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Novel Ca2GdTaO6:Mn4+,M (M = Li+, Na+, K+, and Mg2+) red phosphors for plant cultivation light-emitting diodes: Synthesis and luminescence properties
摘要： Recently, Mn4+-activated red phosphors are becoming potential color converters for application in indoor plant cultivation light-emitting diodes, owing to their satisfactory luminescence properties as well as low cost. Herein, novel Mn4+-activated double perovskite-type Ca2GdTaO6 phosphors have been synthesized by a high-temperature solid-state reaction method in air, which exhibited a broad excitation band with two peaks locating at 355 nm and 496 nm in range of 250-600 nm and had an intense red emission peaking at 676 nm due to Mn4+:2Eg→4A2g spin-forbidden transition ranging from 650 to 750 nm under 355 nm excitation. Concentration-dependent luminescence properties were studied. The optimal Mn4+ doping concentration in Ca2GdTaO6 host was 0.004, and the concentration quenching mechanism was determined to be a dipole-dipole interaction among Mn4+ ions. Furthermore, the Ca2GdTaO6:0.004Mn4+ phosphor possessed the internal quantum efficiency up to 33% when excited at 355 nm. Besides, the decay lifetimes of Ca2GdTaO6:Mn4+ presented a reasonable downward trend with increasing Mn4+ concentration. In addition, the effect of charge compensation (co-doping of Li+, Na+, K+, and Mg2+ ions) on the luminescent properties of Ca2GdTaO6:Mn4+ phosphors was also investigated.
关键词： Indoor plant cultivation,Ca2GdTaO6,Mn4+,Double perovskite,Luminescence properties,Red phosphor
更新于2025-11-20 15:33:11
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Single-Composition White Light Emission from Dy3+ Doped Sr2CaWO6
摘要： A series of Dy3+ ion doped Sr2CaWO6 phosphors with double perovskite structure were synthesized by traditional high temperature solid-state method. It was found that there is significant energy transfer between Dy3+ and the host lattice, and the intensities of emission peaks at 449 nm (blue), 499 nm (cyan), 599 nm (orange), 670 nm (red), and 766 nm (infra-red) can be changed by adjusting the concentration of dopant amount of Dy3+ ion in Sr2CaWO6. The correlated color temperature of Dy3+ ion doped Sr2CaWO6 phosphors can be tuned by adjusting the concentration of Dy3+ ion. Upon optimal doping at 1.00 mol% Dy3+, white light with chromaticity coordinate (0.34, 0.33) was emitted under excitation at 310 nm. Thus, single composition white emission is realized in Dy3+ doped Sr2CaWO6.
关键词： double perovskite,energy transfer,white light-emitting,photoluminescence
更新于2025-11-20 15:33:11
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Multi-active sites derived from a single/double perovskite hybrid for highly efficient water oxidation
摘要： The oxygen evolution reaction (OER) plays a crucial role in the application of water splitting, which is a highly competitive option for a sustainable energy future. Thus, it is vital to design highly active and durable electrocatalyst for OER. Herein a hybrid with the nominal composition of Ba2Co1.5Mo0.25Nb0.25O6-d (denoted as BC1.5MN) electrocatalyst consisting of both double perovskite and single perovskite structures is synthesized by a solid-state reaction method. When tested as an electrocatalyst for OER, the BC1.5MN electrocatalyst requires a current density of 10 mA cm-2 at an overpotential of 400 mV, an onset overpotential of 260 mV, and a Tafel slope of 70 mV dec-1, which are superior to that of precious metal oxide IrO2 catalyst. Chronoamperometric and cyclic voltammetry studies demonstrate that the BC1.5MN electrocatalyst has outstanding durability in alkaline solution. The synergistic effect between multi-active sites derived from a single/double perovskite hybrid structure results in one of the most active perovskite-based OER electrocatalysts in alkaline solution.
关键词： hybrid,oxygen evolution reaction,double perovskite,single perovskite,electronic structure
更新于2025-09-23 15:23:52
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Structure variation and luminescence enhancement of BaLaMg(Sb, Nb)O6:Eu3+ double perovskite red phosphors based on composition modulation
摘要： A series of BaLaMgSb1-xNbxO6:Eu3+ double perovskite red phosphors was successfully obtained. X-ray diffraction and Rietveld refinement analyses were conducted to determine the phase information and the detailed structure parameters. The coordinate variations of both La3+/Eu3+ and Sb5+/Nb5+ were discussed to elucidate the influence of B-site ion doping on the lattice variation. Luminescence properties, excitation and emission spectra, were presented to show the advantages of doping with Nb5+ ion. Ultraviolet-vis diffuse reflectance spectra were performed to reveal the reason for the decreased emission intensity under the charge transfer band excitation. Moreover, band gap energy was estimated to clarify the relationship between the increased intensity (λex = 395 and 465 nm) and Nb5+ concentration. Intensity ratios of I(615)/I(590) were performed to show the symmetry variation of the lattice. Thermal quenching property was also investigated and the quenching mechanism was discussed in detail based on the ionization process.
关键词： White LED,Structure variation,Thermal quenching mechanism,Double perovskite
更新于2025-09-23 15:23:52
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Electronic and optical properties of double perovskite oxide Pb2ScMO6 (M = Ta, Sb) using a first principles approach
摘要： In this study, the electronic and optical properties of the double perovskite (DP) oxides Pb2ScMO6 (M = Sb, Ta) were systematically investigated using the full-potential linearized augmented plane wave model. Calculations were performed using both the generalized gradient approximation and modified Becke–Johnson potentials. The results showed that the O-atom is responsible for the maxima in the density of states (DOS) in the valence band, whereas the Sc-atom contributes to the maximum DOS in the conduction band. The dielectric constants, absorption coefficients, and reflectivity were also calculated for these systems. The results indicated the presence of wide band gaps in both of these DPs, thereby indicating their insulating semiconducting nature.
关键词： photon energy,energy,dielectric,double perovskite,density of states,band gap
更新于2025-09-23 15:23:52
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Thermodynamic Stability Landscape of Halide Double Perovskites via High-Throughput Computing and Machine Learning
摘要： Formability and stability issues are of core importance and difficulty in current research and applications of perovskites. Nevertheless, over the past century, determination of the formability and stability of perovskites has relied on semi empirical models derived from physics intuition, such as the commonly used Goldschmidt tolerance factor, t. Here, through high-throughput density functional theory (DFT) calculations, a database containing the decomposition energies, considered to be closely related to the thermodynamic stability of 354 halide perovskite candidates, is established. To map the underlying relationship between the structure and chemistry features and the decomposition energies, a well-functioned machine learning (ML) model is trained over this theory-based database and further validated by experimental observations of perovskite formability (F1 score, 95.9%) of 246 A2B(I)B(III)X6 compounds that are not present in the training database; the model performs a lot better than empirical descriptors such as tolerance factor t (F1 score, 77.5%). This work demonstrates that the experimental engineering of stable perovskites by ML could solely rely on training data derived from high-throughput DFT computing, which is much more economical and efficient than experimental attempts at materials synthesis.
关键词： halide double perovskite,stability,machine learning,high-throughput
更新于2025-09-23 15:22:29
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Tunable photoluminescence and energy transfer of novel phosphor Sr9La2W4O24:Sm3+, Eu3+ for near-UV white LEDs
摘要： Novel Sr9La2W4O24:xSm3+ and Sr9La2W4O24:0.15Sm3+, yEu3+ orange-red phosphors with double perovskite tungsten structure are synthesized by high-temperature solid-phase reaction method. X-ray diffraction patterns indicate the prepared phosphors are pure phase with a tetragonal structure and the SEM image displays the long string structure with a diameter of one micron. Under the excitation of near-UV light, the Sm3+ and Eu3+ ions activated Sr9La2W4O24 phosphors exhibit their characteristic emissions in the orange-red region, and the emitting light color of the Sr9La2W4O24:0.15Sm3+, yEu3+ phosphors can be adjusted from orange to red by increasing the concentration of Eu3+ ions implying their potential applications as orange-red emitting phosphor for LED in solid-state lighting. The optimal doping concentration of Sm3+ ions in Sr9La2W4O24:xSm3+ phosphors is around 15?mol%. The energy transfer from Sm3+ to Eu3+ is discussed and the major mechanism for concentration quenching is the dipole–dipole (d–d) interaction.
关键词： Sm3+,phosphors,energy transfer,double perovskite,Eu3+,white LEDs
更新于2025-09-23 15:21:01
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A novel double-perovskite LiLaMgTeO6: Mn4+ far-red phosphor for indoor plant cultivation white LEDs: Crystal and electronic structure, and photoluminescence properties
摘要： Deep-red-emitting Mn4t activated oxide phosphors are the hot research topic due to their potential applications in indoor plant cultivation LEDs. In this paper, a novel double-perovskite LiLaMgTeO6:Mn4t phosphor was firstly prepared by high-temperature solid-state reaction method and its structure of the phosphor was determined by X-ray diffraction (XRD) and Rietveld refinement. Density functional theory (DFT) calculations using VASP provide an insight into the bandgap and electronic structures of the LiLaMgTeO6 host. Under UV or blue excitation, LiLaMgTeO6:Mn4t shows a good stability and bright far-red light in the 540e800 nm range with the maximum at 708 nm, which matches well with the absorption band of phytochrome PFR, indicating its potential application in improving plant growth. The optimal Mn4t doping concentration was approximately 0.6 mol%. Furthermore, a white-LEDs device made of a 365 nm chip coated with present phosphor and commercial green, blue phosphors was designed for indoor plant cultivation. The results indicate that the LiLaMgTeO6: Mn4t phosphor possesses great application prospect in white-LEDs for plant cultivation.
关键词： Far red emission,Phytochrome,Double perovskite,LEDs,Thermal stability,Indoor plant cultivation
更新于2025-09-23 15:21:01
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The challenge in realizing an exchange coupled BiFeO3- double perovskite bilayer
摘要： In this work we propose a device design for efficient voltage control of magnetism. The magnetization of a ferrimagnetic double perovskite may be manipulated by an exchange coupled layer of multiferroic BiFeO3. Bilayers of Barium doped BiFeO3 and ferrimagnetic double perovskite Sr2FeMoO6 have been prepared by pulsed laser deposition motivated by the possibility of strong interlayer exchange coupling. While single layers of each material show high quality we observe that in both stacking orders the first layer decomposes during the deposition of the second layer. The reason for the decomposition are strongly differing growth conditions for BiFeO3 and Sr2FeMoO6. This means that the generation of artificial multiferroic stacks requires careful choice of the constituent materials to ensure the bilayer stability.
关键词： BiFeO3,Exchange Bias,Double Perovskite,Perovskite,Sr2FeMoO6,Exchange coupling
更新于2025-09-23 15:19:57
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Multifunctional behavior of Ca-doped niobium-based double perovskite for photovoltaic/solar cell devices
摘要： Smart materials of oxide ceramics are usually in the form of single- or polycrystalline. The present ceramic belongs to the polycrystalline compound of Pb1.5Ca0.5BiNbO6 which has a double perovskite structure with the general form of A1.5A′0.5BB′O6. For synthesis and characterization of the sample, a solid solution casting method, X-ray diffraction, scanning electron micrography, Infra-red spectroscopy, etc., have been utilized. Different characterization reveals that the material has a higher value of room-temperature dielectric constant remnant polarization useful for energy storage devices. Optical equities of the ceramic were further analysed by UV–Vis and PL spectroscopy analysis which reveals that the material can be useful for energy harvesting devices like photovoltaic/solar cells. The estimated thermistor parameter suggests that the material can also be useful for thermal sensor devices.
关键词： Photovoltaic/solar cell devices,Energy storage devices,Ca-doped niobium-based double perovskite,Multifunctional behavior,Thermal sensor devices
更新于2025-09-23 15:19:57