The review summarises state of the art of Research of lead-free piezoelectric ceramics based on alkaline niobates. The challenges include achieving chemical homogeneity of these complex perovskite formulations and optimisation of the piezoelctric response by phase boundary engineering.
COBISS.SI-ID: 31601447
Using a multiscale approach, by combining electron microscopy together with analytical tools, we analyzed the representative multiple-element-modified ceramic material (K,Na,Li)(Nb,Ta)O3-CaZrO3 for which MnO2 was added either before, or after the calcination step. We proved that the functional properties are, to a large degree, sensitive to minor modifications of the synthesis route, and consequently to different material properties on all scales. We showed that all the features, defects and segregation from the micro to the atomic level could be the basis for the challenging reproducibility of modified KNN.
COBISS.SI-ID: 32977959
The 0.9Pb(Mg1/3Nb2/3)O3–0.1PbTiO3 ceramic prepared by mechanochemical synthesis exhibits a much higher electrocaloric temperature change than the solid-state synthesized version, i.e., 2.37 °C at 107 °C and 115 kV/cm. The latter material breaks at fields exceeding 57 kV/Cm. The secondary phases that result from each synthesis are identified and related to different interactions of the individual materials with the electric field.
COBISS.SI-ID: 58273795
The study reveals a unique dynamic response of relaxor ferroelectrics to external fields, reflecting their complex structure in terms of the hierarchical texture of ferroelectric domains on top of the disorder at the atomic scale, both of which strongly affect the mobility of the domain walls.
COBISS.SI-ID: 32051715
We investigated the feasibility of an electrocaloric (EC) cooling device that couples EC and electromechanical responses of highly efficient lead magnesium niobate ceramic material. Two active multilayered cantilevers were stacked in a cascade structure forming a proof-of-concept device that was analyzed in detail. The cooling effect was lower than the EC effect of the material itself, mainly due to poor solid-to-solid heat transfer. This was improved by introducing a layer a glycol that improved the heat transfer.
COBISS.SI-ID: 55105027