Structural Phase Transition Mechanism of Ferroelectrics Thin Films and Nanocrystals

铁电薄膜和纳米晶的结构相变机制

• 批准号: 04640331
• 负责人: WADA Mitsuo
• 金额: $ 1.34万
• 依托单位: SHINSHU UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1992
• 资助国家: 日本
• 起止时间: 1992 至 1993
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-04640331/
• 关键词: Ferroelectrics; Thin Films; Nanocrystals; Stractural Phase Transition; Infrared Spectroscopy; Soft Mode; 相転移

Thin films of the perovskite ferroelectric PbTiO_3, on silicon single crystal substcrates were prepared by sol-gel processing. Single-layr sol-gel thin films can be deposited with thickness up to 200 nm. The thicker films were produced by multiple deposition. The optimum conditions for obtaining homogeneous and crack free thin films were determined. Far infrared absorption spectra were measured by FTIR spectrometer in the frequency region of 4 - 1000 cm^4. Absorption profiles of spectra of films thicker than 1000 nm are quite similar to those observed in bulk crystals, whereas in thinner films those of absorption lines are rather different. Moreover, the lowest-frequency mode at 80 cm^4, which corresponds to the ferroelectric soft mode in the tetragonal phase, decreases its frequency and intensity as the thickness decreases. The possibility of the occurrescence of stratrural changes around thickness of 1000 nm and 500 nm has been Pointed out.

用溶胶-凝胶法在硅单晶衬底上制备了钙钛矿型铁电体PbTiO_3薄膜。单层溶胶-凝胶薄膜的厚度可达200 nm。较厚的膜是由多次沉积。确定了获得均匀无裂纹薄膜的最佳条件。通过FTIR光谱仪在4 - 1000 cm ^4的频率范围内测量远红外吸收光谱。厚于1000 nm的薄膜的光谱的吸收曲线是非常相似的块状晶体中观察到的，而在较薄的薄膜的吸收线是相当不同的。此外，在80 cm ^4处的最低频率模式，对应于四方相的铁电软模式，其频率和强度随着厚度的减小而减小。指出了在1000 nm和500 nm厚度附近发生相变的可能性。

项目成果

M.Wada,Y.Yamashita,A.Sawada & Y.Ishibashi: "Dielectric Dispersion in Ferroelectric Li_<2-x>Na_xGe_4O_9(x〓1)" J.Phys.Soc.Jpn.62. 4503-4510 (1993)

M.Wada、Y.Yamashita、A.Sawada 和 Y.Ishibashi：“铁电 Li_<2-x>Na_xGe_4O_9(x〓1) 中的介电色散”J.Phys.Soc.Jpn.62 (1993)。

M.WADA,Y.Yamashita,A.Sawada & Y.Ishibashi: "Ferroelectric Phase Transition in Li_<2-x>Na_xGe_4O_9" Journal of The Physical Society of Japan. 62. 14-17 (1993)

M.和田,Y.山下,A.泽田

WADA.M.YAMASHITA.Y.SAWADA.A.ISHIBASHI.Y.: "Dielectric Dispersion in Ferroelectric Li_<2・x>Na_xCe_4O_9" J.Phys.Soc.Jpn.62. 4503-4510 (1993)

WADA.M.YAMASHITA.Y.SAWADA.A.ISHIBASHI.Y.：“铁电 Li_<2・x>Na_xCe_4O_9 中的介电色散”J.Phys.Soc.Jpn.62 (1993)。

K.Krec,W.Stainer & M.Wada: "Ferroelectric Phase Transition in Li_2Ge_7O_<15> Investigated by Mossbauer Diffraction" Acta Crystal.A. A49. 198-202 (1993)

克雷克,斯坦纳

M.Wada,Y.Yamashita,A.Sawada & Y.Ishibashi: "Ferroelectric Phase Transition in Li_<2-X>Na_XGe_4O_9 (x=0.5)" J.Phys.Soc.Jpn.62. L14-L17 (1993)

M.和田,Y.山下,A.泽田