Structural and optical properties of rare earth-doped (Ba0.77Ca0.23)1-x(Sm, Nd, Pr, Yb)xTiO3

被引:27
作者
Moraes, A. P. A. [1 ,2 ]
Souza Filho, A. G. [1 ]
Freire, P. T. C. [1 ]
Mendes Filho, J. [1 ]
M'Peko, J. C. [3 ]
Hernandes, A. C. [3 ]
Antonelli, E. [4 ]
Blair, Michael W. [5 ]
Muenchausen, Ross E. [5 ]
Jacobsohn, Luiz G. [6 ,7 ]
Paraguassu, W. [8 ]
机构
[1] Univ Fed Ceara, Dept Fis, BR-60455900 Fortaleza, CE, Brazil
[2] Univ Fed Mato Grosso, BR-78060900 Araguaia, MT, Brazil
[3] Univ Sao Paulo, Inst Fis Sao Carlos, Grp Crescimento Cristais & Mat Ceram, Sao Carlos, SP, Brazil
[4] Univ Fed Itajuba Unifei, BR-3590037 Itabira, MG, Brazil
[5] Los Alamos Natl Lab, Div Mat Sci & Technol, Los Alamos, NM 87545 USA
[6] Clemson Univ, Ctr Opt Mat Sci & Engn Technol COMSET, Clemson, SC 29634 USA
[7] Clemson Univ, Sch Mat Sci & Engn, Clemson, SC 29634 USA
[8] Fed Univ Para, Fac Fis, BR-66075110 Belem, PA, Brazil
基金
巴西圣保罗研究基金会;
关键词
DIFFUSE PHASE-TRANSITION; DIELECTRIC-PROPERTIES; BARIUM-TITANATE; SINTERING BEHAVIOR; X-RAY; CERAMICS; SIMULATION; SPECTROSCOPY; SYMMETRY; CRYSTAL;
D O I
10.1063/1.3594710
中图分类号
O59 [应用物理学];
学科分类号
摘要
The structural, dielectric, and vibrational properties of pure and rare earth (RE)-doped Ba-0.77 Ca0.23TiO3 (BCT23; RE = Nd, Sm, Pr, Yb) ceramics obtained via solid-state reaction were investigated. The pure and RE-doped BCT23 ceramics sintered at 1450 degrees C in air for 4 h showed a dense microstructure in all ceramics. The use of RE ions as dopants introduced lattice-parameter changes that manifested in the reduction of the volume of the unit cell. RE-doped BCT23 samples exhibit a more homogenous microstructure due to the absence of a Ti-rich phase in the grain boundaries as demonstrated by scanning electron microscopy imaging. The incorporation of REs led to perturbations of the local symmetry of TiO6 octahedra and the creation of a new Raman mode. The results of Raman scattering measurements indicated that the Curie temperature of the ferroelectric phase transition depends on the RE ion and ion content, with the Curie temperature shifting toward lower values as the RE content increases, with the exception of Yb3+ doping, which did not affect the ferroelectric phase transition temperature. The phase transition behavior is explained using the standard soft mode model. Electronic paramagnetic resonance measurements showed the existence of Ti vacancies in the structure of RE-doped BCT23. Defects are created via charge compensation mechanisms due to the incorporation of elements with a different valence state relative to the ions of the pure BCT23 host. It is concluded that the Ti vacancies are responsible for the activation of the Raman mode at 840 cm(-1), which is in agreement with lattice dynamics calculations. (c) 2011 American Institute of Physics. [doi:10.1063/1.3594710]
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页数:8
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