The effect of rare-earth (La, Sm, Dy, Ho and Er) and Mg on the microstructure in BaTiO3

Kishi, Hiroshi; Kohzu, Noriyuki; Sugino, Junichi; Ohsato, Hitoshi; Iguchi, Yoshiaki; Okuda, Takashi

doi:10.1016/s0955-2219(98)00370-7

Cited by 244 publications

(104 citation statements)

References 8 publications

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“…Effects of rare earth elements (RE) doping on the phase formation and electrical properties of piezoelectric ceramics such as barium titanate and lead zirconate titanate are well studied [12][13][14][15]. The effect of RE addition on the PMN system has also been studied in the literature to a degree.…”

Section: Introductionmentioning

confidence: 99%

Phase formation and microstructure of Nd+3 doped Pb(Mg1/3Nb2/3)O3 prepared by sol–gel method

Şakar‐Deliormanlı

Çelik

Polat

2007

J Mater Sci: Mater Electron

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The aim of this study was to investigate the effects of the rare earth element neodymium on the phase formation and microstructural development of relaxor ferroelectric lead magnesium niobate, Pb(Mg 1/3 Nb 2/3 )O 3 (PMN) system. Perovskite phase PMN powders were prepared using the sol-gel method and the effect of neodymium doping was investigated at different doping levels ranging from 0.1 mol% to 30 mol%. The precursors employed in the sol-gel process were lead (II) acetate, magnesium ethoxide, and niobium (V) ethoxide. All the experiments were performed at room temperature while the calcination temperatures ranged between 800°C and 1,100°C. Results showed that it was possible to obtain the pure perovskite phase at 950°C using the sol-gel method. Nd +3 addition influenced the phase formation and microstructure of the multicomponent system. Pyrochlore was detected along with the perovskite phase above 10 mol% Nd. Results also demonstrated that grain size of the synthesized powders depended on the Nd +3 concentration. IntroductionLead magnesium niobate (PMN) is a relaxor ferroelectric material that is characterized by a diffuse phase transition over a broad temperature range and a frequency dependent maximum in its relative dielectric permittivity. It demonstrates very high dielectric constant around -10 to -5°C [1]. It has many potential applications such as multilayer ceramic capacitors, actuators and electro-optic devices [2].In the processing of PMN ceramics, synthesis of pure perovskite phase is crucial, the most important problem being the formation of pyrochlore phase which degrades the electrical properties. Previously, several attempts have been made to eliminate the pyrochlore in the PMN structure. The Columbite method introduced by Swartz and Shrout, addition of excess MgO to promote the perovskite formation, and excess PbO addition to compensate lead oxide evaporation during calcination are the commonly used techniques to prevent pyrochlore formation [3][4][5].Among others, the sol-gel method offers several advantages for the preparation of ceramic oxides. This method provides high degree of homogeneity and stoichiometry especially for multicomponent systems in addition to allowing doping on a molecular scale. Hence, there is considerable interest in the preparation of PMN ceramics using sol-gel method [6][7][8][9][10][11].The phase formation and electrical properties of piezoelectric ceramics can be modified by use of dopants. Effects of rare earth elements (RE) doping on the phase formation and electrical properties of piezoelectric ceramics such as barium titanate and lead zirconate titanate are well studied [12][13][14][15]. The effect of RE addition on the PMN system has also been studied in the literature to a degree. Zhong et al. [16] studied the effects of adding a fixed amount of rare earth additives on the microstructure and dielectric properties of PMN-PT ceramics. Their results showed that doping of neodymium (Nd +3 ) resulted in a slight decrease in the grain size and a lowering...

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Section: Introductionmentioning

confidence: 99%

Phase formation and microstructure of Nd+3 doped Pb(Mg1/3Nb2/3)O3 prepared by sol–gel method

Şakar‐Deliormanlı

Çelik

Polat

2007

J Mater Sci: Mater Electron

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“…On the basis of XRD refinement calculations and the comparison of rare-earth ionic radii with Ti and Ba ones, some researchers systematically studied site occupancy of rare-earth ions in BaTiO 3 sintered in a reducing or low-oxygen atmosphere. [42][43][44][45] They divided rare-earth ions into 3 regimes: I large ionic radii r 12 0.094 nm, La, Nd and Sm, II medium-sized ones 0.094 nmr 12 0.087 nm, Gd, Dy, Ho and Er and III smaller ones r 12 0.087 nm, Yb and Lu. These dopants occupy 12-coordinate A Ba sites, both AB sites with amphoteric behavior, and 6-coordinate B Ti sites, respectively, summarized in Table 2.…”

Section: -13mentioning

confidence: 99%

Structure and Dielectric Properties of Eu-Doped Barium Titanate Ceramics

Koda

Suzuki

et al. 2005

J. Ceram. Soc. Japan

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Eu-doped BaTiO 3 ceramics EBT were prepared by the cold-pressing ceramic process on the basis of the formula Ba 1ࢬx Eu x Ti 1ࢬx8 O 3 xࢼ0.01-0.05, 0.10. The effects of Eu doping on the structure, microstructure, dielectric and ferroelectric properties of BaTiO 3 ceramics were studied. EBT ceramics have a high density, a low porosity and a fine grain size of 0.7-1.0 mm. As x3ಚ, EBT ceramics have a tetragonal perovskite structure. The Curie point decreases linearly at a rate of ࢬ11c Cmolಚ Eu ions with increasing Eu content up to 0.04. However, at x0.04, a secondary phase, Eu 2 Ti 2 O 7 , occurs and increases in concentration with increasing Eu, the Curie point remaining constant. The room-temperature dielectric constant of EBT ceramics eö RT ࢼ1600-3100 shows a temperature-independent dielectric region below 50c C at x0.04, a frequency stability below 10 6 Hz and good ageing resistance behavior.

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“…The effects of various kinds and amounts of additives have been studied [2,4,5,9,10,[15][16][17][18][19][20][21][22], including in particular those of rare earth elements with intermediate ionic radii (Dy, Ho, Y and Er) [9,10,[19][20][21][22][23]. In the case of rare earth doping, high insulation resistance can be maintained for a long time, which enables the realization of thinner dielectric layers and extended life time in the use of MLCCs [24].…”

Section: Introductionmentioning

confidence: 99%

Effects of core/shell volumetric ratio on the dielectric-temperature behavior of BaTiO3

et al. 2014

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Two sets of (Mg,Y)-doped BaTiO 3 samples were prepared to investigate the effects of the core/shell volumetric ratio on the dielectric-temperature behavior of BaTiO 3 : one set with samples of the same grain size but different core sizes and the other with samples of the same core size but different shell thicknesses. The microstructural variation of the samples was characterized and their dielectric properties were measured. For both sets of samples, the temperature stability of the dielectric properties was generally improved with a reduction of the volumetric shell ratio regardless of the grain and core sizes. There existed, however, a limit of the reduction; for the studied range, shell thickness of one third of the core radius appeared to be an optimum thickness for the given amounts of dopants. It was concluded that the volumetric shell ratio should be optimized so as not to exceed a specific limit, for our case two thirds of the grain volume, to secure temperature stability of the dielectric properties of BaTiO 3 .

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The effect of rare-earth (La, Sm, Dy, Ho and Er) and Mg on the microstructure in BaTiO3

Cited by 244 publications

References 8 publications

Phase formation and microstructure of Nd+3 doped Pb(Mg1/3Nb2/3)O3 prepared by sol–gel method

Phase formation and microstructure of Nd+3 doped Pb(Mg1/3Nb2/3)O3 prepared by sol–gel method

Structure and Dielectric Properties of Eu-Doped Barium Titanate Ceramics

Effects of core/shell volumetric ratio on the dielectric-temperature behavior of BaTiO3

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