Islam M Aminul, Syed Ishtiaque M, Mamun M Al, Hoque S Manjura
Materials Science Division, Atomic Energy Centre Dhaka, Bangladesh Atomic Energy Commission, Dhaka, Bangladesh.
Department of Physics, University of Dhaka, Dhaka, Bangladesh.
Front Chem. 2024 Mar 7;12:1347423. doi: 10.3389/fchem.2024.1347423. eCollection 2024.
In this study, MgCoFeO (0x with ∆x = 0.1) or MCFO nanoparticles were synthesized using a chemical co-precipitation method and annealed at 200, 400, 600, and 800°C respectively to investigate the structural properties of the materials by X-ray diffractometer (XRD), transmission electron microscopy (TEM), and Fourier-transform infrared spectroscopy (FTIR). Controlled annealing increased particle size for each value of x. The aim was to investigate how specific loss power (SLP) and maximum temperature (T) during local magnetic hyperthermia were affected by structural alterations associated with particle size and composition. The lattice parameter, X-ray density, ionic radius, hopping length, bond length, cation-cation distance, and cation-anion distance increase with an increase in Co content. Raman and FTIR spectroscopy reveal changes in cation distribution with Co content and particle size. Magnetic properties measured by the physical property measurement system (PPMS) showed saturation magnetization (M), coercivity (H), remanent magnetization (M/M), and anisotropy constant (K) of the MgCoFeO nanoparticles increase with Co content and particle size. When exposed to an rf magnetic field, the nanohybrids experienced an increase in both the SLP (specific loss power) and T (maximum temperature) as the particle size initially increased. However, these values reached their peak at critical particle size and subsequently decreased. This occurs since a modest increase in anisotropy, resulting from the presence of Co and larger particle size, facilitates Néel and Brownian relaxation. However, for high anisotropy values and particle size, the Néel and Brownian relaxations are hindered, leading to the emergence of a critical size. The critical size increases as the Co content decreases, but it decreases as the Co content increases, a consequence of higher anisotropy with the increase in Co. Additionally, it is noteworthy that the maximum temperature (T) rises as the concentration of nanohybrids grows, but the specific loss power (SLP) decreases. An increased concentration of chitosan-MCFO nanohybrids inhibits both the Néel and Brownian relaxation processes, reducing specific loss power.
在本研究中，采用化学共沉淀法合成了MgCoFeO（∆x = 0.1时的0x）或MCFO纳米颗粒，并分别在200、400、600和800°C下退火，通过X射线衍射仪（XRD）、透射电子显微镜（TEM）和傅里叶变换红外光谱（FTIR）研究材料的结构性能。对于每个x值，控制退火会增加颗粒尺寸。目的是研究局部磁热疗期间的比损耗功率（SLP）和最高温度（T）如何受到与颗粒尺寸和组成相关的结构变化的影响。晶格参数、X射线密度、离子半径、跳跃长度、键长、阳离子-阳离子距离和阳离子-阴离子距离随Co含量的增加而增加。拉曼光谱和FTIR光谱揭示了阳离子分布随Co含量和颗粒尺寸的变化。通过物理性能测量系统（PPMS）测量的磁性能表明，MgCoFeO纳米颗粒的饱和磁化强度（M）、矫顽力（H）、剩余磁化强度（M/M）和各向异性常数（K）随Co含量和颗粒尺寸的增加而增加。当暴露于射频磁场时，随着颗粒尺寸最初的增加，纳米杂化物的比损耗功率（SLP）和最高温度（T）均有所增加。然而，这些值在临界颗粒尺寸时达到峰值，随后下降。这是因为Co的存在和较大的颗粒尺寸导致各向异性适度增加，促进了奈尔和布朗弛豫。然而，对于高各向异性值和颗粒尺寸，奈尔和布朗弛豫受到阻碍，导致临界尺寸的出现。临界尺寸随Co含量的降低而增加，但随Co含量的增加而减小，这是Co增加导致更高各向异性的结果。此外，值得注意的是，最高温度（T）随着纳米杂化物浓度的增加而升高，但比损耗功率（SLP）降低。壳聚糖-MCFO纳米杂化物浓度的增加会抑制奈尔和布朗弛豫过程，降低比损耗功率。
