Microwave dielectric characterization of the perovskite series A1/2Ln1/2TiO3–NaNbO3 (A = Na, Li; Ln = La,Nd, Sm)
Microwave dielectric characterization of the perovskite series A1/2Ln1/2TiO3–NaNbO3 (A = Na, Li; Ln = La,Nd, Sm)
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DOI：
10.1016/j.jallcom.2010.10.082
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发表时间：
2011-02
影响因子：
6.2
通讯作者：
Z. Liang;L. Yuan;J. Bian
中科院分区：
文献类型：
--
作者：
Z. Liang;L. Yuan;J. Bian
本文通过 XRD、SEM 和微波谐振器方法研究了钙钛矿系列 A1/2Ln1/2TiO3–NaNbO3(A=Na, Li; Ln=La,Nd, Sm) 的结构和微波介电表征。所有样品均表现出单一钙钛矿相。 0.5Na1/2Ln1/2TiO3–0.5NaNbO3(Ln= Nd, Sm)采用Pbnm空间群，而0.5Na1/2La1/2TiO3–0.5NaNbO3采用Cmcm空间群。随着稀土金属离子半径的减小，相对介电常数减小，Qf值增大。所有样品均表现出较大的正τf值。对于(1−x)Li1/2Ln1/2TiO3–xNaNbO3(Ln=Nd,Sm)系列，相对介电常数随着x的增加而增加，而Qf值随着x的增加而减小。随着x的增加，τf值由负值变为正值。通过调整 x 的组成可以获得接近零的 τf 值。可以获得良好的复杂微波介电性能：对于(1−x)Li1/2Sm1/2TiO3–xNaNbO3，ɛr=120，Q×f=2300GHz，τf=9.3ppm/°C，其中x=0.2和ɛr=103，Q×f=2120GHz，τf=-3.4ppm/°C (1−x)Li1/2Nd1/2TiO3–xNaNbO3，其中 x=0.1。
Structure and microwave dielectric characterization of the perovskite series A1/2Ln1/2TiO3–NaNbO3(A=Na, Li; Ln=La,Nd, Sm) have been investigated by XRD, SEM, and microwave resonator method in this paper. All samples exhibited single perovskite phase. 0.5Na1/2Ln1/2TiO3–0.5NaNbO3(Ln= Nd, Sm) adopted Pbnm space group, whereas 0.5Na1/2La1/2TiO3–0.5NaNbO3adopted Cmcm space group. The relative permittivity decreased and Qf value increased with the decrease of rare earth metal ionic radii, respectively. All samples exhibited large positive τfvalue. For (1−x)Li1/2Ln1/2TiO3–xNaNbO3(Ln=Nd, Sm) series, the relative permittivity increased with increasing x, whereas Qf value decreased with the increase of x. The τfvalue changed from the negative to positive value with the increase of x. Near zero τfvalue could be obtained by tuning the composition of x. Good complex microwave dielectric properties could be obtained: ɛr=120, Q×f=2300GHz, τf=9.3ppm/°C for (1−x)Li1/2Sm1/2TiO3–xNaNbO3with x=0.2 and ɛr=103, Q×f=2120GHz, τf=−3.4ppm/°C for (1−x)Li1/2Nd1/2TiO3–xNaNbO3with x=0.1.