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研究并比较了两种不同(Ba0.5,Sr0.5)TiO3(BSTO)薄膜介电-温度特性.采用脉冲激光沉积技术在Pt/Ti/SiO2/Si(100)衬底上制备BSTO薄膜,发现制备条件的不同,可以得到介电性质完全不同的BSTO薄膜.在550℃和氮气氛下制备的BSTO薄膜在常温下具有很高的介电常数,在10kHz下,超过2500,并在200K温度以上介电常数基本不变.它的一些电学性质不同于在正常条件(650℃和氧气氛下)制得的BSTO薄膜,而类似于目前广泛报道的巨介电常数材料如CaCu3Ti4O12.两种薄膜介电性质测试结果表明:氧气氛下制备的BSTO薄膜呈现铁电-顺电相变,符合居里-外斯定律;低温氮气氛下制备的BSTO薄膜,介电弛豫时间和温度的关系符合德拜模型,是热激发弛豫.文中给出了产生这种介电特性的初步解释.
The dielectric-temperature characteristics of two different thin films of Ba0.5 Sr0.5 TiO3 were studied and compared.The BSTO films were prepared on Pt / Ti / SiO2 / Si (100) substrates by pulsed laser deposition, The results show that BSTO films with completely different dielectric properties can be obtained.The BSTO thin films prepared at 550 ℃ and nitrogen atmosphere have high dielectric constant at room temperature and over 2500 at 10kHz and at 200K The dielectric constants above are essentially unchanged, and some of its electrical properties are different from those of BSTO films fabricated under normal conditions (650 ° C and oxygen), similar to the currently widely reported macrocolectic materials such as CaCu3Ti4O12. The dielectric properties of BSTO films prepared under oxygen atmosphere show that the BSTO thin films exhibit ferroelectric-paraelectric phase transition, which accords with the Curie-Weiss law. The relationship between dielectric relaxation time and temperature is in good agreement with Germany The model is thermally induced relaxation. A preliminary explanation of this dielectric property is given.