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Nickel is frequently used as an internal electrode in the advanced base-metal-electrode (BME) multilayer ceramic capacitors (MLCCs). The diffusion of nickel element into the non-reducing perovskite dielectric layers plays an important role in the final quality of MLCCs. In this paper, the diffusion of nickel element from internal electrode to the dielectric ceramic layer was investigated by AES and EPMA experiments. It was shown that during sintering, nickel atoms migrate towards the dielectric layer and an interdiffusion region of hundreds of nanometers in thickness is generated near the internal electrode. The difference in dielectric characteristics between MLCC and disk specimens can be attributed to the existence of the interdiffusion region. [Copyright &y& Elsevier]

In this paper, a bimorph flexural piezoelectric ultrasonic transducer (PUT) with improved design principles for distance measurement was discussed. The profiles of vibration modes of PUT have been measured by laser Doppler interferometry and compared with finite element analysis (FEA) results. The results show the measurement modes and FEA calculated ones are well matched. The combination and comparison between FEA and advanced measurement tools have provided much help to the design and fabrication of PUT. [Copyright &y& Elsevier]

The influences of the Nb/Co ratio on dielectrical properties, and microstructural evolution of the BaTiO3-based X7R ceramics were investigated. The Nb/Co ratios based on the same Co3O4 content of 0.34 wt.% were 3:1, 2:1, 1.7:1, 1.5:1 and 1.3:1, respectively. The ceramics in all of Nb/Co ratio were temperature-stable. The highest dielectric constant at room temperature is 4150. The dielectric constants of the ceramics sintered at the same temperature increased with the decreasing Nb/Co ratio, while the temperature coefficients of capacitance (TCC) rotated clockwise around 25 °C with the decrease of Nb/Co ratio. The TCC under 25 °C increased from negative values to positive ones; the TCC above 25oC decreased to nearly −15%. The dielectric properties of the Nb-rich composition (Nb/Co=3:1) were dependent strongly on the sintering times, while those of the Co-rich compositions were independent on that. The lattice constants parameters (a, c, c/a,) of the ceramics were investigated by XRD analysis. SEM studies showed that the Nb-rich ceramic contained a larger amount of secondary phases, Ba6Ti17O40, than other ceramics. So the Nb/Co ratio can affect the dielectric properties and microstructures of BaTiO3 ceramics significantly. [Copyright &y& Elsevier]

The low-temperature co-firing compatibility between ferrite and dielectric materials is the key issue in the production process of multi-layer chip LC filters. This paper presents the co-firing behavior and interfacial diffusion of ZnTiO3–TiO2 dielectric/Co2Z hexagonal ferrite multi-layer composites. It has been testified that proper constitutional modification is feasible to diminish co-firing mismatch and enhance co-firing compatibility. Interfacial reactions occur at the interface, which can strengthen combinations between ferrite layers and dielectric layers. Titanium and barium tend to concentrate at the interface; iron and zinc have a wide diffusion range. [Copyright &y& Elsevier]

The effects of DC bias fields on the dielectric properties of Ba(Ti1−xZrx)O3 (BTZ) ceramics were investigated. BTZ ceramics exhibited fine DC bias properties. Frequency dispersion and diffusion phase transition were found in BTZ ceramics, whereas the temperature Tm which corresponding to the maximum dielectric constant showed little dependence on the testing frequency. The dielectric constant increased at first and then decreased with the increase of DC bias at the temperature Tm. At temperatures far from Tm the dielectric constant showed a continuous decreasing tendency. The dielectric loss of the ceramics was small and decreased with increasing DC bias at room temperature. The related mechanism was also discussed. [Copyright &y& Elsevier]

The low temperature sintering behaviors and high frequency properties of Cu-modified Co2Z hexaferrites have been investigated. Normally, Cu-modified Co2Z hexaferrite is difficult to be sintered at temperature lower than 1150 °C. By adding a small amount of sintering aid Bi2O3, Cu-modified Co2Z ceramics with high density (more than 95% theoretical density) have been prepared successfully after sintering below 900 °C. The microstructures and properties are significantly influenced by the sintering temperature, the amount of Bi2O3 addition, as well as Cu content. The modified hexaferrite ceramics sintered at 900 °C, exhibited excellent high frequency properties, such as high initial permeability up to 6.6, high quality factor more than 30, high resistivity over 109 Ω cm and good thermal stability. The experimental results show that these materials have a great potential as soft magnetic media for high frequency MLCIs applications. [Copyright &y& Elsevier]

Aqueous gelcasting of PZT is discussed in this paper. Concentrated PZT suspension (50 vol.%) with low viscosity is developed by using triammonium citrate as the dispersant. Zeta potential results suggest that the effect of TAC in decreasing the viscosity of the PZT suspension may be ascribed to its electrostatic stabilization mechanism. A premix solution containing 20 wt.% of AM monomer can provide a mechanical strength of 18 MPa for the green body obtained from 50 vol.% PZT suspension. SEM photos indicate that PZT ceramics with homogeneous microstructure can be fabricated. Comparison of piezoelectric coefficients of gelcast PZT samples with those of the die pressed PZT samples indicates that the additives, including the monomer, the crosslinker and the dispersant etc., show no influence on the piezoelectric property of the PZT samples. [Copyright &y& Elsevier]

Gelcasting is a novel forming method for making high-quality ceramic parts by means of in situ polymerization where only a few percents of a polymerizable binder are needed. In this article the viscosities of lead zirconate titanate (PZT) suspensions with 15–52 vol.% solids loading were studied. After developing a concentrated PZT suspension with a low viscosity, gelcasting was successfully used to form PZT ceramic parts. Microstructures and piezoelectric properties of gelcast samples derived from suspensions with different solids loading were also investigated in comparison with those of die pressed ones. It was found that gelcast samples exhibited slightly stronger piezoelectric effect than the die pressed ones at the same sintering procedure. Based on the comparison of the density and pore structure results of the samples prepared by these two methods, their different piezoelectricity may be attributed to their microstructure difference. [Copyright &y& Elsevier]

The physical characteristics and preparation of novel Z-type hexagonal compound, which have iron deficient composition of Ba3Co2(0.8−x)Cu0.4Zn2xFe23.5O41 (x≤0.30), was investigated. The results show that Zn has little effect on the morphology of compact and homogeneous ferrites with average 10–15 μm of lathy grain size, but make the formation temperature range narrow. In the range of Zn incorporation, the hexagonal cell lattice parameters (a and c) of ferrites reserve stable. However, the key magnetic and electrical properties, such as initial permeability, quality factor, resistivity, dielectric constant and magnetic hysteresis as well as Curie temperature were also characterized. The mechanisms involving in generating these variations were also discussed in this paper. [Copyright &y& Elsevier]

A series of nitrate–citrate gels were prepared from metal nitrates and citric acid via a sol-gel process, in order to synthesize titanium-substituted lithium zinc (LiZn) ferrites with composition of Li0.5(0.4+x)Zn0.6TixFe(2.2−1.5x)O4 (x ranging from 0.05 to 0.20). The thermal decomposition process was investigated by DTA-TGA, IR and XRD techniques. The dried gels can burn in a self-propagating combustion process in air to transform into single-phase, nano-crystalline ferrite particles. The low-temperature sintering was realized using the synthesized powders, and the sintered ferrites have fine-grained microstructures and excellent magnetic properties. Appropriate amounts of titanium substituted for Fe in LiZn ferrites can significantly increase the permeability value. The prepared LiZn ferrites are good materials for multilayer chip inductors. [ABSTRACT FROM AUTHOR]

The influence of Nb2O5 and Co2O3 on the dielectric constant–temperature characteristic of the Sm2O3, CeO2-doped BaTiO3 system was discussed. It can be concluded that Nb5+, Co3+ will be easier to replace the Ti4+ site by using the Nb2O5–Co2O3 composite oxide than by doping Nb2O5, Co2O3 separately. Increasing Co2O3 amount caused a lower dielectric constant and a higher variation rate. A properly sintering temperature can be helpful to flatten the dielectric constant–temperature curve. The BaTiO3-based ceramics doped with the Nb2O5–Co2O3 composition can be sintered at a temperature as low as 1230–1250 °C, and satisfy the X7R required with a high dielectric constant (&epsiv;25 °C>4000) and low dielectric loss (tan δ<2.0%). [Copyright &y& Elsevier]

The sintering and compositional dependencies of dielectric properties in PMW–PT–PNN ceramics have been investigated. The present work confirms that sintering temperature had a large influence on the dielectric properties in this ternary system. It was found that the main causes for the flat temperature dependence are due to shifting and broadening of the dielectric anomaly. [Copyright &y& Elsevier]

The influence of Zn incorporation into Cu-modified Co2Z (Ba3Co2Fe24O41) ferrite on physical characteristics of low-sintered materials, which have stoichiometric compositions of Ba3Co2(0.8−x)Cu0.4Zn2xFe24O41 (x≤0.50), is investigated. The experimental results show that Zn has little effect on the morphology of Cu-modified ferrites. The average 10–15 μm of lathy grain size for Ba3Co2(0.8−x)Cu0.4Zn2xFe24O41 is just like that of Ba3Co2(1−x)Cu0.4Fe24O41. In the range of solid solubility of Zn, the lattice parameters (a and c) of ferrites with Z-type hexagonal phase structure remain stable, compared with the sole Cu-modified ferrite. The variation of key magnetic properties, such as saturation magnetization, remnant magnetization, coercive force, magnetic hysteresis loop and initial permeability, magnetic loss, dielectric constant and Curie temperature of the ferrites as well as the variation mechanism are also addressed in this paper. [Copyright &y& Elsevier]

In order to improve the properties of multi-layer chip inductor device, the dielectric constant and loss tangent as functions of frequency, temperature and composition for a series of samples of Ba3Co2Fe23−12xMn12xO41 hexagonal ferrites were studied. For all samples, a single Z-type phase was established and the lattice constants were calculated. Results show that dielectric constant increases as sintering temperature increases, dielectric constant and loss tangent decrease as frequency increases and as temperature decreases. These effects are attributed to the Maxwell–Wagner double-layer polarization. As the Mn-substitution increased, samples showed abnormal dielectric behavior in the form of relaxation peaks which shifted toward higher frequencies, dielectric constant &epsiv;′ and loss tangent also decrease gradually reaching minimum between x=0.02 and 0.06. The polarization can be explained by the hopping mechanism in that Mn substitution for Fe ions on the B-sites acts to reduce Fe2+ formation. A second mechanism that small polarons may also contribute to the polarization is indicated in this work. [Copyright &y& Elsevier]

Electrical properties and relaxation characteristics for undoped and ZnO-doped BaZrxTi1−xO3 have been studied via complex impedance measurements. The results suggest that at the grain interior Zn2+ substitutes Ti4+ and serves as an acceptor dopant. STEM and EDX analysis confirm the expected presence of Zn and Ti rich phase at the triangle phase boundaries, but find few signals for zinc at the grain core. More insightful studies are needed in order to clarify this point. [Copyright &y& Elsevier]

Ferroxplana ferrites Ba3Co2−xZnxFe24O41 (X=0–1.0) were prepared by a citrate precursor method. X-ray diffraction analysis indicated that single Z-type phase was obtained at a relatively low temperature between 1150°C and 1200°C and no appreciable secondary phase was found. The substitution of Co with Zn caused an increase in the saturation magnetization and a decrease of the Curie temperature. The influences of Zn-substitution on the microstructure and high-frequency properties of the ceramics were investigated. The materials exhibited excellent high-frequency properties. [Copyright &y& Elsevier]

The influences of SrBi2Ta2O9 (SBT) on dielectric and ferroelectric properties of Pb0.94La0.04(Zr0.70Ti0.30)O3 ceramics were investigated systematically. X-ray diffraction (XRD) patterns of PLZT–SBT composite showed that there was no chemical reaction between PLZT and SBT. SEM pictures on fracture section reflected a main transgranular fracture mode. An abnormal and interesting increase of dielectric constant was observed after SBT incorporation. Hysteresis loops of PLZT–SBT composites turned to slimmer shape with the increase of SBT content. No apparent decrease of switchable polarization strength was found in PLZT–SBT composites after repeated polarization switching. HRTEM picture of SBT grain in PLZT–SBT composite revealed a transformation from order to disorder near the tip of grain boundary as well as low angle of grain boundary, which could release concentrated internal stress and served as improvement mechanism of electric fatigue endurance in PLZT–SBT composites. [Copyright &y& Elsevier]

Abstract: Microwave dielectric ceramics of Ba5Nb4−x V x O15 (x =0–1) were prepared by a solid-state reaction method. Vanadium substitution can markedly lower the sintering temperature of Ba5Nb4O15 from 1450 to 1100 °C. The X-ray powder diffraction analysis reveals the multiphase nature of this system. A hexagonal-to-orthorhombic phase transition was also observed for the BaNb2O6 secondary phase. The microwave dielectric properties, such as τ f, ε r and Q × f value, decreased with increasing vanadium content for samples sintered at 1100 °C. There was an apparent increase in τ f and Q × f value for samples (x ≥0.5) sintered at 1200 °C due to the hexagonal-to-orthorhombic phase transition of the BaNb2O6 phase. These results suggested that the microwave dielectric properties of multiphase ceramics strongly depended on the phase compositions and the phase transitions. [Copyright &y& Elsevier]

Piezoelectric ultrasonic motor, a fractional horsepower motor, is different from conventional electromagnetic motor. It combines the features such as lightweight package, high driving torque at low speed, quick response, low consume, zero backlash, self-braking at zero power, no electromagnetic disturbance and noise, and high heat-stability in wicked environment. In this paper, we propose a new type of stepping piezoelectric micro-motor using wiggle vibration mode and three-dimensional contacts between the rotor and stator. Micro-vibration behavior and vibration mode shape of the prototype have been investigated using advanced POLYTEC PSV-300-F laser Doppler vibrometer. The piezoelectric micro-motor has potential applications for camera auto focus lenses, medical apparatus, micro-robots, micro-satellites, precise positioning, micro-machining, aerospace instruments, laser communication, etc. Here, using such two piezoelectric motors an improved manipulator with two degrees of freedom has been realized. [Copyright &y& Elsevier]

Decrease the sintering temperature and doping with multiple functional impurities are necessary to develop the new ceramic electronic components. In this study, we used CdO as a dopant to lower sintering temperature of BaTiO3 with two doping styles: one is synthesis CdO into BaTiO3 to form compound as basic powder, another is adding CdO to the basic powder BaTiO3 before sintering as sintering aid. The different doping style resulted in very different effects. The grain size of the ceramics was controlled efficiently and the sintering was promoted greatly by the first doping style. On the contrary, the ceramic grain is much bigger and the sintering was not promoted efficiently by another doping style. Therefore, the style of doping is very important to the graingrowth controlling. The mechanism of these differences is also discussed. [Copyright &y& Elsevier]

Nanosized LaFeO3 powders of 30 nm particle size were directly prepared by sol-gel auto-combustion at room temperature. The overall process involves three steps: formation of homogeneous sol; formation of dried gel; and combustion of the dried gel. Experiments revealed that LaFeO3 dried gel derived from citrate and nitrate sol exhibits self-propagating combustion at room temperature once it is ignited in air. After auto-combustion, the gel directly transforms into nanosized LaFeO3 particles. The auto-combustion was considered as a heat-induced exothermic oxidation–reduction reaction between nitrate ions and carboxyl group. Differential thermal analysis–thermogravimetry (DTA–TG) was used to study the decomposition of the precursor. The structure of the nanosized LaFeO3 powders was characterized by X-ray diffraction (XRD). [Copyright &y& Elsevier]