Correlation of Wettability and Interfacial Reaction to the Densification and Dielectric Properties of Fluxed-BaTiO₃

Reducing the sintering temperature of BaTiO3 has typically been achieved through the use of a fluxing agent to promote densification by liquid phase sintering. Liquid phase formation in these systems is due either to the melting of the flux or to the formation of a eutectic liquid between the flux and BaTiO3. In this paper, the correlation between the wettability and interfacial reactions between fluxes and BaTiO3 with respect to the densification behavior associated with liquid phase sintering, and the resulting dielectric properties is presented. Fluxes used in this study include 5ZnO*2B2O3, 5CdO*2SiO2, Pb5Ge3O11, CuO*TiO2, 3Bi2O3*B2O3, and LiF

Highly selective and sensitive fluorescent chemosensor for femtomolar detection of silver ion in aqueous medium

AbstractThe chemical sensing for the trace level detection of silver ion in aqueous solution still remains a challenge using simple, rapid, and inexpensive method. We report that thionine can be used as a fluorescent probe for the detection of Ag+ ion. The successive addition of Ag+ ion to the solution containing thionine quenches (turns-off) the fluorescence intensity of thionine. Association and quenching constants have been estimated by the Benesi–Hildebrand method and Stern–Volmer plot, respectively. From the plot, the nature of the fluorescence quenching was confirmed as static quenching. An important feature of our chemosensor is high selectivity towards the determination of silver ion in aqueous solution over the other competitive metal ions. The detection limit of the sensor achieved 5fM for Ag+ ion, which is superior to all previously reported chemosensors. The NMR and FT-IR studies were also carried out to support the complex formation between thionine and Ag+ ion. The practicality of the proposed chemosensor for determination of Ag+ ion was carried in untreated water samples

Characteristics of Bilayer Molybdenum Films Deposited Using RF Sputtering for Back Contact of Thin Film Solar Cells

Mo films prepared under a single deposition condition seldom simultaneously obtain a low resistivity and a good adhesion necessary for use in solar cells. In order to surmount the obstacle, bilayer Mo films using DC sputtering at a higher working pressure and a lower working pressure have been attempted as reported in the literature. In this study, RF sputtering with different powers in conjunction with different working pressures was explored to prepare bilayer Mo film. The first bottom layer was grown at a RF sputtering power of 30 W and a working pressure of 12 mTorr, and the second top layer was deposited at 100 W and 4.5 mTorr. The films revealed a columnar growth with a preferred orientation along the (110) plane. The bilayer Mo films reported an electrical resistivity of 6.35 × 10−5 Ω-cm and passed the Scotch tape test for adhesion to the soda-lime glass substrate, thereby qualifying the bilayer Mo films for use as back metal contacts for CIGS substrates

Direct pyrolysis and ultrasound assisted preparation of N, S co-doped graphene/Fe3C nanocomposite as an efficient electrocatalyst for oxygen reduction and oxygen evolution reactions

Bifunctional electrocatalysts to enable efficient oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are essential for fabricating high performance metal–air batteries and fuel cells. Here, a defect rich nitrogen and sulfur co-doped graphene/iron carbide (NS-GR/Fe3C) nanocomposite as an electrocatalyst for ORR and OER is demonstrated. An ink of NS-GR/Fe3C is developed by homogeneously dispersing the catalyst in a Nafion containing solvent mixture using an ultrasonication bath (Model-DC150H; power − 150 W; frequency − 40 kHz). The ultrasonically prepared ink is used for preparing the electrode for electrochemical studies. In the case of ORR, the positive half-wave potential displayed by NS-GR/Fe3C is 0.859 V (vs. RHE) and for the OER, onset potential is 1.489 V (vs. RHE) with enhanced current density. The optimized NS–GR/Fe3C electrode exhibited excellent ORR/OER bifunctional activities, high methanol tolerance and excellent long-term cycling stability in an alkaline medium. The observed onset potential for NS–GR/Fe3C electrocatalyst is comparable with the commercial noble metal catalyst, thereby revealing one of the best low-cost alternative air–cathode catalysts for the energy conversion and storage application

Effect of Ta2O5 and Nb2O5 Dopants on the Stable Dielectric Properties of BaTiO3–(Bi0.5Na0.5)TiO3-Based Materials

In this study, BaTiO3–(Bi0.5Na0.5)TiO3 ceramics with various amounts of Ta2O5 dopant were investigated for their ability to enhance high-temperature stability to meet X9R specifications. The results were compared to those for ceramics with the common Nb2O5 additive. The best composition appeared to be 0.9BaTiO3–0.1(Bi0.5Na0.5)TiO3 with 2 mol% Ta2O5 dopant sintered at 1215 °C, which had a dielectric constant of 1386, a tanδ value of 1.8%, temperature coefficients of capacitance (TCCs) of −1.3% and 1.2%, and electrical resistivities of 2.8 × 1012 and 1.5 × 1010 Ω·cm at 25 °C and 200 °C, respectively. Its microstructure consisted of fine equiaxed grains with a perovskite structure and an average grain size of 0.46 μm and some rod-like grains of second-phase Ba6Ti17O40 with a size of approximately 3.2 μm. The Ta2O5 dopant caused a reduction in the grain size and a slight increase in trapped pores. The temperature dependence of the dielectric constant flattened and the Curie point was dramatically suppressed with the addition of Ta2O5 dopant, leading to smooth dielectric temperature characteristics over a relatively broad temperature range. The X9R formulations and their dielectric properties were highly repeatable in this study

Thermal and mechanical properties of polylactide/aluminum trihydrate composites with addition of organoclay and carbon fiber

[[sponsorship]]National Natural Science Fundation of China[[conferencetype]]國際[[conferencedate]]20120722~20120725[[booktype]]紙本[[iscallforpapers]]Y[[conferencelocation]]Harbin, Chin

Interaction of Ag/Pd Metallization with Lead and Bismuth Oxide-based Fluxes in Multilayer Ceramic Capacitors

An ongoing challenge for future developments in high-performance ceramic multilayer capacitors and integrated ceramics is to reduce the internal electrode cost and thickness without sacrificing yield or reliability. Key to these developments is a thorough understanding of the interactions which occur between flux-sintered dielectrics and low-cost, Ag/Pd electrodes. in this paper we present results on the pahse equilibria of Ag/Pd electrode systems with Bi2O3 and PbO fluxes. the conditions under which the bismuth reaction occurs and reactions in the Pd-PbO system are reported. Results show that the equilibrium phases which form depend strongly upon the Ag/Pd ratio and temperature. These phases include PdBi2O4, Pd(Bi), PdPbO2, Pd(Pb), and PbPd3. the PdBi2O4 and PdPbO2 phases decompose when PdO destabilizes, resulting in a series of reactions which result in oxygen evolution and partial melting of components. the exact phase relations of the Ag/Pd-Bi2O3-O2(air) system and Ag/Pd-PbO-O2(air) system have been established for the first time and are discussed in terms of their impact on multilayer, cofired structures

Interaction of Silver/palladium Electrodes with Lead-and Bismuth-based Electroceramics

In this study the phase relations between Pd or 70Ag/30Pd electrode systems with commercially important Bi-or Pb-based oxides were determined to establish the conditions under which detrimental interfacial chemical reactions may occur. For the reaction of Pd with Bi compounds, PdBi2O4 formation was observed if the reaction proceeded at temperatures less than 835°C. at higher temperatures a Pd (Bi) alloy formed containing the maximum solubility of the Bi, i.e., 16 at.%. For the reaction of Pd with Pb compounds, a Pd (Pb) alloy formed which in all instances exhibited the maximum solubility of the Pb, i.e., 14 at.%. These reactions had an adverse effect on the local stoichiometry and composition of the dielectric, causing depletion of Bi or Pb. Studies on commercial capacitor dielectrics from DuPont (X7R and Z5U formulations) and Pb (Mg1/3Nb2/3)O3 showed that the use of Pd electrodes decreased the dielectric constant substantially, which was due to the formation of a low permittivity phase in series connectivity with the unaltered dielectric

Designing Hybrid Lanthanum Stannate/Functionalized Halloysite Nanotubes as Electrode Material for Electrochemical Detection of 4‑(Methylamino)phenol (Metol) in Environmental Samples

Electrochemical applications such as electrical conductivity, sensitivity, selectivity, cost-effectiveness, and sampling techniques of different forms of pyrochlore oxide have been a field of current interest. In this regard, pyrochlore structured lanthanum stannate nanoparticles (LSO) decorated with functionalized halloysite nanotubes (f-HNT) were prepared via hydrothermal followed by sonochemical synthesis. The obtained samples were characterized through various spectroscopic and microscopic methods to investigate the LSO@f-HNT structure and morphology. Electrocatalytic studies of LSO@f-HNT were performed by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The beneficial response of LSO interacting with the hollow structured f-HNT groups of aluminol (Al–OH) and siloxane (Si–O–Si) enhances the electron transmission channel and active site size, both of which contribute to improved electrocatalytic performance. The fabricated sustainable LSO@f-HNT electrocatalyst exhibits outstanding selectivity and linear range (0.01–480 μM) with a detection limit of 2.1 nM and produces good recovery results (97.8–99.68%) under the optimized measurement conditions. This study discusses the design of the LSO@f-HNT composite and its application as an electrode material for the sensitive and focused electrochemical detection of hazardous Metol. This research demonstrates that LSO and f-HNT (LSO@f-HNT) is an excellent electrode material for electrochemical detection of Metol in real-world samples