| 학회 | 한국재료학회 |
| 학술대회 | 2007년 봄 (05/10 ~ 05/11, 무주리조트) |
| 권호 | 13권 1호 |
| 발표분야 | 전자재료 |
| 제목 | Effect of Nonlinear Coupling between Polarizations and Stresses on the Ferroeletric Properties of BaTiO3 |
| 초록 | The effects of lateral stresses in the phase transitions of perovskite ferroelectric materials such as BaTiO3 and PbTiO3 have been studied extensively theoretically and experimentally. Pertsev et al. have proposed phase diagrams of BT and PT under 2 dimensional (2D) stresses with the aid of Landau-Devonshire calculations. This 2D clamping condition is compatible with perovskite thin films epitaxially grown on oxide substrates. With compressive stress or with negative misfit strain, the phase transition temperature (T3) from paraelectric cubic phase to ferroelectric tetragonal phase (c-phase; the direction of polarization is perpendicular to the film surface) was calculated to increase linearly with stress. On the other hand, with tensile stress or with negative misfit strain, the phase transition temperature (T1) from paraelectric cubic phase to ferroelectric phase (aa-phase; the direction of polarization is parallel to the film surface) was also calculated to increase linearly with stress. These theoretically calculated results were realized in the pulsed laser deposited BT thin films with SrRuO3 bottom electrode with GdScO3 or DyScO3 substrates. Experimentally observed T3 in BaTiO3 single crystal under two-dimensional pressure, however, showed quadratic increase on external pressure. Similar results were observed in externally stressed Pb(Zr,Ti)O3 thin films and explained by introducing new couplings between σ2 and P2.[4] And the fact that the crystal structure below transition temperature is still tetragonal in compressively strained BaTiO3 thin film and observed polarization values are much larger than calculated values asks us more investigation about the character of phase transition. In this work, the effects of new coupling terms were studied. Polarization values and phase transition temperatures under compressive strains were calculated and compared with previous results. |
| 저자 | 송태권 |
| 소속 | 창원대 |
| 키워드 | Ferroelectrics; Polarization; Landau-Devonshire theory; Stress |
