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31.
《Ceramics International》2016,42(6):6664-6672
Undoped and Zn-doped CuCrO2 nanoparticles were synthesized by sol–gel method as promising wide band gap p-type semiconductor materials for solid-state dye-sensitized solar cells (DSSCs). We studied the influence of Zn dopant concentration on structural, electrical and optical properties of CuCrO2 nanoparticles. The X-ray diffraction data indicated that the delafossite-to-spinel ferrite phase transition occurs by increasing the amount of Zn doping. The average nanoparticle size was determined about 40 nm. A minimum value of electrical resistivity of 5.7 Ω cm was obtained for doping concentration of 5%. Having optimized the Zn-doped CuCrO2 nanoparticles, solid-state DSSCs were fabricated using undoped and Zn-doped CuCrO2 (5%) as solid electrolytes. As the photoanode layer, the vertically aligned TiO2 nanorod arrays were grown on FTO glass using a hydrothermal method. Compared with undoped CuCrO2, the Zn-doped nanoparticles exhibited an improvement in photovoltaic properties. The overall efficiency enhancement of 39% was obtained for the dopant concentration of 5%. The improved power conversion efficiency is attributed to the lowered electrical resistivity and enlarged work function of Zn-doped CuCrO2 nanoparticles. 相似文献
32.
《Ceramics International》2016,42(8):9577-9582
In the current study, a series of lanthanide ions, Tm, Yb and Lu, were used for doping at the Bi-site of the Aurivillius phase Na0.5Bi4.5Ti4O15 (NaBTi) to investigate the structural, electrical and ferroelectric properties of the thin films. In this regard, Na0.5Bi4.5Ti4O15 and the rare earth metal ion-doped Na0.5Bi4.0RE0.5i4O15 (RE=Tm, Yb and Lu, denoted by NaBTmTi, NaBYbTi, and NaBLuTi, respectively) thin films were deposited on Pt(111)/Ti/SiO2/Si(100) substrates by using a chemical solution deposition method. Formations of the Aurivillius phase orthorhombic structures for all the thin films were confirmed by X-ray diffraction and Raman spectroscopic studies. Based on the experimental results, the rare earth metal ion-doped Na0.5Bi4.0RE0.5Ti4O15 thin films exhibited a low leakage current and the improved ferroelectric properties. Among the thin films, the NaBLuTi thin film exhibited a low leakage current density of 6.96×10−7 A/cm2 at an applied electric field of 100 kV/cm and a large remnant polarization (2Pr) of 26.7 μC/cm2 at an applied electric field of 475 kV/cm. 相似文献
33.
《Ceramics International》2016,42(3):3930-3937
Room-temperature multiferroic 0.7BiFeO3–0.3Bi0.5Na0.5TiO3 solid solution ceramics have been prepared by the sol–gel method. We have discussed the annealing temperature dependence of the multiferroic properties. The samples are annealed at 1023, 1123, 1223 and 1323 K for 3 h, respectively. X-ray diffraction patterns identify that all samples are pure. Scanning electron micrographs present the increasing grain size with higher annealing temperature. Magnetic, ferroelectric and dielectric properties are enhanced obviously with the increase in annealing temperature. The coexistence of ferroelectric and ferromagnetic properties is also proved at room temperature. In addition, it reveals that the optimal annealing temperature accompanied with favorable multiferroic properties of 0.7BiFeO3–0.3Bi0.5Na0.5TiO3 solid solution ceramics is near 1223 K. 相似文献
34.
《Ceramics International》2016,42(9):11270-11274
Porous mullites with a whiskers framework and high porosities were fabricated by the reaction sintering (1100 to 1600 °C, 1 h, in an airtight container) of an aerogel block shaped by the sol–gel transition of a mullite precursor composed of SiO2 sol, Al2O3 and AlF3 powders (as reaction catalyst). The effect of heating temperatures on porosity, whisker formation, microstructure feature and compressive strength of the porous mullites was determined by XRD, SEM and compressive test. The results indicate that after heating at temperatures from 1100 to 1600 °C, the porosities of the mullites varied within the range of 84.1–80.2%. The whiskers in the framework well lap-jointed each other to form the large space and became elongated and smooth at high temperatures due to the accelerated vapor–solid reaction rate. A maximum compressive strength of 16.1 MPa was obtained for the whiskers framework heated at 1600 °C; this strength was attributed to the strong bonding among the smooth whiskers. 相似文献
35.
《Ceramics International》2016,42(4):4690-4699
In this study, the rheological behavior of electrospinning solutions containing different copper and calcium salts (Cu(NO3)2·3H2O, CuCl2, Ca(NO3)2·4H2O and CaCl2) were investigated. To find out the suitable electrospinning solution for producing the high purity CaCu3Ti4O12 nanofibers, solutions containing different copper and calcium salts were prepared and CaCu3Ti4O12 fibers with different morphological and size were produced. The results showed that the nature of the metals complexes in the ceramic solutions had an obvious effect on the rheological behavior of the electrospinning solutions. FTIR spectras of the electrospinning solutions demonstrated that the interaction between the metal ions and carbonyl groups in the polyvinylpyrrolidone unit occurred and the polyvinylpyrrolidone chains underwent conformational variations. Intensity of the interaction between the metal ions and polymer chains in chloride salts solutions is more than nitrate salts solutions in order to the viscosities of chloride solutions that are more than nitrate solutions. So, thinner high purity polycrystalline CaCu3Ti4O12 nanofibers with diameters ranging <200 nm were successfully synthesized by selecting a novel solution containing copper and calcium nitrates after sintering at 900 °C for 4 h. 相似文献
36.
37.
《Ceramics International》2014,40(6):7947-7951
Lead free (1−x)(0.8Bi0.5Na0.5Ti0.5O3–0.2Bi0.5K0.5TiO3)–xBiZn0.5Ti0.5O3 (x=0–0.06) (BNT–BKT–BZT) thin films were deposited on Pt(111)/Ti/SiO2/Si(100) substrates by a sol–gel processing technique. The effects of BZT content on the structural, dielectric, ferroelectric and piezoelectric properties of the BNT–BKT–BZT thin films were investigated systematically. The BNT–BKT–BZT thin films undergo a transition from ferroelectric to relaxor phase with increasing temperature. The phase transition temperature decreases with the increase of BZT content. The BNT–BKT–BZT thin film with x=0.04 exhibits the best ferroelectric properties (Pmax=40 µC/cm2 and Pr=10 µC/cm2), largest dielectric constant (ε=560) and piezoelectric constant (d33=40 pm/V). This finding demonstrates that the BNT–BKT–BZT thin film has an excellent potential for demanding high piezoelectric properties in lead free films. 相似文献
38.
《Journal of the European Ceramic Society》2014,34(13):3151-3157
As a new black ceramic pigment, encapsulated carbon black pigment has been prepared by a sol–gel-spraying method. The obtained pigment sintered at 900 °C for 2 h in air has a deep black hue (L* = 19), indicating carbon black can be fully covered. In the pigment, a dense coating layer on carbon black is formed due to the fast transformation from sol into gel by rapid extraction of solvent. The transparent silica phase spaces out the fine crystalline (zirconia or zircon), which permits to display the color of carbon black. This preparation method provides a way to prepare the encapsulated pigments. It will provide more colorful ceramic pigment applied in ceramic decoration by encapsulating. 相似文献
39.
《Journal of the European Ceramic Society》2014,34(13):3139-3149
ZrB2 powder was coated with 5% ZrOC sol–gel precursor and sintered by SPS. Relative densities >98% were achieved at 1800 °C with minimal grain growth and an intergranular phase of ZrC. Carbon content in the precursor determined the type of reinforcing phase and porosity of the sintered composites. XRD, SEM and EDS studies indicated that carbon deficiency resulted in ZrO2 retention, improving ZrB2 densification with oxide particle reinforcement. Excess carbon resulted in ZrC formation as the reinforcing phase, but could yield porosity and residual carbon at grain boundaries. These two types of ZrB2 composites displayed different densification and microstructural evolution that explain their contrasting properties. In the extreme oxidative environment of oxyacetylene ablation, the composites with ZrC-C maintained superior leading edge geometry; whereas for mechanical strength, a bias towards the residual ZrO2 content was beneficial. This highlighted the sensitivity of processing carbon-precursors in the initial sol–gel process and the carbon content in ZrB2-based composite systems. 相似文献
40.
High‐Temperature Capture of CO2 on Lithium‐Based Sorbents Prepared by a Water‐Based Sol‐Gel Technique 下载免费PDF全文
A convenient water‐based sol‐gel technique was used to prepare a highly efficient lithium orthosilicate‐based sorbent (Li4SiO4‐G) for CO2 capture at high temperature. The Li4SiO4‐G sorbent was systematically studied and compared with the Li4SiO4‐S sorbent prepared by solid‐state reaction. Both sorbents were characterized by X‐ray diffraction, scanning electron microscopy, nitrogen adsorption, and thermogravimetry. The CO2 sorption stability was investigated in a dual fixed‐bed reactor. Li4SiO4‐G exhibited a special Li4SiO4 structure with smaller crystalline nanoparticles, larger surface area, and higher CO2 adsorption properties as compared with Li4SiO4‐S. The Li4SiO4‐G sorbent also maintained higher capacities during multiple cycles. 相似文献