摘要
用电子陶瓷工艺制备主晶相为BaTi4O9(BT4)的介电陶瓷 ,研究用锰掺杂的BaTi4O9陶瓷的结构和介电性能。XRD研究表明BaTi4O9属正交晶系 ,空间群Pmmn ,晶格常数为a =1.45 3nm ,b =0 .3 79nm ,c=0 .62 9nm ,每个原胞有两个分子 ,钛原子位于变形的氧八面体之中。这种氧八面体的极化类似于或大于在BaTiO3和PbTiO3铁电相观察到的极化。锰掺杂极大地增强了Q值 ,在 1MHz下测得的Q值为 125 0 0 .而没有掺杂的陶瓷有高的损耗 ,这可能是由于在空气中烧结时形成Ti3+ ,显然锰的作用是在缺陷平衡中作为一种补偿剂 ,依据反应 :Mn3+ +Ti3+ Mn2 + +Ti4+ ,可能有助于Ti4+ 的形成 .BaTi4O9陶瓷具有优良的介电性能 :低介质损耗、中等介电常数和低的介电常数温度系数 .此种陶瓷制造成多层陶瓷电容器开拓了一种新的应用领域 .
A dielectric ceramic, mainly crystalline BaTi4O9(BT4), was prepared using electric-ceramic technology. The structure and the dielectric properties of Mn-doped BaTi4O9 ceramic were investigated. X-ray diffraction studies show that BaTi4O9 is orthorhombic, space group Pmmm, with a=1.453 nm, b=0.379 nm, c=0.629 nm, with two formula units per unit cell. Titanium atom is in the distorted octahedral of oxygen atom. This polarization of the octahedral is similar to or greater in magnitude than that observed in ferroelectric phases of BaTiO3 and PbTiO3. Mn dopants greatly enhance the Q factor up to 12500 at 1 MHz, whereas undoped ceramic indicates high loss perhaps due to the formation of Ti3+ during the air atmosphere sintering. Mn clearly acts as a compensator in defect equilibria, probably helping to maintain Ti4+ according to the reaction: Mn3++Ti3+&rarrMn2++Ti4+. The BaTi4O9 ceramic has an excellent combination of low dielectric loss, moderate dielectric constant and low temperature coefficient of dielectric constant. Its new application as a multilayer ceramic capacitor (MLCC) has been explored.
出处
《硅酸盐学报》
EI
CAS
CSCD
北大核心
2001年第1期80-83,共4页
Journal of The Chinese Ceramic Society
基金
国家863高科技新材料领域资助项目!(Z33-0 11)
关键词
介电性能
锰掺杂
主晶相
四钛酸钡
介电陶瓷
结构
Barium titanate
Dielectric properties
Manganese
Q factor measurement
X ray diffraction
