For HfO2‐based films, which are mainly prepared by atomic layer deposition, the desired ferroelectric (FE) properties typically vanish while extending the thickness beyond a limit of about 50 nm. Herein, the successful fabrication of a 1 μm‐thick piezoelectric La:HfO2 film is demonstrated using chemical solution deposition, paving the way toward sensor and actuator applications. After identifying the optimal La content, the film thickness is increased from 45 nm to 1 μm. Polarization and strain measurements evidence the persistence of the FE properties at all thicknesses and even a slight improvement due to a better orientation of the polar axis at higher thicknesses. Scanning electron microscopy and X‐ray reflectivity reveal a fine‐grained microstructure and a density of only 80% of the theoretical value, which seems to be a common issue of solution‐deposited HfO2‐based films, based on the performed literature survey. Using tilt‐angle‐dependent X‐ray diffraction scans, homogeneous nucleation is found to be the likely root cause of the observed microstructure. It is suggested that this microstructure issue is key for the optimization of cycling stability of solution‐based films to exploit the full potential of the HfO2 for cost‐efficient, thick piezoelectric films.

An aerosol‐assisted sol–gel method is used to prepare mesoporous tin silicate catalysts that exhibit a record activity in the synthesis of ethyl lactate from dihydroxyacetone and ethanol. The method is based on the formation of an aerosol from a solution of precursors and surfactant. During the fast drying of the droplets, the surfactant self‐assembles and the Sn‐silica matrix is formed by polycondensation reactions. After calcination, the resulting material is composed of a true tin‐silicon mixed oxide in the form of spherical microparticles with calibrated mesopores of 5–6 nm. Sn species are incorporated in the silica network, mainly in the form of single sites. This makes these catalysts highly active for the targeted reaction, as shown by record turnover numbers. The catalyst is recyclable and truly heterogeneous as it can be reused for several cycles and it does not leach.

Standing Lamb waves in vibrating plates enable haptic interfaces. If the out‐of‐plane displacement of these waves exceeds 1 µm at frequencies above 25 kHz, a silent friction modulation can be created between a human finger and a vibrating plate. A fully transparent friction‐modulation haptic device based on a piezoelectric thin film is demonstrated. The antisymmetric Lamb mode induced at 73 kHz allows for a functional performance that fulfills all conditions for practical use. Out‐of‐plane displacement reaches 2.9 µm when 150 V unipolar voltage is applied. The average transmittance of the whole transducer reaches 75%. The key points of this technology are: 1) a thin HfO2 layer between lead zirconate titanate film and substrate that prevents chemical reaction between them; 2) the efficient integration of transparent indium tin oxide electrodes and solution‐derived piezoelectric lead zirconate titanate thin film onto optical‐grade fused silica; and 3) the use of a transparent insulating layer made of SU‐8 photoresist.

Inkjet printing is currently gaining momentum as a low‐cost and eco‐friendly additive manufacturing technique for electronics. Patterning of functional metal oxide thin films on high surface energy substrates via inkjet printing remains a challenge and requires assistance from lithographic processes. This work unveils a novel process for lithography and etching‐free patterning of lead zirconate titanate (PZT) films on pristine platinized silicon through the use of inkjet‐printed alkanethiolate‐based templates. The technique requires neither lithography nor etching, respectively, before and after PZT printing. The described process allows for feature sizes in the sub‐100 µm range with control over the thickness of the final film. Inkjet‐printed PZT displays typical ferroelectric and piezoelectric properties of solution‐derived thin films, with remnant polarization 13 µC cm−2, coercive field 58 kV cm−1, permittivity 900, dielectric losses 0.07, and effective longitudinal piezoelectric coefficient 50 pm V−1.

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