应用物理

Vol.6 No.10 (October 2016)

SrCoOx薄膜中的氧空位效应研究
Study on the Effects of Oxygen Vacancy in SrCoOx Thin Films

 

作者:

史志界 , 江正华 , 周 浩 , 汤如俊 :苏州大学物理与光电•能源学部,江苏省薄膜材料重点实验室,江苏 苏州

 

关键词:

SrCoOx退火温度氧空位SrCoOx Annealing Temperature Oxygen Vacancy

 

摘要:

本文中我们采用脉冲激光沉积技术在SrTiO3(001)基底上制备出钙铁石结构的SrCoO2.5(BM-SCO)外延薄膜,在氧气氛围、不同温度下对样品进行后退火工艺处理,使薄膜发生由钙铁石相到钙钛矿相(P-SCO)的拓扑相变。研究结果表明薄膜的磁性和微结构在相变温度(250℃)附近发生很大的变化。当退火温度为250℃ ≤ T < 600℃时,薄膜由BM-SCO转变为BM-SCO与P-SCO的共存相(Mix-SCO),薄膜的磁性明显增强,由反铁磁性转变为铁磁性(Tc~180 K)。当退火温度达到600℃时,完全转变为钙钛矿型SrCoO3–δ。XPS拟合结果显示,退火后Co的价态发生变化,从Co3+转变为Co4+,即薄膜中的部分氧空位被填充。故退火后钙钛矿型SrCoO3–δ的氧含量(3–δ)约为2.75。

In this work, we grew brownmillerite SrCoO2.5 (BM-SCO) epitaxial thin films on (001) SrTiO3 substrates by pulsed laser deposition and performed post-annealing at various temperatures in oxygen atmosphere for topotactic conversion into the perovskite phase (P-SCO). The results show that the magnetic properties and microstructure of the films have a great change near the critical temperature (250˚C). When a BM-SCO film was annealed in lower temperature (250˚C ≤ T < 600˚C), a mixed-phase of BM-SCO and P-SCO (Mix-SCO) was observed, and oxygen intercalation drove the antiferromagnetic phase to ferromagnetic phase (Tc~180 K). We also found that in post-annealing under 600˚C a complete phase transition from the brownmillerite SrCoO2.5 to the perovskite SrCoO3–δ was exhibited. XPS fitting results clearly indicate a change in the Co valence state from 3+ toward 4+. So some oxygen vacancies in the films are filled. Therefore, we conclude that the oxygen concentration (3–δ) in perovskite SrCoO3–δ by post-annealing is about 2.75.

文章引用:

史志界 , 江正华 , 周 浩 , 汤如俊 (2016) SrCoOx薄膜中的氧空位效应研究。 应用物理, 6, 205-211. doi: 10.12677/APP.2016.610026

 

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