Sr含量对La_(1-x)Sr_xMnO_(3-δ)导电陶瓷结构与性能的影响

Effect of Sr Content on Microstructure and Properties of La_(1-x)Sr_xMnO_(3-δ) Conductive Ceramics

采用乙二胺四乙酸(EDTA)-柠檬酸络合法合成了钙钛矿结构La_(1-x)Sr_xMnO_(3-δ)(LSM)粉体,通过干压成型和高温烧结制备了LSM导电陶瓷。研究了Sr含量对制备LSM陶瓷的物相组成、微观结构、烧结特性、电导率、抗弯强度和热膨胀性能等的影响。结果表明:1 425℃保温4 h烧成后,未添加Sr的样品组成为斜方晶系La Mn O3-δ,随着Sr含量提高,LSM陶瓷样品物相晶体结构向六方、四方和立方等不同晶系转变。Sr的添加可促进样品烧结致密化,随着Sr含量增加,样品的室温电导率和抗弯强度表现出先升高后降低变化趋势,但Sr含量对热膨胀性能的影响较小。样品在x=0.6时可获得最大电导率131.4 S/cm,而x=0.8时抗弯强度最高,为101.0 MPa。

A La1-xSrxMnO3-δ（LSM） powder with the perovskite structure was synthesized by an EDTA-citric acid complexation method, and the LSM conductive ceramic was prepared via dry-pressing molding and high-temperature sintering. The effect of Sr content on the phase structure, microstructure and sinterability, electrical conductivity, bending strength and thermal expansion of LSM ceramic samples was investigated. The results show that the sample sintered at 1 425 ℃ for 4 h without Sr addition is composed of LaMnOLa1-xSrxMnO3-δ with an orthorhombic structure. The complex phase transition occurs among hexagonal, tetragonal and cubic crystal structures when Sr content in LSM increases. The addition of Sr can improve the sinterability and promote the densification of samples, and the electrical conductivity at room temperature and bending strength firstly increase and then decrease with the increase of Sr content. However, Sr content has a slight effect on the thermal expansion of samples. The prepared LSM ceramic has a maximal electrical conductivity of 131.4 S/cm as x = 0.6, and the maximum bending strength of 101.0MPa as x = 0.8.