In this study, novel deep-red-emitting Mg2InSbO6:Mn4+ phosphors were prepared through a high-temperature solid-state reaction. The as-prepared phosphors belong to the perovskite structure with the ...space group of R3‾ (No.148). The calculated energy gap value of Mg2InSbO6 is ~1.788 eV. Emission spectrum of the Mg2InSbO6:0.3%Mn4+ was obtained under 301 nm excitation, which centered 665 nm due to the 2Eg→4A2g transition. The optimum concentration of Mg2InSbO6:xMn4+ is confirmed to 0.3% mol, and the concentration quenching effect is ascribed to the dipole–dipole interaction. The relative temperature-dependent PL spectra demonstrate that phosphors possess commendable repeatability and high activation energy. The chromaticity shift diagram shows the phosphors have good resistance of color drifting. The Mg2InSbO6:0.3%Mn4+ phosphor has a high color purity of 99.8%. Furthermore, a red light-emitting diode is fabricated with Mg2InSbO6:0.3%Mn4+ phosphor and a 365 nm near-ultraviolet chip. The emission spectrum of the red LED is perfectly overlapped with plant pigments (chlorophyll a and chlorophyll b) absorption spectrum. Thus, Mn4+-activated Mg2InSbO6:Mn4+ phosphors have the potential to apply in plant-cultivation LEDs.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Due to the huge food demand of the population, the luminescent materials with excellent performance applied for indoor plant cultivation have been extensively studied. In this work, a series of ...Mn4+-doped LaBaZnTaO6 phosphors in were synthesized and its luminescence mechanism has been researched in detail. Due to their broad absorption band, they could be effectively excited by the NUV to blue LED chip. Importantly, suitable emission in the red region overlapped with the absorption of plant pigments making it possible to be used in indoor plant cultivation. On the other hand, high-sensitivity non-contact optical temperature sensor is the focus of current research, so the optical thermometer-based lifetime model also was designed and investigated in this work. Interestingly, the maximum relative sensitivity was 1.38 %K−1@473 K, suggesting a good development potential of the sample in optical thermometry. Finally, the warm WLED device was fabricated and achieved a superior CRI value of 90.95 and a good CCT of 3582 K. All the obtained results suggest that it could become a promising red component to be applied in optical thermometer and lighting sources.
•Novel double-perovskite LaBaZnTa1-xMnxO6 phosphors were successfully prepared.•The crystal structure and photoluminescence properties were investigated.•The packaged LED devices were suggested for dual-functional lighting sources.•The optical thermometer-based lifetime model was introduced.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In this thesis, a novel ultraviolet-activated Li2ZnTi3O8:Mn4+ red emitting phosphor is prepared by the traditional high-temperature solid-state reaction method in air. The crystal structure, ...luminescence properties and decay curves of the phosphor are studied in detail. The sample belongs to spinel cubic crystal structure and there are abundant TiO68− octahedron sites can be occupied by Mn4+. The Li2ZnTi3O8:Mn4+ phosphor shows the red emission in region of 600–800 nm with a maximum at ~681 nm under 330 nm excitation, which can promote the plant growth. The optimal Mn4+ doping concentration is ~0.3 mol%, which is higher than that of other hosts. By calculating the crystal field strength (Dq) and Racah parameter B, we can evaluate that there is a strong crystal environment of Mn4+ in the Li2ZnTi3O8 host lattice, which major comes from the 2Eg → 4A2g transition of Mn4+ ion. Furthermore, the characteristics of thermal quenching are also studied, poor thermal quenching performance may be due to high doping concentration of Mn4+. All data suggest that Li2ZnTi3O8:Mn4+ phosphor can be a potential application in plant-cultivation.
A novel Li2ZnTi3O8:Mn4+ phosphor exhibits efficient red emission under UV excitation, which can be absorbed by chlorophyll in plants, Moreover, it also has higher doping concentration of Mn4+. Display omitted
•Novel Li2ZnTi3O8:Mn4+ red phosphor is synthesized by solid-state reaction method.•Emission band peaking at ~681 nm in the range of 600–800 nm can be observed.•Li2ZnTi3O8:Mn4+ red phosphor has a potential application for plant cultivation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Far-red (FR) and near-infrared (NIR) double-wavelength emitting phosphors Gd2ZnTiO6: Mn4+/Yb3+ (GZT: Mn4+/Yb3+) used for light-emitting diodes (LEDs) towards plant cultivation have been synthesized ...via convenient high-temperature solid-state reaction method. Their structures and luminescent properties were identified by powder X-ray diffraction (XRD) and photoluminescence excitation (PLE) and emission (PL) spectra. The crystal field strength of Mn4+-occupied octahedra TiO68- environment was estimated according to the PL and PLE spectra of the Mn4+ solely doped GZT. Under near ultraviolet light (n-UV) excitation, intense FR emission (ranging from 650 to 720 nm) from Mn4+ and NIR emission (925–1075 nm) from Yb3+ were achieved in Mn4+ -Yb3+ co-doped samples, which matches well with the absorption spectra of the phytochrome PFR and photosynthetic bacteria, respectively. The energy transfer processes from Mn4+ to Yb3+ in GZT: Mn4+/Yb3+ were also investigated in detail, and the FR/NIR intensity ratios could be tuned by adjusting the concentration of Mn4+ and Yb3+ to meet the requirements of different species of plants and bacteria. Results indicated that the present GZT: Mn4+/Yb3+ phosphors possess great potential applications in plant cultivation LEDs.
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•The far red and near-infrared emitting phosphors were synthesized.•PL spectra match well with the phytochrome PFR and photosynthetic bacteria absorption spectra.•The energy transfer process from Mn4+ to Yb3+ was investigated.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Nowadays, how to improve the accuracy of the temperature sensors has become a common concern of researchers. For this purpose, dual-emitting phosphors have been proposed as a novel optical ...thermometer because the two discriminate emission centers can avoid the error caused by spectral overlap. Herein, a new ratio-metric luminescent thermometer Gd2ZnTiO6(GZTO):Bi3+, Mn4+ is designed, which exhibits both red and blue luminescence under 375 nm excitation. Based on the different thermal sensitivity of Mn4+ and Bi3+ ions and the energy transfer from Bi3+ to Mn4+ ions, the luminescent thermometer reveals excellent thermal sensitivity (Sr = 2.4% K−1, Sa = 16.8%K−1) and a wide temperature measurement range (313–473 K). Both of them are superior to the most reported materials. In addition, the luminescence intensity of two ions matches the light absorption bands of photosynthetic pigment well, which indicates that GZTO: Bi3+, Mn4+ phosphors also have a great prospect as a plant growth lamp.
Based on the different thermal sensitivity of Mn4+ and Bi3+ ions and the energy transfer from Bi3+ to Mn4+ ions, the thermometer Gd2ZnTiO6:Mn4+,Bi3+ designed by us reveals excellent thermal sensitivity. The luminescence of thermometer which fits the light absorption bands of photosynthetic pigment well is strong enough to have a great application prospect for plant growth lamp. Display omitted
•A novel thermometer Gd2ZnTiO6: Bi3+, Mn4+ is designed with high sensitivity.•The energy transfer process from Bi3+ to Mn4+ is realized in Gd2ZnTiO6.•The luminescence of phosphors is strong enough to make LED chips.•The luminescence of phosphors can be well absorbed by photosynthetic pigments.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Bi3+-doped, Mn4+-doped, and Bi3+/Mn4+ co-doped oxide phosphors Ca2GdTaO6 (CGT) are prepared via the solid-state reaction method. The phase purity and morphology of CGT: Bi3+, Mn4+ phosphors are ...characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The band structure and density of state for CGT are calculated based on density functional theory (DFT). The bandgap of the CGT host is 3.72 eV. The photoluminescence (PL) and photoluminescence excitation (PLE) spectra of CGT: Bi3+ and CGT: Mn4+ is investigated in detail. The overlap between the emission spectra of Bi3+ and the excitation of Mn4+ proves energy transfer from Bi3+ to Mn4+. The corresponding mechanism of the Bi3+→Mn4+ energy transfer process is investigated in detail based on the decay time and PL spectra. Energy transfer efficiency is also calculated. Upon excitation at 320 nm, Bi3+/Mn4+ co-doped CGT phosphors show dual emission attributed to the blue-violet emission (429 nm) of 3P1→1S0 transition of Bi3+ and red emission (679 nm) of 2Eg→4A2g of Mn4+. The intensity of the blue-violet and red emission peaks can be easily adjusted by controlling the concentration of Bi3+ and Mn4+ in the CGT host. The emission band is well-matched with the absorption bands of chlorophylls a and phytochrome PR under the near-ultraviolet to blue excitation, suggesting that the phosphors have great potential applications in light-emitting diodes (LEDs) to modulate plant growth.
•Bi3+/Mn4+ co-doped CGT phosphors were successfully synthesized by the traditional solid-state reaction method for the first time.•The electronic structure for the CGT host was calculated based on DFT, and the value of the bandgap was 3.72 eV.•Energy transfer occurred between Bi3+ and Mn4+, and the energy transfer efficiency reached 76.4%.•The PL spectra of Bi3+/Mn4+ co-doped CGT phosphors match the absorption spectra of chlorophylls a and phytochrome PR well.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
A novel Mn4+ activated Ca2LaSbO6 (CLS) far-red phosphor was synthesized by high temperature solid state reaction. The samples were characterized by X-ray diffraction (XRD), field emission scanning ...electron microscopy (FE-SEM), photoluminescence spectra, ultraviolet-visible spectra, luminescence decay times, emission-temperature relationship and internal quantum efficiency (IQE). It is found that CLS:Mn4+ phosphor has a strong broad excitation band in the range of 200–550 nm. The samples can be excited by ultraviolet and blue light. There is a wide emission band centered at 685 nm between 600 nm and 760 nm. The optimum doping concentration of Mn4+ is approximately 0.5 mol%. In addition, all the CIE chromaticity coordinates of CLS:0.005Mn4+ located at far-red region. The concentration quenching mechanism is the dipole-dipole interaction of Mn4+ activator. Importantly, the CLS:0.005 Mn4+ sample has an IQE of up to 52.2%. Finally, a 365 nm ultraviolet light emitting diode (LED) chip combined with 0.5 mol% Mn4+ far-red phosphor was used to fabricate the LED device. All the results indicated that CLS:Mn4+ phosphors have potential applications in indoor plant cultivation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
A series of novel and efficient Sr2GdNbO6 (SGNO):Mn4+ red phosphors were synthesized by traditional high-temperature solid-state method. The composition, morphology, luminescent properties and ...thermal quenching mechanism of the materials were studied by X-ray diffraction (XRD), field emission electron scanning microscopy (FE-SEM), ultraviolet–visible diffuse reflectance (UV–vis DR) spectroscopy and fluorophotometer. The phosphors can be excited by 300–500 nm light and emit a deep-red light. The characteristic emission band peaked at 687 nm corresponds to the spin-forbidden transition of Mn4+. The temperature-dependent on photoluminescence (PL) emission spectra from 298 K to 498 K manifest that SGNO:Mn4+ phosphor has an activation energy of 0.412 eV, which confirms the excellent thermal stability of the phosphor. Moreover, the IQE value of SGNO:Mn4+ phosphor is 36.37%. The above results illustrated that SGNO:Mn4+ phosphors are expected to make a contribution to indoor plant cultivation.
•Sr2GdNbO6:Mn4+ deep-red emitting phosphors were prepared.•SGNO:Mn4+ phosphor can be excited by 300–500 nm light and emit a deep-red light.•SGNO:Mn4+ phosphors are suitable for indoor plant growth lighting.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Red and far-red emitting phosphors have been widely used in phosphor-converted light emitting diode (pc-LED) devices to provide lighting for indoor plant growth, thus achieving desired product ...qualities. Among the many ways to optimize phosphors’ optical performance, cationic substitution is one of the most effective methods. In this study, red phosphors (Li2MgTi1-x-yO4: xMn4+, yGe4+) were synthesized by high temperature solid state method and the optical performance of phosphors were improved with increasing Ge4+ constituents. In particular, luminescence intensity of Li2MgTiO4: 0.002Mn4+, 0.1Ge4+ increased by 152% under 468 nm excitation, and the thermostability of emission intensity increases from 22% (y = 0) to 43% (y = 0.1), which is about twice as much. Finally, pc-LED device was fabricated via the red phosphor Li2MgTiO4: 0.002Mn4+,0.1Ge4+ coated on a 470 nm ultraviolet chip. By changing the proportion of the phosphor, the electroluminescence spectra of pc-LED device could match well with the absorption regions of plant pigments. Therefore, Li2MgTiO4: 0.002Mn4+, 0.1Ge4+ phosphor has potential application in plant lighting. Furthermore, this work can offer some helpful references for improving luminescent efficiency by simply modulating the chemical composition.
The luminescence intensity of Li2MgTiO4: 0.002Mn4+, 0.1Ge4+ increased by 152%. The thermostability of emission intensity increases from 22% (y = 0) to 43% (y = 0.1), which is about twice as much. Finally, the pc-LED device could emit bright blue and red light, which matched with the absorption regions of plant pigments well. Display omitted
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Broad red emitting phosphors are essential for the growth of indoor plants. Previous Mn4+-activated far-red phosphors typically displayed narrow emission, which could not well overlap with plant ...pigment absorption. A high temperature solid state technique was used to create the unique double perovskite LaGeSbO6:Mn4+ phosphor with an emission peak centered at 700 nm and an impressive full width at half maximum (FWHM) of 100 nm. The origin of ultra-broadband emission of LGS:Mn4+ phosphors was confirmed by crystal structure and time-resolved spectra owing to the occupation of the two octahedral SbO6 and GeO6 centers by the Mn4+ ion. The quenching mechanism is brought about by the dipole-dipole interaction. The broadband emission is substantially broader than that of other Mn4+-activated red emitting phosphors previously described. Besides, the emission spectrum of LaGeSbO6:0.4%Mn4+ matches well with the phytochrome PFR absorption band for plant development. All of the findings suggested that the novel LaGeSbO6:Mn4+ phosphor could be potentially used in light-emitting diodes for indoor plant culture.
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•Time-resolved emission spectroscopy reveals that dual luminescence centers contribute to the ultra-broad emission band of LaGeSbO6:Mn4+.•The broad emission band is centered at 700 nm with an outstanding FWHM of 100 nm, which matches well with the absorption band of phytochrome PFR for plant growth.•Broad excitation bands ranging within 200–600 nm can be efficiently excited by near-UV and blue LED chips to emit deep red emission.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
