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Magneto-electric (ME) ceramic composites of cobalt ferrite (CoF) and lead zirconate titanate (PZT) were prepared by mechanical mixing of the constituent powders followed by cosintering. The cosintering conditions for nano-sized CoF and submicrometer-sized PZT powders were studied in detail. It was found that the CoF powder needs to be presintered at 700°C for 2 h to minimize the differences in the sintering kinetics of the constituent powders. Despite the low cosintering temperatures (900°C–1000°C) the interdiffusion of the cations from both phases was confirmed with energy-dispersive X-ray analysis and X-ray diffraction. Efforts were made to optimize the cosintering conditions to prepare dense ceramic ME composites, which showed the converse ME effect.

An ink consisting of Pb(Zr0.53Ti0.47)O3 (PZT) particles with a median size of 170 nm and a narrow size distribution, in a dispersion of water and glycerol, and with a low viscosity and surface tension, was used for the fabrication of thick films by piezoelectric ink-jet printing. This study reports the printing conditions, the subsequent thermal treatment of the as-deposited layers, and the properties of the sintered PZT thick film. The film, sintered at 1100°C, had a locally dense microstructure and consisted of grains that are a few 100 nm across, as revealed by scanning electron microscopy. A local piezoelectric response of 15 pm/V was measured in the ink-jet–printed PZT thick film by piezoresponse force microscopy.

We present a general protocol for processing cost-beneficial, environmentally benign aqueous-type suspensions containing metal-oxide nanostructured particles, and their patterning with piezoelectric ink-jet printing technology. The critical issues relevant to ink-jet printing are the preparation and stabilization of nanosized particles in a fluid and adjusting its physical properties to the values appropriate for a particular ink-jet printer mechanism. We discuss and illustrate, on a model titania system, the processing of a highly stable, colloidal, water-based suspension containing particles not bigger than 570 nm, prepared by a ball-milling process. For the ink-jet printing experiments, the surface tension and the viscosity of the suspension were modified by the addition of a small amount of the appropriate non-ionic amphiphiles and glycerol. The formation of droplets, their positioning on the substrate, and the shape and uniformity of the dots on the substrate are discussed and correlated with the fluid properties via the inverse Ohnesorge number Z. It was shown successfully that uniform, regular-shaped TiO2 dots with a diameter of 30 μm and a good positioning accuracy on Si/SiO2 substrates could be obtained by jetting a fluid with Z values of 5 and 9 using a piezoelectric ink-jet printer with a nozzle diameter of 21 μm operating at an amplitude of 13 V and a frequency of 5 kHz.

We developed a new, simple method to prepare pure perovskite Pb(Mg1/3Nb2/3)O3 (PMN) from an aqueous suspension in a single annealing step. In this synthesis it is crucial to suppress the reaction between PbO and Nb2O5, which leads to secondary pyrochlore PbxNbyOz phases. Our method is based on the designed arrangement of particles of the starting compounds. The self-assembly of the colloidal aggregates was governed by particle surface charge, which was adjusted by the suspension pH. At pH below 11.8 particle–particle interactions lead to close contacts between lead oxide and niobium oxide particles in the suspension as well as in the dried powders, whereas at pH above 11.8 close contacts between lead and niobium oxide particles are avoided. The suspensions of the starting powders were prepared at pH 10.0, 11.4, 12.5, and in acetone. After heating of the dried suspension with the pH set at 12.5 at 900°C, a pure perovskite PMN powder was obtained. On the contrary, the powders prepared from the pH 11.4, 10.0, and acetone suspensions still contained the detrimental pyrochlore phase after heating at 900°C. The properties of the ceramics prepared from the pH 12.5 suspension are superior in comparison with the other samples.

In2O3–ZnO two-dimensional (2D) structures were processed by ink-jet printing and heating at 150°C and 450°C with the aim for implementation in transparent electronics. The In–Zn-solution precursor, based on In-alkoxide and Zn-acetate in 2-methoxyethanol, was originally designed for chemical solution deposition of thin films. To adapt it for piezoelectric ink-jet printing, the viscosity and surface tension were adjusted by the addition of a more viscous 1,3-propanediol. The optimum values were obtained for the ink consisting of 55 vol% of 1,3-propanediol. The printing parameters including the temperatures of the cartridge and the substrate, and the drop spacing were adjusted to allow patterning with a 40 μm resolution on SiOx/Si and glass substrates. The ink-jet-printed 2D structures heated at 150°C were amorphous and according to infrared spectroscopy organics-free, and upon heating at 450°C they crystallized without any preferential orientation, similarly as the spin-coated thin films, which were studied as a reference.

We have studied the formation of lead–magnesium–niobate Pb(Mg1/3Nb2/3)O3 perovskite powder produced by high-energy milling of the constituent oxides. By applying a low ball-impact energy and a low ball-impact frequency we were able to identify the reaction sequences. The crystal structure and the amount of crystalline and amorphous phases in the powder were determined using a Rietveld refinement. The morphology, structure and chemical composition of the powder were investigated by transmission electron microscopy. The surface composition, possible contamination and the chemical states of the elements were analyzed by X-ray photoelectron spectroscopy. In the early stage of milling the constituent oxides comminute, refine to nanosize dimensions and become amorphous. In the second step the Pb(Mg1/3Nb2/3)O3 nucleates from the amorphous regions where the stoichiometry corresponds to the perovskite. The perovskite phase nucleates and subsequently grows over the course of the milling. Simultaneously, the pyrochlore phase nucleates from the Pb- and Nb-rich regions; however, its nucleation and recrystallization stop after a certain milling time. The powder mixture consists of nanosized Pb(Mg1/3Nb2/3)O3 particles and an amorphous phase when milled for 94 h. No traces of contamination from the milling media were detected.

We have investigated the synthesis of lead-magnesium-niobate–lead-titanate perovskite powder using high-energy milling of the constituent oxides. The compositions of the crystalline and amorphous phases as a function of milling time were determined with X-ray powder diffraction using a Rietveld refinement. The perovskite can be formed by two reaction routes. In the initial stage of milling, it is formed directly from the highly activated nano-sized constituent oxides, and after a certain milling time it is mainly formed from a pyrochlore phase. The obtained as-milled powder consists of crystalline perovskite and an amorphous phase that crystallizes into the perovskite after heating at 800°C.

The synthesis of Pb(Mg 1/3 Nb 2/3 )O 3 (PMN) with high-energy milling was studied by X-ray powder diffraction (XRD) using the Rietveld-refinement method. The results are discussed in terms of the qualitative and quantitative composition of the crystalline and amorphous phases as a function of milling time. The mechano-synthesis of PbO, Nb 2 O 5 , and MgO leads to the formation of perovskite PMN. In the initial stage of milling, particle size reduction and a high degree of amorphization were observed, together with the simultaneous formation of perovskite and pyrochlore-type structures. A mechanism for the formation of PMN by the mechano-synthesis route is proposed.

La 1-y Sr y Fe 1-x Al x O 3-δ perovskites were studied as potential materials for solid-oxide fuel cell (SOFC) cathodes. The phase relations in the LaFeO 3 -SrFeO 3-δ -LaAlO 3 system were investigated by X-ray powder diffraction analysis. The defect structure of the La 1-y Sr y Fe 1-x Al x O 3-δ perovskites was investigated by Mossbauer spectroscopy and weight-loss analysis. Relations between the nonstoichiometry and the conductivity of the La 1-y Sr y Fe 1-x Al x O 3-δ perovskites were investigated. The incorporation of aluminum (x) into LaFe 1-x Al x O 3 was found to have no influence on the defect structure but to decrease the conductivity. The incorporation of strontium (y) into La 1-y Sr y Fe 1-x Al x O 3-δ promotes the formation of anion vacancies and Fe 4+ that lead to higher conductivity.

— This paper discusses the properties of sputtered multicomponent amorphous dielectrics based on mixtures of high-κ and high-bandgap materials and their integration in oxide TFTs, with processing temperatures not exceeding 150°C. Even if Ta2O5 films are already amorphous, multicomponent materials such as Ta2O5—SiO2 and Ta2O5—Al2O3 allow an increase in the bandgap and the smoothness of the films, reducing their leakage current and improving (in the case of Ta2O5—SiO2) the dielectric/semiconductor interface properties when these dielectrics are integrated in TFTs. For HfO2- based dielectrics, the advantages of multicomponent materials are even clearer: while HfO2 films present a polycrystalline structure and a rough surface, HfO2—SiO2 films exhibit an amorphous structure and a very smooth surface. The integration of the multicomponent dielectrics in GIZO TFTs allows remarkable performance, comparable with that of GIZO TFTs using SiO2 deposited at 400°C by PECVD. For instance, with Ta2O5—SiO2 as the dielectric layer, field-effect mobility of 35 cm2/(V-sec), close to 0 V turn-on voltage, an on/off ratio higher than 106, a subthreshold slope of 0.24 V/dec, and a small/recoverable threshold voltage shifts under constant current (ID= 10 μA) stress during 24 hours are achieved. Initial results with multilayers of SiO2/HfO2—SiO2/SiO2 are also shown, allowing a lower leakage current with lower thickness and excellent device performance.