中文摘要
课题研究了多种过渡金属氧化物块材、薄膜及其异质结的结构、介电和输运特性。用PLD方法成功地在（001）和（110）STO基片上分别制备了（001）和（100）取向的正交HoMnO3外延薄膜，观察到了显著的磁电效应。在反铁磁转变温度下，介电常数上升了9.2%，在1T磁场下，在20K介电常数下降了3%。TbMnO3薄膜在应力状态下，我们在158 K附件发现了一个新的磁转变。在TbMnO3块材中我们研究了低频介电温度谱，发现低温介电弛豫峰来源于晶粒内部局域载流子的跃迁，而高温弛豫峰则是颗粒边界的贡献；而在CoTiO3块材中，高温介电弛豫源于氧空位缺陷引起的偶极子的介电行为。在CaCu3Ti4O12 （CCTO）块材中我们首次在介电温度谱中发现了低温反常热回滞行为。我们用Jonscher的电荷屏蔽模型对高温正常热回滞和低温下反常热回滞做出了统一合理的解释。制备了极性（001）ZnO和非极性（110）ZnO外延膜及异质结。发现极性ZnO面内电阻率比非极性ZnO小近两个数量级，而极性异质结比非极性异质结的开启电压高，说明ZnO的极性对其薄膜及其异质结有不能忽略的影响。
英文摘要
The structural, dielectric, and transport properties of transition metal oxide bulks and thin films were investigated. (001) and (100) orientated HoMnO3 epitaxial thin films were fabricated on (001) and (110) STO single crystal substrates respectively, and the prominent magnetoelectric effects were observed. Below the antiferromagnetic transition temperature, the dielectric constant rises up by 9.2%. The dielectric constant decreases by 3% at 20 K under the magnetic field of 1T. A new magnetic transition at 158 K was discovered in strained TbMnO3 epitaxial thin films. The low frequency temperature dependent dielectric behavior was studied on TbMnO3 bulk samples. The low temperature dielectric relaxation was ascribed to the hopping of the localized charges in grains, with the high temperature relaxation peak to the grain boundaries. While on CoTiO3 bulk samples, the high temperature relaxation was originated from the dipole relaxation induced by the oxygen vacancies. In CaCu3Ti4O12 bulk samples an anomalous thermal hysteresis at low temperatures as well as a normal thermal hysteresis at high temperatures in dielectric permittivity was discovered. The charge screening model proposed by Jonscher was used to reasonably explain the two kinds of thermal hysteresis. The polar and non-polar ZnO epitaxial thin films and their heterojunctions were prepared. The resistivity in the polar thin film plane is smaller by two orders than that in non-polar ZnO thin film plane, indicating that the polar effects in ZnO thin films and their heterojuctions could not be neglected.
结题摘要
课题研究了多种过渡金属氧化物块材、薄膜及其异质结的结构、介电和输运特性。用PLD方法成功地在（001）和（110）STO基片上分别制备了（001）和（100）取向的正交HoMnO3外延薄膜，观察到了显著的磁电效应。在反铁磁转变温度下，介电常数上升了9.2%，在1T磁场下，在20K介电常数下降了3%。TbMnO3薄膜在应力状态下，我们在158 K附件发现了一个新的磁转变。在TbMnO3块材中我们研究了低频介电温度谱，发现低温介电弛豫峰来源于晶粒内部局域载流子的跃迁，而高温弛豫峰则是颗粒边界的贡献；而在CoTiO3块材中，高温介电弛豫源于氧空位缺陷引起的偶极子的介电行为。在CaCu3Ti4O12 （CCTO）块材中我们首次在介电温度谱中发现了低温反常热回滞行为。我们用Jonscher的电荷屏蔽模型对高温正常热回滞和低温下反常热回滞做出了统一合理的解释。制备了极性（001）ZnO和非极性（110）ZnO外延膜及异质结。发现极性ZnO面内电阻率比非极性ZnO小近两个数量级，而极性异质结比非极性异质结的开启电压高，说明ZnO的极性对其薄膜及其异质结有不能忽略的影响。