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The first and second harmonic electromechanical responses and their cross-correlation in Ag-ion conducting glass were investigated using band-excitation electrochemical strain microscopy (ESM). Consecutive ESM images with increasing magnitudes of the applied AC voltage allowed observation of not only reversible surface displacement but also irreversible silver nanoparticle formation above a certain threshold voltage. The second harmonic ESM response was anti-correlated with the first harmonic response in many local regions. Furthermore, the nucleation sites of silver nanoparticles were closely related to the anti-correlated regions, specifically, with low second harmonic and high first harmonic ESM responses. The possible origins of the second harmonic ESM response are discussed.

⟨001⟩pc textured K0.5Na0.5NbO3 (KNN) ceramic was found to exhibit a 65% improvement in the longitudinal piezoelectric response as compared to its random counterpart. Piezoresponse force microscopy study revealed the existence of larger 180° and non-180° domains for textured ceramic as compared to the random ceramic. Improvement in piezoresponse by the development of ⟨001⟩pc texture is discussed in terms of the crystallographic nature of KNN and domain morphology. A comparative analysis performed with a rhombohedral composition suggested that the improvement in longitudinal piezoresponse of polycrystalline ceramics by the development of ⟨001⟩pc texture is determined by the crystal structure.

Imprint is a degradation mechanism in ferroelectrics that results in the displacement of the polarization hysteresis loop along the electric field axis. We develop a model using a nonlinear thermodynamic analysis coupled with electrostatics to show that such internal voltage offsets can originate from asymmetrically distributed trapped space charges. The electrostatic interactions are established through a built-in polarization due to the space charges and the spontaneous polarization. Numerical results for Ba0.8Sr0.2TiO3 show that the maximum electric field offset does not necessarily occur due to charges trapped near the electrodes.

We have grown 5mol% MgO-doped multilayered Ba1−xSrxTiO3 (BST) films having a nominal thickness of 220nm with compositions of each layer as BST60/40, BST75/25, and BST90/10 (upgraded). We also fabricated undoped upgraded BST and uniform BST60/40 films for comparison. Results show that Mg-doping improves dielectric loss (tanδ=0.008) and yields better surface roughness (∼3.1nm) compared to undoped upgraded BST. Mg-doped films displayed excellent temperature stability with temperature coefficient of capacitances of −0.94 and 1.14ppt∕°C from 20to90°C and 20to−10°C, respectively. Mg doping resulted in a moderate dielectric tunability (29%) compared to undoped BST (65.5%) at 444kV∕cm.