Dielectric Properties of Alkoxy-Derived BaTiO3 Films on LaNiO3/Pt/TiOx/Si(100)
BaTiO3 films with higher degrees of (100) orientation were deposited using both of the heterogeneous LaNiO3 nucleation layer and homogeneous BaTiO3 buffer layer. The microstructure and dielectric properties are characterized. The temperature dependence of the dielectric properties is additionally discussed. The alkoxy-derived 1-mum thick BaTiO3 had the unique microstructure and showed predominant (100) orientation. The film showed ferroelectric to paraelectric transition around at 105degC, and improved dielectric properties. The improvement is considered to be due to the simultaneous control of crystallographic and microstructural characteristics by using the double nucleation and buffer layers.
Preparation and Characterization of BaTiO3 Thick Films with Li2O-SiO2 Sintering Aid
The effect of adding a Li2SiO3 (LSO) sintering aid for low temperature fabrication of BaTiO3 (BT) thick films was investigated. LSO-added BT thick films were prepared by the screen printing method on Pt-coated ZrO2 substrates. Their sintering properties were significantly improved by the addition of LSO, and the relative density of the BT thick film fired in air at 1200°C was 96%. The secondary phase was not observed. The dielectric, ferroelectric, and piezoelectric properties of the LSO-added BT thick films were examined. A typical ferroelectric hysteresis loop was observed, and the remnant polarization (Pr) was 7.5 µC/cm2. The dielectric constant was 3200, and tan δ was 2.1%. The maximum piezoelectric constant d31 calculated from the displacement of the Pt/BT/Pt/ZrO2 monomorph cantilever was -140 pm/V, and d33 measured with an atomic force microscope was 320 pm/V.
Measuring Sheet Resistances of Dielectrics Using Co‐Planar Hydrogel Electrochemical Cells with Practical Applications to Characterize the Protective Quality of Paints on Sculptures
Electrical properties of thin dielectric films at the solid-liquid phase boundary are an important performance characteristic of many devices, coatings and sensors. In this paper, co-polymeric hydrogels of polyacrylic acid co-sulfonic acid, swollen with a salt solution to act as the solid electrolyte, were used to assess interfaces using electrochemical impedance spectroscopy (EIS) in a co-planar geometry. Silane-modified glasses were characterized by the co-planar hydrogel EIS cell and found to be distinguishable based on their surface monolayer chemistry. EIS measurements were also made on primed and painted metal substrates, using both test panels and an outdoor sculpture, Tony Smith's Stinger. The panels were then exposed to accelerated and outdoor weathering and showed degradation on the surface paint layers, which was observable electrochemically using EIS and confirmed visually by SEM. Electrochemical spectral features were compared between data from a standard paint-test cell versus this co-planar hydrogel cell; both cell types were able to measure coating capacitance, providing useful information about the condition of the bulk coating. Yet, sheet resistance (Rs) was a spectral feature seen only by the co-planar hydrogel cell. Thus, it can be concluded that the use of such co-planar hydrogel cells can provide an earlier warning sign to coating degradation and such cells provide a new type of spectral information that is not assessable by the standard geometry.