采用甘氨酸-硝酸盐（GNP）法合成出La0.6Sr0.4Co1-yFeyO3（y=0～1.0）体系复合氧化物，对合成产物的结构、烧结性能和导电性能进行表征。研究结果表明，不同Co/Fe比例的合成粉料中形成菱形六面体钙钛矿结构，合成粉料的颗粒细小均匀。在室温 ～900℃温度范围内，La0.6Sr0.4CoO3(y=0)的电导率随着温度的提高而单调降低，其它Co/Fe比例样品的电导率随着温度的增加在600℃附近达到最大值。在低温段，La0.6Sr0.4Co1-yFeyO3体系的导电行为符合小极化子导电机制，导电活化能随Co/Fe比例的降低而增大。与常规固相合成法相比，甘氨酸－硝酸盐法制备的La0.6Sr0.4Co1-yFeyO3具有更高的烧结活性和电导率。

采用固相反应法合成出La0.6Sr0.4Co1-yFeyO3体系复合氧化物样品，XRD分析结果证实不同Co/Fe比例的样品中均形成菱形六面体钙钛矿结构，采用固相烧结法制备出致密的La0.6Sr0.4Co1-yFeyO3体系陶瓷。研究结果表明，在室温～900℃温度范围内，La0.6Sr0.4CoO3（y=0）的电导率随温度的增加而单调降低，其它Co/Fe比例样品的电导率随着温度的增加而出现最大值，电导率达到最大值的温度随Co/Fe比例的降低而提高。在低温段，La0.6Sr0.4Co1-yFeyO3体系的导电行为符合小极子导电机制，导电活化能随Co/Fe比例的降低而增加。

La0.6Sr0.4Co0.8Fe0.2O3 was synthesized by a citrate method, and the contributing factors to the formation of homogeneous fine powder with a pure perovskite-type structure were ascertained. The obtained La0.6Sr0.4Co0.8Fe0.2O3 exhibits superior sinterability and mixed electronic-ionic conduction properties than that synthesized by a traditional solid state reaction method.

Mixed electronic-ionic conducting La0.6Sr0.4Co0.2Fe0.8O3 ceramics were prepared by a citrate method and a conventional solid state method, respectively. The chemical state of oxygen on the surfaces of the ceramics made by the two different methods was characterized by X-ray photoelectron spectroscopy (XPS). It was detected that there are five different kinds of oxygen on the ceramic surfaces, including lattice oxygen (OL), chemisorbed oxygen (Oc) in the forms of, O-2, O-1, and O-1, and oxygen in hydroxyl environment (OH). The concentrations of OC +OH relative to total detected oxygen attain 67.11% and 64.80% for the specimens made by the citrate method and the solid state method, respectively. Compared with the specimen made by the solid state method, the specimen made by the citrate method generally exhibits relative larger electronic conductivity and ionic conductivity at an identical measuring temperature. An essential relation between the chemical states of oxygen on the surfaces and the electrical nature of the ceramics was confirmed. It was considered that the mixed electronic-ionic conducting properties are responsible for the complex chemical states of oxygen on the ceramic surfaces.

Microstructural evolution and mixed electronic-ionic conduction properties of perovskite-type La0.6Sr0.4Co0.8Fe0.2O3 ceramics were investigated in the sintering temperature range 1100-1250℃. The results confirm the crucial role of sintering temperature on microstructure and mixed conduction properties. The improvement of the mixed conduction properties with the increased sintering temperature from 1100℃ to 1200℃ is ascribed to the development of densification. Further increase of the sintering temperature above 1200℃ declined the mixed conduction properties due to the generation of excessive liquid. With respect to the mixed conduction properties, the preferred sintering temperature was ascertained to be 1200℃ for La0.6Sr0.4Co0.8Fe0.2O3 ceramics. The La0.6Sr0.4Co0.8Fe0.2O3 ceramic sintered at 1200℃ exhibited an electrical conductivity of 1.26×103 Ω-1cm-1 and an oxygen ionic conductivity of 3.73×10-2 Ω-1cm-1 at 800℃.

The chemical state of oxygen on the surfaces of mixed electronic-ionic conducting La0.6Sr0.4Co1-yFeyO3 ceramics was characterized by X-ray photoelectron spectroscopy (XPS). It was ascertained that there are five different kinds of oxygen on the ceramic surfaces, including lattice oxygen (OL), chemisorbed oxygen (Oc) in the forms of O-2, O-1 and O-1 2, and oxygen in hydroxyl environment (OH). The concentration of OC+OH relative to total detected oxygen enhanced with the increase of Co/Fe ratio. In order to examine the relation between the chemical states of oxygen on the surfaces and the electrical nature of the ceramics, the mixed electronic-ionic conducting properties were investigated. At an identical measuring temperature, the electronic conductivity and ionic conductivity of La0.6Sr0.4Co1-yFeyO3 ceramics tended to rise with the increase of Co/Fe ratio. It was considered that the mixed electronic-ionic conducting properties are responsible for the complex chemical states of oxygen on the ceramic surfaces.

The structure, piezoelectric properties and ferroelectric properties of (Na0.5Bi0.5)1-xBaxTiO3 ceramics were investigated. A gradual change in crystalline structure and microstructure with the increase of BaTiO3 (BT) concentration was observed. It was ascertained that the rhombohedral-tetragonal morphotropic phase boundary (MPB) of the ceramics lies in the composition range of 0.04<x<0.08 at room temperature. The piezoelectric constant (d33) of the ceramics attains a maximum value of 155 pC/N at x=0.08. From the viewpoint of both piezoelectric constant and electromechanical coupling factor (kp), the composition of x=0.06 exhibits preferred piezoelectric properties. A dependence of piezoelectric properties on ferroelectric properties was detected for (Na0.5Bi0.5)1-xBaxTiO3 ceramics. It was found that both remanent polarization (Pr) and coercive field (Ec) contribute to the piezoelectric properties of the ceramics.

(Na0.5Bi0.5)1-xBaxTiO3 powders were synthesized by a citrate method, and the piezoelectric and ferroelectric properties of the ceramics were investigated. The results indicate that the citrate method is an advantageous alternative route to the conventional method in producing (Na0.5Bi0.5)1-xBaxTiO3 ceramics. Homogeneous and fine powders with a pure perovskite structure were derived from precursor solutions with a mole ratio of citric acid to total metal cation content (C/M) of 1.25 by calcining at 600℃ for 1h. The ceramics made by the citrate method exhibit superior piezoelectric properties near the rhombohedral-tetragonal morphotropic phase boundary. The piezoelectric constant (d33) and electromechanical coupling factor (kp) attain maximum values of d33=180 pCN-1 and kp=0.28 at x=0.06, corresponding to a relatively large remanent polarization of Pr=37.1 μCcm-2 and a relatively low coercive field of Ec=42.7 kVcm-1.

properties of (Na0.5Bi0.5)0.94Ba0.06TiO3 are more sensitive to poling temperature due to the relatively low depolarization temperature. Moderate increase of sintering temperature improved the poling process and piezoelectric properties due to the development of microstructural densification and crystal structure. With respect to sintering behavior and piezoelectric properties, a sintering temperature range of 1130-1160℃ was ascertained for (Na0.5Bi0.5)0.90Ba0.10TiO3.

The sintering and electronic conducting properties of La0.8Ca0.2CrO3 synthesized by a glycine-nitrate process (GNP) were investigated in comparison with that synthesized by the conventional solid state reaction (SSR) method. The results demonstrate the advantage of the GNP method in producing La0.8Ca0.2CrO3 ceramic. Compared with the powder synthesized by the SSR method, that synthesized by the GNP method shows a higher sinterability due to its fine morphology. The relative densities of the ceramics made by the GNP and SSR methods attain 96.5% and 96.0% when sintering at 1450℃ and 1550℃, respectively. In the case of similar relative densities, the ceramic made by the GNP method (sintered at 1450℃) exhibits superior electronic conducting properties than that made by the SSR method (sintered at 1550℃). This is attributed to a desired microstructure of the ceramic made by the GNP method.