Yuan Zhou

High-performance low-cost multilayer textured Pb(Mg1/3Nb2/3)O3–PbZrO3–PbTiO3 (PMN–PZT) piezoelectric ceramic benders were fabricated by combining templated grain growth (TGG) and low-temperature co-firing ceramics (LTCC) process. The d×g values of textured samples were 700–800% higher than that of the random counterpart, which results in 500–600% increase in the output power from vibration energy harvesting. The output power and power density of tri-layer textured sample at the acceleration of 0.43 g were measured to be 903 µW and 15.5 mW/cm3, respectively. The results demonstrate that the multilayer structure results in an increase in output current and a decrease in the matching resistive load.

We report correlation between the electro-mechanical, ferroelectric, optical and opto-electric behavior in Pb(Zn1/3Nb2/3)O3–Pb0.97La0.03(Zr,Ti)O3 transparent ceramics. Optical interaction during current–voltage (I–V) measurements enhanced the current output and revealed its strong dependence on wavelength and power of the impinging radiation. Piezoresponse force microscopy revealed that the improved characteristics at low stoichiometric excess of various elements were related to nano-sized stripe domains. Raman analysis indicated the presence of short-range clusters with rhombohedral–tetragonal phase distributed at much above the Curie temperature. The results reveal the potential of these ceramics in wireless opto-electric devices operating over a wide-range of wavelengths and temperatures. These classes of ceramics have successfully demonstrated in literature for use in pyroelectric generators and UV light energy harvesting, piezoelectric transformers.

We demonstrate a near-flat self-biased magnetoelectric (ME) effect in geometry gradient magnetostrictive-piezoelectric laminates. The near-flat behavior was characterized by a stable ME response over a wide range of magnetic DC bias. By adjusting the configuration of the magnetostrictive layer, we were able to control the magnitude of the self-biased magnetoelectric coefficient. The ME response was found to be almost independent of the applied DC bias in the range of 0∼260 Oe. This bandwidth was almost 650%∼3800% higher than that of the conventional ME composites. This significant advancement opens great potential towards the development of high stability/sensitivity magnetic field sensors and energy harvesters.

We report a magnetoelectric energy harvester structure that can simultaneously scavenge magnetic and vibration energy in the absence of DC magnetic field. The structure consisted of a piezoelectric macro-fiber composite bonded to a Ni cantilever. Large magnetoelectric coefficient ∼50 V/cm Oe and power density ∼4.5 mW/cm³ (1 g acceleration) were observed at the resonance frequency. An additive effect was realized when the harvester operated under dual-phase mode. The increase in voltage output at the first three resonance frequencies under dual-phase mode was found to be 2.4%, 35.5%, and 360.7%. These results present significant advancement toward high energy density multimode energy harvesting system.

This study reports the effect of interfacial structure on the magnetoelectric and ferroelectric characteristics in magnetoelectric laminate thin/thick films. Both bilayer and trilayer magnetoelectric heterostructures were deposited on a Pt/Ti/SiO₂/Si substrate using pulsed laser deposition (PLD) and sol-gel deposition (SGD) respectively. BaTiO₃ [BTO] / Pb(Zr_0.6Ti_0.4)O₃ [PZT] and CoFe₂O₄ [CFO] were used as piezoelectric and magnetostrictive materials. The interface between CFO/PZT and CFO/BTO films was found to exhibit excellent interface without any cracks or delamination. PLD grown BTO on CFO was found to exhibit the columnar structure. SG deposited PZT/CFO/PZT tri-layer structure exhibited granular structure with high density. Ferroelectric and magnetoelectric coefficient of as-grown films was investigated to understand the effect of interface characteristics. Good ME coupling for the trilayer structure provided important insight about the nature of elastic strain coupling.

In this paper, we analyze and elucidate the microstructure and surface morphology evolution of the piezoelectric BaTiO₃ films grown by pulsed laser deposition on platinized silicon substrates. The films exhibited a columnar structure where the surface morphology evolved from a pyramid to star-like to hexagram shape with (111)-preferred orientation and increasing film thickness. In each column, a twin lamellae structure was formed that was found to enhance the lateral growth and coalescence of the grains. The high stability along the reentrant angle of the twin lamellae controlled the competition between the columnar growth and their coarsening. We present a growth model for BaTiO₃ films and demonstrate the correlation of the growth mode and lamella twins during morphological evolution.