[en] The interaction of NO₂ with BaO/Al₂O₃/NiAl(110) model NO_x storage materials was investigated at BaO coverages corresponding to practical systems. The results obtained from these model systems show excellent correlation with those of practical systems. We found a specific, strong interaction between BaO and Al₂O₃, and this interaction profoundly influences the NO_x chemistry. BaO readily forms a Ba-aluminate-like surface phase, and upon the interaction with NO₂, Ba ions are pulled out from this surface layer to form Ba(NO₃)₂ clusters

[en] The study of critical current densities j_c of oxide superconductors and their thick films is a very important practical task because the value of j_c is one of the main criteria for their utilization in modern cryoelectronics. For most devices based on the Josephson effect, the value of j_c ∼ 10² - 10³ A/cm² is acceptable, which is easily attainable for polycrystalline thick films obtained by stenciling. The study of the current-transport phenomenon involves a number of difficulties, especially for direct current, because both the sample itself and the lead-in contacts are resistance-heated during the measurements, which, in turn, results in lower values of the j_c. Measurements with pulsed currents allow one to lower the power that is applied to the sample; the heat that is released in the sample is reduced, in comparison to measurements with direct current, by a factor of the pulsed-current duty cycle. In addition, measurements with direct current detects only the appearance of resistance; it provides no information on the rest of the transition from the normal to the superconductive state, i.e., on the so-called 'tail' of the transition. In this work, the authors studied critical current densities of thick HTSC yttrium-barium cuprate films of the 1-2-3 composition using pulsed current

[en] Various physical treatments of BaCuO₂ samples result in irreversible changes in its Raman spectrum. The prominent peaks at 576 and 628 cm^-1 in the spectra of sintered pellets of BaCuO₂ disappear upon further annealing in air or oxygen or upon mere regrinding of the pellets. Further annealing in air, oxygen, or vacuum does not restore these peaks. Similar but less intense peaks reappear upon exposure of pellets to laboratory environment for several weeks, but these broaden and disappear upon further exposure. These spectral characteristics contrast with those observed in Y123 Raman spectrum. It is concluded that the peaks at 582 cm^-1 and 636 cm^-1 in the spectra of sintered pellets of Y123 are not due to the presence of BaCuO₂

[en] FESEM studies carried out on a high J_c YBa₂Cu₃O_7-δ superconductor, fabricated by Perform Optimized Infiltration Growth Process (POIGP), showed presence of a variety of nano-twins all over the sample. Crossing twins were observed in the vicinity of closely spaced small sized Y₂BaCuO₅ (Y-211) particles. In the regions where Y-211 particles were well separated, no crossing twins were observed. The lattice mismatch effects at Y-211/Y-123 interfaces affecting the widths of the twins in the proximity of Y-211 particles are observed. (author)

[en] e-e scattering between charge carriers in the CuO₂ planes and a 1D electron system causes a temperature-dependent pair-breaking effect on the formation of a commensurate charge-density wave in the 1D system. In order to distinguish between the BCS and CDW states, the nuclear-spin relaxation rates due to magnetic and quadrupole coupling, R_C/R_N and Q_C/Q_N, and the infrared conductivity σ₁(ω) due to singe-particle excitations are found in the presence of the T-dependent pair-breaking process

[en] To study the effects of reduced magnetic anisotropy on hysteresis loops of hard magnets for possible use in self-biased microwave devices, a new family of magnetically oriented (c-axis) In-substituted Ba ferrite was prepared by conventional ceramic techniques. Earlier studies of BaFe_12-x(In,Sc)_xO₁₉ series in single-crystal form have shown that magnetization 4πM and anisotropy field H_k decrease sharply with increasing x. Since hysteresis loops with optimum energy products require uniformly small grains (1 to 3 μm), sintering temperatures were carefully controlled over a range from 1180 to 1075 degree C for 2 h, depending on In content. For nominal values of x ranging from 0 to 1.5, square hysteresis loops with H_c values decreasing from 3500 to 150 Oe were recorded with a high-field hysteresisgraph. The effective H_k values were measured and compared with single-crystal data to estimate the degree of grain alignment for each composition

[en] This book tells of piezoelectric ceramics on BaTiO_3 Pb(Zr, Ti)O_3, properties of piezoelectric ceramics, measurement method of piezoelectric ceramics, manufacturing method of piezoelectric ceramics, property of PbZrO_3-PbTiO_3, transparent ceramics like electro-optics effect, electro-optics ceramics, application of a producer of high voltage, application of ultrasonic generator, ZnO piezoelectric film and its application such as property of ZnO, piezoelectric of ZnO film, manufacturing method of ZnO.

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No abstract available

[en] A synthetic procedure has been developed for the yttrium-barium-copper oxides, in terms of a liquid-mixed citrate precursor and the use of yttrium oxide, barium carbonate, and basic copper carbonate as starting materials. The stability of the citrate gels against phase separation is investigated as a function of the content of metal oxides in the gels and critical concentrations for the individual metals are derived in terms of the maximum metal-to-citric acid ratio across the Y(O)-Ba(O)-Cu(O) phase diagram. Sintering properties and compositions of the products are investigated as functions of the thermal treatment of the citrate precursor. The present citrate-gel procedure does not make use of internal oxidants like nitrates and polymerization agents like glycol. This approach decreases and incineration temperature and leads to a nanodispersed precursor, which e.g., yields virtually phase-pure YBa₂Cu₃O₇ already after the first firing at 900 C in pure O₂