Effect Of Interfaces On Structure And Dielectric Properties Of CMN/CT Multilayered Films

It is well known that the development of thin film science has been based on the surface and interface physics. The mechanical, thermal and electrical properties of surface and interface have been the foundation of many thin-film devices, possessing vital influence on the structures and properties of thin film, herein the properties of composite thin films rather have"1+1>2"synergistic effect than the simple accumulation from its different components. Hence only have a good command of surface and interface structure could we improve synthetic process of film materials, obtain the film material with great structural stability and favorable properties, study correlation between structures and properties deeply and proceed on the design and preparation of multilayered structural functional thin film material effectively.In this paper, Pechini method was employed to prepare Ca (Mg1/3Nb2/3) O3 (CMN) and CaTiO3 (CT) precursor solution. The effects of electrode and heterogeneous interfaces on microstructure, morphology and dielectric properties of Ca(Mg1/3Nb2/3)O3/CaTiO3 (CMN/CT) multilayered (ML) thin films which were prepared by liquid spin-coating process were investigated systemically. The results showed that the CMN/CT ML thin films, in which CT and CMN phases could exist independently, possessed pure single perovskite structure, even thickness and dense smooth surfaces, different electrode interface and different number of heterogeneous interfaces hardly effected on phase structure of the films, but had obvious impact on the morphology and dielectric properties of CMN/CT ML thin films. Under the same layer nnumbers, heterogeneous components and numbers of heterogeneous interfaces, the surface morphology and dielectric propertiesthe of the sample NI-4-2 with CMN as the first layer and the last layer were better than the sample NI-4-1 with CT as the first layer and the last Layer. When the layer numbers, heterogeneous components and electrode interface layer were invariable, the dielectric constant increased, the dielectric loss and RMS roughness of the films surfaces decreased with the increase in number of heterogeneous interfaces of CMN/CT ML thin films. The morphology and dielectric properties of the TNI-1, TNI-3, TNI-5, TNI-11, TNI-4-1 and TNI-4-2 multilayer films with the heterogeneous interface layers treated by 15% HNO3 were better than the corresponding samples which have not been treated.In order to analyse quantitatively the regularity of interface layers'influence on the dielectric properties of thin films, the circuit analysis method was introduced through the simply topological connection relations of discrete components such as pure resistor and capacitor. According to the multilayer mode and dielectric loss mechanism of CMN/CT heterogeneous thin films, the equivalent circuit of CMN/CT ML thin films was simulated, and the theoretical formulae of the dielectric constant and loss of thin films were established. The effect of interface layer's contribution on the dielectric properties of CMN/CT ML thin films dielectric properties has been investigated theoretically. The results indicated that the theoretical results of the dielectric constant and loss agreed well with experimental ones, the heterogeneous interface layers of CMN/CT ML thin films could improve the dielectric properties of thin films, and the electrode interface layers also had an impact which is different with different electrode dielectric layer on the dielectric properties of thin films, and reducing the thickness of the interfacial transition layer was useful to improve the dielectric properties of CMN/CT multilayered thin films. Theoretical analysis was agreed well with experimental results.