采用固相反应法合成了(Sr0.2Nd0.208Ca0.488)Ti1-x(Mg1/3Ta2/3)xO3(0.2≤x≤0.5,SNCTMTx)系微波介质陶瓷,分析了SNCTMTx(0.2≤x≤0.5)陶瓷的相组成、显微结构、烧结特性和微波介电性能之间的关系.XRD晶体结构分析表明:当x=0.2时,SNCTMTx陶瓷为单一正交钙钛矿结构,当x值增为0.3~0.5时,陶瓷体呈现正交钙钛矿相、SrO与未知相多相共存状态.随着(Mg1/3Ta2/3)4+含量的增加,体系中第二相的出现及含量的改变导致εr先增后减,而Q×f值出现先降后升的原因是B位离子1:2有序度的出现与范围的增加抑制了第二相进一步恶化品质因子;此外,τf逐渐向近零方向偏移与氧八面体的畸变程度密切相关.当x=0.5时,在1530℃烧结4 h得到的SNCTMTx陶瓷微波介电性能较优:εr=55.3,Q×f≈7400 GHz,τf≈23.6×10–6/℃.
(Sr0.2Nd0.208Ca0.488)Ti1-x(Mg1/3Ta2/3)xO3(0.2≤x≤0.5, SNCTMTx) ceramics were prepared by solid sate reaction technique. Wherein, the relation between phase compositions, microstructures, sintering properties, and microwave dielectric properties of the SNCTMTx(0.2≤x≤0.5) ceramic systems were studied. The XRD results indicated that a single phase with orthorhombic perovskite-like structure was formed in the sample withx = 0.2, and a mixed phase system was formed in the samples with given compositional rangex = 0.3 – 0.5 composed of orthorhombic perovskite phase, SrO phase and unknown second phase. Additionally, theεrfirst increased and then decreased, affected by the appearance and the content of the second phase. Meanwhile, theQ×fvalue showed down first and then up with the increase of (Mg1/3Ta2/3)4+ content because the in-creasing degree of 1:2 ordering could suppress the reduction in quality factor. Moreover, theτf gradually shifted to near-zero direction, which resulted from the variation of the oxygen octahedral distortion. The SNCTMTx (x=0.5) ceramic sintered at 1530℃ for 4 h showed better microwave dielectric properties withεr = 55.3,Q×f≈ 7,400 GHz andτf≈ 23.6×10–6/℃.
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