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1.
In order to improve the thermal oxidation resistance of carbon fiber-reinforced porous silicon oxycarbide (SiCO) ceramic composites, an Al2O3-containing TaSi2–MoSi2–borosilicate glass coating was formed on the surface of the composites via brushing and sintering. The anti-oxidation property of the coated composites at 1873 K was investigated. Microstructures and chemical compositions of the sample before and after anti-oxidation test were determined using XRD, SEM and EDS. After heating in air at 1873 K for 20 min, the Al2O3-containing TaSi2–MoSi2–borosilicate glass coating effectively protects the SiCO ceramic composites and the coated sample kept its appearance well without obvious defects on the surface. The cross-sectional SEM images show that the coating is covered by a film of oxidation products with a thickness of about 40 μm, which is dense and crack free. Inside the A-TMG coating, irregular-shaped silicides are surrounded by continuous borosilicate glass and no penetrating holes or visible cracks are found. Al2O3 increases the viscosity of the borosilicate glass, which improves oxidation resistance of the coated sample by enhancing gas-penetration resistance of the glass. In contrast, the sample without Al2O3 in the coating slurry is severely oxidized and exhibits lots of open pores on the surface after oxidation test.Al2O3 improves the oxidation resistance of TaSi2–MoSi2–borosilicate glass coating through increasing the viscosity and inhibiting gas penetration into matrix at high temperature, thus prevents porous SiCO ceramic composites from being oxidized. 相似文献
2.
Ni–Co–Al2O3 composite coatings were prepared by pulsed electrodeposition and electrophoresis–electrodeposition on aluminum alloy. The content of Al2O3 particles of the Ni–Co–Al2O3 composite coating prepared by electrophoresis–electrodeposition was significantly higher than the composite coating prepared by pulsed electrodeposition. The composite coating prepared by electrophoresis–electrodeposition exhibited a better anti-wear performance than that prepared by pulsed electrodeposition. The morphology, composition and microstructure of the composite coatings were determined by means of X-ray diffractometer (XRD) and scanning electron microscopy (SEM). The hardness and friction properties of the samples were tested on the microhardness tester and the friction and wear loss tester respectively.Ni–Co–Al2O3 composite coatings were prepared by pulsed electrodeposition and electrophoresis–electrodeposition on aluminum alloy. 相似文献
3.
Reactive adsorption desulfurization (RADS) of Fluidized Catalytically Cracked (FCC) gasoline on reduced and unreduced NiO/ZnO–Al2O3–SiO2 adsorbents was studied. Various characterizations such as powder X-ray diffraction (XRD), H2-temperature-programmed reduction (H2-TPR), the H2/O2 pulse titration (HOPT), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) are used to evaluate the effects of hydrogen pretreatment of the adsorbents. XRD and HOPT results indicate that NiO is hard to be reduced to Ni0 under the conditions of RADS. H2-TPR shows that NiO might be reduced to Ni0 at the temperature of 598 °C, much higher than the temperature of RADS. The Ni 2p3/2 spectrum of Ni0 is not observed for the reduced adsorbent, but the main peak of Ni 2p3/2 of NiS is found for the spent adsorbent. The unreduced NiO/ZnO–Al2O3–SiO2 adsorbent performs a better desulfurization than the reduced adsorbent at the beginning of desulfurization process. NiO and Ni0 are assumed as the main active components and present a good desulfurization ability in RADS. Finally, a change in the RADS mechanism is presented and discussed.A possible reaction mechanism of desulfurization on NiO/ZnO–Al2O3–SiO2 is discussed. 相似文献
4.
In this study, a CaO–SiO2–Al2O3–MgO–FeO–CaF2(–Cr2O3) slag was chosen according to the compositions of the stainless steel slag for industrial production, and a CaO block was added to the molten slag after the synthetic slag was fully melted. The influences of unmelted lime on the distribution of elements and the structure of product layers at the lime/slag boundary, particularly the existing state of chromium oxide in the chromium-bearing stainless steel slag, were deeply discussed by scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) and FactSage 7.1. The experiment results indicated that when the unmelted lime existed in the CaO–SiO2–Al2O3–MgO–FeO–CaF2 slag system, two product layers of periclase (MgO) and dicalcium silicate (Ca2SiO4) at the boundary of the CaO block were formed. However, when the CaO block was added in the CaO–SiO2–Al2O3–MgO–FeO–CaF2–Cr2O3 stainless steel slag, besides MgO and Ca2SiO4 product layers, needle-shaped calcium chromite (CaCr2O4) was also precipitated around the CaO block. Moreover, a small amount of Cr dissolved in the periclase phase. Eh–pH diagrams showed that the CaCr2O4 and MgO phase unstably existed in a weak acid aqueous solution. Therefore, the existence of unmelted lime in the stainless steel slag could enhance the leachability of chromium.The effect of unmelted lime on the distribution of elements and structure of product layers in CaO–SiO2–MgO–Al2O3–FeO–CaF2(–Cr2O2) stainless steel slag and the action of unmelted lime phase mechanism in experimental slags was conducted. 相似文献
5.
Yaxian Zhao Jincheng Du Xin Cao Chong Zhang Gang Xu Xvsheng Qiao Yong Liu Shou Peng Gaorong Han 《RSC advances》2021,11(12):7025
We investigated the short- and medium-range structural features of sodium aluminosilicate glasses with various P2O5 (0–7 mol%) content and Al/Na ratios ranging from 0.667 to 2.000 by using molecular dynamics simulations. The local environment evolution of network former cations (Si, Al, P) and the extent of clustering behavior of modifiers (Na+) is determined through pair distribution function (PDF), total correlation function (TDF), coordination number (CN), Qxn distribution and oxygen speciation analysis. We show that Al–O–P and Si–O–Al linkage is preferred over other connections as compared to a random model and that Si–O–Si linkage is promoted by the P2O5 addition, which is related to structural heterogeneity and generates well-separated silicon-rich and aluminum–phosphorus-rich regions. Meanwhile, due to the relatively high propensity of Al to both Si and P, heterogeneity can be partly overcome with high Al content. A small amount of Si–O–P linkages have been detected at the interface of separated regions. Clustering of Na+ is also observed and intensified with the addition of P2O5. Based on the simulated structural information, a modified random network model for P2O5-bearing sodium aluminosilicate glass has been proposed, which could be useful to optimize the mobility of sodium ions and design novel functional glass compositions.(A) A modified structural model proposed for P2O5-bearing sodium aluminosilicate glasses. (B) Degree of preferred connection (DPC) of different T–O–T network linkage for LAP, MAP and HAP glass compositions with various P2O5 content. 相似文献
6.
Yangshan Sun Delong Cai Zhihua Yang Hailiang Li Quan Li Dechang Jia Yu Zhou 《RSC advances》2018,8(31):17569
A dense MgO–Al2O3–SiO2 based glass-ceramic coating was prepared by a doctor blade process on a porous BN/Si2N2O ceramic surface followed by heat treatment at 1050 °C under nitrogen flow. The phase composition, microstructure, mechanical properties and water absorption of the coating were studied. The coating consisted of α-cordierite phase with a small amount of glass phase. The dense coating without pores and cracks was favorable to seal and densify the porous ceramic surface due to part of the molten glass infiltrating the surface pores. The coating was defect-free and tightly bonded to the substrate because of a larger bonding area between the coating and the substrate. The elastic modulus and bending strength of the glass-ceramic coating were 37.9 GPa and 67.1 MPa, respectively. Moreover, the coated samples had a high Vickers hardness and low water absorption.A dense MgO–Al2O3–SiO2 based glass-ceramic coating was prepared by a doctor blade process on a porous BN/Si2N2O ceramic surface followed by heat treatment at 1050 °C under nitrogen flow. 相似文献
7.
Bionic design is efficient to develop high-performance lightweight refractories with sophisticated structures such as hollow ceramic fibers. Here, we report a four-stage procedure for the preparation of Al2O3–ZrO2(Y2O3) hollow fibers using the template of cogon—a natural grass. Subsequently, to optimize the thermal performance of the fibers, four sets of preparation parameters, namely, x(Al2O3), solute mass ratio of the mixture, dry temperature, and sintering temperature were investigated. Through an orthogonal design, the optimal condition of each parameter was obtained as follows: x(Al2O3) was 0.70, solute mass ratio of the mixture was 15 wt%, dry temperature was 80 °C, and sintering temperature was 1100 °C. Overall, Al2O3–ZrO2(Y2O3) hollow fibers show relatively low thermal conductivity (0.1038 W m−1 K−1 at 1000 °C), high porosity (95.0%), and low density (0.05–0.10 g cm−3). The multiphase compositions and morphology of Al2O3–ZrO2(Y2O3) hollow fibers, which may contribute to their thermal properties, were also discussed.Lightweight Al2O3–ZrO2(Y2O3) hollow fibers with low thermal conductivity were prepared by a natural template—cogon grass. 相似文献
8.
Yubing Hu Yajing Zhang Jie Du Chunyan Li Kangjun Wang Lidong Liu Xinrui Yu Kai Wang Nan Liu 《RSC advances》2018,8(53):30387
A series of CuO–ZnO–Al2O3/HZSM-5 hybrid catalysts with different Cu/Zn ratios and disparate Al2O3 doping were prepared and characterized by XRD, BET, H2-TPR, NH3-TPD and XPS techniques. The optimal Cu/Zn ratio is 7 : 3, and the introduction of a suitable amount of Al2O3 to form hybrid catalysts increased the BET specific area and micropore volume, facilitated the CuO dispersion, decreased the CuO crystallite size, increased the interaction between CuO and ZnO, enhanced the number of weak acid sites, altered the copper chemical state and improved the catalytic performance consequently. The highest CO2 conversion, DME selectivity and DME yield of 27.3%, 67.1% and 18.3%, respectively, were observed over the CZA7H catalyst. The suitable temperature of 260 °C and the appropriate space velocity of 1500 h−1 for one-step synthesis of dimethyl ether (DME) from carbon dioxide (CO2) hydrogenation were also investigated. The 50 h stability of the CZA7H catalyst was also tested.The introduction of Al2O3 increased the number of weak acid sites, altered the copper chemical state and improved the catalytic performance and stability consequently. 相似文献
9.
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
10.
Alberto Alvarez-Fernandez Frdric Nallet Philippe Fontaine Cian Cummins Georges Hadziioannou Philippe Barois Guillaume Fleury Virginie Ponsinet 《RSC advances》2020,10(67):41088
In the field of functional nanomaterials, core–satellite nanoclusters have recently elicited great interest due to their unique optoelectronic properties. However, core–satellite synthetic routes to date are hampered by delicate and multistep reaction conditions and no practical method has been reported for the ordering of these structures onto a surface monolayer. Herein we show a reproducible and simplified thin film process to fabricate bimetallic raspberry nanoclusters using block copolymer (BCP) lithography. The fabricated inorganic raspberry nanoclusters consisted of a ∼36 nm alumina core decorated with ∼15 nm Au satellites after infusing multilayer BCP nanopatterns. A series of cylindrical BCPs with different molecular weights allowed us to dial in specific nanodot periodicities (from 30 to 80 nm). Highly ordered BCP nanopatterns were then selectively infiltrated with alumina and Au species to develop multi-level bimetallic raspberry features. Microscopy and X-ray reflectivity analysis were used at each fabrication step to gain further mechanistic insights and understand the infiltration process. Furthermore, grazing-incidence small-angle X-ray scattering studies of infiltrated films confirmed the excellent order and vertical orientation over wafer scale areas of Al2O3/Au raspberry nanoclusters. We believe our work demonstrates a robust strategy towards designing hybrid nanoclusters since BCP blocks can be infiltrated with various low cost salt-based precursors. The highly controlled nanocluster strategy disclosed here could have wide ranging uses, in particular for metasurface and optical based sensor applications.Large area Al2O3–Au raspberry-like nanoclusters and other complex structures have been created by iterative block-copolymer self-assembly, paving the way to a new generation of on-demand metallic architectures. 相似文献
11.
Titanium dioxide, as a promising photocatalytic material, has attracted extensive attention in the field of photocatalytic degradation of organic pollutants in sewage. However, the photocatalytic performance needs to be further improved. In this work, fluorinated ZnO–TiO2 composites (F-ZTO) were prepared by a simple coprecipitation method. The photocatalytic performance of the samples was studied in detail with methyl orange as the target degradation product. The results indicated that under the same conditions, the degradation rates of 6% F-ZTO, F-TiO2 and TiO2 for methyl orange reached 93.75%, 76.56% and 62.89% respectively. This showed that the method used in this work could effectively improve the photocatalytic degradation performance of titanium dioxide. 6% F-ZTO showed an excellent photocatalytic activity, which was attributed to the small grain size, the large specific surface area and the effective inhibition of photoelectron–hole recombination due to fluorination and zinc oxide coupling. In three consecutive cycles, the photocatalytic activity was almost maintained, indicating that 6% F-ZTO had a good recycling performance.Fluorinated ZnO-TiO2 composites (F-ZTO) were prepared by a simple coprecipitation method, the method used could effectively improve the photocatalytic property of titanium dioxide, and 6% F-ZTO showed an excellent activity and recycling performance. 相似文献
12.
A series of MOx–Cr2O3–La2O3/TiO2–N (M = Cu, Fe, Ce) catalysts with nitrogen doping were prepared via the impregnation method. Comparing the low-temperature NH3-SCR activity of the catalysts, CeCrLa/Ti–N (xCeO2–yCr2O3–zLa2O3/TiO2–N) exhibited the best catalytic performance (NO conversion approaching 100% at 220–460 °C). The physico-chemical properties of the catalysts were characterized by XRD, BET, SEM, XPS, H2-TPR, NH3-TPD and in situ DRIFTS. From the XRD and SEM results, N doping affects the crystalline growth of anatase TiO2 and MOx (M = Cu, Fe, Ce, Cr, La) which were well dispersed over the support. Moreover, the doping of N promotes the increase of the Cr6+/Cr ratio and Ce3+/Ce ratio, and the surface chemical adsorption oxygen content, which suggested the improvement of the redox properties of the catalyst. And the surface acid content of the catalyst increased with the doping of N, which is related to CeCrLa/TiO2–N having the best catalytic activity at high temperature. Therefore, the CeCrLa/TiO2–N catalyst exhibited the best NH3-SCR performance and the redox performance of the catalysts is the main factor affecting their activity. Furthermore, in situ DRIFTS analysis indicates that Lewis-acid sites are the main adsorption sites for ammonia onto CeCrLa/TiO2–N and the catalyst mainly follows the L–H mechanism.A series of MOx–Cr2O3–La2O3/TiO2–N (M = Cu, Fe, Ce) catalysts with nitrogen doping were prepared via the impregnation method. 相似文献
13.
Ehsan Delfani Alireza Khodabakhshi Sajjad Habibzadeh Leila Naji Mohammad Reza Ganjali 《RSC advances》2021,12(2):907
Capacitive deionization (CDI), as an emerging eco-friendly electrochemical brackish water deionization technology, has widely benefited from carbon/metal oxide composite electrodes. However, this technique still requires further development of the electrode materials to tackle the ion removal capacity/rate issues. In the present work, we introduce a novel active carbon (AC)/Co3O4–Sb2O3–SnO2 active material for hybrid electrode capacitive deionization (HECDI) systems. The structure and morphology of the developed electrodes were determined using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and Brunauer–Emmett–Teller (BET)/Barrett–Joyner–Halenda (BJH) techniques, as well as Fourier-transform infrared (FT-IR) spectroscopy. The electrochemical properties were also investigated by cyclic voltammetry (CV) and impedance spectroscopy (EIS). The CDI active materials AC/Co3O4 and AC/Co3O4–Sb2O3–SnO2 showed a high specific capacity of 96 and 124 F g−1 at the scan rate of 10 mV s−1, respectively. In addition, the newly-developed electrode AC/Co3O4–Sb2O3–SnO2 showed high capacity retention of 97.2% after 2000 cycles at 100 mV s−1. Moreover, the electrode displayed excellent CDI performance with an ion removal capacity of 52 mg g−1 at the applied voltage of 1.6 V and in a solution of potable water with initial electrical conductivity of 950 μs cm−1. The electrode displayed a high ion removal rate of 7.1 mg g−1 min−1 with an excellent desalination–regeneration capability while retaining about 99.5% of its ion removal capacity even after 100 CDI cycles.Capacitive deionization (CDI), as an emerging eco-friendly electrochemical brackish water deionization technology, has widely benefited from carbon/metal oxide composite electrodes. 相似文献
14.
Ruifeng Wang Lungang Chen Xinghua Zhang Qi Zhang Yuping Li Chenguang Wang Longlong Ma 《RSC advances》2018,8(71):40989
Novel catalytic material with high catalytic activity and hydrothermal stability plays a key role in the efficient conversion of levulinic acid (LA) to γ-valerolactone (GVL) in water. In this study, mixed oxides Al2O3–TiO2, Al2O3–MoO3 and Al2O3–Co3O4 were synthesized by co-precipitation using aqueous solution of NaOH as precipitant. Ru catalysts supported on mixed oxides were prepared by impregnation method and their catalytic performances were tested in the hydrogenation of LA to GVL on a fixed bed reactor. The physicochemical properties of the catalysts were characterized by XRD, H2-TPR, NH3-TPD, and BET techniques. The TiO2 component significantly affected the acidity of the catalyst, and thus its catalytic activity for the GVL yield was affected. The desired product GVL with a yield of about 97% was obtained over the Ru/Al2O3–TiO2 catalyst under mild conditions (WHSV = 1.8 h−1, T = 80 °C). Moreover, the catalyst Ru/Al2O3–TiO2 exhibited excellent thermal stability in the test period of time.Novel catalytic material with high catalytic activity and hydrothermal stability plays a key role in the efficient conversion of levulinic acid (LA) to γ-valerolactone (GVL) in water. 相似文献
15.
A. Barrera F. Tzompantzi J. Campa-Molina J. E. Casillas R. Prez-Hernndez S. Ulloa-Godinez C. Velsquez J. Arenas-Alatorre 《RSC advances》2018,8(6):3108
The photocatalytic activity in the degradation of 4-chlorophenol (4-ClPh) in aqueous medium (80 ppm) using 2.0 wt% Ag/Al2O3–Gd2O3 (Ag/Al–Gd-x; where x = 2.0, 5.0, 15.0, 25.0 and 50.0 wt% of Gd2O3) photocatalysts prepared by the sol–gel method was studied under UV light irradiation. The photocatalysts were characterized by N2 physisorption, X-ray diffraction, SEM, HRTEM, UV-Vis, XPS, FTIR and fluorescence spectroscopy. About 67.0% of 4-ClPh was photoconverted after 4 h of UV light irradiation using Ag/γ-–Al2O3. When Ag/Al–Gd-x photocatalysts were tested, the 4-ClPh photoconversion was improved and more than 90.0% of 4-ClPh was photoconverted after 3 h of UV light irradiation in the materials containing 15.0 and 25.0 wt% of Gd2O3. Ag/Al–Gd-25 was the material with the highest efficacy to mineralize dissolved organic carbon, mineralizing more than 85.0% after 4 h of UV light irradiation. Silver nanoparticles and micro-particles of irregular pentagonal shape intersected by plane nanobelts of Al2O3–Gd2O3 composite oxide were detected in the Ag/Al–Gd-25 photocatalyst. This material is characterized by a lowest recombination rate of electron–hole pairs. The low recombination rate of photo-induced electron–hole pairs in the Ag/Al–Gd-x photocatalysts with high Gd2O3 contents (≥15.0 wt%) confirmes that the presence of silver nanoparticles and microparticles interacting with Al2O3–Gd2O3 composite oxide entities favors the separation of photo-induced charges (e− and h+). These materials could be appropriate to be used as highly efficient photocatalysts to eliminate high concentrations of 4-ClPh in aqueous medium.Ag/Al2O3–Gd2O3 showed high efficacy to photodegradate 4-chlorophenol, the strong interaction between silver nano-particles and micro-particles and Al2O3–Gd2O3 entities favors the decrease in the recombination rate. 相似文献
16.
The dehydrocyclization–cracking of methyl oleate was performed by ZnZSM-5–Al2O3 hierarchical composite-supported Pt catalysts in the range of 450–550 °C under 0.5 MPa hydrogen pressure. Most catalysts converted methyl oleate completely and produced aromatics with more than 10 wt% yield as well as valuable fuels even at 450 °C. The reactivity of catalysts changed remarkably depending on the addition method of Pt, while supporting Pt of 0–0.16 wt% did not affect the pore structure of each catalyst. When Pt was introduced into the composite support by the conventional impregnation method, remarkable hydrocracking proceeded through the decarboxylation and decarbonylation of methyl oleate and the successive conversion of C17 fragments and gave the significant amounts of gaseous products. Nevertheless, the selectivity for the aromatics of the gasoline fraction was relatively high and the yields of aromatics reached maximum 19% at 500 °C under 0.5 MPa, suggesting that gaseous olefins would be cyclized through the Diels–Alder reaction on ZnZSM-5 in the composite support. In contrast, when Pt was introduced into catalysts by ion-exchange with ZnZSM-5, the significant conversion of methyl oleate was inhibited and produced liquid fuels in a wide range.The ideal reaction route in the dehydrocyclization–cracking of methyl oleate catalyzed by Pt/ZnZSM-5–Al2O3 is to produce xylene, toluene, and hydrogen through decarboxylation. 相似文献
17.
Yushan Wu Jianghui Lin Guangyuan Ma Yanfei Xu Jianli Zhang Chanatip Samart Mingyue Ding 《RSC advances》2020,10(4):2067
The selectivity and activity of a nickel catalyst for the hydrogenation of carbon dioxide to form methane at low temperatures could be enhanced by mesoporous Al2O3–CeO2 synthesized through a one-pot sol–gel method. The performances of the as-prepared Ni/Al2O3–CeO2 catalysts exceeded those of their single Al2O3 counterpart giving a conversion of 78% carbon dioxide with 100% selectivity for methane during 100 h testing, without any deactivation, at the low temperature of 320 °C. The influence of CeO2 doping on the structure of the catalysts, the interactions between the mesoporous support and nickel species, and the reduction behaviors of Ni2+ ions were investigated in detail. In this work, the addition of CeO2 to the composites increased the oxygen vacancies and active metallic nickel sites, and also decreased the size of the nickel particles, thus improving the low temperature catalytic activity and selectivity significantly.The addition of CeO2 to form Ni composite catalysts increased the oxygen vacancies and active metallic nickel sites thus improving the low temperature CO2 methanation performance. 相似文献
18.
Qingbo Wang Junying Zhang Weimin Dong Lintao Liu Hang Wen Qian Yao Jing Li Jiyang Wang 《RSC advances》2019,9(13):7078
TeO–B2O3–BaO glasses with different compositions were prepared by the conventional melt-quenching technique. The spectral properties of Tm3+/Ho3+ co-doped TeO–B2O3–BaO glasses with different doping concentrations were studied. In order to analyze the spectroscopic properties in detail, the Judd–Ofelt intensity parameters, spontaneous radiative probabilities, branching ratios, absorption and emission cross-sections, and gain coefficient spectra were calculated using Judd–Ofelt and McCumber theory based on the absorption and emission spectra. Meanwhile, the optimal doping concentration was determined as Tm2O3: 1.0 mol% and Ho2O3: 1.0 mol%. The results show that Tm3+/Ho3+ co-doped TeO–B2O3–BaO glass is an ideal mid-infrared laser gain medium.TeO2–B2O3–BaO glasses with different compositions and Tm3+/Ho3+ co-doped TeO2–B2O3–BaO glasses with different doping concentrations were prepared and studied. 相似文献
19.
Zaireen Fatima Chandkiram Gautam Ajeet Singh Sarvesh Kumar Avinashi Bal Chandra Yadav Afroj Ahmed Khan 《RSC advances》2022,12(49):31585
The present work mainly focuses on the fabrication of a porous glass 40SiO2–35H3BO3–19V2O5–6P2O5via a melt-quenching technique. The structural, morphological, and sensing behaviour of the glass sample was investigated successfully. The calculated density and molar volume of the fabricated glass are 2.4813 ± 0.124 g cm−3 and 35.7660 ± 1.708 cm3 mol−1. XRD, SEM and TEM analyses confirmed the amorphous nature of the glass. FTIR results revealed the O–H bond formations, which indicate that the presence of water molecules is probably due to the porous nature of the glass. Further, BET analysis confirmed the mesoporous nature of the glass sample with a mean pore diameter of 7 nm. The sensing response of the synthesized glass at 1000 ppm concentration of CO2 was found to be 3.05 with a response time 22.6 s and recovery time 25.8 s. Hence, this porous glass can be easily synthesized, is affordable, and was found to be useful for CO2 gas sensing applications.The present work mainly focuses on the fabrication of a porous glass 40SiO2–35H3BO3–19V2O5–6P2O5via a melt-quenching technique. 相似文献
20.
Dong Zhang 《RSC advances》2022,12(23):14562
CeO2–ZrO2-M2O3 (M = La, Y, Bi) mixed oxide has been prepared by a solvothermal synthesis method. The physico–chemical properties of the mixed oxide have been studied by X-ray powder diffraction (XRD), Raman spectroscopy, BET, X-ray photoelectron spectroscopy (XPS), TEM and temperature-programmed reduction (TPR), and the catalytic activity for soot oxidation has been studied by thermogravimetry (TG). La3+, Y3+ and Bi3+ exhibit positive effects on lowering the oxidation temperature of the soot. The XRD and Raman results showed formation of mixed oxides and TEM images suggested the nanosized nature of the particles. The benefit of yttrium or lanthana doping on the catalytic activity of ceria can be related to active oxygen formation provoked by the defective structure of ceria due to the presence of La3+ and Y3+. The benefit of Bi3+ doping on catalytic activity can be related to the reduction at low temperature both with Bi2O3 and ceria.Nano CeO2-based oxides with meso-pores have been synthesized by a solvothermal method. 相似文献