Hanif Mehwish, Farooq Omer, Rafiq U, Anis-Ur-Rehman M, Ul Haq A
Department of Electrical and Electronic Engineering, Universiti Teknologi Petronas, Tronoh, Malaysia. Applied Thermal Physics Laboratory (ATPL), Department of Physics, COMSATS University Islamabad 44000, Pakistan. Department of Basic Sciences, Riphah International University, Islamabad 4400, Pakistan.
Nanotechnology. 2020 Apr 3;31(25):255707. doi: 10.1088/1361-6528/ab76ea. Epub 2020 Feb 17.
To synthesize lithium ferrite with various Gd concentrations (LiFeGdO), x = 0.00, 0.025, 0.05, 0.075, 0.1, solutes were dissolved in glycol, i.e. by using the without water and surfactant (WOWS) sol-gel method. X-ray diffraction (XRD) analysis confirmed that the material possessed an inverse spinel cubic structure and is single phase. Pellets of all samples were sintered at 700 °C and XRD confirmed that samples were crystalline, phase pure and had an inverse spinel cubic lattice. Scanning electron microscopy indicated that the grains were agglomerated and had a predominantly spherical shape. It is concluded that Gd acts as a grain refiner in lithium ferrite up to a Gd concentration of 0.05. AC conductivity and dielectric constant increased by increasing Gd concentration. The Maxwell-Wagner model and Johnsher's power law were used to explain the dielectric properties. DC conductivity was measured from 100 to 600 °C. DC conductivity was explained by the hopping mechanism. It is concluded that DC resistivity and dielectric constant values are related reciprocally in the prepared sample. AC electrical properties were also measured at a constant frequency of 1 MHz in the temperature range from 400 to 600 °C. Gd-substituted lithium ferrite showed high AC conductivity, high DC resistivity and constant dielectric values, but low dielectric loss values as compared to pure lithium ferrite.
为了合成具有不同钆（Gd）浓度（LiFeGdO，x = 0.00、0.025、0.05、0.075、0.1）的锂铁氧体，将溶质溶解在乙二醇中，即采用无水无表面活性剂（WOWS）溶胶 - 凝胶法。X射线衍射（XRD）分析证实该材料具有反尖晶石立方结构且为单相。所有样品的颗粒在700°C下烧结，XRD证实样品为晶体、相纯且具有反尖晶石立方晶格。扫描电子显微镜表明晶粒团聚且主要呈球形。得出结论：在钆浓度达到0.05之前，钆在锂铁氧体中起到晶粒细化剂的作用。交流电导率和介电常数随钆浓度的增加而增大。采用麦克斯韦 - 瓦格纳模型和约翰舍尔幂定律来解释介电性能。在100至600°C范围内测量直流电导率。直流电导率由跳跃机制来解释。得出结论：在所制备的样品中，直流电阻率和介电常数的值呈反比关系。在400至600°C的温度范围内，还在1 MHz的恒定频率下测量了交流电性能。与纯锂铁氧体相比，钆取代的锂铁氧体表现出高交流电导率、高直流电阻率和恒定的介电值，但介电损耗值较低。
