| High dielectric ceramics have a very wide application in the market, because of its important application in electrical and electronics, IT, electric fields of applied science is the hot dot of the research center in many countries. BaTiO3 with high dielectric is the dominant material of the environment-friendly materials. Because of its high temperature coefficient and the instability with voltage and frequency and many other undesirable properties, in order to improve its dielectric properties ,the modification of its structure is always the focus of the international research field. Barium titanate is simple compound with highest dielectric constant, its room-temperature dielectric constant closes to 1600,as the dominant high dielectric capacitor materials. The continuous trend of miniaturization in the field of dielectrics requires higher and higher volumetric efficiencies, which can be realized in two ways : (1) raising dielectric permittivity ; (2) reducing dielectric layer thickness. Although with the control of the different synthesis method and grain size, we meet the Y5V index, room permittivity increased to about 6000, but it still can not overcome such as high temperature coefficient and instability with the voltage and frequency and many other undesirable properties. At present, all science workers use rare earth which is referred as"the vitamin of the modern industry",as the dopants of barium titanate to modify its structure so as to optimize its dielectric properties. Therefore, this paper adopts barium titanate as the research object, codoping one or more different kinds of rare earth elements, make it incorporated into BaTiO3 lattice A sites or B sites , for the purpose of further improvement of BaTiO3 dielectric properties. According to mutual substitution of the atoms and charge balance mechanism , we obtain a novel dielectric ceramics found on BaTiO3. Study the technology of the ceramic preparation process of single-phase ceramic by the cold pressing . And using the X-ray powder diffraction (XRD) , calculating the lattice constant ; using scanning electron microscope (SEM) to analyze the purity of phase; and commenting on the grain size and distribution, the purity of the product , the solid solubility of rare earth , comments of dielectric properties , the effect of the ferroelectric hysteresis on dielectric properties, insulation performance, and defect of chemistry.In this article the cold-pressing ceramic processing technique was used to prepare Barium Titanate samples doped with Europium, codoped with strontium and zirconium, lanthanum and the zirconium, strontium and cerium , (Ba,Sr)(Ti,Ce)O3 ceramics by slight La doping.based on the interatomic mutual substitution and the electric charge balance mechanism, the strontium and the lanthanum occupy the A(Ba) sites, the zirconium and the cerium occupy the B(Ti) sites, Eu2+ ions occupy the A(Ba) sites, the Eu3+ ions occupy the A(Ba) sites or occupy the B(Ti) sites.Through various tests and calculations we know that: when zirconium co-doped with lanthanum or strontium on barium titanate ceramics, though it forms a single-phase solid solution, from the XRD or dielectric testing we can know that density is lower than only the zirconium doped barium titanate ceramics . The maximum dielectric constant is smaller than the only zirconium doped barium titanate ceramics.The mainly relationship is that Zr4+ ions with the larger ionic radius substitute Ti sites in the octahedral TiO6 skeleton of the perovskite ,cause larger cell expansion,. but less in relation with the formation of complex defects doping in A sites and B sites. Barium titanate ceramics codoped with strontium and zirconium have a lower dielectric loss, barium titanate ceramic codoped with lanthanum and zirconium have a lower dielectric。At low temperature they are a good energy-saving materials.Barium titanate ceramics codoped with strontium and cerium did not form the typical perovskite structure, and have a peak at 28.6°. This shows that it did not form single-phase structure.Sr and Ce can not be fully incorporated into the BaTiO3 lattice, namely, the solid solution of Sr and Ce in BaTiO3 is weaker than the case of each ion-doped in BaTiO3.The solid solution of (Zr, Sr) in BaTiO3 is much higher than that of (Ce, Sr) in BaTiO3. As (Zr, Sr) codoped in BaTiO3 , single phase ceramics can be formed, but when (Ce, Sr) codoped in BaTiO3 , second phase BaCeO3 appears.In order to enhance the solid solution of the (Ce, Sr) in BaTiO3,we can dope trivalent rare-earth occupy A sites so as to generate Ti vacancies ,and further improve the incorporation of Ce, thus avoid appearance of the second phase BaCeO3.Slight lanthanum was doped in barium titanate codoped with cerium and strontium used the same technique.XRD and dielectric test of samples was measured. We can know that the slight lanthanum doped in barium titanium generate Ti vacancies and make it easy for the incorporation of Ce. XRD pictures show us a more obvious perovskite structure. The appeareace of BaCeO3 will be lower with the reduction of the strontium content , and can modify the formation of the structure and properties of ceramics.The high-purity BaCO3, TiO2, and Eu2O3 re-agents were adopted to prepare 5 % Eu-doped BaTiO3 ceramics according to mixed valence. Site occupation and valence state of Eu ions in barium titanate were investigated by X-ray diffraction (XRD), electron spin resonance (ESR), Raman spectroscopy (RS), and dielectric measurements. The results indicated that Eu ions prefer occupying Ba sites to Ti sites and induce Ti-vacancy defects. The occurrence of mixed valence of Eu3+/Eu2+ is dependent of Ba/Ti and (Ba+Eu)/Ti ratios. When Ba/Ti = 1, a large amount of Eu ions are incorporated into Ba sites and induce Ti-vacancy defects, and some Eu ions enter Ti sites to show amphoteric behavior with self-compensation mode ( Eu3B +a ? Eu3T+i), but no mixed valence occurs. When Ba/Ti < 1 and (Ba+Eu)/Ti > 1, Eu ions occupy Ba sites, and the lower Ba/Ti ratio may give rise to the occurrence of mixed valence of Eu3+/Eu2+.
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