在交流磁场中Fe3O4粒子的热生成行为:通过倾斜分析微观结构的分析
Manas Srivastava1, Ruchi Agrawal1,2, Atom Rajiv Singh1
1Chemistry Division, Bhabha Atomic Research, Centre, Mumbai 400085, India. nraghu_mani@yahoo.co.in.
Dalton transactions (Cambridge, England : 2003)
|January 15, 2025
概括
这项研究研究了氧化铁 (Fe3O4) 磁性纳米粒子,揭示了温度依赖的磁性和表面结构. 热量产生因粒子度和交流电场功率而异,为纳米粒子行为提供了洞察力.
科学领域:
- 材料科学 材料科学 材料科学
- 纳米技术纳米技术
- 磁力学 磁力学 是一种
背景情况:
- 了解氧化铁 (Fe3O4) 纳米颗粒的磁性特性对于生物医学和数据存储的应用至关重要.
- 表面效应,如倾斜结构,显著影响纳米粒子的行为.
- 描述微观结构对于准确的属性解释至关重要.
研究的目的:
- 为了研究不同温度下Fe3O4纳米颗粒的磁场依赖磁化.
- 分析表面倾斜结构对磁性特性的影响.
- 探索Fe3O4纳米粒子在交流电磁场下的热生成能力.
主要方法:
- 磁性测量 (磁化,强制性,交换偏差) 在5K和300K.
- 分析不同交流磁场功率和纳米粒子度下的热量产生.
- 使用传输电子显微镜 (TEM) 进行微结构分析,具有倾斜阶段 (0°14°),包括暗场 (DF) 和明场 (BF) 成像.
主要成果:
- 观察到温度依赖的交换偏差 (H_EB) 和强制性 (H_c),表明核心磁化和表面反铁磁贡献的变化.
- 随着交流电场功率和度的变化,热量产生变化;在高功率/度下,吸收和,导致样本中产生类似的热量.
- 微观结构分析揭示了聚合物,多孔性和其他特征,这对于理解观察到的磁性特性至关重要.
结论:
- Fe3O4纳米粒子磁化受到温度和表面结构的强烈影响.
- 热量产生可通过交流场参数和度控制,在高水平时具有和效应.
- 详细的微观结构特征对于准确解释Fe3O4纳米粒子特性至关重要.
相关概念视频
Ferromagnetism
2.4K
Materials like iron, nickel, and cobalt consist of magnetic domains, within which the magnetic dipoles are arranged parallel to each other. The magnetic dipoles are rigidly aligned in the same direction within a domain by quantum mechanical coupling among the atoms. This coupling is so strong that even thermal agitation at room temperature cannot break it. The result is that each domain has a net dipole moment. However, some materials have weaker coupling, and are ferromagnetic at lower...
2.4K
Motional Emf
3.1K
Magnetic flux depends on three factors: the strength of the magnetic field, the area through which the field lines pass, and the field's orientation with respect to the surface area. If any of these quantities vary, a corresponding variation in magnetic flux occurs. If the area through which the magnetic field lines are passing changes, then the magnetic flux also changes. This change in the area can be of two types: the flux through the rectangular loop increases as it moves into the...
3.1K
Atomic Nuclei: Nuclear Relaxation Processes
613
In the absence of an external magnetic field, nuclear spin states are degenerate and randomly oriented. When a magnetic field is applied, the spins begin to precess and orient themselves along (lower energy) or against (higher energy) the direction of the field. At equilibrium, a slight excess population of spins exists in the lower energy state. Because the direction of the magnetic field is fixed as the z-axis, the precessing magnetic moments are randomly oriented around the z-axis.
613
Induced Electric Fields: Applications
1.6K
An important distinction exists between the electric field induced by a changing magnetic field and the electrostatic field produced by a fixed charge distribution. Specifically, the induced electric field is nonconservative because it does not work in moving a charge over a closed path. In contrast, the electrostatic field is conservative and does no net work over a closed path. Hence, electric potential can be associated with the electrostatic field but not the induced field. The following...
1.6K
Potential Due to a Magnetized Object
260
Magnetic dipoles in magnetic materials are aligned when placed under an external magnetic field. For paramagnets and ferromagnets, dipole alignment occurs in the direction of the magnetic field. However, the dipoles align opposite to the field in the case of diamagnets. This state of magnetic polarization due to the external field is called magnetization. Magnetization is defined as the dipole moment per unit volume. It plays a similar role to polarization in electrostatics.
The vector...
The vector...
260
Magnetostatic Boundary Conditions
862
An electric field suffers a discontinuity at a surface charge. Similarly, a magnetic field is discontinuous at a surface current. The perpendicular component of a magnetic field is continuous across the interface of two magnetic mediums. In contrast, its parallel component, perpendicular to the current, is discontinuous by the amount equal to the product of the vacuum permeability and the surface current. Like the scalar potential in electrostatics, the vector potential is also continuous...
862


