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Near-infrared light-emitting diodes (NIR-LEDs) have been a potential candidate in food composition analysis, tempera-ture and security monitoring, biometrics, and medical applications. To realize t...

A novel orange-yellow-emitting Ba3Y4O9:Bi3+ phosphor (550 nm) has been firstly discovered. Meanwhile, we report isomorphic Ba3Lu4O9:Bi3+ with green emission (526 nm). Based on the cation substitution strategy, a series of Ba3Y4−wLuwO9:Bi3+ (0 ≤ w ≤ 4) solid solution phases are successfully constructed, realizing consecutive photoluminescence control from orange-yellow to green light. The occurrence of site migration of Bi3+ ions from Y2/Lu2 and Y4/Lu4 to Y1/Lu1 and Y3/Lu3 sites results in the blueshift of Ba3Y4−wLuwO9:Bi3+ (0 ≤ w ≤ 4), which is confirmed by the linear increase of PL intensity I(1+3)/I(2+4) with the substitution of Lu3+ ions for Y3+ ions. Besides, the improved thermal stability of Ba3Y4−wLuwO9:Bi3+ (0 ≤ w ≤ 4) with the substitution of Lu3+ for Y3+ originates from the better structure rigidity. The fabricated white light-emitting diodes (WLEDs) exhibit excellent warm white light, indicating that the as-prepared Ba3Y4−wLuwO9:Bi3+ (0 ≤ w ≤ 4) phosphors can act as a green to yellow emitting component in WLED lighting.

Non-rare earth doped oxides with red emission are one of the current research hotspots for achieving the warm white light range in the phosphor converted white light emitting diodes (pc-WLEDs) field. In the current work, a novel Mn4+-activated La2CaHfO6 red phosphor is reported for the first time and its crystal structure is analyzed by Rietveld refinement. The photoluminescent properties of La2CaHfO6:Mn4+ are investigated in detail with the help of diffuse refletance spectroscopy, photoluminescence spectroscopy, and temperature-dependent PL spectroscopy. Based on the diffuse refletance spectra, the calculated optical band gap for La2CaHfO6 is 4.9 eV, indicating that La2CaHfO6 could be a suitable host for activators' doping. Under 380 nm near-ultraviolet (n-UV) light excitation, the as-prepared La2CaHfO6:Mn4+ displays intense red emission centered at 693 nm. Through an accurate calculation of Dq/B (2.47) and nephelauxetic effect β1 (0.949), the origination of strong crystal field (CF) and deep-red emission is demonstrated. By combining the representative La2CaHfO6:0.002Mn4+, blue BAM:Eu2+, and green (Ba,Sr)2SiO4:Eu2+ phosphors with a 380 nm UV chip to fabricate the pc-WLEDs device, a white light is obtained with low correlated color temperature (CCT = 5165 K) and high color rendering index (Ra = 87.8), demonstrating that the as-prepared La2CaHfO6:Mn4+ phosphors can be used as red-emitting candidate in pc-WLEDs lighting.

A series of cyan-to-green emission tunable Ce3+-activated Ca1−xSrxSc2O4 phosphor compounds were developed through a high-temperature solid-state reaction. The crystal structures were analyzed by XRD and the Rietveld refinement, which confirm the phase purity and clarify the structural variation. The photoluminescence properties and thermal stabilities of the studied phosphors were investigated in detail. The diffuse reflectance spectra revealed the optical band gap to be 4.60 eV and 4.45 eV for CaSc2O4 and SrSc2O4 host, respectively. Due to the suitable optical bandgap, the Ce3+ ions could realize a highly efficient emission in the Ca1−xSrxSc2O4 matrix. The as-prepared phosphors show highly efficient emissions in the green to cyan regions of visible light. All developed compounds demonstrate asymmetric broad-bands with shoulders on the lower-energy sides. Cation substitution-dependent color-tunable evolution as a function of Sr2+ content in Ce3+-doped Ca1−xSrxSc2O4 was observed and investigated in detail. The regular blue-shift emission located in the cyan region with increasing Sr2+ content was attributed to the combined effect of the crystal field splitting and site-preferential occupation. The corresponding luminescence mechanism was analyzed through luminescence life decay measurements. Moreover, the increase of Sr2+ content could efficiently enhance the emission intensity and decrease thermal quenching, which should be ascribed to the lattice modification. The bright cyan and green emission band in the developed compounds, due to transitions in the 5d–4f levels of Ce3+, was found to be ideal for application in solid-state lighting devices. The feasibility of the compound as a potential white LED phosphor was demonstrated by fabricating a white LED with excellent emission properties.

In order to study the influence of different spacing and angles of the axes of the two tunnels on the deformation and operation safety of existing tunnel in near-tunnel construction, the project in Fuzhou is taken to analysis. We use the finite element analysis software to construct a three-dimensional finite element model and carry on the numerical simulation, obtaining vertical vault displacement curves under different spacing and angles of the axes of the two tunnels. Then, we compare it with the actual monitoring data and do further analysis, we get following conclusions: (1) the main performance of the existing tunnel deformation is upward, the deformation decreases with the increase of the spacing and crossing angle, and the effect of the spacing on the existing tunnel vault deformation is far greater than the crossing angle. (2) When the spacing is less than 1.5 times of the new tunnel hole diameter, the maximum tunnel vault deformation occurs in the tunnel cross surface; when the spacing is greater than 1.5 times of the new tunnel hole diameter, the maximum tunnel vault deformation gradually moves toward to the center of the existing tunnel. The research results can provide some references for the design and construction of similar projects.

The response speeds of electric boilers (EB) and energy storage devices (ESD) are different. The frequency bands of wind power that followed by EB and ESD are also different. In order to match EB and ESD with wind power in different time scales, an improved Variational Mode Decomposition (IVMD) is proposed. The original fully adaptive decomposition method is improved to an adaptive decomposition method based on the specified center frequency. Then, a multi-time scale rolling dispatch model for integrated electricity-heating systems is established. The center frequencies are determined according to the long-term trend of wind power, the response speeds of ESD and EB. Wind power is decomposed in three layers by IVMD. The first layer matches the long-term trend of wind power, which formulates the plan of units and EB. The second layer, which is adapted to the response speed of energy-type energy storage device (ETESD), determines the plan of ETESD, output adjustments of units and EB. The third layer, which is compatible with power-type energy storage device (PTESD), formulates the plan of PTESD. Finally, the analysis in case study verifies that it can effectively reduce the amount of wind curtailment and load shedding by the use of IVMD.

To optimize luminescence properties of oxonitridosilicate phosphors are extremely necessary for improving lighting quality of white light-emitting diodes (WLEDs). Herein, we designed Ce3+, Eu2+ codoping and P5+↔Si4+ substitution in the presentative Ba3Si6O12N2:Eu2+ green phosphor to realize an enhancement of luminescence efficiency and thermal stability. Rietveld refinement results of Ce3+, Eu2+, P5+-doped Ba3Si6O12N2 (BSON) confirmed the formation of pure trigonal phase (P-3) of Ba3Si6O12N2 and the successful doping of Ce3+, Eu2+, P5+ ions. Ce3+ and Eu2+ ions randomly occupy two Ba crystallographic sites. Interestingly, a near unity energy transfer (ET, ~100%) from Ce3+ ions to Eu2+ ions is observed. Meanwhile, the doping of P5+ ions into BSON also helps improving the luminescence efficiency and thermal stability, which should be attributed to the charge compensation and the relax of lattice strain. In addition, the white light emitting diodes (WLEDs) fabricated by employing P5+-doped BSON: Eu2+ present a better electroluminescence performance than BSON: Eu2+. This study could serve as a guide in developing optimized oxonitridosilicates phosphors with improved luminescence performances based on complete energy transfer and lattice variations in local coordination environments through cation substitutions, and the as-prepared Ce3+/P5+-codoped Ba3Si6O12N2:Eu2+ could be an excellent green-emitting phosphor for UV-to-Visible LED chips pumped WLEDs.

Nowadays, red phosphor plays a key role in improving the lighting quality and color rendering index of phosphor‐converted white light emitting diodes (w‐LEDs). However, the development of thermally stable and highly efficient red phosphor is still a pivotal challenge. Herein, a new strategy to design antithermal‐quenching red emission in Eu3+, Mn4+‐codoped phosphors is proposed. The photoluminescence intensity of Mg3Y2(1− y )Ge3O12:yEu3+, Mn4+ (0 ≤ y ≤ 1) phosphors continuously enhances with rising temperature from 298 to 523 K based on Eu3+ → Mn4+ energy transfer. For Mg3Eu2Ge3O12:Mn4+ sample, the integrated intensity at 523 K remarkably reaches 120% of that at 298 K. Interestingly, through codoping Eu3+ and Mn4+ in Mg3Y2Ge3O12, the photoluminescence color is controllably tuned from orangish‐red (610 nm) to deep‐red (660 nm) light by changing Eu3+ concentration. The fabricated w‐LEDs exhibit superior warm white light with low corrected color temperature (CCT = 4848 K) and high color rendering index (R a = 96.2), indicating the promising red component for w‐LED applications. Based on the abnormal increase in antistokes peaks of Mn4+ with temperatures, Mg3Eu2Ge3O12:Mn4+ phosphor also presents a potential application in optical thermometry sensors. This work initiates a new insight to construct thermally stable and spectra‐tunable red phosphors for various optical applications., A proposal for designing antithermal‐quenching red phosphors with consecutive emission enhancement (beyond 120%) up to 523 K and controllably luminescence color adjustment from orange to deep red light based on Eu3+ → Mn4+ energy transfer for potential application in white light emitting diodes and optical low‐temperature thermometry sensors is presented.

Currently, non-contact fluorescence intensity ratio (FIR)-based luminescent thermometry has been extensively attracted great attention for its promising applications in electromagnetic field, micro-temperature field and thermally harsh environments. In this work, the double-perovskite LaMg0.402Nb0.598O3: Pr3+ (LMNO: Pr3+) thermometric phosphor is firstly designed and successfully synthesized via a high-temperature solid-state method. Under 450 nm excitation, the as-prepared samples simultaneously exhibit blue emission (3P0 → 3H4), green emission (3P1 → 3H4) and red emission (1D2 → 3H4, 3P0 → 3F2) of Pr3+. They present different dependence on the temperature due to the intervalence charge transfer state (IVCT). Accordingly, the four FIR models between 3P1 → 3H4 and 3P0 → 3H4 (G/B), 3P1 → 3H4 and 3P0 → 3F2 (G/R2), 1D2 → 3H4 and 3P0 → 3H4 (R1/B) and 1D2 → 3H4 and 3P0 → 3F2 (R1/R2) are used as temperature detecting signal in the range of 298–523 K, and the maximum absolute and relative sensitivity of LaMg0.402Nb0.598O3: 1.2% Pr3+ sample reached 0.0597 K−1 at 523 K and 0.7250% K−1 at 473 K, respectively. Excellent temperature sensing features are also demonstrated in the LaMg0.402Nb0.598O3: 0.3% Pr3+ and LaMg0.402Nb0.598O3: 2.0% Pr3+ samples. Except for high sensitivity for temperature sensing, the designed Pr3+-doped double-perovskite materials also realize the self-calibration by simultaneous monitoring of four models of FIR. Moreover, after five cycles, the relative luminescence intensity of LaMg0.402Nb0.598O3: 1.2% Pr3+ sample remains stable. These results indicate that LaMg0.402Nb0.598O3: Pr3+ phosphors have great promising application as self-calibrated optical temperature sensors.

In this work, two component substitution types of Si4+→[Cs+-Al3+] and [Mg2+-Mg2+]→[Cs+-Al3+] were successfully designed in Eu2+-doped CsAlSi2O6 pollucite phosphors. The photoluminescence color can be controllably tuned from cyan (513 nm) to blue (437 nm), and full width at half maximum (FWHM) can be adjusted in the region of 79–169 nm. Besides, the thermal stability is obviously improved, where PL intensity at 200 °C increases from 59% (CsAlSi2O6:5%Eu2+) of the original intensity to 96% [(CsAl)0.6Mg0.8Si2O6:5%Eu2+] and 86% [(CsAl)0.9Si2.1O6:5%Eu2+], respectively. The corresponding mechanisms of spectral adjustment and thermal stability enhancement were investigated. The proposed strategies can play a key role in exploiting novel and efficient phosphors for high-power w-LEDs lighting.