Deposition And Physical Characteristics Of Several Perovskitestructure Ceramics And Superlattice Film

Strongly correlated electron system has attracted lots of attention by both physics and material science communities because it has not only plenty of physical properties, but also great applications. It displays unique properties such as metal-insulator transition, spin-orbital coupling, high-temperature superconductivity and colossal magnetoresistance (CMR), etc., due to strong correlations between spin, charge, orbital and lattice degrees of freedom. As being the focus studying topic, perovskite oxides have numerous interesting properties, such as (anti)ferroelectricity, (anti)ferromagnetic and superconductivity, etc., while these properties could couple to generate some new properties such as multiferroic property.In this thesis we have performed the research of several perovskite oxides piezoelectric ceramics, magnetic triple perovskite ceramics, superlattice thin films and investigated the structure, electrical and magnetic properties of these samples. Detail abstracts are as follows.Lead-free piezoelectric ceramics:Piezoelectric ceramics are important functional materials in industry due to their high piezoelectric performance and good mechanical property. They’re applied in sensor, actuator, transducer, etc. Lead-based ABO3-based Pb(Zr1-xTix)O3(PZT) piezoelectric ceramics exhibit better properties than lead-free counterparts and therefore dominate the market of piezoelectric devices. However, lead is toxic and consequently should be expelled from device materials. For the perspective of environmental protection it is necessary to develop high performance lead-free piezoceramics.Magnetic triple perovskites ceramics:Conventional materials with colossal magnetoresistance has low Curie temperature(Tc) below room temperature(RT) which means they would not have high spin polarization in RT or higher temperature, so these materials cannot be applied for spintronics. It is necessary to find strongly correlated electron system with CMR and high Tc. Ferromagnetic double perovskites exemplified by Sr2FeMo06 have high Tc above RT, large magnetoresistance, and half metallic behavior, therefore, these materials have advantageous for potemtial applications in spintronics. In addition to continuous work on double perovskites, few triple perovsktes with the formula of A3BB’B"O9 have been reported. Triple perovsktes have some unique structural characteristics like face-sharing octahedral and various functional properties like antiferromagnetic, ferromagnetic, or even enhanced magnetoelectric behavior. However, triple perovskites with ferromagnetism are rare in literatures. Triple perovskites SraCrFeMoO9 ceramics have been prepared and the structures, cations’ chemical states, magnetic and transport properties are investigated and discussed.Perovskites superlattice thin films:In recent years, heterostructures composed of different perovskites have attracted much attention. Heterstructures provide opportunities to manipulate thecompetition of various quantum states via artificially designed interfaces, to generate novel functionalities that cannot be found in the respective component units. By pulsed laser deposition, we can atomically modulate the microstructure, magnetic and electrical characteristics of the heterostructures. In this thesis, we discuss the deposition of several perovskites superlattice thin films and their electric and magnetic properties.