Complex non-180◦ domain configurations with strong variations in characteristic length (from micrometre size down to the nanoscale) and morphology were found in 0.65Pb(Mg1/3Nb2/3)O3-0.35PbTiO3 (PMN-PT) thick films. The study was done on textured films on the matrix area, away from the grown crystals. This strong variation in domain configurations is most probably the result of the slowing down of the kinetics of the relaxor-to-ferroelectric transition on approaching a grain size around the micrometre, an effect previously reported for bulk ceramics, which results in the stabilization of sub-micrometre and nanoscale intermediate domain configurations. In addition, the influence of the in-plane compressive stress exerted by the substrate on the domain structure was studied as well.
COBISS.SI-ID: 25895463
Thick films of ceramic materials are characterized by constrained sintering due to the clamping of the film onto a rigid substrate. Our research was therefore focused on improving the densification of the K0.5Na0.5NbO3 (KNN) thick films. The potassium-sodium germanate (KNG), which was developed by our group, is known to act as a liquid-phase sintering aid in bulk KNN ceramics. In order to confirm its applicability in KNN thick films, we prepared KNN thick films with and without the KNG. The sintered films prepared without the KNG were porous (24% shrinkage after sintering at 1115°C), whereas the sintered KNN films prepared with 1 mass % of KNG addition were denser (39 – 45% shrinkage after sintering at 1100°C). Additionally, we determined the role of isostatic pressing on the thickness and surface roughness of the films. We found that the isostatic pressing has little effect on film thickness, however, it did resulted in reduced surface roughness (from 8 to 4 micrometres). The acquired knowledge is important for the preparation of high quality KNN thick films with good piezoelectric properties.
COBISS.SI-ID: 26115879