Study of the electrical and magnetic properties of Cr doped Ni-Mn

• Main Authors: SU, CHUN-HSAING, 蘇駿翔
• Other Authors: LEI, CHIEN-MING
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/8pmwtk

碩士 === 中國文化大學 === 化學工程與材料工程學系奈米材料碩士班 === 105 === In this work, The Ni0.9Mn0.1CrxFe2-xO4 (x=0.0, 0.1, 0.2, 0.3, and 0.5) ceramics have been synthesized with the solid-state method to study the dielectric property and temperature dependent of the Neel relaxation behavior in these compounds. All un-dopant and Cr-doped samples were formed spinel cubic structure, which has been checked by powder X-ray diffraction and a-axis the lattices constant was decreased with Cr-doped level increasing due to smaller Cr-ion radii. The OM pictures in the Ni-Mn ferrite samples are shown that the grain size is increasing with sintering temperature increasing, but decreasing with Chromium concentration increasing. The grain size has been counted by the intercept technique through the OM images. Room temperature VSM measurement is showed that saturation magnetization is decreasing with Cr concentration increasing due to nonmagnetic Cr-ion increasing. AC magnetic susceptibility measurement is showed that all samples obey Neel magnetic relaxation behavior. Low temperatures AC magnetic susceptibility has been measured vary temperature, which was fitted the Debye relaxations model to calculate the resonance frequency (f0), and the magnetic anisotropy energy can be computed by the lnf0 versus reciprocal temperature plot. The magnetic anisotropy energy of 1623K sintering temperature of Cr-doped samples is gradually increasing with Cr-doped level x increasing except un-dopant sample. The amplitude magnetic anisotropy energy of Ni0.9Mn0.1Cr0.1Fe1.9O4 samples is gradually decreasing with sintering temperature increasing except 1473K sintering temperature sample. Room temperature dielectric property measurement is showed that dielectric constant is decreasing with Cr-doped level increasing and dielectric loss is increasing with sintering temperature increasing. We reported that bulk or powder samples’ magnetic anisotropy energy can measure by temperature dependent AC susceptibility method, and dielectric property can improve by Cr-doped processing and sintering temperature control.