Defect greatly affects the microscopic structure and electrical properties of perovskite piezoelectric ceramics, but the microscopic mechanism of defect‐driven macroscopic properties in the materials is not still completely comprehended. In this work, K0.5Na0.5NbO3+x mol CuSb2O6 lead‐free piezoelectric ceramics were fabricated by a solid‐state reaction method and the defect‐driven evolution of piezoelectric and ferroelectric properties was studied. The addition of CuSb2O6 induces the formation of dimeric false(CunormalNb″′−VnormalO∙∙false)′ (DC1) and trimeric false(VnormalO∙∙−CunormalNb″′−VnormalO∙∙false)∙ (DC2) defect dipoles. At low doping concentration of CuSb2O6 (0.5‐1.0 mol%), DC1 and DC2 coexist in the ceramics and harden the ceramics, inducing a constricted double P‐E loop and high Qm of 895 at x=0.01. However, DC2 becomes more dominant in the ceramics with high concentration of CuSb2O6 (≥1.5 mol%) and thus leads to softening behavior of piezoelectricity and ferroelectricity as compared to the ceramic with x=0.01, giving a single slanted P‐E loop and relatively low Qm of 206 at x=0.025. All ceramics exhibit relatively high d33 of 106‐126 pC/N. Our study shows that the piezoelectricity and ferroelectricity of K0.5Na0.5NbO3 ceramics can be tailored by controlling defect structure of the materials.

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The mode of asymmetric induction in an enantioselective intramolecular allylic substitution reaction catalyzed by a combination of palladium and a chiral phosphoric acid was investigated by a combined experimental and statistical modeling approach. Experiments to probe nonlinear effects, the reactivity of deuterium-labeled substrates, and control experiments revealed that the chiral phosphate anion is involved in stereoinduction. Using multivariable linear regression analysis, we identified that the presence of multiple noncovalent interactions with the chiral environment of the phosphate anion are integral to enantiocontrol in the transition state. The synthetic protocol to form chiral pyrrolidines was further applied to the asymmetric construction of C−O bonds at fully-substituted carbon centers in the synthesis of chiral 2,2-disubstituted benzomorpholines.

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