PIEZO 2015: Electroceramics for End-users VIII

Piezoelectric materials constitute a wide range of components and devices which find applications in our everyday lives, and in numerous industrial sectors, including medicine, safety, automotive electronics, or non-destructive testing. The eight papers collected in this special issue of Advances in Applied Ceramics represent a selection of topics, which were discussed at PIEZO 2015 Electroceramics for End-users VIII conference. The meeting took place in Maribor, Slovenia from January 25 to 28, 2015, and was the eighth event in the series of bi-annual conferences organised by the Piezo Institute, international not-for-profit organisation established in 2008 by the multidisciplinary EC-funded MIND consortium of academic researchers and leading European companies.

The papers on lead-based ceramics report on processing and characterization of these highly-efficient piezoelectrics. Bakarič et al. studied the effect of pore size and porosity on the functional properties of Pb(Zr_0.53Ti_0.47)O₃ (PZT) ceramics and found that tailored pores in the micron-size range could work as an efficient backing in high-frequency ultrasound transducers.¹ In a study of quasi-static multilayer actuators Mangeot et al.² addressed the importance of their functional characterisation at temperatures up to 200 ^oC, needed for specific applications, e.g. in aeronautics. The large signal properties of both soft- and hard-PZT based actuators are reported, with focus on dielectric losses and creep. Lead-based relaxor ferroelectrics, such as PbMg_1/3Nb_2/3O₃-PbTiO₃ (PMN-PT), are characterized by high dielectric permittivity and polarization, and a large change of polarization with temperature, thus resulting in large electrocaloric (EC) temperature changes. The contribution of Uršič et al.³ addresses the influence of the grain size on the EC temperature change in PMN-PT 70/30 with micron sized grains.

The solid-state crystal growth is a special method for growing single crystals based on the abnormal grain growth in a polycrystalline matrix. The growth of (100-x)(K_0.5Na_0.5)NbO₃-xSrTiO₃ lead-free piezoelectric single crystals on KTaO₃ seeds by this approach was studied by Farooq et al.⁴ It is shown that the addition of SrTiO₃ delays the onset of both single crystal growth and abnormal grain growth in the matrix phase. Wang et al.⁵ studied the structure and ferroelectric properties of lead-free piezoelectric (1-x)Na_0.5Bi_0.5TiO₃-xKNbO₃ (x = 0.02–0.08) ceramics depending on the amount of the KNbO₃ content. The dielectric permittivity versus temperature relationships for the studied compositions revealed two transition temperatures and frequency dispersion, typical for relaxor ferroelectrics. Within the study of the 0.94(Bi_0.5Na_0.5)TiO₃-0.06BaTiO₃ ceramic a procedure to study the X-ray diffraction peak fitting, which could be applied to ceramics with the morphotropic phase boundary compositions is described. ⁶

Bustillo et al. ⁷ proposed a characterization method based on domain wall switching modelling, which was validated by comparison with experimental data. It is shown that such approach may be applied for both microscopic and macroscopic characterization of piezoelectric ceramics. The ferroelectric domain structure is the most important parameter influencing the attainable electromechanical response of piezoelectric ceramics. In a review paper of Deluca⁸ on microscopic texture characterisation several analytical methods to study the microscopic orientation distribution of ferroelectrics are reviewed, with a focus on X-ray diffraction and Raman spectroscopy.

We sincerely hope that this issue of Advances in Applied Ceramics will be useful to researchers working in the field of piezoelectric and multifunctional materials, technologies and devices research and development.

Notes

1. T. Bakarič, T. Rojac, A.-P. Abellard, B. Malič, F. Levassort, and D. Kuščer: ‘Effect of pore size and porosity on the piezoelectric and acoustic properties of Pb(Zr_0.53Ti_0.47)O₃ ceramics’, Adv. App. Ceram., 2016, 115, 66–71.

2. Ch. Mangeot and B. Andersen: ‘Investigation of large signal properties of quasi-static PZT actuators at elevated temperature’, Adv. App. Ceram., 2016, 115, 72–76.

3. H. Uršič, L. Fulanović, M. Vrabelj, Z. Kutnjak, B. Rožič, S. Drnovšek and B. Malič: ‘Electrocaloric properties of 0.7 PbMg_1/3Nb_2/3O₃-0.3PbTiO₃ ceramics with different grain sizes’, Adv. App. Ceram., 2016, 115, 77–80.

4. M. U. Farooq, S.-Y. Ko, and J. G. Fisher: ‘Effect of SrTiO₃ content on the growth of (100-x)(K_0.5Na_0.5)NbO₃-xSrTiO₃ lead free piezoelectric single crystals grown by the solid state crystal growth method’, Adv. App. Ceram., 2016, 115, 81–88.

5. G. Wang, D.A. Hall, T.P Comyn, L. Daniel, and A.K. Kleppe: ‘Structure and Ferroelectric Behaviour of Na_0.5Bi_0.5TiO₃-KNbO₃ Ceramics’, Adv. App. Ceram., 2016, 115, 89–95.

6. A.M. Gonzalez, L. Pardo, M.E. Montero-Cabrera, and L.E. Fuentes-Cobas: ‘Analysis of the rhombohedral-tetragonal symmetries coexistence in lead-free 0.94(Bi_0.5Na_0.5)TiO₃-0.06BaTiO₃ ceramics from nanopowders’, Adv. App. Ceram., 2016, 115, 96–105.

7. J. Bustillo, M. Domenjoud, and J. Fortineau: ‘Characterization of piezoelectric ceramics using inverse problem solving of a polarization switching modeling’, Adv. App. Ceram., 2016, 115, 106–111.

8. M. Deluca: ‘Microscopic texture characterisation in piezoceramics’, Adv. App. Ceram., 2016, 115, 112–122.