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The thermoelectric properties of Sr0.61Ba0.39Nb2O6−δ ceramics, reduced in different conditions, are investigated in the temperature range from 323 K to 1073 K. The electrical transport behaviors of the samples are dominated by the thermal-activated polaron hopping in the low temperature range, the Fermi glass behavior in the middle temperature range, and the Anderson localized behavior in the high temperature range. The thermal conductivity presents a plateau at high-temperatures, indicating a glass-like thermal conduction behavior. Both the thermoelectric power factor and the thermal conductivity increase with the increase of the degree of oxygen-reduction. Taking these two factors into account, the oxygen-reduction can still contribute to promoting the thermoelectric figure of merit. The highest ZT value is obtained to be ∼0.19 at 1073 K in the heaviest oxygen reduced sample. [ABSTRACT FROM AUTHOR]

Sr0.9Ba0.1-x Ti0.8Nb0.2 O3 ceramics (x=0, 0.01, 0.02 and 0.05) are prepared by solid state reaction, whose thermoelectric properties are investigated from 323 K to 1073 K. By introducing A-site nonstoichiometry, the absolute See-beck coefficient is enhanced, while the electrical resistivity is surprisingly reduced due to the significantly enhanced carrier mobility. These results are dramatic in thermoelectric materials, effectively enhancing the power factor. Moreover, the thermal conductivity is reduced, thus the thermoelectric performance of Sr0.9Ba0.1 Ti0.8Nb0.2O3 ceramic is significantly enhanced by A-site nonstoichiometry. [ABSTRACT FROM AUTHOR]

The effect of Co2O3 on the microstructure and electrical properties of Ta-doped SnO2 varistors was investigated. It was found that a sample doped with 0.1 mol% Co2O3 had the highest nonlinear coefficient α = 33, the highest breakdown electrical field EB = 872 V mm−1 and the lowest relative dielectrical constant εr = 598 (measured at 1 kHz). However, 0.1 mol% Co2O3 is not sufficient for densification of SnO2 ceramics, and the relative density of the sample doped with 0.1 mol% Co2O3 (85.8%) is much lower than that of the samples doped with 0.3, 0.5, 0.8 and 1.2 mol% Co2O3 (about 98%). The highest breakdown electrical field and lowest relative dielectric constant of the sample doped with 0.1 mol% Co2O3 are mainly the result of the loose microstructure and the smallest average grain size. The measurements of grain boundary barrier height, ΦB, and grain boundary resistance, RGB, indicate that CoSn× should be located at the depletion layer and is important to the formation of the grain boundary barrier. [ABSTRACT FROM AUTHOR]

Abstract: The effect on the microstructure and electrical properties of (Co, Ta)-doped SnO2 varistors upon the addition of SrCO3 was investigated. The threshold electric field of the SnO2-based varistors increased significantly from 318 to 3624V/mm, the relative dielectric constants of the SnO2-based varistors decreased greatly from 1509 to 69 as SrCO3 concentration was increased up to 2.5mol%. The significant decrease of the SnO2 grain size, from 8.19 to 1.03μm with increasing SrCO3 concentration over the range of 0–2.5mol%, is the origin for increase in the threshold voltage and decrease of the dielectric constants. The grain size reduction is attributed to the segregation of SrCO3 at grain boundaries hindering the SnO2 grains from conglomerating into large particles. Varistors were found to have superhigh threshold voltage and comparatively large nonlinear coefficient α. For 1.5mol% SrCO3-doped sample, threshold electrical field E and nonlinear coefficient α were measured to be 1738V/mm and 23.7, for 2.0mol% SrCO3-doped sample, E and α were 2204V/mm and 24, and for 2.5mol% SrCO3-doped sample, E and α were 3624V/mm and 22. Superhigh threshold voltage and large nonlinear coefficient qualify the Sr-doped SnO2 varistor as an excellent candidate in use for high voltage protection system. The reasons why the grain resistivity of the SnO2-based varistors increased with increasing SrCO3 concentration and the boundary resistivity of the SnO2-based varistors gradually decreased with increasing SrCO3 concentration were explained. [Copyright &y& Elsevier]

Abstract: The effects of Dy2O3 on the microstructure and electrical properties of the SnO2 based varistor system were investigated. It was found that Dy2O3 significantly affects the grain size and electrical properties of the SnO2-based varistors. The sample with 1.00mol% Dy2O3 has the best nonlinear electrical property and the highest nonlinear coefficient (α =26.3) among all samples. By SEM, TEM and EDS images, it was found dysprosium segregates at the grain boundary, which is responsible for “p-type characteristics” of the grain boundaries. The reason that grain size decreases with increasing Dy2O3 concentration is given. The reason why the varistor sample has the excellent nonlinearity is explained. [Copyright &y& Elsevier]

Abstract: The effect on microstructual and electrical properties of (Co, Nb)-doped SnO2 varistors upon the addition of Er2O3 was investigated by scanning electron microscopy and I–V and ε–f relations’ measurements. The threshold electric field of the SnO2-based varistors increased significantly from 305Vmm-1 to 1083Vmm-1, from 384Vmm-1 to 1300Vmm-1, and from 532Vmm-1 to 2270Vmm-1 for samples sintered at 1350°C, 1300°C and 1250°C, respectively, for 1h separately. The relative dielectric constants of the SnO2-based varistors decreased greatly from 2003 to 451 as Er2O3 concentration was increased up to 2.0mol% sintered at 1350°C for 1h, from 1258 to 339 sintered at 1300°C for 1h and from 988 to 185 sintered at 1250°C for 1h. The significant decrease of the SnO2 grain size was found with the Er2O3 dopant for the samples sintered at various temperatures, which is the origin for the increase in the threshold voltage and decrease in the dielectric constants. The grain-size reduction is attributed to the segregation of Er2O3 at grain boundaries, which hinders the SnO2 grains from conglomerating into large particles. Varistors were found to have high density and fairly stable nonlinear coefficient α. For all Er2O3-doped samples, relative density was measured to be more than 98.00% except x=2.0mol% sintered at 1250°C during 1h and nonlinear coefficient α was measured to be around 16. High density and stable nonlinear coefficient α qualify the Er-doped SnO2 varistor as a comparative candidate for high-voltage protection system. [Copyright &y& Elsevier]

Abstract: The CuO and Ta2O5-doped SnO2 system was obtained by conventional ceramics processing. The ceramic phases of samples was analyzed by X-ray diffraction (XRD) and the microstructure by means of scanning electron microscopy (SEM). The electrical field of a single phase of CuO and Ta2O5-doped SnO2 system was studied as a function of current density behavior and compared with the CoO and Ta2O5-doped SnO2 system. A high nonlinear coefficient α=37.9 was obtained. To illustrate the grain–boundary barrier formation of CuO and Ta2O5-doped SnO2-based varistors, a modified defect barrier model is introduced. [Copyright &y& Elsevier]

Abstract: A novel approach was developed to calculate temperature-dependent Seebeck coefficient of heavily doped systems. The electronic density of states (DOS) and Fermi energy were determined and then, using these two parameters, the Seebeck coefficient was calculated by using Boltzmann transport theory. This approach is applied to heavily La-doped SrTiO3. The calculated Seebeck coefficient agrees well with the experimental data. By analyzing the results, it was shown that Seebeck coefficient is greatly affected by the asymmetry of DOS with respect to Fermi energy. [Copyright &y& Elsevier]

Abstract: The Aurivillius type potassium lanthanum bismuth titanate (K0.5La0.5Bi4Ti4O15, KLBT) polycrystalline ceramics with 0.0–1.0wt.% CeO2 were synthesized using conventional solid-state processing. X-ray diffraction analysis revealed that the cerium-modified KLBT ceramics have a pure four-layer Aurivillius type structure. The effects of cerium oxide on the piezoelectric, ferroelectric and dielectric properties on the KLBT ceramics were investigated. By the cerium modification, the piezoelectric activities of KLBT ceramics were significantly improved and the dielectric loss decreased. The piezoelectric coefficient d 33 for the 0.50wt.% CeO2-modified KLBT was found to be 28pCN−1, the highest value among the modified KLBT-based piezoceramics. The reason for piezoelectric activities enhancement with Ce modification was given. The dielectric spectroscopy presented that the Curie temperature for all the KLBT ceramics is higher than 400°C. [Copyright &y& Elsevier]

Abstract: The effects of Sc2O3 doping on the electrical properties of (Co, Ta, Cr)-doped SnO2 varistors were investigated and the maximal nonlinear coefficient () of the sample doped with 0.03mol% Sc2O3 was obtained. It was found that the breakdown electrical field of samples increased significantly with increasing Sc2O3 concentration and the sample doped with 0.08mol% Sc2O3 has the highest breakdown electrical field of 3336V/mm. The measurement of grain size and sample impedances reveal that the increase of grain boundary resistance is the substantial reason for the increase of breakdown electrical field. The increase of grain boundary resistance may be caused by the increase of depletion layer thickness and it can be illustrated by the decrease of relative dielectric constant with increasing Sc2O3 concentration. [Copyright &y& Elsevier]

Abstract: The effect of La2O3 additive on a SnO2-based varistor material sintered at 1350°C for 80min was investigated. It was found that La2O3 significantly decreases the grain size and improves the non-linear electrical properties of SnO2-based varistors. The sample with 1.00mol% La2O3 has the best non-linear electrical property and the highest non-linear coefficient (α=23.0) among all the samples. The reason that the grain size decreases with increasing La2O3 concentration is explained. The permittivity decrease with increasing La2O3 concentration is caused by the ratio of grain size to barrier width. A modified defect barrier model was introduced in which the negatively charged acceptors substituting for Sn ions should be located at the grain boundaries. [Copyright &y& Elsevier]

Abstract: The varistor properties of Sc2O3-doped SnO2·Co2O3·Nb2O5 ceramics were investigated. It was found that the non-linear coefficient presents a peak of 17.1 at the concentration of 0.06mol% Sc2O3, the average grain size decreases from 10 to 5μm, the breakdown electrical field increases from 199 to 1790V/mm and relative electrical permittivity decreases from 2600 to 60 as Sc2O3 concentration was increased up to 0.09mol%. The increase of the breakdown electrical field with increasing Sc2O3 concentration is mainly attributed to the decrease of the average grain size. The reason why the permittivity decreases with increasing Sc2O3 concentration was originated from the ratio of the grain size to the barrier width. To illustrate the grain-boundary barrier formation of (Sc, Co, Nb)-doped SnO2 varistors, a modified defect barrier model was introduced, in which the negatively charged acceptors substituting for Sn ions should be located at SnO2 lattice sites in the depletion layers, instead at the grain interfaces. [Copyright &y& Elsevier]

Abstract: The effects of CuO on the SnO2·Co2O3·Ta2O5 varistor system sintered at 1250°C for 80min were investigated. It was found that CuO significantly affects the grain size and electrical properties of the SnO2-based varistors. The grain size rises from 4.7 to 11.4μm, the breakdown electrical field decreases from 485 to 265Vmm−1 and relative dielectric constant (at 1kHz) increases from 970 to 2451 with an increase in CuO concentration from 0.00 to 1.00mol%. The sample with 0.25mol% CuO has the best nonlinear electrical property and the highest nonlinear coefficient (α =15.7) among all samples. The reason why grain size increases with increasing CuO concentration is explained. Also, the interpretation of the increase in nonlinearity is given. [Copyright &y& Elsevier]

The effects of Pr2O3 on the SnO2·Co2O3·Ta2O5 varistor system sintered at 1300°C for 80min were investigated. It is found that Pr2O3 affects the grain size, electrical properties and the dielectric properties of the SnO2-based varistors. The average grain size decreases from 9.4 to 5.6μm, the breakdown electrical field increases from 2460 to 11,346V/cm, relative dielectric constant (at 1kHz) falls from 1988 to 290 and the resistivity (at 1kHz) rises from 39.3 to 178.3kΩcm with an increase in Pr2O3 concentration from 0.00 to 1.00mol%. The sample with 0.10mol% Pr2O3 has the best nonlinear electrical property and the highest nonlinear coefficient (α=23.9) among all samples. The reason that the grain size decreases with increasing Pr2O3 concentration is explained. A modified defect barrier model is introduced to illustrate the grain-boundary barrier formation of Pr2O3-doped SnO2-based varistors. [Copyright &y& Elsevier]

The electrical nonlinearity of (Ni, Ta) doped SnO2 varistor system was investigated. The nonlinear coefficient α and the barrier height of this varistor system were calculated. It is found that the variations of electrical nonlinear coefficients with acceptor concentrations are in accordance with that of the barrier heights. 0.75 mol% Ni2O3 doped sample sintered at 1370 °C exhibits a high nonlinear coefficient α of 21 and a high breakdown electric field (697 V mm−1 at 1 mA cm−2), but presents a relatively low densification. Among the samples sintered at 1420 °C, the sample doped with 0.75 mol% Ni2O3 and 0.05 mol% Ta2O5 possesses the highest breakdown electric field (469 V mm−1 at 1 mA cm−2) and the highest electrical nonlinear coefficient α of 16.3, which is consistent to its highest defect barrier φB of 0.693 eV. An atom mode for the acceptors and donors to penetrate into SnO2 lattice was put forward. To illustrate the grain-boundary barrier formation of (Ni, Ta) doped SnO2 varistors, a modified defect barrier model was introduced, in which the negatively charged acceptors substituting for Sn ions should not be located at the grain interfaces instead at SnO2 lattice sites of depletion layers. [Copyright &y& Elsevier]

A best nonlinearity properties is obtained in the varistors of Sn–Ni–Nb, via the investigation of the varistors with compositions of (99.2−x)% SnO2+0.75% Ni2O3+0.05% Nb2O5+x% CuO. The sample doped with 1.0 mol% CuO exhibits the highest electrical nonlinear coefficient (α=25) and the highest relative density (96.1%). SEM micrographs show that grain size increases with increasing CuO content. The phenomenon can be explained by interface defect model, the substitution of Cu2+ for Sn4+ facilitates the formation of the defect barriers and facilitates the grain growing. Breakdown voltage increases with increasing CuO when doping less than 1.0 mol% CuO, and reaches a maximum (946 V mm−1) at 1.0 mol% CuO dopant then decreases with increasing CuO. It can also be explained by the effect of Cu2+ substituting for Sn4+. [Copyright &y& Elsevier]

The electron localization in Nb-doped CaMnO3 is analyzed in terms of the space and energy distribution of electronic states employing first-principles calculations. The energy difference of Mn 3d states and Nb 4d states makes NbO6 octahedra impede electrical conduction, so the random distribution of Nb in lattices leads to the localization of electrons near the bottom of the conduction bands. Therefore, although more carriers are introduced when Nb-doping content increases, both the electrical conductivity and absolute thermopower decrease in Nb heavy doped CaMnO3. The calculated transport properties agree well with the experimental data, supporting the analysis of localization.

This study assessed the antibody persistence, and the immunogenicity and safety of a booster dose of a DTaP-IPV//PRP∼T (Pentaxim®, Sanofi Pasteur's AcXim family) combined vaccine and of standalone vaccines one year after primary vaccination in the People's Republic of China. Participants (N=719) previously primed with DTaP-IPV//PRP∼T at 2, 3, 4 months (Group A, N=255), 3, 4, 5 months (Group B, N=233), or DTaP (Wuhan Institute of Biological Products), PRP-T (Act-Hib®) and IPV (Imovax® Polio) at 3, 4, 5 months (Group C, N=231) received boosters of the same vaccines at 18-20 months of age. Seroprotection (SP) and seroconversion (SC) were determined before and 1 month after the booster. Safety was monitored from parental reports. In all groups 87.6-100% of participants had pre-booster protective anti-PRP, -diphtheria, -tetanus and -poliovirus antibody titers; post-booster, all SP rates were 100% and SC was ≥ 80.4% for anti-pertussis titers ≥ 4-fold increase. Reactogenicity was low for each group. These data support the use of the DTaP-IPV//PRP∼T vaccine in the People's Republic of China compared to separate DTaP, IPV, and PRP∼T administration in terms of both safety and immunogenicity., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Objective: The aim of this study was to demonstrate the immunogenicity and safety of diphtheria, tetanus, pertussis (acellular, component), poliomyelitis (inactivated) vaccine (adsorbed) and Haemophilus influenzae type b conjugate vaccine (DTaP-IPV//PRP-T) combined vaccine compared with commercially available DTaP (diphtheria, tetanus and pertussis), Haemophilus influenzae type b (Hib), tetanus conjugate and IPV monovalent vaccine., Methods: Subjects were randomly divided into three groups, Group A and Group B were DTaP-IPV//PRP-T combined vaccine (PENTAXIM(TM)) vaccinated at 2, 3, 4 months of age or 3, 4, 5 months of age respectively; Group C was commercially available DTaP. Hib tetanus conjugate (Act-HIB(TM)) and IPV (IMOVAX PolioTM(TM)) vaccines vaccinated at 3, 4, 5 months of age. All groups received booster dose at 18 to 20 months of age, with antibody titers tested. Non-inferiority analysis was demonstrated in terms of seroprotection/seroconversion rates between Group A, Group B respectively and Group C. Safety information was collected after each vaccination to assess the safety of investigational vaccines., Results: The non-inferiority of DTaP-IPV//PRP-T combined vaccine vaccinated at 2, 3, 4 or 3, 4, 5 months of age versus DTaP, Hib tetanus conjugate and IPV vaccine was demonstrated for all vaccine antigens in both primary and booster phases in terms of seroprotection/seroconversion rates. DTaP-IPV//PRP-T combined vaccine was well tolerated. The rate of solicited/unsolicited severe adverse reactions was very low and similar to the control vaccines., Conclusion: DTaP-IPV//PRP-T combined vaccine was highly immunogenic with good safety profile in Chinese infants, which was comparable to the commercially available control vaccines.

The principle and application in the environmental analysis of Solid Phase Extraction (SPE) combined with Room Temperature Phosphorescence (RTP) analysis were reviewed. The principle, device, separation modes, operation procedures and application of SPE were commented. The merits and shortages in the operation procedure and quantitative analysis of classic RTP were also summarized. The potential application in the trace sample analysis and the advantage of coupling technique of SPE and RTP were indicated. The sensitivity and selectivity of the coupling technique could be greatly increased because of the strong enrichment ability of the SPE materials and the high selectivity of RTP. So far the technique has been successfully used in the analysis of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and polychlorinated dibenzofurans (PClDBFs) in the environmental samples according to their phosphorescence emission after preconcentration on the Whatman 1PS filter paper and C18 or C8 SPE membranes.