Papers by Keyword: SrBi₄Ti₄O₁₅

Abstract: In this study, SrBi₄Ti₄O₁₅ (SBT) thin films were deposited onto the SiO₂/p-Si(100) and Pt/Ti/SiO₂/p-Si(100) substrates by using sol-gel method. After deposition, the SBT thin films were then heated by a rapid thermal annealing (RTA) process conducted in air for 1min at 600-800°C. The surface morphologies and the crystalline structures of the SBT thin films were investigated by using SEM and XRD patterns. The grain sizes increased and the pores decreased with rising RTA temperature. In addition, the coercive field decreased and the remanent polarization and saturation polarization increased with rising RTA temperature. The lnJ-E^1/2 curves of the SBT thin films were also investigated to find the leakage current mechanisms correspond either to the Schottky emission or to the Poole-Frenkel emission.

Abstract: Thin films of MBi₄Ti₄O₁₅ (M = Ca and Sr) with preferential crystal orientation were fabricated using underneath perovskite layers on various substrates. One-axis BLSD films on (100)LaNiO₃/(111)Pt/Ti/(100)Si and epitaxial BLSD films on (100)SrRuO₃//(100)SrTiO₃ were fabricated by chemical solution deposition (CSD). Dielectric constants of the CaBi₄Ti₄O₁₅ and SrBi₄Ti₄O₁₅ films on (100)LaNiO₃/(111)Pt/Ti/(100)Si were approximately 250, while those on (100)SrRuO₃//(100)SrTiO₃ were 220, respectively. The temperature coefficients of capacitance (TCCs) of these films were below 10% in atmospheric temperature range between R.T. and 300°C, which is significantly smaller than those of conventional (Ba,Sr)TiO₃-based capacitors.

Abstract: Thin films of a bismuth layer-structured dielectric oxides (BLSD), SrBi4Ti4O15, with preferential crystal orientation were prepared by means of chemical solution deposition (CSD) technique on (111)Pt/(100)Si substrate with bottom nucleation layers of conductive perovskite oxides, LaNiO3 and SrRuO3. CSD technique was utilized for the film preparation of SrBi4Ti4O15. These films possessed highly crystal orientation of (00l) BLSD planes parallel to the substrate surface. The leakage current densities of the SrBi4Ti4O15 films on (100)SrRuO3//(100)LaNiO3/(111)Pt/Ti/(100)Si and on (100)LaNiO3/(111)Pt/Ti/(100)Si were approximately 10-6 and 10-7 A/cm2 respectively. The dielectric constants of these films in a frequency range of 102 - 106 Hz were from 310 to 350 and 250 to 260 respectively. The value of capacitance change of these films in the range from 20 to 300 oC was about +8 and +5% respectively.

Abstract: (001)-, (1110), and (105)- oriented SrBi4Ti4O15 films with its c-axis tilted 0, 45 and 55o from the surface normal were epitaxially grown by metal organic chemical vapor deposition and the temperature dependency of the dielectric constant was systematically investigated. Relative dielectric constant, εr, and its temperature dependency increased when the tilting angle of the c-axis from the substrate surface normal increased. Temperature dependency of εr was positive in case of the (105) and (1110) orientation, which is in good agreement with the conventional ferroelectric materials. On the other hand, it became negative for (001) orientation. This shows the orientation dependency of εr in SrBi4Ti4O15.