Journal of Industrial and Engineering Chemistry ( IF 6.1 ) Pub Date : 2021-07-02 , DOI: 10.1016/j.jiec.2021.06.028 Sidra Khalid 1 , Saira Riaz 1 , Samia Naeem 1 , Aseya Akbar 2 , S. Sajjad Hussain 1 , YB Xu 3 , Shahzad Naseem 1
Production of single-phase materials with multifunctional properties is still a challenge faced by material scientists. In addition, obtaining high spin polarization efficiency in the materials that exhibit multifunctional properties is a big issue. A novel approach is suggested in this work for obtaining multifunctionality and spin polarization in the same material. This approach has combined the effect of microwave radiations and aluminum (Al) doping in iron oxide thin films during synthesis. Combined effect of microwave radiations and Al doping results in controlling / tuning the structural transitions in iron oxide thin films. Pristine and 2–10 wt% Al doped iron oxide thin films are prepared and studied in detail. Raman analysis shows that 2 and 4 wt% Al concentration results in γ-Fe2O3 + Fe3O4 phase with 71.3% and 64.5% of γ-Fe2O3 content, respectively. XRD and Raman analyses confirm the transition from γ-Fe2O3 to Fe3O4 thin films at Al concentrations of 6–10 wt%. Structural transformation shows that microwave radiations catalyzes that Al3+ions to occupy the vacancies on B sites of iron oxide thus, lead to the formation of Fe3O4. Observation of Verwey transition ~ 126 K also supports the transition in phases of iron oxide with increase in saturation magnetization from 251.3emu/cm3 (pristine films) to 405.6emu/cm3 (8 wt% Al concentration). High dielectric constant of ~ 135.5 (log f = 5.0) is observed for 8 wt% Al concentration. Conductivity and detailed impedance & modulus analyses depict Mott’s hopping phenomenon along with presence of different relaxation times. Coupling between magnetic and dielectric properties is observed at room temperature. Magnetoresistance curves indicate spin polarization efficiency of ~24%.
中文翻译:
铝改性薄氧化铁薄膜中的自旋极化和磁介电耦合-微波介导的溶胶-凝胶方法
生产具有多功能特性的单相材料仍然是材料科学家面临的挑战。此外,在具有多功能特性的材料中获得高自旋极化效率是一个大问题。在这项工作中提出了一种新方法,用于在同一材料中获得多功能性和自旋极化。这种方法结合了微波辐射和合成过程中氧化铁薄膜中铝 (Al) 掺杂的影响。微波辐射和铝掺杂的综合作用导致控制/调整氧化铁薄膜的结构转变。制备并详细研究了原始和 2-10 wt% Al 掺杂的氧化铁薄膜。拉曼分析表明,2 和 4 wt% 的 Al 浓度导致 γ-Fe 2 O 3 + Fe 3 O 4相的γ-Fe 2 O 3含量分别为71.3% 和64.5% 。XRD 和拉曼分析证实了从 γ-Fe 2 O 3到 Fe 3 O 4薄膜的转变,Al 浓度为 6-10 wt%。结构转变表明微波辐射催化Al 3+离子占据氧化铁B位的空位,从而导致Fe 3 O 4的形成。观察到 Verwey 转变 ~ 126 K 也支持氧化铁相的转变,饱和磁化强度从 251.3emu/cm 3 增加(原始薄膜)至 405.6emu/cm 3(8 wt% Al 浓度)。 对于 8 wt% 的铝浓度,观察到~ 135.5 (log f = 5.0) 的高介电常数。电导率和详细的阻抗和模量分析描绘了莫特跳跃现象以及不同弛豫时间的存在。在室温下观察到磁性和介电特性之间的耦合。磁阻曲线表明自旋极化效率约为 24%。