共查询到20条相似文献,搜索用时 15 毫秒
1.
Hui-Bing Xu Wei-Dong Zhuang Rong-Hui Liu Yuan-Hong Liu Tian-Liang Zhou Yujin Cho Wei Gao Chun-Pei Yan Naoto Hirosaki Rong-Jun Xie 《RSC advances》2018,8(61):35271
A series of Ce3+-, Tb3+- and Ce3+/Tb3+-doped La3Si8N11O4 phosphors were synthesized by gas-pressure sintering (GPS). The energy transfer between Ce3+ and Tb3+ occurred in the co-doped samples, leading to a tunable emission color from blue to green under the 360 nm excitation. The energy transfer mechanism was controlled by the dipole–dipole interaction. The Ce3+/Tb3+ co-doped sample had an external quantum efficiency of 46.7%, about 5.6 times higher than the Tb-doped La3Si8N11O4 phosphor (8.3%). The thermal quenching of the Tb3+ emission in La3Si8N11O4:Tb,Ce was greatly reduced from 74 to 30% at 250 °C, owing to the energy transfer from Ce3+ to Tb3+. The blue-green La3Si8N11O4:0.01Ce,0.05Tb phosphor was testified to fabricate a warm white LED that showed a high color rendering index of 90.2 and a correlated color temperature of 3570 K. The results suggested that the co-doped La3Si8N11O4:Ce,Tb phosphor could be a potential blue-green down-conversion luminescent material for use in UV-LED pumped wLEDs.The peak emission intensity and thermal stability of Tb3+ in codoped La3Si8N11O4:Ce,Tb sample are strongly enhanced via Ce3+ to Tb3+ energy transfer. 相似文献
2.
Gyu Jin Jeong Tae Wook Kang Young Ji Park Ye Jin Park Younki Lee Byungseo Bae Sun Woog Kim 《RSC advances》2021,11(40):24949
The Ce3+/Tb3+ doped Ba3La2(BO3)4 phosphors were synthesized by a conventional solid state reaction method. The synthesized phosphor samples are a single phase of Ba3La2(BO3)4 and showed angular-shaped fine grains with average particle size from 5 μm to 10 μm. The Ba3La2(BO3)4:Ce3+ phosphors showed an asymmetric broad blue emission under excitation at 365 nm and the Ba3La2(BO3)4:Tb3+ phosphors exhibited typical green emission assigned to the 4f–4f transition of Tb3+ under excitation at 254 nm. Under near-UV (365 nm) excitation, Ba3La2(BO3)4:Ce3+,Tb3+ phosphors showed both a blue emission band and green emission peaks due to Ce3+ and Tb3+, respectively. By optimizing the composition, cyan-blue emission with high color purity (CIE chromaticity coordinate values x = 0.2557 and y = 0.3839) was obtained for the Ba3La2(BO3)4:0.05Ce3+,0.03Tb3+ phosphor, and the internal quantum efficiency of the phosphor at the excitation wavelength of 365 nm is estimated to be 50%. The dental glazing paste prepared by mixing organic binder, Ba3La2(BO3)4:Ce3+,Tb3+ phosphors, and low Tg glass was successfully vitrified when it was heated at 600 and 700 °C, and showed high chemical stability of the luminescence properties in acidic aqueous solution (pH = 4).Herein, we demonstrated the possibility of using Ba3La2(BO3)4:Ce3+,Tb3+ phosphors in dental glazing paste. 相似文献
3.
In situ high-pressure experiments on La2Zr2O7 and La0.5Gd1.5Zr2O7 have been carried out at up to approximately 40 GPa using synchrotron X-ray diffraction and Raman spectroscopy combined with a diamond anvil cell technique. Both La2Zr2O7 and La0.5Gd1.5Zr2O7 undergo a phase transition from a pyrochlore phase (Fdm) into a cotunnite-like phase (Pnma) at 22.7 and 23.3 GPa, respectively. This type of phase transition is mainly controlled through the order-disorder occupancy of cations, and Gd3+ substitution of La3+ reduces the stability of zirconate pyrochlore. However, abnormal changes to the unit-cell volumes and vibrational modes observed at 5.5 GPa in La2Zr2O7 and 6.5 GPa in La0.5Gd1.5Zr2O7 are attributed to an anion disorder in the pyrochlore. In situ high-pressure experiments on La2Zr2O7 and La0.5Gd1.5Zr2O7 have been carried out at up to approximately 40 GPa using synchrotron X-ray diffraction and Raman spectroscopy combined with a diamond anvil cell technique. 相似文献
4.
The upconversion-based optical heating and temperature sensing characteristics are investigated in the Er3+/Yb3+/Bi3+ tri-doped La2O3 nano-phosphor synthesized through a solution combustion method. The structural measurements reveal an increase in lattice parameters and particles size of the phosphor on increasing the concentrations of Bi3+ ions. The energy dispersive spectroscopic (EDS) measurements confirm the presence of La, Er, Yb, Bi and O elements in the tri-doped phosphor. The absorption spectra show the large number of bands due to Er3+, Yb3+ and Bi3+ ions. The Er3+/Yb3+ co-doped phosphor gives strong green emission bands at 523 and 548 nm upon 976 nm excitation due to 2H11/2 → 4I15/2 and 4S3/2 → 4I15/2 transitions of Er3+ ion, respectively. The emission intensity of these bands is enhanced upto 15 times in the presence of Bi3+ ions. The emission intensities of the 523 and 548 nm bands vary non-linearly with the pump power. The fluorescence intensity ratio (FIR) of the thermally coupled 523 and 548 nm emission bands shows efficient optical heating in the tri-doped phosphor. The FIR of the 523 and 548 nm emission bands further varies with the increase in temperature of the phosphor. The relative temperature sensing sensitivity has been calculated to be 71 × 10−4 K−1 at 450 K for the tri-doped phosphor. Thus, the Er3+/Yb3+/Bi3+ tri-doped La2O3 nano-phosphor may provide a platform to use it in the photonic devices, as an optical heater and temperature sensor.The Er3+/Yb3+/Bi3+ tri-doped La2O3 nano-phosphor gives efficient induced optical heating and temperature sensing. This study is useful to understand these characteristics in different materials with various pump powers and temperatures. 相似文献
5.
Meng Ju Lu Pan Chuanzhao Zhang Yuanyuan Jin Mingmin Zhong Song Li Shichang Li Tie Yang Xiaotian Wang 《RSC advances》2020,10(48):28674
Trivalent rare-earth holmium ion (Ho3+) doped yttrium oxide (Y2O3) has attracted great research interest owing to its unique optoelectronic properties and excellent performances in many new-type laser devices. But the crystal structures of the Ho3+-doped Y2O3 system (Y2O3 : Ho) are still unclear. Here, we have carried out a first-principle study on the structural evolution of the trivalent Ho3+ doped Y2O3 by using the CALYPSO structure search method. The results indicate that the lowest-energy structure of Ho3+-doped Y2O3 possesses a standardized monoclinic P2 phase. It is found that the doped Ho3+ ion are likely to occupy the sites of Y3+ in the host crystal lattice, forming the [HoO6]9− local structure with C2 site symmetry. Electronic structure calculations reveal that the band gap value of Ho3+-doped Y2O3 is approximately 4.27 eV, suggesting the insulating character of Y2O3 : Ho system. These findings could provide fundamental insights to understand the atomic interactions in crystals as well as the information of electronic properties for other rare-earth-doped materials.Our study successfully identified the ground-state structure of Ho3+-doped Y2O3 crystal for the first time. 相似文献
6.
Ting Zhang Ai Du Chuanxiang Chen Xiujie Ji Bin Zhou Jun Shen Zhihua Zhang 《RSC advances》2019,9(58):33883
A ZnGa2O4:Cr3+-based aerogel was prepared by using polyacrylic acid (PAA) as a dispersant and propylene oxide (PO) as a crosslinking agent via CO2 supercritical drying. The results of BET and SEM show that there is a certain degree of macroporosity (d > 50 nm) in the aerogel. It has a dendritic structure and the interior is relatively loose. EDS mapping illustrates that the elements Zn, Ga, and Cr are evenly distributed in the aerogel. In addition, the diffuse reflectance spectra and the emission spectrum of samples with different calcination temperatures were also characterized. Both demonstrated, when the calcination temperature is greater than 600 °C, that the sample crystallizes and has a significant emission, which is consistent with the XRD and TG-DSG results. Finally, the ZnGa2O4:Cr3+-based aerogel also exhibits excellent long afterglow performance and high photocatalytic performance with 80.1% methylene blue (MB) degradation at 20 min.A ZnGa2O4:Cr3+-based aerogel was prepared by using polyacrylic acid (PAA) as a dispersant and propylene oxide (PO) as a crosslinking agent via CO2 supercritical drying. 相似文献
7.
Amine Bendahhou Karim Chourti Mohamed Loutou Soufian El Barkany Mohamed Abou-Salama 《RSC advances》2022,12(18):10895
Undoped Ba(Zr0.9Ti0.1)O3 and rare-earth-doped (Ba1−xRE2x/3)(Zr0.9Ti0.1)O3 (RE3+ = La3+, Sm3+) perovskite compounds were synthesized by the conventional solid-state reaction route. Both solubility of rare earth in Ba(Zr0.9Ti0.1)O3 and formation of perovskite structure with the Pmm space group were verified by the Rietveld method using X-ray diffraction data. SEM micrographs of all ceramics revealed high densification, low porosity, and even homogeneous grain distribution of various dimensions over the total surface. The frequency-dependent electrical properties were analyzed by complex impedance spectroscopy. Different types of studies such as the Nyquist plot, real and imaginary part of impedance, conductivity, modulus formalism, and charge carriers activation energy were used to explain the microstructure–electrical property relationships.Undoped Ba(Zr0.9Ti0.1)O3 and rare-earth-doped (Ba1−xRE2x/3)(Zr0.9Ti0.1)O3 (RE3+ = La3+, Sm3+) perovskite compounds were synthesized by the conventional solid-state reaction route. 相似文献
8.
Andrzej M. Konkowski Benedykt Kukliski Mariusz Kubus Jacek Ryl Karol Szczodrowski Dorota Wileska H.-Jürgen Meyer 《RSC advances》2018,8(20):11006
We report on a glass-nanocomposite material consisting of yttrium aluminum garnet (Y3Al5O12, YAG) nanocrystals co-doped with Yb3+, Tm3+ and Ho3+ ions as well as entrapped into a SiO2 xerogel. This 94YAG·5Yb2O3·0.8Tm2O3·0.2Ho2O3@SiO2 (abbr. YAG:YbTmHo@SiO2) nanocomposite material has been prepared by sol–gel procedure. Its structure and morphology has been characterized by means of X-ray diffraction (XRD) and scanning electron microscope (SEM) techniques as well as energy dispersive X-ray (EDX), X-ray photoelectron (XPS) and luminescence spectroscopies. The luminescent glass-nanocomposite exhibited an up-conversion effect under λexc = 980 nm and emission when excited under 355 nm in steady-state conditions. Then time-resolved luminescence emission was observed, when the sample was excited at 290 and 355 nm by a pulse laser. Average decay times for the SiO2 matrix and for some transitions of the Tm3+ and Ho3+ dopants present in the YAG:YbTmHo@SiO2 material have been evaluated. The luminescent nanocomposite when excited under 290 or 355 nm wavelengths in both conditions emits blue light. However, the nanocomposite is promising as a single-source white-light phosphor owing to its up-conversion luminescence under 980 nm excitation. Such optical features make the studied material an alternative phosphor.We present a glass-nanocomposite of the type YAG:YB3+, Tm3+, Ho3+@SiO2 as an alternative white phosphor based on up-conversion effect. 相似文献
9.
The double doping strategy based on energy transfer is an effective way to regulate the NIR spectral distribution. In this work, Ca3In2Ge3O12:xNd3+ (CIG:xNd3+) and Ca3−xIn1.93Ge3O12:0.07Cr3+,yNd3+ (CIG:0.07Cr3+,yNd3+) phosphors are successfully prepared via a high-temperature solid-state method. CIG:0.07Cr3+ shows broadband emission centered at 804 nm, which covers most of the excitation peaks of Nd3+ ions. Under excitation at 480 nm, Cr3+ can provide effective energy transfer to Nd3+. In addition, CIG:0.07Cr3+,0.15Nd3+ has good temperature stability, and maintains 68.98% of the room-temperature intensity at 150 °C. The phosphors can convert short-wave photons to long-wave photons and enhance solar cell utilization, demonstrating the potential application of this material in solar spectral conversion technology.Improvement of the luminescence properties of Ca3In2Ge3O12:Cr3+,Nd3+via energy transfer and its potential application in silicon solar cells. 相似文献
10.
A series of Mg2Y2Al2Si2O12:Dy3+,Eu3+ phosphors were synthesized by the solid-state method. The luminescent properties and crystal structures of the Mg2Y2Al2Si2O12:Dy3+,Eu3+ phosphors were analyzed. The XRD results show that the synthesized Mg2Y2Al2Si2O12:Dy3+,Eu3+ phosphors are of pure phase. Mg2Y2Al2Si2O12:Dy3+ can emit blue and yellow light under 367 nm light excitation; when doped with Eu3+, there is an obvious energy transfer from Dy3+ to Eu3+, and warm white light can be realized by adjusting the concentrations of Dy3+ and Eu3+ in Mg2Y2Al2Si2O12. A warm white LED device was fabricated by combining Mg2Y1.88Al2Si2O12:0.05Dy3+,0.07Eu3+ and a UV LED chip (370 nm) under a voltage of 3.2 V and current of 5 mA, the characteristics of the white LED being CIE = (0.4071, 0.3944), CCT = 3500 K and CRI = 91.3.MYAS:xDy3+,yEu3+ can produce warm white light with CIE chromaticity coordinates of (0.4071, 0.3944) and relative color temperature of 3500 K. 相似文献
11.
R. Thangarasu B. Babu N. Senthil Kumar Mon-Shu Ho O. N. Balasundaram T. Elangovan 《RSC advances》2019,9(29):16541
In this paper, we report a wet chemical precipitation method used to synthesize pure and Cu-doped V2O5 nanorods with different doping concentrations (CuxV2O5 where x = 3, 5 or 7 at%), followed by annealing at 600 °C and characterizations using several techniques. Indeed, a growth mechanism explaining the morphological evolution under the experimental conditions is also proposed. The XRD patterns revealed that all of the studied samples consist of a single V2O5 phase and are well crystallized with a preferential orientation towards the (200) direction. The presence of intrinsic defects and internal stresses in the lattice structure of the CuxV2O5 samples has been substantiated by detailed analysis of the XRD. Apart from the doping level, there was an assessment of identical tiny peaks attributed to the formation of a secondary phase of CuO. SEM images confirmed the presence of agglomerated particles on the surface; the coverage increased with Cu doping level. XPS spectral analysis showed that Cu in the V5+ matrix exists mainly in the Cu2+ state on the surface. The appearance of satellite peaks in the Cu 2p spectra, however, provided definitive evidence for the presence of Cu2+ ions in these studied samples as well. Doping-induced PL quenching was observed due to the absorption of energy from defect emission in the V5+ lattice by Cu2+ ions. We have proposed a cost-effective, less complicated but effective way of synthesizing pure and doped samples in colloidal form, deposited by the nebulizer spray technique on p-Si to establish junction diodes with enhanced optoelectronic properties.A wet chemical precipitation method was used to synthesize pure and Cu-doped (3, 5 or 7 at%) V2O5 nanorods and photodiodes were fabricated. 相似文献
12.
Kyriakos N. Papageridis Nikolaos D. Charisiou Savvas Douvartzides Victor Sebastian Steven J. Hinder Mark A. Baker Ayesha A. AlKhoori Sara I. AlKhoori Kyriaki Polychronopoulou Maria A. Goula 《RSC advances》2021,11(15):8569
The present study provides, for the first time in the literature, a comparative assessment of the catalytic performance of Ni catalysts supported on γ-Al2O3 and γ-Al2O3 modified with La2O3, in a continuous flow trickle bed reactor, for the selective deoxygenation of palm oil. The catalysts were prepared via the wet impregnation method and were characterized, after calcination and/or reduction, by N2 adsorption/desorption, XRD, NH3-TPD, CO2-TPD, H2-TPR, H2-TPD, XPS and TEM, and after the time-on-stream tests, by TGA, TPO, Raman and TEM. Catalytic experiments were performed between 300–400 °C, at a constant pressure (30 bar) and different LHSV (1.2–3.6 h−1). The results show that the incorporation of La2O3 in the Al2O3 support increased the Ni surface atomic concentration (XPS), affected the nature and abundance of surface basicity (CO2-TPD), and despite leading to a drop in surface acidity (NH3-TPD), the Ni/LaAl catalyst presented a larger population of medium-strength acid sites. These characteristics helped promote the SDO process and prevented extended cracking and the formation of coke. Thus, higher triglyceride conversions and n-C15 to n-C18 hydrocarbon yields were achieved with the Ni/LaAl at lower reaction temperatures. Moreover, the Ni/LaAl catalyst was considerably more stable during 20 h of time-on-stream. Examination of the spent catalysts revealed that both carbon deposition and degree of graphitization of the surface coke, as well as, the extent of sintering were lower on the Ni/LaAl catalyst, explaining its excellent performance during time-on-stream.Highly selective and stable Ni supported on La2O3–Al2O3 catalyst on the deCO/deCO2 reaction paths for the production of renewable diesel. 相似文献
13.
Chunliu Li Linchao Zhang Junfeng Yang Zhuoming Xie Tao Zhang Jianxin Wang Qianfeng Fang Xianping Wang 《RSC advances》2019,9(6):3436
In this work, to improve the cyclability and high-temperature performance of cubic spinel LiMn2O4 (LMO) as cathode materials, Nb5+-doped LiMn2O4 powders coated and uncoated with Al2O3 and/or B2O3 were synthesized via the modified solid-state reaction method. It was found that Nb5+-doped and B2O3 + Al2O3-coated LMO powders comprising 5 μm granular agglomerated fine primary particles smaller than 350 nm in diameter exhibited superior electrochemical properties with initial discharge capacity of 101.68 mA h g−1; we also observed capacity retention of 96.31% after 300 cycles at room temperature (RT) and that of 98% after 50 cycles at 55 °C and 1C rate.Nb-doped and Al2O3 + B2O3-coated granular secondary LMO particles enabling superior cycling performance at 25 and 55 °C. 相似文献
14.
Kun Nie Ranran Zhou Chi-An Cheng Xiuqiang Duan Ziyao Hu Lefu Mei Haikun Liu Luoxin Wang Hua Wang Xiaoxue Ma 《RSC advances》2022,12(51):33200
The polychromatic phosphor with an apatite structure Ca2La3(SiO4)3F:0.15Tb3+,xSm3+ (CLSOF:0.15Tb3+,xSm3+) was synthesized via a solid-state route. The phase and morphology of the phosphor has been investigated by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The structures of the as-prepared phosphor were verified by means of the Rietveld method. The optical performance was investigated thoroughly and the phosphors could emit multicolor light from short wavelengths to long wavelengths by gradually increasing the doping contents of samarium. All the results support that the energy transfer in CLSOF:0.15Tb3+,xSm3+ contributes to the color tunable property of the phosphor.The photoluminescence spectra of Ca2La2.85−x(SiO4)3F:0.15Tb3+,xSm3+ phosphors (left) could emit typical multicolor light with increasing doping contents of samarium (right). 相似文献
15.
Yuichi Okazaki Seiji Oda Akihiko Takamatsu Shogo Kawaguchi Hirofumi Tsukasaki Shigeo Mori Shunsuke Yagi Hidekazu Ikeno Ikuya Yamada 《RSC advances》2022,12(9):5094
The rational design principle of highly active catalysts for the oxygen evolution reaction (OER) is desired because of its versatility for energy-conversion applications. Postspinel-structured oxides, CaB2O4 (B = Cr3+, Mn3+, and Fe3+), have exhibited higher OER activities than nominally isoelectronic conventional counterparts of perovskite oxides LaBO3 and spinel oxides ZnB2O4. Electrochemical impedance spectroscopy reveals that the higher OER activities for CaB2O4 series are attributed to the lower charge-transfer resistances. A density-functional-theory calculation proposes a novel mechanism associated with lattice oxygen pairing with adsorbed oxygen, demonstrating the lowest theoretical OER overpotential than other mechanisms examined in this study. This finding proposes a structure-driven design of electrocatalysts associated with a novel OER mechanism.Postspinel-structured oxides, CaB2O4 (B = Cr3+, Mn3+, and Fe3+), have exhibited systematically higher catalytic activities in the oxygen evolution reaction (OER) than nominally conventional counterparts of perovskite LaBO3 and spinel ZnB2O4. 相似文献
16.
Using urea as a precipitation agent, Tb3+, Eu3+ co-doped Y2O3 nanophosphors were synthesized by a homogeneous precipitation method. The sizes of the sample particles were controlled by changing the molar ratio of the urea and rare earth ions. The microstructure and crystallographic structure of the sample were determined through powder X-ray diffraction (PXRD) and field emission scanning electron microscopy (FE-SEM). The test results show that the sample is body centered cubic. As the molar ratio of urea to rare earth ions increases, the size of the sample particles decreases. The temperature-dependent emission spectra of Tb3+, Eu3+ co-doped Y2O3 phosphors with different particle sizes were measured. The results showed that because the fluorescence intensity ratio (FIR) of Tb3+ and Eu3+ varies with temperature, it can be used to visually reflect changes in temperature. In addition, the temperature sensing sensitivity of Tb3+ and Eu3+ co-doped Y2O3 phosphors increased upon a decrease in the particle size, but the relative sensitivity decreased with a decrease in the particle size. The physical mechanism of the sensitivity and relative sensitivity changes with the size of the sample particles was also explained.Using urea as a precipitation agent, Tb3+, Eu3+ co-doped Y2O3 nanophosphors were synthesized by a homogeneous precipitation method. The size dependence-optical temperature sensing properties of nanophosphors have been studied. 相似文献
17.
18.
Jiyou Zhong Weiren Zhao Lunwei Yang Peng Shi Zifeng Liao Menglong Xia Wenhua Pu Wei Xiao Ligen Wang 《RSC advances》2018,8(24):13054
A series of red-emitting Ca3ZrSi2O9:Eu3+,xBi3+ phosphors was synthesized using a conventional high temperature solid-state reaction method, for the purpose of promoting the emission efficiency of Eu3+ in a Ca3ZrSi2O9 host. The site preference of Bi3+ and Eu3+ in the Ca3ZrSi2O9 host was evaluated by formation energy. The effects of Bi3+ on electronic structure, luminescent properties, and related mechanisms were investigated. The inner quantum yield of the optimized sample increased to 72.9% (x = 0.08) from 34.6% (x = 0) at 300 nm ultraviolet light excitation. The optimized sample (x = 0.08) also showed excellent thermal stability, and typically, 84.2% of the initial emission intensity was maintained when the temperature increased to 150 °C from 25 °C, which is much higher than that without Bi3+ doping (70.1%). The mechanisms of emission properties and thermal stability enhancement, as well as the redshift of the charge transfer band (CTB) induced by Bi3+ doping in the Ca3ZrSi2O9:Eu3+ phosphor, were discussed. This study elucidates the photoluminescence properties of Bi3+-doped Ca3ZrSi2O9:Eu3+ phosphor, and indicates that it is a promising luminescent material that can be used in ultraviolet light-emitting diodes.A red-emitting phosphor Ca3ZrSi2O9:Eu3+,Bi3+ with high quantum yield and thermal stability was developed by introducing Bi3+ as an efficient sensitizer. 相似文献
19.
Shaoying Wang Qi Sun Balaji Devakumar Liangling Sun Jia Liang Xiaoyong Huang 《RSC advances》2018,8(53):30191
Novel Mn4+-activated far-red emitting SrMg2La2W2O12 (SMLW) phosphors were prepared by a conventional high-temperature solid-state reaction method. The SMLW:Mn4+ phosphors showed a broad excitation band peaking at around 344 nm and 469 nm in the range of 300–550 nm. Under 344 nm near-ultraviolet light or 469 nm blue light, the phosphors exhibited a far-red emission band in the 650–780 nm range centered at about 708 nm. The optimal Mn4+ doping concentration in the SMLW host was 0.2 mol% and the CIE chromaticity coordinates of SMLW:0.2% Mn4+ phosphors were calculated to be (0.7322, 0.2678). In addition, the influences of crystal field strength and nephelauxetic effect on the emission energy of Mn4+ ions were also investigated. Moreover, the internal quantum efficiency of SMLW:0.2% Mn4+ phosphors reached as high as 88% and they also possessed good thermal stability. Specifically, the emission intensity at 423 K still maintained about 57.5% of the initial value at 303 K. Finally, a far-red light-emitting diode (LED) lamp was fabricated by using a 365 nm near-ultraviolet emitting LED chip combined with the as-obtained SMLW:0.2% Mn4+ far-red phosphors.Novel Mn4+-activated SrMg2La2W2O12 far-red emitting phosphors with an internal quantum efficiency as great as 88% and excellent thermal stability were prepared towards applications in indoor plant cultivation LEDs. 相似文献
20.
U. Younas M. Atif A. Anjum M. Nadeem T. Ali R. Shaheen W. Khalid Z. Ali 《RSC advances》2023,13(8):5293
Lanthanum (La3+) doped Ba1−xLaxTiO3 (x = 0.0, 0.0025, 0.005, 0.0075) ceramics were synthesized by the composite-hydroxide-mediated method. Rietveld refinement of the XRD patterns confirmed the formation of a perovskite crystal structure that transforms from tetragonal to pseudo-cubic with La3+ doping content (x). Scanning electron microscopy displayed a dense and homogeneous microstructure with reduced grain size on La3+ doping. The frequency and temperature-dependent dielectric measurements showed an improvement in the dielectric permittivity, a decrease in the ferroelectric–paraelectric transition temperature, and an increase in the dielectric diffusivity with increasing La3+ doping content. Complex impedance analysis indicated the semiconducting behavior with a positive temperature coefficient of resistance effect, which could be explained in terms of a charge compensation mechanism in the donor doped BaTiO3. The ferroelectric hysteresis loops revealed that these ceramics are ferroelectric in nature, while an improvement in the energy storage density and energy storage efficiency was observed for the doped samples due to reduced grain size on La3+ doping. Here, the sample with x = 0.005 has a high dielectric permittivity, a low dielectric tangent loss, and the highest energy storage efficiency. This makes this composition interesting for energy storage applications.The improved dielectric and energy storage properties of La3+-doped BaTiO3 ceramics make them attractive for use in energy storage applications. 相似文献