Preparation and dielectric properties of CuAlO2 ceramics

Within this work, the focus was on preparation of the delafossite CuAlO2 single phase powder and ceramic with a high density by the solid state synthesis, and on dielectric properties of the as-synthesized ceramic. The reaction between the nanoboehmite γ-AlOOH, with a high specific surface area, and the Cu2O, with the particles below 1 μm, was enhanced by comminution in a high energy mill, which resulted in reduction of the particle size and consequently shorter diffusion paths between constituent powders. The phase pure CuAlO2 powder was synthesized upon heating the reagent powder mixture two times for 10 h at 1100oC in the inert argon atmosphere as confirmed by the X-ray analysis. The ceramic with 86% of theoretical density was obtained after sintering the CuAlO2 powder compact at 1100oC for 2 h in air. According to the X-ray analysis the ceramic sample was single-phase. The bulk of the sample revealed a dense microstructure with a uniform distribution of porosity within the delafossite matrix. However, traces of Cu-rich impurities have been identified at the surface of the pellets by the EDXS analysis. The semiconducting nature of the ceramic sample was confirmed by the temperature dependent dielectric parameters measurements (ε’ and tgδ) in the 10 kHZ-1MHz frequency range between 297 and 473 K

Ceramic packaging of PiezoMEMS devices

In the contributionthe design and the fabrication of two different types of ceramic packaging for PiezoMEMS devices ispresented. The first ceramic packaging is designed for housing the piezoelectric energy harvester. This packaging is made using LTCC technology and in the final application willintegrate piezoelectric device, electroniccircuit, storage capacitor and other components into the complex microsystem. The second packaging is developed for piezoelectric vibrating device as a part of water-purification system. In this case,the thick-film technology is used for electrical interconnection of piezoelectric actuators and for the hermetic watertight insulation of the system

Inkjet-printing-derived lead-zirconate-titanate-based thick films for printed electronics

International audienc

Lead-Free Sodium Potassium Niobate-Based Multilayer Structures for Ultrasound Transducer Applications

Thick films with nominal composition (K0.5Na0.5)0.99Sr0.005NbO3 (KNNSr) on porous ceramics with identical nominal composition were investigated as potential candidates for environmentally benign ultrasonic transducers composed entirely of inorganic materials. In this paper, the processing of the multilayer structure, namely, the thick film by screen printing and the porous ceramic by sacrificial template method, is related to their phase composition, microstructure, electromechanical, and acoustic properties to understand the performance of the devices. The ceramic with a homogeneous distribution of 8 μm pores had a sufficiently high attenuation coefficient of 0.5 dB/mm/MHz and served as an effective backing. The KNNSr thick films sintered at 1100 °C exhibited a homogeneous microstructure and a relative density of 97%, contributing to a large dielectric permittivity and elastic constant and yielding a thickness coupling factor kt of ~30%. The electroacoustic response of the multilayer structure in water provides a centre frequency of 15 MHz and a very large fractional bandwidth (BW) of 127% at −6 dB. The multilayer structure is a candidate for imaging applications operating above 15 MHz, especially by realising focused-beam structure through lenses to further increase the sensitivity in the focal zone

Far infrared and Raman response in tetragonal PZT ceramic films

PbZr0.38Ti0.62O3 and PbZr0.36Ti0.64O3 thick films deposited by screen printing on (0 0 0 1) single crystal sapphire substrates and prepared at two different sintering temperatures, were studied by Fourier-transform infrared reflectivity, time-domain THz transmission spectroscopy and micro-Raman spectroscopy. The dielectric response is discussed using the Lichtenecker model to account for the porosity of the films and to obtain the dense bulk dielectric functions. Results are compared with bulk tetragonal PZT 42/58 ceramics. The dynamic response in the films is dominated by an overdamped lead-based vibration in the THz range, as known in PZT, but its evaluated dielectric contribution is affected by the porosity and roughness of the surface

Bulk relaxor ferroelectric ceramics as a working body for an electrocaloric cooling device

The electrocaloric effect (ECE), i.e., the conversion of the electric into the thermal energy has recently become of great importance for development of a new generation of cooling technologies. Here, we explore utilization of [Pb(Mg1/3Nb2/3)O3]0.9[PbTiO3]0.1 (PMN-10PT) relaxor ceramics as active elements of the heat regenerator in an ECE cooling device. We show that the PMN-10PT relaxor ceramic exhibits a relatively large electrocaloric change of temperature TEC >1 K at room temperature. The experimental testing of the cooling device demonstrates the efficient regeneration and establishment of the temperature span between the hot and the cold sides of the regenerator, exceeding several times the TEC within a single PMN-10PT ceramic plate

Structure and the Electrical Properties of Pb(Zr,Ti)O3 - Zirconia Composites

In this work, the effect of introducing tetragonal yttria-stabilized zirconia (TZ) particles in soft [Pb0.98Ba0.01][(Zr0.53Ti0.47)0.98Nb0.02]O3 (PZT) was investigated. Both microstructure and electrical properties of the PZT–xTZ (x = 0, 2, 5, 10, 20 vol%) composites were studied and correlated. The addition of zirconia hinders the matrix grain growth, resulting in smaller grains. According to X-ray diffraction analysis, zirconia containing composites have a higher rhombohedral-to-tetragonal phase ratio, in addition to lower dielectric and piezoelectric properties, in comparison to pure PZT. Electrical properties, in terms of strain– and polarization–electric field hysteresis curves, are presented and correlated with the observed phase compositions and microstructures. The extrinsic contribution to the piezoelectric properties in PZT and PZT–xTZ was studied by measuring the frequency and the stress field amplitude dependences of the piezoelectric d33 coefficient