ORDERING STRUCTURE AND DIELECTRIC-PROPERTIES OF UNDOPED AND LA/NA-DOPED PB(MG1/3NB2/3)O3
ORDERING STRUCTURE AND DIELECTRIC-PROPERTIES OF UNDOPED AND LA/NA-DOPED PB(MG1/3NB2/3)O3
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DOI：
10.1111/j.1151-2916.1989.tb06180.x
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发表时间：
1989-04-01
影响因子：
3.9
通讯作者：
HARMER, MP
中科院分区：
文献类型：
--
作者：
CHEN, J;CHAN, HM;HARMER, MP
透射电子显微镜用于研究未掺杂和La/Na掺杂的Pb（Mg 1/3 Nb 2/3）O3（PMN）中的有序畴结构，其中掺杂样品的成分被特别选择以阐明有序机制。结果表明，Mg 2+和Nb 5+离子在未掺杂PMN的B-位亚晶格上是短程有序的，畴尺寸为2 ~ 5 nm。这种短程有序导致B位组成在纳米尺度上发生波动，并且这种组成不均匀性被认为是扩散相变行为的原因。La 2 O3的施主掺杂可以补偿由短程有序引起的局部电荷不平衡，从而提高有序度。然而，用Na 2 O掺杂受体增加了电荷效应，因此抑制了有序化。讨论了Na掺杂和La掺杂对PMN介电性能的影响。
Transmission electron microscopy was used to study the ordered domain structures in undoped and La/Na‐doped Pb(Mg1/3Nb2/3)O3(PMN), where the compositions of the doped samples were specifically chosen so as to elucidate the ordering mechanism. The results showed that the Mg2+ions and Nb5+ions are short‐range ordered on the B‐site sublattice in undoped PMN, with a domain size of 2 to 5 nm. This short‐range ordering gives rise to B‐site composition fluctuations occurring on a nanometer scale, and it is this compositional inhomogeneity which is believed to be responsible for the diffuse phase transition behavior. Donor doping with La2O3can compensate for the local charge imbalance resulting from the short‐range order and thus enhances the degree of ordering. Acceptor doping with Na2O, however, increases the charge effect, and hence ordering is suppressed. The effect of Na doping and La doping on the dielectric properties of PMN is also discussed.