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Effect of Eu3+ Doping on Electric, Luminescent and Magnetic Multifunctional Properties of Ba0.77Ca0.23TiO3 Ceramics

Author: YangQiHua
Tutor: ShenMingRong；FangLiang
School: Suzhou University
Course: Materials Physics and Chemistry
Keywords: Ba0.77Ca0.23TiO3 ferroelectric ceramics Eu3+ doping electricity photoluminescence magnetism
CLC: TB34
Type: Master's thesis
Year: 2010
Downloads: 28
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Abstract


The increase development of modern industry calls for multifunction materials. Such materials have drawn a great deal of attention due to more weight-efficient, volume- efficient performance than traditional integrated systems. ABO3-like compounds with the perovskite-type structure, such as BaTiO3, SrTiO3, CaTiO3 and their solid solutions, have drawn a great deal of attention due to their attractive ferroelectric and dielectric properties. Among (Ba, Ca)TiO3 system, the partial replacement of barium by calcium can improve the electromechanical behavior. Especially, the solid solution limit with Ca concentration about 23mol% have shown the highest remnant polarization (Pr) and electrostrictive strain. Wang et al [Adv. Mater. (2005) 17, 1254-1258] reported that a small amount (0.2 mol%) Pr3+-doped (Ba0.77Ca0.23)TiO3 ceramics had shown the simultaneously electrostrictive, mechanoluminescent and electroluminescent multifunctional properties. In addition, the multifunctional properties of such materials are strongly affected by using the different rare-earth (RE) doping methods. Jiang et al [Appl. Phys. Lett. (2009) 94, 071110-3] described that the enhancement of dielectric and photoluminescent properties in Eu3+-doped SrTiO3 ceramics could be realized by using different doping mechanisms.In this thesis, the structural, electrical, luminescent and magnetic properties of multifunction Eu3+ doped Ba0.77Ca0.23TiO3 ceramics were investigated. Firstly, We investigated the effect of Eu doping concentrations on the multifunction properties of samples. Secondly, the effects of three different doping mechanisms, Ca site substitution with Ca vacancy compensation (BCT23-A); Ti site substitution with O vacancy compensation (BCT23-B); simultaneous substitution at both Ca and Ti sites with self-compensation (BCT23-AB), on the multifunctional properties of Ba0.77Ca0.23TiO3 (BCT23) ceramics were also studied.On one hand, with the increase of Eu concentrations, the structural phase of the BCT23-A samples had gradually changed from tetragonal to cubic structure. The remnant polarization (Pr) and dielectric constant were also decreased. Moreover, the dielectric peak position decreased and became increasingly broad, which implied relaxor feature appeared in the doped samples. As expected, the doped samples showed the luminescent properties due to the doping effect of Eu. The intensities of the photoluminescent spectra initially increase with Eu doping concentration and dramatically reduce for higher concentration. A linear M-H behavior was also obtained for all BCT23-A samples. On the other hand, different doping positions also play an important role on the microstructure, electrical, luminescent properties of the samples. Compared with those of the BCT23-A and BCT23-AB samples, the BCT23-B sample exhibited the broadest dielectric peaks with the lowest Curie point and dielectric constant. However, the luminescent intensity of BCT23-B was highest. In BCT23-AB sample, since less additional defects were generated due to the self-compensation mechanism, the ferroelectric property was higher than those of BCT23-A and BCT23-B. Furthermore, there was no obvious difference on the M-H behavior for the BCT23-A, BCT23-B and BCT23-AB samples. Our results showed that by using different Eu doping sites and concentrations, we could modify the dielectric, ferroelectric, photoluminescent and magnetic properties of BCT23 ceramics, which could be considered as a promising multifunction material due to its luminescent/dielectric/magnetic properties. The most above conclusions were published on Materials Chemistry and Physics.

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