共查询到20条相似文献,搜索用时 31 毫秒
1.
Patricia Capellato Barbara S. Smith Ketul C. Popat Ana P.R. Alves Claro 《Materials science & engineering. C, Materials for biological applications》2012,32(7):2060-2067
In this study, the mechanical substrate and topographical surface properties of anodized Ti30Ta alloy were investigated using scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS) and contact angle measurement. The anodization process was performed in an electrolyte solution containing HF (48%) and H2SO4 (98%) in the volumetric ratios 1:9 with the addition of 5% dimethyl sulfoxide (DMSO) at 15 V, 25 V and 35 V for 20 and 40 min, producing a nanotube architecture when anodized at 35 V for 40 min. Human dermal fibroblasts (HDF, neonatal) were utilized to evaluate the biocompatibility of Ti30Ta nanotubes and Ti30Ta alloy after 1 and 3 days of culture. Cellular adhesion, proliferation, viability, cytoskeletal organization and morphology were investigated using fluorescence microscope imaging, biochemical assay and SEM imaging respectively. The results presented identify altered material properties and improved cellular interaction on Ti30Ta nanotubes as compared to Ti30 Ta alloy. 相似文献
2.
This paper examines the phase transformation, pore evolution, microstructural and mechanical changes that occur in inorganic polymer cement (IPC) in the presence of three different grade of fine aggregates (ф < 100 μm) of ladle slag, nepheline syenite and quartz sand. Experimental results indicate that polycondensation was enhanced in nepheline syenite based specimens, compared to quartz sand, due to the increase in HMAS phases in relation to the dissolution and interaction of amorphous/disordered fraction of aggregates. HCS and HCAS with HMAS phases were identified in the ladle slag based specimens. The formation of these new phases reduced both the cumulative pore volume and pores size. The apparent increase in volume of capillary pores in ladle slag based specimens was explained by the residual bubbles from the carbonates included in raw slag. The flexural strength of the inorganic polymer cement increases from 4 MPa to 4.2, 4.8 and 6.8 MPa with the addition of 20 wt% of quartz sand, nepheline syenite and ladle slag respectively. These values increase significantly between 28 and 180 days of curing (9.1 MPa for ladle slag and 10.0 MPa for nepheline syenite). It was concluded that fines can be used to remove the HM and poorly bounded alumina oligomers in metakaolin based inorganic polymer matrices and improve the interfacial zone for the design of an optimum grade and high-performance composites. 相似文献
3.
A lot of studies have been devoted to the porous Si, erbium-doped Si and Si-embedded in dielectric matrix of SiO or SiN together with long-time conventional furnace annealing. Besides, it is noted that these Si nanostructured films were highly resistive and non-conducting. In this paper, we have investigated the effect of annealing temperature on the microstructure and photoluminescence of low-resistivity Si/SiN/TaN nanocomposite thin films which are deposited by magnetron sputtering and followed by rapid thermal annealing (RTA). All samples are of luminescence and staying low resistivity at about 1462–2162 μΩ cm which increases with increasing annealing temperatures. The asymmetric broad photoluminescence (PL) peak covered the wavelengths of 400–700 nm. The wide visible PL spectra can be deconvoluted into three bands of blue (~ 455 nm), green-yellow (~ 525 nm), and orange emissions (~ 665 nm), which correspond to the emission origins from unsatisfied states in imperfections of interface between the Si:O and SiN:O, located states related to the mixed SiO or SiN bonds in SiN:O layer and nc-Si embedded in SiN:O matrix. The detailed mechanism of broad visible PL was investigated in terms of microstructure and bonding configuration evolution. The relationship between the annealing temperature, microstructure and PL behavior of Si/SiN/TaN multilayer films is discussed and established. 相似文献
4.
《Optical Materials》2014,36(12):2366-2371
Tris-(8-hydroxyquinioline) aluminium (Alq3) is widely used in organic light emitting diodes as an emission and electron transport layer. In this study the effect of solvent molecules, in the solid state crystal lattice, on the photoluminescence properties of synthesized mer-tris(8-Hydroxy-quinolinato-N, O)-indium(iii) hydrate 0.5 methanol solvate (mer-[In(qn)3]⋅H2O⋅0.5 CH3OH) was studied. Single crystals were obtained through a recrystallization process and single crystal X-ray diffraction was performed to obtain the unit cell structure. The main absorption peaks were assigned to ligand centered electronic transitions, while the solid state photoluminescence excitation peak at 440 nm was assigned to the 0–0 vibronic state of In(qn)3. Broad emission at 510 nm was observed and was ascribed to the relaxation of an excited electron from the S1–S0 level. A powder sample was annealed at 130 °C for 2 h. A decrease in intensity was observed and could possibly be assigned to a loss of solvent species. To study the photon degradation, the sample was irradiated with an UV lamp for ∼15 h. The emission data was collected and the change in photoluminescence intensity with time was monitored. High resolution X-ray photoelectron spectroscopy (XPS) scans of the O-1s peak revealed that after annealing the binding energy shifted to lower energies indicating a possible loss of the H2O and CH3OH present in the crystal. The O-1s peak of the degraded sample indicated the possible formation of CO (∼532.5 eV), COH and OCOH (∼530.5 eV) on the phenoxide ring. 相似文献
5.
Z.H. Lai J.C. Zhu J.H. Jeon B. Zhang J. Yu 《Materials Science and Engineering: A》2009,499(1-2):267-270
To improve the oxidation resistance of MoSi fused slurry coating fabricated in vacuum, MoSiN multi-layer coatings were synthesized on C/C composites in nitrogen atmosphere by fused slurry using same Mo and Si element powders. The phase compositions and microstructures were characterized by X-ray diffractometry (XRD), optical microscopy (OM), scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS). The results indicate that the MoSiN coating contains SiC inner layer and MoSi2/Si main layer, which was similar with MoSi coating. Additionally, a thin outer layer with nano-filiform morphology has been found on the coating surface, which consists of SiC, Si3N4, AlN, Al2O3 and sialon phase. Oxidation experiments show that the MoSiN multi-layer coating exhibits excellent oxidation resistance at 1400 °C and anti-oxidizing potential ability at 1450 °C. 相似文献
6.
S. Jesurani S. Kanagesan R. Velmurugan C. Thirupathi M. Sivakumar T. Kalaivani 《Materials Letters》2011,65(21-22):3305-3308
The precursor of CaCu3Ti4O12 (CCTO) nano particles have been successfully synthesized by sol–gel method at 90 °C. The dried precursor powder was milled and then calcined at 450 °C, 550 °C, 650 °C, 800 °C, 850 °C and 950 °C for 3 h. The phase formation of CCTO was analyzed by step by step using FTIR and XRD. Particle size and shape were evaluated by AFM. The XRD results of the powder calcined at 800 °C indicated the formation of CCTO phase. AFM studies showed that average particle size of the CCTO powder range 90–120 nm. The absorption bands corresponding to vibrations of CaO, CuO and TiOTi were observed at 606, 525 and 463 cm? 1 using FTIR. The samples sintered at 1040 °C showed the densities as high as 96% of theoretical density. The grain sizes of sintered pellets were determined by FE-SEM. The dielectric properties of prepared samples were studied by LCR meter. 相似文献
7.
Hoonbae Kim Myung Hoon Ha Donggeun Jung Heeyeop Chae Hyoungsub Kim 《Materials Research Bulletin》2012,47(10):3008-3010
In microelectronics industry, integration of the low dielectric constant (low-k) material films is a continuing issue due to the decreasing device feature size. To improve electric properties, various post-deposition treatments of the low-k material films can be used. In this work, we used room temperature treatment of He/H2 plasma and investigated the effects of plasma treatment on the electrical properties of low-k SiOCH films. Plasma treatment time changed from 300 to 1800 s. After treatment, the dielectric constant was decreased from 2.9 to 2.48, and the thickness of the low-k SiCOH films changed by only ~5%. The leakage current densities of the low-k SiCOH films were decreased to ~10?11 A/cm2, with treatment time ≥600 s. The breakdown occurred only around 2 V for films plasma-treated for 600 and 900 s. However, for 1800 s treatment time, the breakdown voltage was enhanced dramatically and breakdown occurred at applied voltage higher than 40 V. The surface composition change of the films after treatment was investigated by X-ray photoelectron spectroscopy (XPS). As the plasma treatment time was increased, the intensities of CC/CH and CSi peaks were decreased while the intensities of SiO and CO peaks were increased. It is thought that increase of oxygen content of the SiCOH film, after plasma treatment, contributed to leakage current reduction and breakdown voltage increase. 相似文献
8.
《Materials Research Bulletin》2006,41(6):1112-1117
Transparent 45SiO225Al2O35CaO10NaF15CaF2 glass ceramics doped with different levels of Er3+ were prepared. The spherical CaF2 nanocrystals with 10–20 nm in size were verified to be homogeneously embedded among the glassy matrix. Room temperature absorption and emission spectra corresponding to 4I13/2 ↔ 4I15/2 transitions of Er3+ ions in precursor glasses and glass ceramics, respectively had been measured. For glass ceramics, with increasing of Er3+ content from 0.1 to 2.0 mol%, the FWHM values of the emission bands increased from 42 to 71 nm; meanwhile, the lifetime of 4I13/2 level slightly reduced. However, both the values of FWHM and lifetime were larger than those of precursor glasses due to the change of ligand field of Er3+ ions. 相似文献
9.
《Materials Chemistry and Physics》2005,89(2-3):417-422
Sol–gel derived TiO2/SiO2/ormosil hybrid planar waveguides have been deposited on soda-lime glass slides and silicon substrates, films were heat treated at 150 °C for 2 h or dried at room temperature. Different amounts of water were added to sols to study their impacts on microstructures and optical properties of films. The samples were characterized by m-line spectroscopy, Fourier transform infrared spectroscopy (FT-IR), UV/VIS/NIR spectrophotometer (UV–vis), atomic force microscopy (AFM), thermal analysis instrument and scattering-detection method. The refractive index was found to have the largest value at the molar ratio H2O/OR = 1 in sol (OR means OCH3, OC2H5 and OC4H9 in the sol), whereas the thickest film appears at H2O/OR = 1/2. The rms surface roughness of all the films is lower than 1.1 nm, and increases with the increase of water content in sol. Higher water content leads to higher attenuation of film. 相似文献
10.
The surface-related reactions during discolouration of Bisphenol A Polycarbonate (BPA-PC), used as LED lens plates, under thermal stress are studied. X-ray photoelectron spectroscopy (XPS) has been used to monitor the changes in the surface chemistry of BPA-PC plates over a temperature range of 100–140 °C for a period up to 3000 h. Increasing time under thermal stress is associated with the discolouration, and increase in the yellowing index (YI) of PC plastic lens. The XPS results show that discolouration is associated with oxidation at the surface, finding a significant increase in the signal ratio O1s/C1s in the XPS spectra of degraded specimens. During thermal ageing, the CH concentration decreases and new oxide features CO and OCO form, with the latter being a support for oxidation at the surface being a major reaction during discolouration. Results also show that irradiation with blue light during thermal ageing accelerates the kinetics of discolouration and the increased O1s/C1s ratio in XPS spectra. 相似文献
11.
Characteristic absorption and photoluminescence (PL) of TiO2 and disperse red-19 (DR-19) composite have been investigated. Two step synthetic processes were employed to incorporate the DR-19 to the TiO2 sol–gel. Firstly, urethane bonds between the DR-19 (OH) and 3-isocyanatopropyl triethoxysilane (ICPTES, NCO) were fabricated (ICPDR) prior incorporation to the TiO2 sol–gel. Secondary, hydrolysis of the ethoxy group from the ICPDR and condensation reaction between silanol groups from ICPDR and TiO2 sol–gel were performed by adding ICPDR to the TiO2 sol–gel and aged for several days at room temperature (ICPDRTiO2). There was no absorption peak shift with increasing the DR-19 concentration in methanol. However, UV–visible absorption band was shifted toward red approximately 0.09 eV for the ICPDRTiO2 film, which indicated the formation of dimmer or more aggregates. The PL peaks of ICPDRTiO2 were red-shifted compared with DR-19 in methanol (0.12 eV) and ICPDR film (0.09 eV). The relatively large emission peak shift toward red could be due to the fluorescence resonance energy transfer (FRET) between DR-19 and TiO2 in ICPDRTiO2 matrix. 相似文献
12.
《Advanced Powder Technology》2022,33(8):103695
Fe(III) ion can strongly inhibit the sulphidation amine flotation of smithsonite. However, its modification mechanism on smithsonite surface is still obscure. In this work, a systematic study of the modification of Fe(III) ion on smithsonite (1 0 1) surface was performed using DFT calculation. The optimal number of H2O ligands for Fe(III) ion hydrates in aqueous conditions was probed, and [Fe(OH)2(H2O)4]+ and [Fe(OH)4]? were identified as the major modification species, then their adsorption and bonding mechanisms were further revealed by analyzing the frontier orbitals, density of state, Mulliken population, and electron density. The calculated adsorption structures were consistent with the former experiment, and we found the O site that bonded to the C atom on smithsonite surface was the most favorable position for [Fe(OH)2(H2O)4]+ and [Fe(OH)4]? adsorptions. Besides, their adsorption mechanisms on smithsonite surface were principally due to the combined effect of FeO bond and hydrogen bonding. Simultaneously, hydrogen bonding greatly enhanced the stability of the adsorption structures. Moreover, the dominant orbital contribution for the bonding of FeO was primarily due to the orbital hybridization between Fe 3d and O 2p orbitals. This work can help in deeper understanding of the depression of Fe(III) ion on the sulphidation amine flotation of smithsonite. 相似文献
13.
《Materials Research Bulletin》2006,41(3):674-682
The colorless sample of Sr2MgWO6 was prepared by conventional solid-state reaction of stoichiometric amounts of SrCO3, WO3 and MgO and characterized by powder X-ray diffraction (XRD) studies. In the temperature range of 300–15 K, detailed structural studies on Sr2MgWO6 were carried out by Rietveld refinements of the observed powder neutron diffraction (ND) data. At ambient temperature Sr2MgWO6 crystallizes in tetragonal (space group I4/m) lattice with unit cell parameters: a = 5.5882(2) and c = 7.9452(7) Å, V = 248.11(3) Å3, Z = 2. This tetragonal (I4/m) structure is retained down to 15 K. The structural analysis of the sample at different temperatures indicates no appreciable change in the MgO and WO bond lengths. However, a decrease in the tilt angle is observed with increasing temperature. The negative thermal expansion of the c-axis is attributed to increasing transverse displacement amplitude of the bridging oxygen atoms along this axis. 相似文献
14.
T. Sahbani W. Smirani Salem S. Al-Deyab M. Rzaigui 《Materials Research Bulletin》2012,47(6):1455-1458
Crystals of a new hybrid compound C8H12N+, HSO4?·H2O were synthesized in aqueous solution and characterized by X-ray diffraction and IR absorption spectroscopy. This compound crystallizes in the orthorhombic non-centrosymmetrical space group P212121 and an unit cell with a = 5.74(2) Å, b = 9.17(2) Å, c = 21.34(4) Å, V = 1124(6) Å3, and Z = 4. Its crystal structure is a packing of alternated inorganic and organic layers parallel to (a,b) planes. The different components are connected by a bi-dimensional network of strong OH…O and NH…O hydrogen bonds. Then, in order to detect phase transitions and watch changes in the conductivity behaviour, investigations by DTA–TG and differential scanning calorimetry (DSC) and electrical conductivity measurements were carried out. 相似文献
15.
Sn0.96−xLa0.04CuxO2 (0 ⩽ x ⩽ 0.03) nanocrystals have been successfully synthesized by employing a simple co-precipitation method. The crystal structure of the synthesized nanocrystals was found to be tetragonal rutile of tin oxide by using X-ray diffraction technique and was not affected by doping. The change in lattice parameters was discussed based on the secondary phase formation and presence of Cu2+/Cu3+ in LaSnO2 lattice. The variation in size and shape of the nanocrystals by Cu-doping was discussed using scanning electron microscope. The chemical stoichiometry of Sn, Cu, La and O was confirmed by energy dispersive X-ray spectra. The best optical transparency and lower absorption observed at Sn0.97La0.02Cu0.01O2 nanocrystals seems to be optimal for industrial applications especially as transparent electrode. The initial blue shift of energy gap from 3.65 eV (Cu = 0%) to 3.78 eV (Cu = 1%) (ΔEg ≈ 0.13 eV) is due to the distortion in the crystal structure of the host compound and generation of defects. The red shift of energy gap after Cu = 1% is due to the charge-transfer transitions between the metal ions d-electrons and the SnO2 conduction or valence band. Lattice mode of SnO2 at 686 cm−1 in Sn0.98La0.02O2 nanocrystals and anti-symmetric SnOSn stretching mode of the surface bridging oxide around 634–642 cm−1 in Cu doped Sn0.98La0.02O2 nanocrystals was confirmed by Fourier transform infrared spectra. 相似文献
16.
E. Lima E. Raphael F. Sentanin L.C. Rodrigues R.A.S. Ferreira L.D. Carlos M.M. Silva A. Pawlicka 《Materials Science and Engineering: B》2012,177(6):488-493
Dispersion of photoluminescent rare earth metal complexes in polymer matrices is of great interest due to the possibility of avoiding the saturation of the photoluminescent signal. The possibility of using a natural ionic conducting polymer matrix was investigated in this study. Samples of agar-based electrolytes containing europium picrate were prepared and characterized by physical and chemical analyses. The FTIR spectra indicated strong interaction of agar OH and 3,6-anhydro-galactose CO groups with glycerol and europium picrate. The DSC analyses revealed no glass transition temperature of the samples in the ?60 to 250 °C range. From the thermogravimetry (TG), a thermal stability of the samples of up to 180 °C was stated. The membranes were subjected to ionic conductivity measurement, which provided the values of 2.6 × 10?6 S/cm for the samples with acetic acid and 1.6 × 10?5 S/cm for the samples without acetic acid. Moreover, the temperature-dependent ionic conductivity measurements revealed both Arrhenius and VTF models of the conductivity depending on the sample. Surface visualization through scanning electron microscopy (SEM) demonstrated good uniformity. The samples were also applied in small electrochromic devices and showed good electrochemical stability. The present work confirmed that these materials may perform as satisfactory multifunctional component layers in the field of electrochemical devices. 相似文献
17.
K.G. Sanjaya Ranmohotti M. Dariush Montasserasadi Jonglak Choi Yuan Yao Debasish Mohanty Elisha A. Josepha Shiva Adireddy Gabriel Caruntu John B. Wiley 《Materials Research Bulletin》2012,47(6):1289-1294
A two-step topochemical reaction strategy utilizing oxidative intercalation with gaseous chalcogen hydrides is presented. Initially, the Dion-Jacobson-type layered perovskite, RbLaNb2O7, is intercalated reductively with rubidium metal to make the Ruddlesden-Popper-type layered perovskite, Rb2LaNb2O7. This compound is then reacted at room-temperature with in situ generated H2S gas to create RbS layers within the perovskite host. Rietveld refinement of X-ray powder diffraction data (tetragonal, a = 3.8998(2) Å, c = 15.256(1) Å; space group P4/mmm) shows the compound to be isostructural with (Rb2Cl)LaNb2O7 where the sulfide resides on a cubic interlayer site surrounded by rubidium ions. The mass increase seen on sulfur intercalation and the refined S site occupation factor (~0.8) of the product indicate a higher sulfur content than expected for S2? alone. This combined with the Raman studies, which show evidence for an HS stretch, indicate that a significant fraction of the intercalated sulfide exists as hydrogen sulfide ion. Intercalation reactions with H2Se(g) were also carried out and appear to produce an isostructural selenide compound. The utilization of such gaseous hydride reagents could significantly expand multistep topochemistry to a larger number of intercalants. 相似文献
18.
《Materials science & engineering. C, Materials for biological applications》2006,26(5-7):782-787
We have studied 5 MeV Au2+ ion implantation with fluences between 7 × 107 and 2 × 108 cm− 2 in Si by deep level transient spectroscopy (DLTS) and scanning capacitance microscopy (SCM). The DLTS measurements show formation of electrically active defects such as the two negative charge states of the divacancy (V2(/–) and V2(–/0)) and the vacancy–oxygen (VO) center. It is observed that the intensity of the V2(/–) peak is lower compared to that of V2(–/0) by a factor of 5. This has been attributed to a highly localized distribution of the defects along the ion tracks, which results in trapping of the carriers at V2(–/0) and incomplete occupancy of V2(/–). The SCM measurements obtained in a plan view show a random pattern of regions with a reduced SCM signal for the samples implanted with fluence above 2 × 108 cm− 2. The reduced SCM signal is attributed to extra charges associated with acceptor states, such as V2(–/0), formed along the ion tracks in the bulk Si. Indeed, the electron emission rate from the V2(–/0) state is in the range of 10 kHz at room temperature, which is well below the probing frequency of the SCM measurements, resulting in “freezing” of electrons at V2(–/0). 相似文献
19.
《Materials Research Bulletin》2006,41(3):608-611
Well-defined hexagonal nanosheets of layered zinc hydroxysulfate (Zn(OH)2)3(ZnSO4)(H2O)5 with the side length of 1–20 μm and thickness of ∼50 nm has been synthesized by the thermal treatment of ZnSO4–hexamethylenetetramine precursor in water–ethanol mixed solvent at 75 °C. The sheet-like morphology was found to closely depend upon the experimental conditions, such as the solvent and the precursor composition. In particular, the products can be easily converted to ZnO nanosheets upon exposing to the irradiation of electron beam. 相似文献
20.
In this work, the chemical interaction between carbon nanotubes (MWCNT) functionalized with acyl chloride (SOCl2) and polymer chain tetrafuncional N,N,N′,N′-tetraglycidyl-4,4′-diaminodiphenylmethane (TGDDM) and hardener 4,4′diaminodiphenyl sulfone (DDS) has been monitored by Fourier transform infrared spectroscopy (FTIR) with a attenuated total reflectance (ATR) coupled. MWCNT were obtained from the pyrolysis of a mixture of camphor and ferrocene into a oven. The functionalization process was done by oxidative treatment in order to incorporate carboxylic group over the walls of MWCNT, before to be used SOCl2. The functionalized carbon nanotubes were evaluated by X-ray photoelectron spectroscopy (XPS), Raman and transmission electron microscopy (TEM). Nanostructured composites were processed by using epoxy resin with MWCNT in varying percentages. In this work it was observed that different percentages of functionalized nanotubes modify the interaction between the composite matrix and curing agent, where can be observed that in specimens with content less than 1 wt% MWCNT the chemical bond occurs preferentially from the opening of the SO double bond of the hardener and when is used MWCNT content higher than 1 wt% there is little chemical interaction with the SO bond of the hardener and most MWCNT binds to amine. 相似文献