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首页> 外文期刊>The European physical journal, B. Condensed matter physics >Correlations of structural, magnetic, and dielectric properties of undoped and doped CaCu3Ti4O12
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Correlations of structural, magnetic, and dielectric properties of undoped and doped CaCu3Ti4O12

机译：未掺杂和掺杂的CaCu3Ti4O12的结构，磁性和介电性能的相关性

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摘要

The present work reports synthesis, as well as a detailed and careful characterization of structural,magnetic, and dielectric properties of differently tempered undoped and doped CaCu3Ti4O12 (CCTO) ceramics. For this purpose, neutron and X-ray powder diffraction, SQUID measurements, and dielectric spectroscopy have been performed. Mn-, Fe-, and Ni-doped CCTO ceramics were investigated in great detail to document the influence of low-level doping with 3d metals on the antiferromagnetic structure and dielectric properties. In the light of possible magnetoelectric coupling in these doped ceramics, the dielectric measurements were also carried out in external magnetic fields up to 7 T. At low temperatures the dielectric constant shows a minor but significant dependence on the applied magnetic field. Undoped CCTO is well-known for its colossal dielectric constant in a broad frequency and temperature range. With the present extended characterization of doped as well as undoped CCTO, we want to address the question why doping with only 1% Mn or 0.5% Fe decreases the room-temperature dielectric constant of CCTO by a factor of 100 with a concomitant reduction of the conductivity, whereas 0.5% Ni doping changes the dielectric properties only slightly. In addition, diffraction experiments and magnetic investigations were undertaken to check for possible correlations of the magnitude of the colossal dielectric constants with structural details or with magnetic properties like the magnetic ordering, the Curie-Weiss temperatures, or the paramagnetic moment. It is revealed, that while the magnetic ordering temperature and the effective moment of all investigated CCTO ceramics are rather similar, there is a dramatic influence of doping and tempering time on the Curie-Weiss constant.
机译：本工作报告了合成以及对不同回火的未掺杂和掺杂的CaCu3Ti4O12（CCTO）陶瓷的结构，磁性和介电性能的详细描述。为此，已经进行了中子和X射线粉末衍射，SQUID测量和介电谱。对Mn，Fe和Ni掺杂的CCTO陶瓷进行了详细的研究，以记录低水平掺杂3d金属对反铁磁结构和介电性能的影响。考虑到这些掺杂陶瓷中可能的磁电耦合，还可以在高达7 T的外部磁场中进行介电测量。在低温下，介电常数显示出对所施加磁场的微小但显着的依赖性。未掺杂的CCTO以其在很宽的频率和温度范围内的巨大介电常数而闻名。通过目前对掺杂和未掺杂CCTO的表征，我们想解决一个问题，为什么仅添加1％Mn或0.5％Fe进行掺杂会使CCTO的室温介电常数降低100倍，同时降低CCTO。电导率，而0.5％的镍掺杂仅稍微改变介电性能。此外，进行了衍射实验和磁研究，以检查巨大介电常数的大小与结构细节或磁特性（如磁序，居里-魏斯温度或顺磁矩）的可能关系。结果表明，尽管所有研究的CCTO陶瓷的磁有序温度和有效力矩都相当相似，但掺杂和回火时间对居里-魏斯常数有很大的影响。

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