Preparation and Characterization of <TEX>$Bi_{4-x}Sm_xTi_3O_{12}(0<leqxgeq2)$</TEX>  Thin Films Using Sol-Gel Processing

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J. Korean Ceram. Soc. > Volume 34(8); 1997 > Article

Journal of the Korean Ceramic Society 1997;34(8): 897.

졸겔공정을 이용한 $Bi_{4-x}Sm_xTi_3O_{12}(0 박막제조 및 특성평가

이창민, 고태경

인하대학교, 소재연구소, 무기재료공학과

Preparation and Characterization of $Bi_{4-x}Sm_xTi_3O_{12}(0 Thin Films Using Sol-Gel Processing

ABSTRACT

Thin films of Bi4-xSmxTi3O12(0$leq$x$leq$2) were prepared on Pt/Ti/SiO2/Si(100) at $700^{circ}C$ using spin-coating with sols derived from Bi-Sm-Ti complex alkoxides. From X-ray diffraction analysis, it was observed that Sm-substituted phases resembled ferroelectric Bi4Ti3O12 in structure. Variations of their lattice parameters depending on the amount of Sm-substitution showed that an anomalous structural distortion might exist at x=1. The grain sizes of the thin films decreased from 0.115 ${mu}{textrm}{m}$ to 0.078${mu}{textrm}{m}$ with increasing the amount of Sm-substitution. The dielectric constants and the remanent polarizations of the thin films decreased with increasing the amount of the Sm-substitution, which were related to decrease of the stereo-active Bi3+ ion contributing to polarization. However, these values were exceptionally high at x=1, compared to those of the other substituted phases. Such an anomaly suggests that the phase of x=1 has 1:1 chemical ordering between Sm and Bi in structure. The thin films of all compositions except x=2 showed ferroelectricity. The thin film of x=2 was paraelectric, whose grains were too fine to exhibit ferroelectricity.

Key words: Thin film, Spin-coating, $Bi_4Ti_3O_{12}$ Sm-substitution, Structure, Ferroelectricity