We report the synthesis, structure, microstructure, chemical stability in H2O and CO2, and electrical transport properties of an oxide ion-conducting perovskite-related structure Ba3In2MO8 (M = Zr, Ce, Zr0.5Ce0.5). Powder X-ray diffraction confirmed the formation of a simple cubic perovskite-like structure for Ba3In2ZrO8 (a = 4.205(9) ?), Ba3In2CeO8 (a = 4.234(1) ?), and Ba3In2Zr0.5Ce0.5O8 (a = 4.285(8) ?). The increase in lattice constant is consistent with the Shannon’s ionic radius trend. Among the three samples
investigated, Ba3In2ZrO8 was found to be stable against reaction with pure CO2 at elevated temperature, while the Ce and 1:1 Zr and Ce compounds were unstable at 600 °C. Ba3In2ZrO8, Ba3In2CeO8, and Ba3In2Zr0.5Ce0.5O8 were found to be chemically unstable in H2O at about 50 °C. The bulk electrical conductivity of the samples prepared at different temperatures was found to be nearly
the same; the total conductivity (bulk + grain–boundary + electrode) seems to change with sintering temperature. Both Ba3In2ZrO8 and Ba3In2CeO8, prepared at 1,400 °C, exhibited comparable electrical conductivity of about 6 × 10−3 S cm−1 at 800 °C, which is comparable to that of conventional Y2O3-doped ZrO2 electrolyte. These compounds are very promising electroltes, provided that their chemical and mechnical stabitities are improved
without losing any ionic conductivity. 相似文献
The ferroelectric and switching properties of spray deposited cesium nitrate: poly (vinyl alcohol) composite films at different
substrate temperatures (Ts) have been studied. The optimum value of remanent polarization was obtained in the film deposited at Ts=200°C, which may be due to larger structural distortion (c/a ratio) and less porosity as revealed by x-ray diffraction and field emission scanning electron microscope (FESEM) analysis.
The switching current transients have been analyzed by nucleation limited switching model (NLS) with the Lorentzian distribution
function. This model gives excellent agreement with the experimental polarization current throughout the whole time range.
The switching parameters were determined in the composite films deposited at different Ts and found to be optimum at Ts=200°C. The effect of pulse amplitude on the domain switching properties has also been studied and analyzed. The peak value
of polarization current exhibits an exponential dependence on the external applied field. 相似文献
The X-ray Absorption Near Edge Structure (XANES) of the AuLIII edge in gold metal and in its two compounds AuCN and AuCl3 have been recorded. The observed chemical shifts of the edge and the fine structure peaks in the compounds are discussed.
It is observed that the energy shifts ΔE of the AuLIII due to chemical effects in aurous cyanide (AuCN) and auric chloride (AuCl3) with respect to the pure Au edge is 2.9 eV in AuCN and 0.7eV in AuCl3. The edge widths in AuCN and AuCl3 are found to be almost the same for both the compounds, presumably because electronegativities of CN and Cl are not very
different. The observed fine structure peaks of the discontinuities of AuCN and AuCl3 are displaced progressively away from the main edge. 相似文献
Uncertainty quantification for linear inverse problems remains a challenging task, especially for problems with a very large number of unknown parameters (e.g., dynamic inverse problems) and for problems where computation of the square root and inverse of the prior covariance matrix are not feasible. This work exploits Krylov subspace methods to develop and analyze new techniques for large‐scale uncertainty quantification in inverse problems. In this work, we assume that generalized Golub‐Kahan‐based methods have been used to compute an estimate of the solution, and we describe efficient methods to explore the posterior distribution. In particular, we use the generalized Golub‐Kahan bidiagonalization to derive an approximation of the posterior covariance matrix, and we provide theoretical results that quantify the accuracy of the approximate posterior covariance matrix and of the resulting posterior distribution. Then, we describe efficient methods that use the approximation to compute measures of uncertainty, including the Kullback‐Liebler divergence. We present two methods that use the preconditioned Lanczos algorithm to efficiently generate samples from the posterior distribution. Numerical examples from dynamic photoacoustic tomography demonstrate the effectiveness of the described approaches. 相似文献
The present article reports the synthesis and characterisation of a highly conducting composite polymer gel electrolyte, namely polyethylene glycol–polyvinyl alcohol (PVA)–ammonium succinate system. Formation of an amorphous composite gel electrolyte has been evidenced in differential scanning calorimetry experiments. Thermogravimetric analysis of the composite gel electrolyte has shown better thermal stability of films containing 25 wt% PVA. Composite gel system containing 10 wt% PVA exhibits optimal ionic conductivity (4.0 × 10?4 s cm?1) and its variation with temperature follows Vogel, Tamman and Fulcher relationship. The magnitude of variation in ionic conductivity (with temperature) of these composite electrolytes and its Williams, Landel and Ferry fit reveals liquid-like charge transport. Composite electrolyte with 25 wt% PVA appears to be a suitable candidate for device applications on the basis of experimental findings. 相似文献
The heat transfer performance and entropy analysis are done in a compact loop heat pipe (CLHP) with Al2O3/water and Ag/water nanofluid. A compact loop heat pipe having a flat square evaporator with dimensions of 34 mm (L)?×?34 mm (W)?×?19 mm (H) has been fabricated and tested for the heat load ranging from 30 to 500 W. The experimental tests are conducted by keeping the CLHP in the vertical orientation with distilled water, silver (Ag)/water and aluminium oxide (Al2O3)/water nanofluid having low volume concentrations of (0.09% and 0.12%). The effect of wall and vapour temperature, evaporator and condenser heat transfer coefficient, thermal resistance on the applied heat loads is experimentally investigated and compared. The experimental results showed that the evaporator thermal resistance is reduced by 34.70% and 20.21%, respectively, for 0.12 vol% of Ag, Al2O3 nanoparticles when compared with that of the distilled water. For the same volume concentrations of Ag, Al2O3 nanoparticles, an enhancement of 34.52%, 23.7%, 39.27% and 30.8%, respectively, observed for the convective heat transfer coefficients at the evaporator and condenser. The entropy is also reduced by 19.08% and 11.58% when Ag and Al2O3 nanofluids are used as the operating fluid. From the experimental tests, it is found that the addition of small amount of Ag nanoparticles in the working fluid enhanced the operating range by 15% when compared with that of Al2O3/water nanofluid without the occurrence of any dry-out conditions.
Chloroform extract from the leaves of Turraea vogelii Hook f. ex Benth demonstrated cytotoxic activity against a chronic myelogenous leukemia cell, K-562 with IC50 of 14.27 μg/mL, while chloroform, ethyl acetate and methanol extracts from the stem of the plant inhibited K-562 cells growth with IC50 of 19.50, 24.10 and 85.40 μg/mL respectively. Bioactive chloroform extract of Turraea vogelii leaves affords two triterpenoids: oleana-12,15,20-trien-3β-ol (1), and oleana-11,13-dien-3β,16α,28-triol (2), with six fatty esters, ethyl hexaeicos-5-enoate (3), 3-hydroxy-1,2,3-propanetriyltris(tetadecanoate) (4), 1,2,3-propanetriyl(7Z,7′Z,7′′Z)tris(-7-hexadecenoate) (5), 1,2,3-propanetriyl(5Z,5′Z,5′′Z)tris(-5-hexadecenoate) (6), 1,2,3-propanetriyltris(octadecanoate) (7), and 2β-hydroxymethyl tetraeicosanoate (8). Tetradecane (9), four fatty acids: hexadecanoic acid (10), tetradecanoic acid (11), (Z)-9-eicosenoic acid (12), and ethyl tetradec-7-enoate (13) were isolated from chloroform extract of Turraea vogelii stem. 1,2,3-propanetriyltris(heptadecanoate) (14), (Z)-9-octadecenoic acid (15) and (Z)-7-tetradecenoic acid (16) were isolated from ethyl acetate extract while (Z)-5-pentadecenoic acid (17) was obtained from methanol extract of the plant stem. Compounds 1, 2, 5, 6, 11, 12, 15, 16 and 17 exhibited pronounced antiproliferative activity against K-562 cell lines. 相似文献
Specimens of iron-doped indium oxide (In1-xFex)2O3 with x?=?0.015, 0.03, 0.045 and 0.06, amalgamated through a traditional solid-state reaction method followed by H2/air sintering, were characterised using an X-ray diffractometer (XRD), a vibrating sample magnetometer (VSM), and a scanning electron microscope (SEM) to investigate their structural, magnetic and morphological properties respectively. According to XRD plots, all the specimens exhibit cubic bixbyite structures along with ancillary phases. Magnetic assessment showed that In2O3 has a negative susceptibility, exhibiting diamagnetic behaviour at room temperature. The doping of Fe ions induces ferromagnetic (FM) ordering, which is enhanced with increasing doping content. The strength of the magnetisation increases when the specimens are exposed to H2 but is reduced on further air sintering. A bound magnetic polaron (BMP) model is successfully fitted to the observed FM data involving localised carriers and magnetic cations. A multivariate assessment viz. a hierarchical cluster analysis (HCA) was used to corroborate and strengthen the experimental determined magnetic properties. A homogeneous particle distribution was observed in all SEM micrographs and is validated through MATLAB-based simulation by applying a watershed segmentation algorithm. Surface plots also confirm the change in magnetic properties with increase in doping concentration. 相似文献