Synthesis and Properties of Lead Magnesium Niobate Zirconate Relaxor Materials

Two materials were prepared with composition PbMg0.3-Nb0.6Zr0.1O3 (PMNZ/10) and PbMg0.32Nb0.65Zr0.03O3 (PMNZ/3). Slight modifications in lead oxide content of these materials were made to study its influence on the sintering properties. The stoichiometric PMNZ/3 gave the best results. It has a sintering temperature as low as 900°C and a relative dielectric constant of 10 000 at room temperature

Dysprosium-doped (Ba, Sr) TiO3 thin films on nickel foilsfor capacitor applications

The substitution in (Ba0.70Sr0.30)TiO3 thin films by the rare-earth element dysprosium prepared at 1000°C by chemical solution deposition on nickel foils was investigated. The relatively large thermal budget applied (via annealing temperature) is shown to enhance the solubility of the Dy3+doping ion into the crystal lattice of the perovskite films. Preference for B-site occupancy of this amphoteric cation was further promoted by the addition of BaO excess (1 mol%), which results in slightly larger grains in the films as observed by scanning electron microscopy. Despite this Ba-rich composition, the presence of secondary phases in the thin films was not detected by X-ray diffraction. Transmission electron microscopy revealed no evidence for local segregation of Dy at grain boundaries, neither the formation of NiO at the interface between the film and the metal foil was observed. The substitution of Ti4+ by Dy3+ leads to the formation of strong electron acceptors in the system, which balance the number of ionized oxygen vacancies arisen from the reductive crystallization atmosphere used during processing. As a consequence, the dielectric loss (tan σ) and leakage conduction measured in the resulting thin-film capacitors were significantly reduced with respect to nominally undoped samples. The improvement of this capacitor feature, combined with the relatively high permittivities obtained in the films (490-530), shows the effectiveness of dysprosium doping within a thin-film fabrication method for potential application into the multilayer ceramic capacitor technology

Effect of TiO2 doped Ni electrodes on the dielectric properties and microstructures of (Ba0.96_{0.96}Ca0.04_{0.04})(Ti0.85_{0.85}Zr0.15_{0.15})O3_{3} multilayer ceramic capacitors

The effects of TiO2-doped Ni electrodes on the microstructures and dielectric properties of (Ba0.96Ca0.04)(Ti0.85Zr0.15)O3 multilayer ceramic capacitors (MLCCs) have been investigated. Nickel paste with a TiO2 dopant was used as internal electrodes in MLCCs based on (Ba0.96Ca0.04)(Ti0.85Zr0.15)O3 (BCTZ) ceramic with copper end-termination. The microstructures and defects were analysed by microstructural techniques (SEM/HRTEM) and energy-dispersive spectroscopy (EDS). The continuity of the electrode of the MLCC was measured using a scanning electron microscope, which showed that the continuity of the electrode for the MLCC with a TiO2-doped Ni electrode was approximately 90%. However, continuity of the electrode for a conventional MLCC was below 80%. The continuity of the TiO2-doped Ni electrode showed significant improvement in the MLCC, which was due to no reaction between Ni and BCTZ

Dysprosium-Doped (Ba,Sr)TiO 3 Thin Films on Nickel Foilsfor Capacitor Applications

The substitution in (Ba0.70Sr0.30)TiO3 thin films by the rare-earth element dysprosium prepared at 1000°C by chemical solution deposition on nickel foils was investigated. The relatively large thermal budget applied (via annealing temperature) is shown to enhance the solubility of the Dy3+doping ion into the crystal lattice of the perovskite films. Preference for B-site occupancy of this amphoteric cation was further promoted by the addition of BaO excess (1 mol%), which results in slightly larger grains in the films as observed by scanning electron microscopy. Despite this Ba-rich composition, the presence of secondary phases in the thin films was not detected by X-ray diffraction. Transmission electron microscopy revealed no evidence for local segregation of Dy at grain boundaries, neither the formation of NiO at the interface between the film and the metal foil was observed. The substitution of Ti4+ by Dy3+ leads to the formation of strong electron acceptors in the system, which balance the number of ionized oxygen vacancies arisen from the reductive crystallization atmosphere used during processing. As a consequence, the dielectric loss (tan σ) and leakage conduction measured in the resulting thin-film capacitors were significantly reduced with respect to nominally undoped samples. The improvement of this capacitor feature, combined with the relatively high permittivities obtained in the films (490–530), shows the effectiveness of dysprosium doping within a thin-film fabrication method for potential application into the multilayer ceramic capacitor technology

Hydroxyl Defect Effect on Reoxidation of Sc-Doped (Ba,Ca)(Ti,Zr)O 3 Fired in Reducing Atmospheres

The behavior of grain and grain-boundary conductivity of acceptor (Sc)-doped (Ba,Ca)(Ti,Zr)O3 ceramics sintered in moist reducing atmosphere and subsequently reoxidized in dry and moist atmosphere was investigated by means of impedance spectroscopy (IS). In moist firing atmosphere, water vapor was found to react with oxygen vacancies, forming positively charged hydroxyl defects inline image on regular oxygen sites in the crystal lattice. Proton hopping is considered to raise the ionic conductivity significantly. Therefore, hydroxyl defects inline image in turn influence the grain conduction. Hydroxyl defects inline image are also considered to be responsible for alternations of the dielectric maximum at the Curie point

Hydrothermal synthesis and characterization of europium doped bariumtitanate nanocrystallites

International audienceBarium titanate nanocrystallites were synthesized by a hydrothermal technique from barium chloride and tetrabutyl titanate. Single-crystalline cubic perovskite BaTiO3 consisting of spherical particles with diameters ranging from 10 to 30 nm was easily achieved by this route. In order to study the influence of the synthesis process on the morphology and the optical properties, barium titanate was also prepared by a solid-state reaction. In this case, only the tetragonal phase which crystallizes above 900°C was observed. High-temperature X-ray diffraction measurements were performed to investigate the crystallization temperatures as well as the particle sizes via the Scherrer formula. The lattice vibrations were evidenced by infrared spectroscopy. Eu3+ was used as a structural probe, and the luminescence properties recorded from BaTiO3:Eu3+ and elaborated by a solid-state reaction and hydrothermal process were compared. The reddish emission of the europium is increased by the nanometric particles