Large photovoltaic effect with ultrahigh open-circuit voltage in relaxor-based ferroelectric Pb(In_(1/2)Nb_(1/2))O_(3)-Pb(Mg_(1/3)Nb_(2/3))O_(3)-PbTiO_(3)ceramics

Recently,the anomalous photovoltaic effect of ferroelectric materials has attracted considerable attention in the construction of efficient solar cells owing to the above-bandgap photovoltage of these materials.In this study,we investigate the anomalous photovoltaic effect of relaxor-based ferroelectric Pb(In_(1/2)Nb_(1/2))O_(3)-Pb(Mg_(1/3)Nb_(2/3))O_(3)-PbTiO_(3)(PIMN-PT)ceramics with large remnant polarization and a narrow optical bandgap.Excellent photovoltaic performance with an ultrahigh open-circuit voltage of 23 V(575 V/cm)is achieved,which is higher than the open-circuit voltages of all reported polycrystalline materials with similar thickness.The phase structure,microstructure morphology,domain structure,ferroelectric and optical characteristics are analyzed,which could provide clues to the origin of the ultrahigh open-circuit voltage of PIMN-PT ceramics.The results suggest that the relaxor-based ferroelectric PIMNPT system is a potential candidate for photovoltaic solar energy conversion devices.

Domain structure and dielectric diffusion-relaxation characteristics of ternary Pb(In_(1/2)Nb_(1/2))O_(3)-Pb(Mg_(1/3)Nb_(2/3))O_(3)-PbTiO_(3)ceramics

Relaxor-based ternary Pb(In1/2Nb1/2)O_(3)-Pb(Mg_(1/3)Nb_(2/3))O_(3)-PbTiO_(3)(PIN-PMN-PT)single crystals and ceramics are promis­ing candidates for high-performance electromechanical conversion devices.It is known that the domain structure and dielectric diffusion-relaxation characteristics are crucial to the excellent performances of relaxor ferroelectrics.In this work,we prepared the PIN-PMN-PT ceramics with various PIN/PMN proportions and systematically investigated their domain structure and dielec­tric diffusion-relaxation properties.The effect of PIN/PMN proportion on the domain size and dielectric diffusion-relaxation characteristics was also studied.The investigations showed that PIN-PMN-PT ceramics presented multi-type domain patterns comprising irregular island domains and regular lamellar domains.Moreover,the dependent relations of PIN/PMN proportions on the dielectric diffusion and domain size indicated that the PIN composition has a stronger lattice distortion than PMN composi­tion;increasing the PIN proportion can enhance the dielectric diffusion and decrease the domain size.Our results could deepen the understanding of structure-property relationships of multicomponent relaxor ferroelectrics and guide the design and exploration of new high-performance ferroelectric materials.

Performance enhancement of ultrasonic transducer made of textured PNN-PZT ceramic

In this paper,0.36Pb(Ni_(1/3)Nb_(2/3))O_(3)-0.24PbZrO3-0.40PbTiO_(3)(PNN-PZT)ceramic was prepared,and texture engineering was performed on this PNN-PZT ceramic to improve its electromechanical properties and temperature stability.Single element ultra-sonic transducers were prepared using PNN-PZT,PNN-PZT textured ceramics,and their performance were evaluated and com-pared using a PZT-5H ceramic based transducer as the benchmark.It is shown that the sensitivity and bandwidth of the PNN-PZT textured ceramic-based transducer are much superior to regular PNN-PZT ceramic and PZT-5H ceramic based transducers.

Decision making framework for autonomous vehicles driving behavior in complex scenarios via hierarchical state machine

With the development of autonomous car,a vehicle is capable to sense its environment more precisely.That allows improved drving behavior decision strategy to be used for more safety and effectiveness in complex scenarios.In this paper,a decision making framework based on hierarchical state machine is proposed with a top-down structure of three-layer finite state machine decision system.The upper layer classifies the driving scenario based on relative position of the vehicle and its surrounding vehicles.The middle layer judges the optimal driving behavior according to the improved energy efficiency function targeted at multiple criteria including driving efficiency,safety and the grid-based lane vacancy rate.The lower layer constructs the state transition matrix combined with the calculation results of the previous layer to predict the optimal pass way in the region.The simulation results show that the proposed driving strategy can integrate multiple criteria to evaluate the energy efficiency value of vehicle behavior in real time,and realize the selection of optimal vehicle driving strategy.With popularity of automatic vehicles in future,the driving strategy can be used as a reference to provide assistance for human drive or even the real-time decision-making of autonomous driving.