(Ba1-xSrx) La4Ti4O15(x=0.8～0.95)陶瓷的微结构及微波介电性能研究

摘要

采用固相反应法制备了(Ba1-xSrx)La4Ti4O15(x=0.8～0.95)复合体系微波介质陶瓷,并对其进行物相组成、晶体结构分析以及微波介电性能的研究.研究结果表明,(Ba1-xSrx)La4Ti4O15陶瓷主晶相为SrLa4Ti4O15,并伴随有第二相SrLa8Ti9O15.SEM观察表明,Ba0.2Sr0.8La4Ti4O15陶瓷内部微观结构致密,晶粒尺寸在10～20 μm之间,晶界清晰.随着x值逐渐增大,(Ba1-xSrx)La4Ti4O15陶瓷中晶粒形态发生变化,气孔增多.在x=0.8时,(Ba1-xSrx)La4Ti4O15陶瓷具有优良的微波介电性能,即εr=40.86,Q×f≈62806 GHz,τf=-20×10-6/℃.随着Ba2+的含量逐渐增加,该陶瓷的介电常数εr单调上升,品质因子Q×f值增加,说明适量的Ba2+替代Sr2+能改善陶瓷的微波介电性能.%The (Ba1-xSrx)La4Ti4O15 (x=0.8-0.95) ceramics were prepared by the solid-state reaction method and the phase compositions, crystal structures and microwave dielectric properties were investigated. The results show that the (Ba1-xSrx)La4Ti4O15 ceramics have the main phase of SrLa4Ti4O15 and the second phase of SrLa8Ti9O15. The SEM images indicate that the Ba0.2Sr0.8La4Ti4O15 ceramic with dense microstructures has grain sizes of about 10-20 μm and clear crystal boundaries. The grain shapes of the (Ba1-xSrx)La4Ti4O15 ceramics change with increasing x values, and the pores in the samples increase. (Ba1-xSrx)La4Ti4O15 ceramics with x=0.8 possesses excellent microwave dielectric properties, listed as follows, the dielectric constant εr =40.86, the quality factor Q×≈62806 GHz, and the temperature coefficient of resonant frequency Γf =-20 × 10-6/℃. The monotone increases of the dielectric constant er and the quality factor Qxf of the ceramics with increasing Ba2+ contents, mean that the proper substitution of Ba2+ for Sr2+ can improve microwave dielectric properties of the (Ba1-xSrx)La4Ti4O15 ceramics.