Thin film growth effects on electrical conductivity in entropy stabilized oxides
Thin film growth effects on electrical conductivity in entropy stabilized oxides
复制标题
DOI：
10.1016/j.jeurceramsoc.2020.12.021
复制
发表时间：
2020-06
期刊：
影响因子：
--
通讯作者：
V. Jacobson;D. Diercks;B. To;A. Zakutayev;G. Brennecka
中科院分区：
文献类型：
--
作者：
V. Jacobson;D. Diercks;B. To;A. Zakutayev;G. Brennecka
熵稳定作为设计新型材料的新方法引起了人们的广泛关注。该领域的大部分工作都集中在块状陶瓷加工上，而对熵稳定薄膜的探索相对不足。对通过脉冲激光沉积 (PLD) 沉积的多晶 (Mg 0.2 Co 0.2 Ni 0.2 Cu 0.2 Zn 0.2) O 薄膜进行了广泛的多变量研究，结果表明，基底温度和沉积压力对薄膜织构和晶格参数具有强烈且可重复的影响。进一步的分析表明，在较低温度和较低氧室压力下沉积的薄膜的电阻比在较高温度和压力下生长的相同薄膜低约 40 倍。在富氧环境中对这些薄膜进行退火会增加其电阻率，以匹配在较高温度和压力下生长的薄膜的电阻率。因此，假设电导率是由过渡金属价态变化介导的极化子跳跃的结果，该变化补偿了氧的非化学计量。
Entropy stabilization has garnered significant attention as a new approach to designing novel materials. Much of the work in this area has focused on bulk ceramic processing, leaving entropy-stabilized thin films relatively under-explored. Following an extensive multi-variable investigation of polycrystalline (Mg 0.2 Co 0.2 Ni 0.2 Cu 0.2 Zn 0.2) O thin films deposited via pulsed laser deposition (PLD), it is shown here that substrate temperature and deposition pressure have strong and repeatable effects on film texture and lattice parameter. Further analysis shows that films deposited at lower temperatures and under lower oxygen chamber pressure are∼ 40× less electrically resistive than otherwise identical films grown at higher temperature and pressure. Annealing these films in an oxygen-rich environment increases their electrical resistivity to match that of the films grown at higher temperatures and pressures. Because of this, the electric conductivity is hypothesized to be the result of polaron hopping mediated by transition metal valence changes which compensate for oxygen off-stoichiometry.