A transmission electron microscope study of commercial X7R-type multilayer ceramic capacitors
A transmission electron microscope study of commercial X7R-type multilayer ceramic capacitors
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DOI：
10.1016/s0955-2219(97)00184-2
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发表时间：
1998
影响因子：
5.7
通讯作者：
F. Azough;R. AL-Saffar;R. Freer
中科院分区：
文献类型：
--
作者：
F. Azough;R. AL-Saffar;R. Freer
用透射电子显微镜对A、B、C三家厂家生产的X7R型多层陶瓷电容器进行了研究。所有样品都含有具有不同核壳结构的颗粒，其核心几乎是纯的BaTiO_3，并且在室温下呈现磁畴结构。A类样品的颗粒尺寸为1-2μm，壳“宽”，含有铅、铋、铌、钡和钛。在介电颗粒与Ag-Pd电极之间存在富含Si、Al、Ba和Ti的键合相。将样品加热到130℃以上会导致铁电畴结构丢失，取而代之的是位错网络。B型和C型样品的晶粒度为0.5~1.0μm，铁电芯层被富含Nb、Co、Ba和Ti的“窄”壳层包裹。银-钯内电极为孪生电极。在三组多层陶瓷电容器中都发现了I型和II型核壳结构。
X7R-type multilayer ceramic capacitors produced by three commercial manufacturers (A, B and C) have been investigated by transmission electron microscopy. All the specimens contained grains with distinct core-shell structures; the cores were almost pure BaTiO3and exhibited domain structures at room temperature. Specimens of type A had a grain size of 1–2μm, with ‘wide’ shells containing Pb, Bi, Nb, Ba and Ti. A bonding phase, rich in Si, Al, Ba and Ti was detected between the dielectric grains and Ag-Pd electrodes. Heating the samples to temperatures above 130 °C caused the ferroelectric domain structure to be lost and replaced by a dislocation network. Specimens of type B and C had a grain size of 0.5–1.0 μm; the ferroelectric cores were surrounded by ‘narrow’ shells rich in Nb, Co, Ba and Ti. The Ag-Pd internal electrodes were twinned. Type I and type II core-shell structures were found in all three sets of multilayer ceramic capacitors.