锰掺杂Ba_(0.6)Sr_(0.4)TiO_3-MgTiO_3复相陶瓷的制备和介电性能(英文)  

Preparation and Dielectric Properties of Mn-Doped Ba_(0.6)Sr_(0.4)TiO_3-MgTiO_3 Composite Ceramics

作　　者：李明利[1] 徐明霞[1] 梁辉[1] 李晓雷[1] 徐廷献[1] 

机构地区：[1]天津大学材料科学与工程学院、教育部先进陶瓷与加工技术重点实验室,天津300072

出　　处：《物理化学学报》2008年第8期1405-1410,共6页Acta Physico-Chimica Sinica

基　　金：国家自然科学基金(13603811)资助项目

摘　　要：以分析纯的Ba(NO3)2、Sr(NO3)2、草酸和钛酸丁酯为原料,采用草酸盐共沉淀法制备了钛酸锶钡(Ba0.6Sr0.4TiO3,BST)纳米粉体.XRD和SEM分析结果表明,该方法制备出立方相的Ba0.6Sr0.4TiO3粉体,平均粒径小于100nm,具有较高的烧结活性.用传统固相法制备了锰掺杂钛酸锶钡-钛酸镁(Ba0.6Sr0.4TiO3-MgTiO3,BST-MT)复相陶瓷,系统研究了掺杂0.1%-2.0%(x,摩尔分数,下同)锰对钛酸锶钡-钛酸镁复相陶瓷微观形貌和介电性能的影响机理.结果表明,当锰的掺杂量小于1.5%时,Mn作为受主掺杂取代占据钙钛矿ABO3的B位,因此导致居里点略微向高温偏移和相变扩散的发生,锰的掺杂导致晶格畸变,促进了晶粒生长,使晶界相比例下降,因此介电损耗随着锰掺杂量的增大而减小;当锰的掺杂量为1.5%时,介电损耗达到最小值,继续增大掺杂量,介电常数下降,介电损耗上升.Barium strontium titanate （Ba0.6Sr0.4TiO3, BST） nano-powders were prepared using Ba（NO3）2, Sr（NO3）2, oxalic acid dehydrate, and tetrabutyl titanate （Ti（OC4H9）4） as precursors by the chemical co-precipitation method. The product was characterized by thermogravimetry-differential scanning calorimetry （TG-DSC） thermal analyses, X-ray diffraction （XRD）, and scanning electron microscopy （SEM）. The experimental results indicated that the resulting Bao.6Sr0.4TiO3 nano-powders were homogeneous with agglomerated nature. The Ba0.6Sr0.4TiO3-MgTiO3 （BST-MT） bulk composite ceramics doped by Mn were obtained by the traditional solid phase method. The XRD patterns demonstrated that Mn-doped BST was unable to change the perovskite crystalline structure of BST materials. SEM photographs revealed that the crystalline grains became larger with increasing the content of doping Mn （〈1.5% （χ, molar fraction）） and then the size of grains decreased after the Mn content exceeded 1.5% in the BST ceramics, suggesting the effect of Mn doping on the morphologies of BST-MT composites. The dielectric properties of BST-MT composite ceramics doped with 0.1%-2.0% （χ） Mn were investigated systematically. Two effects of Mn doping on the dielectric properties of the BST-MT composite ceramics were observed. At low Mn doping concentrations （〈1.5%）, Mn mainly acted as an acceptor dopant to replace Ti at the B site of ABO3 perovskite structure, leading to a diffused phase transition. It was also observed that the grain size increased drastically as the Mn content increased and thus caused the decrease of dielectric loss. At higher Mn doping concentrations （〉1.5%）, the grain size decreased and the suppression of permittivity and the drastic increase of the dielectric losses were observed, which indicated a ＂composite＂ mixing effect.

关 键 词：钛酸锶钡 锰掺杂 微观形貌 介电性能 

分 类 号：TQ174.1[化学工程—陶瓷工业]