Nforna Edwin Akongnwi, Tsobnang Patrice Kenfack, Fomekong Roussin Lontio, Tedjieukeng Hypolite Mathias Kamta, Lambi John Ngolui, Ghogomu Julius Numbonui
Department of Fundamental Science, Higher Technical Teacher Training College, University of Bamenda, P.O. Box 39, Bambili, Cameroon.
Department of Chemistry, University of Dschang, P.O. Box 67, Dschang, Cameroon.
R Soc Open Sci. 2021 Feb 3;8(2):201883. doi: 10.1098/rsos.201883.
Samples of cobalt-doped neodymium orthoferrite compounds, NdCoFeO (0.0 ≤ x ≤ 0.5) were synthesized via glycine auto-combustion between 250 and 300°C and calcined at 500°C for 2 h. X-ray diffraction showed that all compounds had an orthorhombic perovskite structure with space group Pbnm. Increasing cobalt doping gradually reduced the lattice parameters and contracted the unit cell volume. Both X-ray diffraction and scanning electron microscopy showed that the particles were spherical and in the nano-sized range (19-52 nm) with pores between grains. Vibrating sample magnetometry at room temperature indicated that NdFeO has a high coercive field (1950 Oe) and cobalt substitution for iron led to a decrease in the coercive field, saturation and remanent magnetization, which was as a result of decreased magnetic moments in the crystal and reduced canting of the FeO octahedra. The increase in magnetization and coercive fields with increase of Co was connected to the microstructure (bond lengths and angles, defects, pores, grain boundaries) and crystallite size. The compounds NdCoFeO show antiferromagnetism with weak ferromagnetism due to uncompensated non-collinear moments. These compounds could serve as prototypes for tuning the properties of magnetic materials (ferromagnetic and antiferromagnetic) with potential applications in data storage, logic gates, switches and sensors.
通过在250至300°C之间的甘氨酸自燃烧合成了钴掺杂的正铁酸钕化合物NdCoFeO（0.0≤x≤0.5）的样品，并在500°C下煅烧2小时。X射线衍射表明，所有化合物均具有空间群为Pbnm的正交钙钛矿结构。钴掺杂量的增加逐渐减小了晶格参数并收缩了晶胞体积。X射线衍射和扫描电子显微镜均表明，颗粒呈球形且在纳米尺寸范围内（19 - 52纳米），晶粒之间存在孔隙。室温下的振动样品磁强计表明，NdFeO具有高矫顽场（1950奥斯特），用钴替代铁导致矫顽场、饱和磁化强度和剩余磁化强度降低，这是由于晶体中的磁矩减小以及FeO八面体的倾斜度降低所致。随着Co含量增加，磁化强度和矫顽场的增加与微观结构（键长和键角、缺陷、孔隙、晶界）和微晶尺寸有关。化合物NdCoFeO由于未补偿的非共线磁矩而表现出具有弱铁磁性的反铁磁性。这些化合物可作为调节磁性材料（铁磁性和反铁磁性）性能的原型，在数据存储、逻辑门、开关和传感器方面具有潜在应用。
