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1.
Chia Ching Kee Bee Chin Ang Hendrik Simon Cornelis Metselaar 《Ceramics International》2021,47(4):4803-4812
In this paper, calcium silicate hydrate doped with various amounts of Eu (Eu–CSH) via hydrothermal and coprecipitation methods have been systematically investigated. The hydrothermal method produced xonotlite while coprecipitation gave 11 Å tobermorite. Regardless of the synthesis method, incorporation of Eu inhibited the crystallite growth and particle size of the as-synthesized powders, while increasing their thermal stability. In both phases, Eu3+ was found to occupy the cation sites in preference to Ca2+. Comparing both synthesis methods, the hydrothermally synthesized powders were of higher crystallinity and thermal stability than the powders prepared by coprecipitation. Moreover, Eu–CSH powder by hydrothermal exhibited stronger photoluminescence intensity than the one by coprecipitation, primarily attributed to its higher degree of crystallinity. Thus, they showed higher potential for nanomedicine application where a combination of biocompatibility and light emission is desired. 相似文献
2.
Huan He Junfeng Li Lei Liu Shanshan Bao Xianfei Chen Peicong Zhang Wentao Zhang Xuefei Lai 《Ceramics International》2018,44(5):5070-5075
A series of Eu3+-doped C12H18Ca3O18 phosphors were synthesized through a facile hydrothermal method and the properties of as-prepared phosphors were explored by X-ray diffractometer (XRD), scanning electron microscope (SEM), and photoluminescence (PL) spectrometer. The exploration results indicated that the C12H18Ca3O18:Eu3+ had been successfully synthesized. The morphology of C12H18Ca3O18:Eu3+ was a strip with the size of 100–4000 nm × 50–400 nm × 50–200 nm and the ratio of length to width of 2–80. The strongest emission peak of C12H18Ca3O18:Eu3+ around 620 nm was ascribed to 5Do→7F2 transition of Eu3+, and the peaks centered at 590, 653 and 694 nm respectively corresponded to 5Do →7F1, 7F3, and 7F4 transitions. C12H18Ca3O18: Eu3+ gave the red light emission, as indicated by color coordinate analysis. The photoluminescence intensity of the phosphors prepared under the Eu3+ concentration of 6% was the highest. The crystal structure of C12H18Ca3O18:Eu3+ was changed after europium ions occupied the lattice position of calcium ions. Europium ion could displace calcium arbitrarily. As a new kind of matrix, calcium citrate possesses the properties of both organic and inorganic compounds and the luminescent C12H18Ca3O18: x Eu3+ particles may be applied in biological fluorescent tags and luminescent materials. 相似文献
3.
《Ceramics International》2020,46(12):19807-19814
Nanosized ZrO2 particles are applied in high-performance thermal barrier coatings and catalyst carriers. To synthesize nanosized zirconia, precipitation from aqueous solutions followed by hydrothermal treatment is widely conducted. In this work, a modified hydrothermal treatment route is described for high-yield fabrication of well-dispersible nanosized t–ZrO2. Zirconium oxychloride and sodium hydroxide were used as the precursor and precipitant, respectively. N, N-bis(2-hydroxyethyl) glycine (bicine) was used as surface stabilizer to inhibit the early agglomeration of nuclei, and ultrasonication was used to enhance the dispersion of ZrO2 nanocrystals. The hydrothermal treatment was optimized for reaction temperature, time, fill fraction, and solid content. The synthesized zirconia was characterized using X-ray diffraction, dynamic light scattering, field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). The yield of zirconia increased to 134 g/L after hydrothermal. Tetragonal ZrO2 obtained with hydrothermal treatment at 200 °C for 8 h at a fill fraction of 80% has a good dispersibility, with an average particle size of 20 nm and a narrow size distribution. 相似文献
4.
Eu3+-doped NaBaPO4 was prepared by a high-temperature solid-state reaction. The phase formation was confirmed by X-ray powder diffraction measurements. The laser site-selective excitation and emission spectra have been investigated in the 5D0 → 7F0 region by using a pulsed, tunable and narrowband dye laser. The excitation spectra corresponding to the 7F0 → 5D0 transition consist of two transitions at 579.6 nm Eu(I) and 578.9 nm Eu(II), indicating the Eu3+ ions occupy two crystallographic sites of Ba2+ ions. The decay lifetimes of the two Eu3+ sites were measured. Two crystallographic sites for Eu3+ ions doped in NaBaPO4 lattice were assigned from the luminescence characteristic and structure features. Meanwhile, the charge compensation mechanism of Eu3+ doping in NaBaPO4 was discussed. 相似文献
5.
Zhi Zhou Bianbian Wang Yuan Zhong Wei Zhang Ye Zhang Peixing Gao Nan Zhou 《Ceramics International》2018,44(16):19779-19786
Artificial light source for indoor cultivation has been vastly impeded by the lack of high far red emitting phosphors. Recently, Mn4+ activated phosphors were reported to be promising luminescent materials to solve above matter. In this study, controllable design of Ca14Al10Zn6O35:0.15Mn4+ (CAZO:0.15Mn4+) far red emitting phosphors was realized via pH assisted hydrothermal approach. The pure CAZO:0.15Mn4+ phosphors were obtained merely when the reaction pH was 1 or 2. Meanwhile, by adjusting the pH value of the reaction solution, far red emission CAZO:0.15Mn4+ phosphors with grains, sphere-like as well as aggregated bulk particles can be achieved at pH =?4, pH =?6 and pH =?10, respectively. Furthermore, the structures and morphologies depended photoluminescence (PL) performances of CAZO:0.15Mn4+ were checked. The best PL performance was found for the phosphor produced at pH =?6, while over acidic or alkaline conditions would lower the emission intensity. In addition, this phosphor also exhibit good thermal resistance which can maintain 78% initial intensity at 150?°C. The practical indoor tobacco cultivation demonstrated that CAZO:0.15Mn4+ obtained through this pH adjusted hydrothermal route is a promising phosphor for indoor plant growth lighting. 相似文献
6.
Nickel phosphide was synthesized via a hydrothermal reaction between nickel chloride (NiCl2·6H2O) and red phosphor (P) in water at 200 °C. Phase constitution, morphology and composition were determined by XRD, SEM and EDS, respectively. The effect on the final products of experimental conditions such as the molar ratio of red phosphor to nickel chloride and reaction time were discussed, as well as the formation mechanism of nickel phosphides. 相似文献
7.
Xuesong Zhu Chunxiang Cao Shubing Su Ailin Xia Huiyan Zhang Hailing Li Zhiyuan Liu Chuangui Jin 《Ceramics International》2021,47(11):15173-15179
The spinel ZnFe2O4 specimens were obtained via a hydrothermal and a ceramic method, respectively, and their structural and magnetic properties were comparatively studied. It was found that all the specimens exhibited a single-phase and mixed spinel structure. The magnetism of specimens synthesized via the hydrothermal method is obviously better than that of specimen prepared via the ceramic method. This can be ascribed to the different occupancy of Fe ions resulted from the loss of Zn during the hydrothermal process. 相似文献
8.
《Ceramics International》2022,48(2):2082-2091
Sm3+ doped LaBMoO6 phosphors were prepared by using the solid-state reaction method. The microstructure, morphology, chemical element composition, absorption, luminescent performance, decay life and thermal stability of Sm3+ doped LaBMoO6 samples were studied. Sm3+ doped LaBMoO6 phosphors mainly emit orange light at 596 nm with a decay lifetime of milliseconds under the excitation of 405 nm. The chromaticity coordinates of Sm3+ doped LaBMoO6 samples are located in the orange region, which also have great thermal stability. The Sm3+ doped LaBMoO6 phosphors can be used as orange-emitting materials in W-LED devices. 相似文献
9.
10.
W.N. Budhysutanto H.J.M. Kramer D. van Agterveld A.G. Talma P.J. Jansens 《Chemical Engineering Research and Design》2010
Hydrotalcite-like compounds are layered materials with anionic exchange and adsorption properties. Alternatively, this material is synthesized by hydrothermal treatment of magnesium oxide (MgO) and aluminium trihydroxide (ATH). Since this synthesis deals with solid raw materials, and the reaction proceeds through a solution mediated dissolution–precipitation process, it is a challenge to enhance the reactivity of the raw materials. This research aims to investigate the effect of four different pre-treatments: blending, ultrasound treatment, and wet grinding on the conversion rate. In experiments at 80 °C, only 3R1 polytype HTlc was formed, while a mixture of 3R1 and 3R2 polytypes was found in the experiments at 170 °C. All the pre-treatment techniques cause a decrease in particle size of the raw materials whereby wet grinding induced the strongest effect. Experimentally the fastest conversions at both synthesis temperatures were achieved by wet grinding. A reaction mechanism is proposed which explains the observed conversions as a function of the particles size of the reactants, the exposure time of the MgO to water and the reaction temperature. Two important parameters to be taken into account in the synthesis are thus exposure to water prior to the reaction and the particle size of the raw materials. 相似文献
11.
Jing-Jing Dong Chun-Yang Zhen Hui-Ying Hao Jie Xing Zi-Li Zhang Zhi-Yuan Zheng Xing-Wang Zhang 《Nanoscale research letters》2013,8(1):378
In this paper, controllable synthesis of various ZnO nanostructures was achieved via a simple and cost-effective hydrothermal process on the Si substrate. The morphology evolution of the ZnO nanostructures was well monitored by tuning hydrothermal growth parameters, such as the seed layer, solution concentration, reaction temperature, and surfactant. X-ray diffraction and photoluminescence measurements reveal that crystal quality and optical properties crucially depend on the morphology of the ZnO nanostructures. The ease of synthesis and convenience to tune morphology and optical properties bring this approach great potential for nanoscale applications. 相似文献
12.
Gloria M. Hernández Ortiz Rodrigo Parra María A. Fanovich 《Ceramics International》2018,44(4):3658-3663
Comparative synthesis ways for preparing HA (Ca10(PO4)6(OH)2) nanoparticles in presence of hexamethylenetetramine (HMTA) and cetyltrimethylammonium bromide (CTAB) were carried out. The reactions were performed in a Teflon-lined stainless-steel reactor at 120 °C during 12 h. The effects of the additive concentration and the cooling mode (fast and slow) were analyzed. The obtained powders were characterized by X-ray Diffraction (XRD), Raman Spectroscopy, Dynamic Light Scattering (DLS) and Scanning Electron Microscopy (SEM). The two hydrothermal ways carried out for preparing HA nano powders produced a pure crystalline phase of HA. When the fast cooling mode was used, the obtained particles exhibited smaller mean particle sizes. The highest concentrations of used additives (HTMA or CTAB) resulted in opposite effect on the obtained mean particle size of HA particles. These observations were associated to the different behavior of these additives in the HA formation processes. 相似文献
13.
Yingchun Shan Guanbing Hou Xiannian Sun Xiaoguang Han Changqing Hong Jiujun Xu Jiangtao Li 《Ceramics International》2021,47(13):18012-18019
Glucose and ball-milled α-Al2O3 mixed powder was hydrothermal treated to synthesize Al2O3/C mixture, which was directly heated to 1700–1750 °C for 10 min holding in N2. Fine and single phase AlON powders were successfully fast prepared by one-step carbothermal reduction and nitridation (CRN). With aggregation of as-purchased α-Al2O3 being effectively disconnected by ball milling, α-Al2O3 particles were perfectly coated with carbon by hydrothermal treatment, which inhibited coalescence of Al2O3 during heating and enabled fast formation of AlON to further shorten holding duration. As a result, one-step fast fabricated pure AlON powder has fine primary particles with weak interconnections. At 170 rpm, powders were ball-milled to D50 ≤ 1.00 μm for 4 h, and D50 = 0.33 μm for 24 h. Moreover, primary particle size is controllable by adjusting holding time, synthesis temperature and heating speed. One-step CRN method provides a practical way to prepare pure AlON powder with the required primary particles. 相似文献
14.
Mn-kaolinite was hydrothermally synthesized, for the first time, using silicic acid, Mn-carbonate and aluminum nitrate mixed with aqueous solutions of KOH at 100–200 °C for 24–96 h. Without the addition of Mn-carbonate to silicic acid and aluminum nitrate mixture, no crystalline material could be synthesized by hydrothermal treatment up to 200 °C for 6 days. However, by the addition of Mn-carbonate to the above precursors, Mn-kaolinite was synthesized at both 100 and 200 °C for 1 or 2 days, indicating that Mn played an important role in the formation of kaolinite. At a reaction temperature of 100 °C, the Mn-kaolinite peaks became sharper with increasing reaction duration, as expected. 相似文献
15.
I. Martínez-Merlín A.I. Ramos-Guerra U. Balderas R.G. Casañas-Pimentel C. Falcony 《Ceramics International》2019,45(9):11362-11367
Hafnium oxide nanoparticles doped with trivalent samarium (HfO2:Sm3+) were synthesized by hydrothermal route from chloride reagents. Different samarium doping concentrations (0, 0.5, 1, 3, 5 and 10?at% with respect to Hf) and different post-annealing temperatures (200, 400, 600, 800 and 1000?°C) were evaluated. The resulting nanoparticles showed an oval morphology with average sizes below 30?nm. A sensitive relationship between the samarium concentration and the resulting crystal structure of the material was observed by X-Ray diffraction and further evidenced by the cathodoluminescence and photoluminescence spectra. Low concentrations of samarium (0, 0.5 and 1?at%) generated a monoclinic phase, whereas higher concentrations of samarium (5 and 10?at%) generated a metastable cubic phase. The average crystallite sizes calculated by the Scherrer's equation were close to 8?nm and 12?nm for cubic and monoclinic phases, respectively. The luminescent emission corresponded to the characteristic 4f-4f transitions of the samarium ion with a principal peak centered at 610?nm. The best luminescent properties were obtained with the sample doped with samarium at 0.5?at%, annealed at 600?°C. 相似文献
16.
ZnO nanopowders were synthesized by hydrothermal and solvothermal method by using CTAB as surfactant, and the effects of CTAB on the morphologies of ZnO nanopowders were investigated. The results showed that the presence of CTAB could greatly vary the shape of the ZnO crystals. ZnO nanorods were prepared from the hydrothermal system without CTAB and flowers-like ZnO nanostructures were produced from hydrothermal system with 0.4 M and 0.5 M CTAB. Low concentration of CTAB in ethanol was conducive to the formation of ZnO nanorods, but the concentration continued to increase, the morphology of sample transformed into hexagonal bipyramid, and then transformed into spherical. The synthesis mechanism of ZnO powders with different morphologies has been presented. 相似文献
17.
《Ceramics International》2017,43(15):11907-11919
Densification of calcium hydroxyapatite fine powders doped with different concentrations of Mg (2, 4 and 6 mol% Mg, MgHA) was successfully achieved for the first time in a nearly fully dense state using the hydrothermal hot pressing (HHP) technique at low temperatures. Consolidation of MgHA powders was studied under different temperatures (150–240 °C), reaction times (1–6 h), and powder particle size (20 nm–1.5 µm). X-Ray diffraction analyses indicated that the particle densification under HHP conditions proceeded without any variation in the crystalline structure and regardless of the Mg content. The results from this work showed that an increase in temperature accelerates the reaction between MgHA particles and water (solvent) mixed during the hydrothermal treatment. Particle packing associated with bulk densification was achieved through a massive dissolution-recrystallisation mechanism, which induced the formation of small particles that rapidly crystallised on the surface of the partially dissolved original MgHA particles. The optimum conditions to obtain pellets with a high apparent density of 3.0758 ± 0.001 g/cm3 and tensile strength value of 12.6 ± 0.6 MPa were 10 wt% of water at a temperature of 240 °C with a 6 h reaction time and 6 mol% of Mg (MgHA3). The use of the HHP technique coupled with the fine particle size and reactivity of the MgHA precursor powders with water allowed us to produce disks that were compacted to a nearly full dense state with a low content of open porosity of 2.0%. 相似文献
18.
Electrolyte powders with low sintering temperature and high-ionic conductivity can considerably facilitate the fabrication and performance of solid oxide fuel cells (SOFCs). Gadolinia-doped ceria (GDC) is a promising electrolyte for developing intermediate- and low-temperature (IT and LT) SOFCs. However, the conventional sintering temperature for GDC is usually above 1200 °C unless additives are used. In this work, a nanocrystalline powder of GDC, (10 mol% Gd dopant, Gd0.1Ce0.9O1.95) with low-sintering temperature has been synthesized using ammonium benzoate as a novel, environmentally friendly and cost-effective precursor/precipitant. The synthesized benzoate powders (termed washed- and non-washed samples) were calcined at a relatively low temperature of 500 °C for 6 h. Physicochemical characteristics were determined using thermal analysis (TG/DTA), Raman spectroscopy, FT-IR, SEM/EDX, XRD, nitrogen absorptiometry, and dilatometry. Dilatometry showed that the newly synthesized GDC samples (washed and non-washed routes) start to shrink at temperatures of 500 and 600 °C (respectively), reaching their maximum sintering rate at 650 and 750 °C. Sintering of pelletized electrolyte substrates at the sintering onset temperature for commercial GDC powder (950 °C) for 6 h, showed densification of washed- and non-washed samples, obtaining 97.48 and 98.43% respectively, relative to theoretical density. The electrochemical impedance spectroscopy (EIS) analysis for the electrolyte pellets sintered at 950 °C showed a total electrical conductivity of 3.83 × 10?2 and 5.90 × 10?2 S cm?1 (under air atmosphere at 750 °C) for washed- and non-washed samples, respectively. This is the first report of a GDC synthesis, where a considerable improvement in sinterability and electrical conductivity of the product GDC is observed at 950 °C without additives addition. 相似文献
19.
Seok Han KimSridhar Komarneni 《Ceramics International》2011,37(3):1101-1107
Lead zirconate titanate (PZT) fine particles (80 nm to 0.8 μm) were prepared by hydrothermal method using a Ti3+ precursor, TiCl3. In contrast with conventional hydrothermal methods using Ti4+-reagents, pure PZT particles without lead titanate (PTO) impurities were synthesized using the Ti3+-reagent at a low temperature of 110 °C which is lower than the previously reported temperatures of 160 and 130 °C, using Ti4+-reagents of TiO2 and TiCl4, respectively. Additionally, the crystallization time using the Ti3+-reagent is shorter than those using Ti4+-reagents at the same temperature of 140 °C. The high reaction rate of the Ti3+-reagent containing gels prepared here is probably due to the presence of much more defects in their PTO intermediates. The present hydrothermal method using Ti3+ precursor could lead to energy savings because of low temperature synthesis and the present method is potentially useful for non-pressurized equipment in manufacturing plants for synthesizing PZT particles. 相似文献
20.
Chang Ik Lee 《Polymer》2006,47(15):5253-5258
We synthesized Eu-containing nanoparticles using the ultra-dilute solution method and characterized by FT-IR, NMR, GPC, DSC, and UV-visible absorption/photoluminescence spectra. The size of Eu-containing nanoparticles was 30-150 nm and the nanoparticles were soluble in common organic solvents. A study of the dependence of emission intensities of the Eu-containing nanoparticles on the Eu content showed that the emission intensities increased nearly linearly with increasing Eu content. In addition, no significant emission concentration quenching phenomenon was observed at the Eu content of 0-9.5 mol%. 相似文献