO- n / x -CN heterojunction was proposed based on the results of capture experiments, which improves photocatalytic performance through enhancing the separation of photogenerated carriers and promotes the generation of O 2 − and OH. This work utilizes the piezoelectric effect and heterojunctions to enhance interior and surface carriers separation to improve the catalytic activity, which offers a new scheme to design excellent photocatalysts. [ABSTRACT FROM AUTHOR]

With the development of temperature measurement technology, people put forward higher requirements for the accuracy and precision of temperature measurement. However, most of the current luminescent thermometers use a single optical signal for temperature detection, which has a certain range of temperature insensitivity, resulting in inaccurate temperature measurement. Here, an all-inorganic rare-earth halide double perovskite Cs 2 NaErCl 6 : Yb3+ (CNEC: Yb3+) phosphor was synthesized, which not only expressed triple-mode thermometric properties based on thermally coupled levels (TCLs), non-thermally coupled levels (N-TCLs) and lifetime (FL), but also capable of providing self-referencing and high-sensitivity temperature measurements under excitation at 980 nm. Benefiting from the low phonon energy of the matrix, high doping concentration and the excellent internal up-conversion quantum efficiency (UCQY) about 6.52% of optimal composition CNEC: 40%Yb3+, all modes exhibit superior sensitivities, reversibility and thermal resolution under 980 nm irradiation. In addition, a flexible thin film thermometer composed of CNEC: 40%Yb3+ was prepared to realized multi-mode thermal monitoring of local hot spots of electronic components. The excellent three-mode temperature measurement results indicated that CNEC: Yb3+ phosphors have great potential in temperature sensing. [Display omitted] • Halide double perovskite Cs 2 NaErCl 6 : Yb3+ was prepared. • Triple-mode thermometric properties based on thermally coupled levels, non-thermally coupled levels and lifetime were investigated. • Application of the present thermometer was evaluated in monitoring local hot spots of electronic components. [ABSTRACT FROM AUTHOR]

For Up-conversion (UC) optical thermometers based on luminescence intensity ratio (LIR) technology, the eternal pursuit is achieving high sensitivity to minimize its temperature measurement uncertainty, in which the selection strategy of matrix and dopants is one of the important factors. Phonon energy, as a basic property of matrix, greatly affects the temperature-dependent luminous intensity. Herein, Yb3+/Er3+ co-doped NaYF 4 (NY), Y 2 O 3 (YO), KLa(MoO 4) 2 (KLM), LaNbO 4 (LN) and LaPO 4 (LP) phosphors were used to be experimental objects because the phonon energy of them has distinct gradient. By comparing the sensitivities of Yb3+-Er3+ co-doped different matrices, it is found that the sensitivity is positively correlated with the matching degree (MD) between phonon energy and energy gap (ΔE) of thermal coupled levels (TCLs). This is because of the stronger mismatch between the energy gap and the effective phonon energy makes the non-radiative thermalization rates slower, thus affecting the rate of LIR change. The above conclusion gives a guidance method for selecting suitable matrix of high-sensitivity fluorescent thermometers. • Luminescence of Er3+-Yb3+ co-doped phosphors with different phonon energy were investigated. • Their sensing behaviors based on FIR of 2H 11/2 /4S 3/2 → 4I 15/2 transitions from Er3+. • Relationship between S a and the matching degree of phonon energy and the TCL gaps was constructed. [ABSTRACT FROM AUTHOR]

A series of Ba 2 CaW 1- x O 6 : x Mn4+ (BCWO: x Mn4+) far-red emitting phosphors were successfully synthesized via a high-temperature solid-state reaction method. The phase purity and crystal structure were analyzed by X-ray diffraction (XRD) and Rietveld refinement. The luminescent properties and crystal field strength of Mn4+-occupied octahedra [WO 6 ] environment were estimated according to the photoluminescence (PL) and photoluminescence excitation (PLE) spectra. Under near ultraviolet light (n-UV) excitation, far-red light (peaking at 695 nm) was obtained from BCWO: 0.75%Mn4+, which matches well with the absorption band of the phytochrome P FR. In addition, the thermal stability of the phosphor was investigated according to temperature-dependent PL spectra. The Mn4+ doped Ba 2 CaWO 6 phosphor offers good luminescence performance and high thermal stability, and shows great potential for application in plant cultivation LEDs as a suitable far-red emitting phosphor. [Display omitted] • A novel phosphors Ba 2 CaWO 6 : Mn4+ were successfully synthesized by solid-state reaction. • The optimized Ba 2 CaWO 6 : Mn4+ phosphor exhibited far-red light peaked on 695 nm excited by near ultraviolet (n-UV) light. • The crystal field environment of Mn4+ ions were analyzed, and the Mn4+ ions are located in the strong crystal field. • The thermal stability of Ba 2 CaWO 6 : 0.75%Mn4+ phosphor was investigated according to temperature-dependent PL spectra. [ABSTRACT FROM AUTHOR]