共查询到20条相似文献,搜索用时 15 毫秒
1.
TiO2–NiO and TiO2–WO3 nanocomposites were prepared by hydrothermal and surface modification methods. The samples were analyzed using X-ray diffraction, Scanning Electron Microscope images, Transmission Electron Microscope, Energy dispersive analysis, Zeta potential, Electrophoretic mobility and Photocatalysis activity measurement. XRD data sets of TiO2–NiO, TiO2–WO3 powder nanocomposite have been studied for the inclusion of NiO, WO3 on the anatase-rutile mixture phase of TiO2 by Rietveld refinement. The cell parameters, phase fraction, the average grain size, strain and bond lengths between atoms of individual phases have been reported in the present work. Shifted positional co-ordinates of individual atoms in each phase have also been observed. 相似文献
2.
Titanium and its alloys, the most commonly used materials for dental and orthopaedic implants are generally coated with bioactive materials such as sol-gel derived titania, silica and calcium phosphate in order to render these materials bioactive. In the present work a coating containing nanosized titania particles having anatase structure was developed on titanium substrate by thermal decomposition of titanium tetrachloride in isopropanol. A modified titania-silica mixed oxide coating was developed by incorporating the required amount of silica in the coating system. The presence of silica at small weight percentage caused improvement of adhesion and corrosion resistance of the coating. In vitro bioactivity tests were performed in 1.5 Kokubo's simulated body fluid after alkaline treatment of the titania/titania-silica coatings and the performance was compared with that of the titania coating developed by simple thermal oxidation. TF-XRD, FTIR and SEM-EDAX were used to investigate the microstructural morphology and crystallinity of the coatings. Elemental analysis of simulated body fluid was carried out using ICP-AES and spectrophotometry. Enhanced biogrowth was facilitated on the titania coating incorporated with low silica content. 相似文献
3.
E. N. Galashov V. V. Atuchin T. A. Gavrilova I. V. Korolkov Y. M. Mandrik A. P. Yelisseyev Zhiguo Xia 《Journal of Materials Science》2017,52(22):13033-13039
Garnet phosphor Y3Al5O12:Ce3+ is prepared in the Y2O3–Al metal–CeO2 ternary system by the solid-state reaction method in the air. For the first time, metal Al is used as a source of aluminum for the reaction instead of traditional oxide Al2O3. It is shown that the chemical reaction can be realized at lower temperatures and without use of special reducing atmosphere. The structural and spectroscopic properties of the prepared powder phosphor are very close to those earlier reported for the Y3Al5O12:Ce3+ single crystal. 相似文献
4.
Hui-Juan Wang Tilman Zscheckel Bo-Tao Li Hui-Xing Lin Christian Bocker Christian Rüssel Lan Luo 《Journal of Materials Science》2017,52(3):1330-1347
Crystallization and microstructure of glasses with the molar compositions 1MgO·1.2Al2O3·2.8SiO2·1.2TiO2·xLa2O3 (x = 0.1 and 0.4) were thermally treated at different temperatures in the range from 950 to 1250 °C and then analyzed by X-ray diffraction and scanning electron microscopy, in combination with energy-dispersive X-ray spectroscopy and electron backscatter diffraction. It was found that the microstructure is first homogeneous with the precipitation of randomly distributed crystals and then indialite domains with embedded perrierite and rutile crystals are formed. For higher temperatures or prolonged times, more domains appear and expand into the bulk of the sample. Finally, the entire sample consists of the indialite domains and the boundaries that are enriched in rutile, perrierite, and magnesium aluminotitanate. Nevertheless, very distinct differences are observed between the samples with different La2O3 concentrations. For the sample with x = 0.4, the domains were detected at lower temperatures, while the quantity and size of the domains increase faster due to the promoted precipitation of indialite. For the sample with x = 0.1, in addition to the domain boundaries, secondary boundaries between the “regions” (assemblages of the domains) are observed in a larger length scale. The average size of the crystalline phases found between the “regions” is larger than that typically observed at the domain boundaries. The sizes of the crystals at the boundaries decrease with higher concentrations of La2O3, and the crystals (especially perrierite) within the domains become larger, resulting in a more homogeneous microstructure. This results in better dielectric properties, i.e., much higher quality factor for the sample with x = 0.4 in comparison to that with x = 0.1 after heat-treatment at 1150 or 1250 °C. 相似文献
5.
HIMANSHU TRIPATHI AREPALLI SAMPATH KUMAR S P SINGH 《Bulletin of Materials Science》2016,39(2):365-376
The aim of the present investigation was to study the role of Al2O3 in the Li2O–CaO–P2O5–SiO2 bioactive glass for improving the bioactivity and other physico-mechanical properties of glass. A comparative study on structural and physico-mechanical properties and bioactivity of glasses were reported. The structural properties of glasses were investigated by X-ray diffraction, Fourier transform infrared spectrometry, scanning electron microscopy and the bioactivity of the glasses was evaluated by in vitro test in simulated body fluid (SBF). Density, compressive strength, Vickers hardness and ultrasonic wave velocity of glass samples were measured to investigate physical and mechanical properties. Results indicated that partial molar replacement of Li2O by Al2O3 resulted in a significant increase in mechanical properties of glasses. In vitro studies of samples in SBF had shown that the pH of the solution increased after immersion of samples during the initial stage and then after reaching maxima it decreased with the increase in the immersion time. In vitro test in SBF indicated that the addition of Al2O3 up to 1.5 mol% resulted in an increase in bioactivity where as further addition of Al2O3 caused a decrease in bioactivity of the samples. The biocompatibility of these bioactive glass samples was studied using human osteoblast (MG-63) cell lines. The results obtained suggested that Li2O–CaO–Al2O3–P2O5–SiO2-based bioactive glasses containing alumina would be potential materials for biomedical applications. 相似文献
6.
M. Alfano G. Di Girolamo L. Pagnotta D. Sun J. Zekonyte R. J. K. Wood 《Journal of Materials Science》2010,45(10):2662-2669
In this study, ceria–yttria co-stabilized zirconia (CYSZ) free-standing coatings, deposited by air plasma spraying (APS),
were isothermally annealed at 1315 °C in order to explore the effect of sintering on the microstructure and the mechanical
properties (i.e., hardness and Young’s modulus). To this aim, coating microstructure, before and after heat treatment, was
analyzed using scanning electron microscopy, and image analysis was carried out in order to estimate porosity fraction. Moreover,
Vickers microindentation and depth-sensing nanoindentation tests were performed in order to study the evolution of hardness
and Young’s modulus as a function of annealing time. The results showed that thermal aging of CYSZ coatings leads to noticeable
microstructural modifications. Indeed, the healing of finer pores, interlamellar, and intralamellar microcracks was observed.
In particular, the porosity fraction decreased from ~10 to ~5% after 50 h at 1315 °C. However, the X-ray diffraction analyses
revealed that high phase stability was achieved, as no phase decomposition occurred after thermal aging. In turn, both the
hardness and Young’s modulus increased, in particular, the increase in stiffness (with respect to “as produced” samples) was
equal to ~25%, whereas the hardness increased to up to ~60%. 相似文献
7.
Gadolinium doped bismuth borate glasses containing up to 30 mol% Y2O3 were prepared by fast melt quenching method. The effect of yttrium on the local order in 3B2O3 · Bi2O3 and B2O3 · Bi2O3 glass matrices, particularly on the bismuth sites, was investigated by infrared (IR) spectroscopy and electron paramagnetic
resonance (EPR) of Gd3+ ions. The IR results show that the local structure is more ordered in the glass system with higher bismuth content and the
progressive addition of yttrium increases the local disorder in both bismuth–borate glass matrices. The EPR results indicate
that Gd3+ ions occupy both bismuth and yttrium sites and reflect the same structural disorder like that suggested by IR results. 相似文献
8.
Keisuke Yasuda Toshiyuki Masui Takahiro Miyamoto Nobuhito Imanaka 《Journal of Materials Science》2011,46(11):4046-4052
Catalytic combustion of methane was investigated on Pt and PdO-supported CeO2–ZrO2–Bi2O3/γ-Al2O3 catalysts prepared by a wet impregnation method in the presence of polyvinylpyrrolidone. The catalysts were characterized
by X-ray fluorescence analysis, X-ray powder diffraction, X-ray photoelectron spectra, transmission electron microscopy, and
BET specific surface area measurements. The Pt/CeO2–ZrO2–Bi2O3/γ-Al2O3 and PdO/CeO2–ZrO2–Bi2O3/γ-Al2O3 catalysts were selective for the total oxidation of methane into carbon dioxide and steam, and no by-products such as HCHO,
CO, and H2 were obtained. The catalytic activities of the PdO/CeO2–ZrO2–Bi2O3/γ-Al2O3 catalysts were relatively higher than those of the Pt-supported catalysts, due to the facile re-oxidation of metallic Pd
into PdO based on lattice oxygen supplied from the CeO2–ZrO2–Bi2O3 bulk. A decrease in the calcination temperature during the preparation process was found to be effective in enhancing the
specific surface area of the catalysts, whereby particle agglomeration was inhibited. Optimization of the PdO amount and calcination
temperature enabled complete oxidation of methane at temperatures as low as 320 °C on the 11.6 wt% PdO/CeO2–ZrO2–Bi2O3/γ-Al2O3 catalyst prepared at 400 °C. 相似文献
9.
S. Bindra Narang Shalini Bahel S. Dash 《Journal of Materials Science: Materials in Electronics》2010,21(11):1186-1190
The influences of Bi substitution on microwave dielectric properties of Ba4(La0.5Sm0.5)9.33Ti18O54 solid solutions were investigated. Dielectric ceramics with general formula Ba4(La(0.5−z)Sm0.5Bi
z
)9.33Ti18O54, z = 0.0–0.2 were prepared by conventional solid state route. The structural analysis of all the samples was carried out by
X-ray diffraction and scanning electron microscopy. The dielectric properties were investigated as a function of Bi contents
using open-ended coaxial probe method in the frequency range 0.3–3.0 GHz at room temperature. Dielectric constant varies from
83 to 88 and loss tangent from 2.1 × 10−3 to 5.5 × 10−3 at 3 GHz with temperature coefficient of resonant frequency changing from 106.7 to −8.4 ppm/oC as Bi contents increases from
z = 0.00–0.20. It has been found that dielectric constant and temperature coefficient of resonant frequency improve whereas
loss tangent is adversely affected with increase in Bi substitution. 相似文献
10.
L. I. Podzorova A. A. Il’icheva O. I. Pen’kova V. P. Sirotinkin O. S. Antonova A. A. Konovalov 《Inorganic Materials》2018,54(5):454-459
We have studied phase formation in calcium-modified Al2O3–ZrO2–CeO2 nanopowders during sol–gel synthesis. The results demonstrate that heat treatment of the nanopowders first leads to the formation of a zirconium dioxide-based solid solution stabilized with cerium cations. Raising the heat treatment temperature helps the crystallization of corundum, a stable phase of aluminum oxide, to reach completion. In the temperature range 1400–1550°C, we observe the formation of a second aluminum-containing phase: calcium cerium hexaaluminate consisting of long prismatic grains. 相似文献
11.
Abdeslam Chagraoui Imane Yakine Abdelmjid Tairi Abdenajib Moussaoui Mohamed Talbi Mohamed Naji 《Journal of Materials Science》2011,46(16):5439-5446
A glass-forming domain is found and studied within Bi2O3–Sb2O3–TeO2 system. The glasses composition were obtained in pseudo-binary xSbO1.5, (1−x)TeO2 for 0.05 ≤ x ≤ 0.20. The constitution of glasses in the system Sb2O3–TeO2 was investigated by DSC, Raman, and Infrared spectroscopy. The influence of a gradual addition of the modifier oxides on
the coordination geometry of tellurium atoms has been elucidated based Infrared and Raman studies and showed the transition
of TeO4, TeO3+1, and TeO3 units with increasing Sb2O3 content. XRD results reveal the presence of three crystalline: γ-TeO2, α-TeO2, and SbTe3O8 phases during the crystallization process. The density of glasses has been measured. The investigation in the ternary system
by the solid state reaction using XRD reveals the existence of a solid solution Bi1−x
Sb1−x
Te2x
O4 isotopic to BiSbO4 with 0 ≤ x ≤ 0.1. 相似文献
12.
Semih Seyyidoğlu Macit Özenbaş Necmeddin Yazıcı Ayşen Yılmaz 《Journal of Materials Science》2007,42(15):6453-6463
In this study, ZrP2O7 was synthesized by the solid state reaction of ZrO2 and NH4H2PO4 at 900 °C. Then, in set 1; 10, 5, 1, 0.5, 0.1, 0.05, 0.03% previously prepared Sr2P2O7 were doped into ZrP2O7, and Sr2P2O7 slightly affect the unit cell parameter of cubic ZrP2O7 (a = 8.248(6)–8.233(8) Å). The reverse of this process was also applied to Sr2P2O7 system (set 2). ZrP2O7 changes the unit cell parameters of orthorhombic Sr2P2O7 in between a = 8.909(5)–8.877(5) Å, b = 13.163(3)–13.12(1) Å, and c = 5.403(2)–5.386(4) Å. Analysis of the vibrations of the P2O 7 4? ion and approximate band assignments for IR and Raman spectra are also reported in this work. Some coincidences in infrared and Raman spectra both sets were found and strong P–O–P bands were observed. Surface morphology, EDX analysis, and thermoluminescence properties of both sets were given the first time in this paper. 相似文献
13.
E. V. Dudnik A. V. Shevchenko A. K. Ruban V. P. Red’ko L. M. Lopato 《Inorganic Materials》2008,44(4):409-413
Using hydrothermal treatment of coprecipitated hydroxides, we have prepared nanocrystalline ZrO2-rich ZrO2-Y2O3-CeO2-Al2O3 powder. The effect of heat treatment on the properties of the powder has been studied in the temperature range 400–1300°C. The powder has been shown to have a metastable phase composition, which is attributable to structural and size factors and also to the fact that the ZrO2 and Al2O3 crystallites inhibit the growth of each other. Sintering the powder under various conditions, we have obtained ceramics with fracture toughnesses from 6.4 to 16.8 MPa m1/2. 相似文献
14.
CeO2 and Co3O4–CeO2 nanoparticles were synthesized, thoroughly characterized, and evaluated in the COPrOx reaction. The CeO2 nanoparticles were synthesized by the diffusion-controlled precipitation method with ethylene glycol. A notably higher yield was obtained when H2O2 was used in the synthesis procedure. For comparison, two commercial samples of CeO2 nanoparticles (Nyacol®)—one calcined and the other sintered—were also studied. Catalytic results of bare CeO2 calcined at 500 °C showed a strong influence of the method of synthesis. Despite having similar BET area values, the CeO2 synthesized without H2O2 was the most active sample. Co3O4–CeO2 catalysts with three different Co/(Co + Ce) atomic ratios, 0.1, 0.3, and 0.5, were prepared by the wet impregnation of the CeO2 nanoparticles. TEM and STEM observations showed that impregnation produced mixed oxides composed of small CeO2 nanoparticles located both over the surface and inside the Co3O4 crystals. The mixed oxide catalysts prepared with a cobalt atomic ratio of 0.5 showed methane formation, which started at 200 °C due to the reaction between CO2 and H2. However, above 250 °C, the reaction between CO and H2 became important, thus contributing to CO elimination with a small H2 loss. As a result, CO could be totally eliminated in a wide temperature range, from 200 to 400 °C. The methanation reaction was favored by the reduction of the cobalt oxide, as suggested by the TPR experiments. This result is probably originated in Ce–Co interactions, related to the method of synthesis and the surface area of the mixed oxides obtained. 相似文献
15.
L. T. Denisova L. A. Irtyugo Yu. F. Kargin L. G. Chumilina N. V. Belousova V. M. Denisov N. A. Galiakhmetova 《Inorganic Materials》2017,53(3):300-306
The compounds BiVO4, Bi4V2O11, and Bi12V2O23 have been prepared by solid-state synthesis using stoichiometric mixtures of Bi2O3 and V2O5. The effect of temperature on the heat capacity of the synthesized bismuth vanadates has been studied by differential scanning calorimetry in the range 350–950 K. The C p (T) curves have extrema at 531.7 K for BiVO4 and at 725.2 and 852.8 K for Bi4V2O11, which are due to polymorphic transformations of these compounds. 相似文献
16.
Qinglei Sun Hongqing Zhou Haikui Zhu Hongqing Qi Lisong Hu Zhenxing Yue 《Journal of Materials Science: Materials in Electronics》2016,27(8):7750-7754
(Zr0.8Sn0.2)TiO4 (ZST) ceramics were fabricated via conventional solid-state reaction method. Sintering behavior, phase composition, microstructure and microwave dielectric properties of Y2O3–ZnO doped ZST ceramics were investigated. Only a single ZST phase was identified by X-ray diffraction patterns. The variation tendencies of dielectric constants as well as Q × f values were in accordance with the bulk densities. The appropriate Y2O3 and ZnO additions could not only efficiently lower the sintering temperature to 1240 °C, but also noticeably improve the densification and microwave dielectric properties of ZST ceramics. But excessive additives deteriorated the microstructures and comprehensive properties of samples. A dielectric constant ε r of 39.73, a Q × f value of 48,545 GHz (at 5.5 GHz), and a τ f value of ?2.13 ppm/°C were obtained for 1 wt% ZnO doped ZST ceramics with 0.5 wt% Y2O3 addition sintered at 1240 °C. 相似文献
17.
T. Shimazu H. Maeda E. H. Ishida M. Miura N. Isu A. Ichikawa K. Ota 《Journal of Materials Science》2009,44(1):93-101
High-damping materials are widely used in engineering fields. In order to increase the precision of vibration control to different
levels, high-damping materials with high-rigidity are required. This study attempts to develop a new high-damping high-rigidity
material using ductile ceramics based on the Al2TiO5–MgTi2O5 system, which has many continuous microcracks along the grain boundaries. Ductile ceramics have high internal friction (Q
−1 = 0.01–0.037), but very low rigidity (<10 GPa). The rigidity of Al2TiO5–MgTi2O5 ceramics was improved by combining them with a polymer such as acrylic resin. The Young’s modulus and internal friction of
the composites of Al2TiO5–MgTi2O5 ceramics and acrylic resin are investigated. They show high-damping capacity (Q
−1 = 0.03–0.04) with high rigidity (E = 50–60 GPa), and their properties depend on those of the polymer. Thus, the composites fabricated using the above method
can serve as high-damping high-rigidity materials. 相似文献
18.
Jin Huang Huanfu Zhou Nan Wang Xianghu Tan Guangchao Fan 《Journal of Materials Science: Materials in Electronics》2017,28(6):4565-4569
3MgO–Al2O3–3TiO2 (MAT) ceramics were prepared by a conventional solid-state reaction method. The crystal structure, sintering behavior and microwave dielectric properties of ceramics were investigated using X-ray diffraction, scanning electron microscopy and network analyzer. MAT ceramics contained the coexistence of three phases, including MgAl2O4, MgTiO3 and MgTi2O5. The ceramics sintered at 1350 °C for 4 h presented excellent comprehensive performances with relative permittivity (ε r ) of 15.4, quality factor (Q × f) of 91,000 GHz and temperature coefficient of resonant frequency (τ f ) about ?55.1 ppm/°C. 相似文献
19.
X. H. Zheng X. C. Jiang D. P. Tang C. Zhang 《Journal of Materials Science: Materials in Electronics》2011,22(7):781-784
CaO–SrO–Li2O–Ln2O3–TiO2 ceramics were prepared by solid state reaction method, where Ln2O3 consists of equal proportions of Nd2O3 and Sm2O3. Dielectric properties and crystal structure were investigated with respect to the content of TiO2. Single phase with an orthorhombic perovskites structure was formed within the composition range of investigation. The frequency
dependence of dielectric properties of the present ceramics was extensively investigated. Dielectric constant was less sensitive
to frequency. However, dielectric loss and temperature coefficients were both very sensitive to frequency and gradually decreased
with increasing frequency, such as the variation was more than ten times between 1 MHz and several GHz. The relationship between
the temperature coefficient and dielectric loss was also discussed at different frequencies. And the mechanism of the frequency
dependence was discussed in term of the role of Li ions. 相似文献
20.
A homogeneous α-Al2O3 crystal membrane was fabricated by the sol–gel technique on 316L porous stainless steel (PSS) substrate with an average pore
size of 1.0 μm. The preparation process was optimized by carefully choosing the binder, the concentrations of the casting
solutions and the sintering temperatures of the membranes. Compared to methylcellulose and polyethylene glycol 20000, polyvinyl
alcohol 1750 was found to be the most effective binder to fabricate a homogeneously structured Al2O3 membrane without defects. The concentration to prepare an uniform coverage membrane with a thickness of ~10 μm was 0.032 mol/L.
When sintered at 1000 °C, γ-Al2O3 membrane with ~3 μm grains was obtained. When sintered at 1200 °C, γ-Al2O3 completely transformed into α-Al2O3 and the grains grew to ~5 μm. Accordingly, the process was applied to a bigger pore-sized PSS with an average pore size of
1.5 μm to fabricate an α-Al2O3 intermediate layer to initially modify its surface. A single α-Al2O3 crystal layer with a thickness of ~5 μm and an average pore size of 0.7 μm was achieved. Subsequently, TiO2, SiO2, and TiO2–SiO2 hybrid membranes were tried on the modified PSS. Defect-free microfiltration membranes with average pore sizes of ~0.3 μm
were readily fabricated. The results indicate that the sol–gel method is promising to initially modify the PSS substrates
and the sol–gel-derived α-Al2O3 crystal layer is an appropriate intermediate layer to modify the PSS and to support smaller grain-sized top membranes. 相似文献