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CaBi2Nb2O9 (CBN)‐based high‐temperature piezoelectric ceramics with the formula of CaBi2Nb2−x(W3/4Cu1/4)xO9 were prepared via the traditional solid‐state reaction method. Both the bulk microstructure and the electrical performance of the W/Cu co‐doped CBN‐based ceramics were systematically investigated. The results indicated that the W/Cu incorporation into the Nb‐site altered the crystal structure, which enhanced the piezoelectricity and resistivity. The ceramic with the composition CaBi2Nb1.96(W3/4Cu1/4)0.04O9 exhibited good performance with a high d33 (~14 pC/N) and TC (~939℃). Moreover, the ceramic exhibited a good electrical resistivity (ρ) of 4.91 × 105 Ω·cm and a low dielectric loss (tanδ) of 0.1 at 600℃. Furthermore, the ceramic that was annealed at 900℃ for 2 h presented a d33 value of 13 pC/N, thus indicating good thermal stability of the piezoelectric properties. All these results confirm that the CaBi2Nb1.96(W3/4Cu1/4)0.04O9 ceramic may act as a potential promising candidate for piezoelectric device applications in high‐temperature environments. [ABSTRACT FROM AUTHOR]

In this study, the electrical properties of Bi4Ti3O12‐based Aurivillius‐type ceramics were tailored by a B‐site co‐doping strategy combining high valence Ta5+ and low valence Cu2+. A series of Bi4Ti3−x(Cu1/3Ta2/3)xO12 (BTCT) (x = 0, 0.005, 0.01, 0.015, 0.02, 0.025, and 0.03) ceramics were prepared by the conventional solid‐state reaction method. The effect of Cu/Ta co‐doping on the crystal structure, microstructure, dielectric properties, piezoelectric properties, ferroelectric properties, and electrical conductivity of these ceramics was systematically investigated. Co‐doping significantly enhanced the piezoelectric properties and DC electrical resistivity of the resulting composites. The optimized comprehensive performances were obtained at x = 0.015 with a large piezoelectric coefficient (34 pC/N) and a relatively high resistivity of 9.02 × 106 Ω cm at 500°C. Furthermore, the ceramic also exhibited stable thermal annealing behaviors and excellent fatigue resistance. The results of this study demonstrated great potential of the Cu/Ta co‐doped Bi4Ti3O12 ceramics for high‐temperature piezoelectric device applications. [ABSTRACT FROM AUTHOR]

High‐resolution deformation measurements in a functionally graded hard tissue such as human dentin are essential to understand the unbound water‐loss mediated changes and their role in its mechanical integrity. Yet a whole‐field, 3‐dimensional (3D) measurement and characterization of fully hydrated dentin in both macro‐ and micro‐scales remain to be a challenge. This study was conducted in 2 stages. In stage‐1, a stereo‐digital image correlation approach was utilized to determine the water‐loss and load‐induced 3D deformations of teeth in a sagittal section over consecutively acquired frames, from a fully hydrated state to nonhydrated conditions for a period up to 2 hours. The macroscale analysis revealed concentrated residual deformations at the dentin‐enamel‐junction and the apical regions of root in the direction perpendicular to the dentinal tubules. Significant difference in the localized deformation characteristics was observed between the inner and outer aspects of the root dentin. During quasi‐static loadings, further increase in the residual deformation was observed in the dentin. In stage‐2, dentin microstructural variations induced by dynamic water‐loss were assessed with environmental scanning electron microscopy and atomic force microscopy (AFM), showing that the dynamic water‐loss induced distention of dentinal tubules with concave tubular edges, and concurrent contraction of intertubular dentin with convex profile. The findings from the current macro‐ and micro‐scale analysis provided insight on the free‐water‐loss induced regional deformations and ultrastructural changes in human dentin. [ABSTRACT FROM AUTHOR]

The interface electrochemical and chemical mechanism of the low alloy steel in a 3.5% NaCl solution containing the Ce3+-based inhibitor was investigated by the electrochemical techniques in conjunction with the surface analysis technologies. It was shown that the Ce3+-based inhibitor was an anodic inhibitor with more than 90.0% inhibitory efficiency. The net-shaped inhibiting film with 200 to 500-nm greyish balls was observed on the specimen surface. During the corrosion reaction occurred on the surface of the low alloy steel, the hydrolysis reaction of P3O10 5- and the disproportionation reaction of Ce3+ ions simultaneously occurred, too, resulting in the formation of the net-shaped inhibiting film with nano-scale greyish ball-type products, which contained Ce element and had an obvious effect on the electrochemical process of the low alloy steel in a 3.5% NaCl solution containing the Ce3+-based inhibitor. Therefore, the EIS spectra of the low alloy steel in a 3.5% NaCl solution containing the Ce3+-based inhibitor were composed of a capacitive loop at a high-frequency region and an inductive impedance loop at a low-frequency region. The charge-transfer resistance (Rt) increased with the immersion elapsed time, indicating that the inhibition efficiency of the Ce3+-based inhibitor increased with immersion elapsed time. The calculated data based on the fitted electrochemical parameters showed the partial coverage of the inhibitor. This was further revealed by the analysis of electrochemical kinetics that the inductive impedance (L) loop at a low frequency region resulted from the localized absorption of the Ce3+- based inhibitor on the surface of the low alloy steel in a 3.5% NaCl solution. It was also verified by micro-morphologies. [ABSTRACT FROM AUTHOR]