查找使用阿拉丁产品的科研文献

Tunable luminescence of Bi3+/Eu3+-doped SiO2–Al2O3-MCO3 (M = Ca, Sr, Ba) glasses for WLED

Falin Zhang,Xiaoying Liang,Rongfei Wei,Hai Guo,Fangfang Hu

In this work, a group of Bi 3+ /Eu 3+ -doped SiO 2 –Al 2 O 3 -MCO 3 (M = Ca, Sr, Ba) glasses were fabricated through melt-quenching method. Their structure and photoluminescence characters were studied via X-ray diffraction (XRD), UV–Vis transmission spectra (TRS), excitation spectra, emission spectra and decay lifetimes. The XRD results show that no nano-crystal phase forms in glass matrix with different doping concentrations of Bi 3+ and Eu 3+ ions. Through regulating optical alkalinity value, the intensity of Bi 3+ ions increases and the peak position shifts to red wavelength. The Bi 3+ /Eu 3+ co-doped glasses show a blue-white-yellow-red luminescence by changing concentration of Eu 3+ ions. Energy transfer efficiency from Bi 3+ to Eu 3+ can reach as high as 10.54%. At 423 K, the emission intensity of 55SiO 2 –10Al 2 O 3 –35BaO-0.25Bi 2 O 3 (GBE0.5) is 31.1% of that at 308 K. Meanwhile, the activation energy of the glass matrix is 0.251 eV. All results suggest that these Bi 3+ /Eu 3+ co-doped glass samples possess potential application in LED field.

The immobilization of Sr(ll) and Co(ll) via magnetic easy-separation organophosphonate-hydroxyapatite hybrid nanoparticles

Keren Lu,Zhiren Zhao,Jin Cui,Cuiyun Bai,Hongling Zhang,Xuetao Zhao,Fengyun Wang,Mingzhu Xia,Yanru Zhang

The magnetic Hexamethylene diamine tetramethylene phosphonic acid (HDTMP)-hydroxyapatite nanoparticles (HD-MHAP) were firstly prepared and applied for the immobilization of radioactive Sr 2+ (Strontium ion) and Co 2+ (Cobalt ion). The molar ratio of organic phosphine in HDTMP to total phosphorus was 10% (10HD-MHAP) and can also be easily separated from aqueous solution. At the equilibrium concentration of Sr 2+ and Co 2+ (200 mg/L), the adsorption capacity of MHAP and 10HD-MHAP on Co 2+ was 28.4 mg/g and 172.3 mg/g, respectively and for Sr 2+ , the adsorption capacity was 54.9 mg/g and 320.7 mg/g. Additionally, the desorption percentage of Sr 2+ (%) and Co 2+ (%) was very low, which was 0.66 and 1.61, respectively. This is significant because the irreversible adsorption of HDTMP/Fe 3 O 4 /HAP composite for Sr 2+ and Co 2+ ensures the captured radionuclides will not be released back into the aquatic systems. Moreover, the affinity between HDTMP and HAP and the coordination of HDTMP and Sr 2+ or Co 2+ was probed by Multiwfn wavefunction analysis. The results indicated that the formation of a ternary surface complex of MHAP-HDTMP-M (Sr 2+ or Co 2+ ) was the key to the excellent immobilization performance of HD-MHAP composite for Sr 2+ or Co 2+ .

Novel high-entropy microwave dielectric ceramics Sr(La0.2Nd0.2Sm0.2Eu0.2Gd0.2)AlO4 with excellent temperature stability and mechanical properties

Feng Li Lin,Bing Liu,Cheng Chao Hu,Kai Xin Song

Novel high-entropy Sr(La 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Gd 0.2 )AlO 4 ceramics with a layered perovskite structure have been prepared via the standard solid-state reaction method. The design of high-entropy improves the bond valence and subsequently optimizes the large negative temperature coefficient of resonant frequency ( τ f = −32 ppm/°C) of the simple SrLaAlO 4 ceramics. Excellent temperature stability ( τ f = −6 ppm/°C) together with a relative permittivity ( ε r ) of 18.6 and a quality factor ( Qf = 14,509 GHz) are obtained in Sr(La 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Gd 0.2 )AlO 4 ceramics sintered at 1475 °C. It indicates that the present ceramics have great application prospects in passive microwave components such as resonators and filters. Meanwhile, significant improvements in compressive strength and strain are achieved, which are 1040 MPa and 15.7% for Sr(La 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Gd 0.2 )AlO 4 compared to 583 MPa and 12% in SrLaAlO 4 . The enhanced mechanical properties originate from the dislocation strengthening mechanism as the intertwining of interlayer lattices is revealed from the high-resolution transmission electronic micrographs.

AIn3Si4P9 (A = Ca, Sr): quaternary phosphides with double-helix structures exhibiting high laser-induced damage thresholds

Ming-Shu Zhang,Bin-Wen Liu,Xiao-Ming Jiang,Guo-Cong Guo

Two quaternary phosphides AIn3Si4P9 (A = Ca, 1; Sr, 2) belonging to the non-centrosymmetric space group P41212 are discovered and synthesized through the solid-state method for the first time. They present extraordinary double-helix frameworks composed of corner-shared tetrahedral [InP4] and [SiP4] units. Although compounds 1 and 2 have undesirable band gaps (1.25 and 1.15 eV), their extremely low thermal expansion coefficients (∼10−6) result in high laser-induced damage thresholds approximately seven times that of benchmark AgGaS2 under a 2050 nm laser. Moreover, both compounds show weak second-harmonic generation intensities primarily caused by Kleinman forbidden nonlinear optical coefficients. Theoretical calculations further reveal that the electron transitions mainly originated from the tetrahedral [InP4] and [SiP4] units.

Facile Synthesis of MOF-Derived Hierarchical Flower-Like Sr-Doped Co3O4 Structure for Effective TEA Sensing

Heming Sun,Xiaonian Tang

Enabling efficient visible light photocatalytic water splitting over SrTaO2N by incorporating Sr in its B site

Xiaoqin Sun,Fangfang Wu,Gang Liu,Xiaoxiang Xu

The perovskite oxynitride SrTaO2N is a promising compound for solar energy conversion because it has strong visible light absorption at wavelengths as long as 650 nm. However, its photocatalytic activity is generally very poor, primarily because of the high defect concentration induced during its synthetic procedures as well as photocatalytic self-decomposition events. In this work, we introduce Sr into the B site of SrTaO2N to form a complex perovskite oxynitride, Sr3(Sr1/3Ta2/3)3O9−xNy (i.e. Sr4Ta2O9−xNy). The new compound has a much lower defect concentration compared to SrTaO2N and much higher stability against photocatalytic self-decomposition. More importantly, Sr4Ta2O9−xNy demonstrates significantly improved photocatalytic activity for water oxidation and reduction reactions under visible light irradiation (λ ≥ 400 nm) than SrTaO2N, approaching an apparent quantum efficiency as high as 3.4% at 420 ± 20 nm.

Solution-processed Sr-doped NiOx as hole transport layer for efficient and stable perovskite solar cells

Jiankai Zhang,Wujian Mao,Xian Hou,Jiaji Duan,Jianping Zhou,Sumei Huang,Wei Ou-Yang,Xuehua Zhang,Zhuo Sun,Xiaohong Chen

Nickel oxide (NiO x ) hole transport layer (HTL)-based planar perovskite solar cells (PSCs) have attracted much attention due to high power conversion efficiency (PCE) and simple processing. In this work, smooth and compact Sr-doped NiO x films with different Sr doping concentration were successfully prepared through a simple low temperature sol-gel method. The 1 at.% Sr-doped NiO x HTL-based PSCs exhibited the best performance with PCE of 20.07%, which is greatly higher than PCE of reference NiO x based PSCs (15.73%). Furthermore, the unencapsulated PSCs based on Sr:NiO x HTL still retains over 60% of the original PCE value aging for 100 days under ambient air, showing better stability. The superior performance of Sr-doped NiO x based PSCs is attributed to better electrical conductivity, crystallinity of perovskite film and energy level matching with perovskite layer, which can greatly improve hole transport and extraction abilities and reduce carrier recombination, resulting in high PCE and better stability.

Microfluidic-templating alginate microgels crosslinked by different metal ions as engineered microenvironment to regulate stem cell behavior for osteogenesis

Yujie Zhang,Chuanfeng An,Yang Zhang,Haoyue Zhang,Abdullah Faqeer Mohammad,Qiao Li,Weijian Liu,Fei Shao,Jiayi Sui,Changle Ren,Kai Sun,Fang Cheng,Jia Liu,Huanan Wang

Cell microenvironment is a collection of dynamic biochemical and biophysical cues which functions as the key factor in determining cell behavior. Encapsulating single cell into micrometer-scale hydrogels which mimics the cell microenvironment can be used for single cell analysis, cell therapies, and tissue engineering. Here, we developed a microfluidics-based platform to engineer the niche environment at single cell level using alginate microgels crosslinked by different metal ions to regulate stem cell behavior for bone regeneration. Specifically, we revealed that Ca 2+ in the engineered microenvironment promoted osteogenic differentiation of encapsulated stem cells and substantially accelerated the matrix mineralization compared to Sr 2+ in vitro . However, the superior osteoinductive capacity of Ca 2+ compared with Sr 2+ led to comparable bone healing in a rat bone defect model. This attributed to Sr 2+ in microgels to inhibit the osteoclast activity and bone resorption after implantation. In summary, the present study demonstrates metal ions as a critical factor in the environmental cues to affect cell behavior and influence the efficacy of stem cell-based therapy in tissue regeneration, and provides new insights to engineer an expecting microenvironment for regenerative medicine.

Alkaline earth modified activated carbon supported Cu catalysts with enhanced selectivity in the hydrogenation of dimethyl oxalate to methyl glycolate

Zanji Rong,Weihua Shen,Yunjin Fang

In this work, the effect of alkaline earth metal modification on the catalytic performance of activated carbon supported Cu was investigated. The experimental results showed that the introduction of Ca and Sr improved the selectivity of methyl glycolate (MG) during hydrogenation of dimethyl oxalate (DMO) in gas phase. The optimal loading amount of Ca was 0.1 wt%, and under the optimal conditions (temperature 240 °C, pressure 2 MPa, hydrogen–ester ratio of 80, feedstock 15% DMO methanol solution, and WLHSVDMO = 0.9 h−1) the selectivity of MG was as high as 94%, and the conversion of DMO was 97%. The optimal loading of Sr was 0.2 wt% with MG selectivity up to 89% and DMO conversion of 98%. The results of catalyst characterization showed that both Ca and Sr modifications were beneficial to further reduce the particle size of Cu, improve the dispersion of Cu, increase the basicity of the catalyst, and improve the stable presence of Cu+ during the reaction process. Cu+ was beneficial to the stabilization of the MG species, in which Cu+ accounted for more in the Ca-modified catalysts Cu+/(Cu+ + Cu0) = 0.65, and in the Sr-modified ones Cu+/(Cu+ + Cu0) = 0.51. Therefore, both Ca and Sr modified catalysts showed improvement in the selectivity of MG.

Refined Sr ion ratio to improve room-temperature TCR of La1-xSrxMnO3 (0.175 ≤ x ≤ 0.235) polycrystalline ceramics

Liang Xiaolu,Wang Zhenyu,Chen Zihao,Jiang Jiabin,Han Jiamei,Wang Yao,Wang Haitao,Pan Zimeng,Sun Jiankun,Ma Jun,Jiang Xuexing,Peng Jubo,Liu Xiang,Gu Xin

Perovskite manganite oxides have attracted considerable attention due to their strong electronic correlation. However, their practical application is challenged by high manufacturing costs and inferior electrical properties. In this study, the sol–gel method was employed to precisely control the Sr content in La 1− x Sr x MnO 3 (LSMO, x  = 0.175, 0.195, 0.215, and 0.235) polycrystalline ceramics, the relationship between doping levels and electrical transport properties was systematically investigated. The results show that substituting La 3+ with Sr 2+ can effectively tune the electrical transport properties of LSMO ceramics. X-ray diffraction analysis indicates that all samples exhibit a single-phase perovskite structure with no secondary phases detected. Scanning electron microscopy images reveal that the sample surfaces have good grain connectivity, with grain size increasing as the Sr doping level increases. The resistivity–temperature curves of the samples were measured using the standard four-probe method, and significant differences of electrical transport properties were observed within the range of Sr doping studied. Notably, when the Sr doping level is x  = 0.195, the temperature coefficient of resistivity ( TCR ) value of LSMO ceramics increases significantly to 10.3% K −1 at the peak TCR temperature ( T k ) of 296.3 K. In summary, these results offer a theoretical basis and guidance for future development of highly sensitive uncooled infrared bolometers.

Enhancing luminescence of AF2: Ln3+ (A = Ca, Sr; Ln = Eu, Tb) by the use of carbon dots

Lisha Zhang,Yudong Ji,Weidong Li,Bing Zhang,Qiang Ma,Bowen Qin,Yilei Zhang,Dan Yue,Zhenling Wang

Lanthanide ions-doped fluoride nanocrystals have excellent application prospect. However, low photoluminescence quantum yield (PLQY) is usually along with lanthanide ions-doped fluoride nanocrystals owing to their low molar absorptivity and narrow absorption band . In order to increase the absorption cross section of Ln 3+ in fluoride nanocrystals, a facile synthesis strategy to enhance luminescence of AF 2 : Ln 3+ (A = Ca, Sr; Ln = Eu, Tb) by the use of carbon dots (CDs) has been developed in this work. A series of characterizations including TEM , XRD , FTIR and XPS demonstrated that the CDs have been successfully combined with the surface of AF 2 : Ln 3+ nanocrystals. The combination of CDs has little influence on the microstructure and phase structure of AF 2 : Ln 3+ , and CDs@AF 2 : Ln 3+ nanocrystals have uniform and regular shape with cubic phase. CDs are used as a broadband sensitizer and lead to the broadband excitation of Ln 3+ , resulting in the enhancement around 10-fold of Ln 3+ luminescence emission in AF 2 : Ln 3+ nanocrystals after CDs combination. The corresponding PLQY increases almost three times, and the luminescence enhancement mechanism by combining CDs is proposed. In addition, the CDs@AF 2 : Ln 3+ nanocrystals are used to prepare CDs@AF 2 : Ln 3+ /PVA films, which exhibits excellent luminescence properties under the excitation of UV light . This work provides a superior method for enhancing the luminescence properties of lanthanide ions-doped nanocomposites and demonstrates practical potential as promising candidates for light-converting thin films .

The effects of Sr concentration on physicochemical properties, bioactivity and biocompatibility of sub-micron bioactive glasses spheres

Qing Hu,Weihui Jiang,Xiaofeng Chen,Yuli Li,Qiming Liang

We synthetized a series of strontium-substituted submicron bioactive glasses spheres (Sr-SBG, SiO 2 -P 2 O 5 -CaO-SrO) in which strontium was substituted for calcium on a mole percentage basis, then investigated the effect of strontium-substituted amount on morphologies, physicochemical properties, apatite-forming bioactivity of SBG and evaluated the proliferation, differentiation and mineralization of Sr-SBG with different strontium substitution amounts by co-cultured with human dental pulp cells (HDPCs). Results showed that Sr-SBG with different strontium substitution amounts were successfully fabricated and substituting different strontium amounts did not affect the morphology and particle size of SBG. All the Sr-SBG possessed good apatite-forming ability, but substituting a certain amount of strontium for calcium would weaken the apatite-forming ability of SBG. Additionally, all the Sr-SBG extractions promoted proliferation, early odontogenic differentiation and mineralization of HDPCs, however, the cell proliferation, differentiation and mineralization abilities would be reduced when the substituted amount of strontium was excess (15   mol%). This study suggests that Sr-SBG with moderate strontium substitution amounts can be used as   a more promising biomaterial for dental repair.