Phase structure and dielectric properties of doped BaTiO₃ ceramics

Abstract

The effects of two rare earth oxides such as CeO₂ and Sm₂O₃ on the phase structure and dielectric properties of BaTiO₃ ceramic were investigated. Results indicate that the dielectric constant of this system will increase greatly with the increasing content of these two oxides, and Ce⁴⁺ substitutes for Ba²⁺ located at A-site in ABO₃ structure. Quantitative XRD analysis shows that c/a ratio in the sample with addition of CeO₂ will increase, which implies the increase of tetragonality in system, causing the augment of dielectric constant, and the decrease of the crystal’s geometrical symmetry results in curie-temperature moving towards low temperature; Sm³⁺(0.096 nm) substitutes for Ba²⁺(0.135 nm) possessing larger radius in A-site and the electrovalency in A-site increases, the mutual effect is strengthened, so the polarization is enhanced, and the dielectric constant increases notablely.

Keywords

BaTiO₃ / dielectric properties / additive / CeO₂ / Sm₂O₃

References

[1] Yamada H., Hibino M., Kudo T. Lithium Insertion to ReO₃-type Metastable Phase in the Nb₂O₅-WO₃ System[J]. Solid State Ionics, 2001, 140(3–4): 249-255.

[2] Okino Y., Shizuno H., Kusumi S., . Dielectric Properties of Rare-earth-oxide-doped BaTiO₃ Ceramics Fired in Reducing Atmosphere[J]. Jpn. J. Appl. Phys., 1994, 33(9B.spec.issue): 5 393-5 396.

[3] Caballero A. C., Fernandez J. F., Villegas M., . Intermediate Phase Development in Phosphorus-doped Barium Titanate[J]. J.Am.Ceram. Soc., 2000, 83(6): 1 499-1 505.

[4] Morrison F. D., Sinclair D. C., West A. R. Charge Compensation Mechanisms in La-doped BaTiO₃[J]. Journal of Electroceramics, 2001, 6(3): 219-232.

[5] Luan K., zhang C. The Effect of Rare Earth Ce on the Dielectric Properties of BaTiO₃ Ceramic[J]. Rare Earth, 1990, 2(3): 21-23.

[6] li W., Qi J., Wang Y., . Doping Behaviors of Nb₂O₅ and Co₂O₃ in Temperature Stable BaTiO₃-based Ceramics[J]. Material Letters, 2002, 57(1): 1-5.

[7] Shannon R. D. Revised Effective Ionic Radii and Systematic Studies of Interatomic Distances in Halides and Chalcogenides[J]. Acta Crystallographica, 1976, A32(pt.5): 751-767.

[8] Hiroshi K., Noriyuki K., Junichi S., . Effect of Rare-earth (La, Sm, Dy, Ho and Er) and Mg on the Microstructure in BaTiO₃[J]. Journal of the European Ceramic Society, 1999, 19(6–7): 1 043-1 046.