Araujo J F D F, Bruno A C, Louro S R W
Department of Physics, Pontifícia Universidade Católica do Rio de Janeiro, Rio de Janeiro 22451-900, Brazil.
Rev Sci Instrum. 2015 Oct;86(10):105103. doi: 10.1063/1.4931989.
We constructed a versatile magnetometer assembly for characterizing iron oxide nanoparticles. The magnetometer can be operated at room temperature or inside a cryocooler at temperatures as low as 6 K. The magnetometer's sensor can be easily exchanged and different detection electronics can be used. We tested the assembly with a non-cryogenic commercial Hall sensor and a benchtop multimeter in a four-wire resistance measurement scheme. A magnetic moment sensitivity of 8.5 × 10(-8) Am(2) was obtained with this configuration. To illustrate the capability of the assembly, we synthesized iron oxide nanoparticles coated with different amounts of a triblock copolymer, Pluronic F-127, and characterized their magnetic properties. We determined that the polymer coating does not affect the magnetization of the particles at room temperature and demonstrates that it is possible to estimate the average size of coating layers from measurements of the magnetic field of the sample.
我们构建了一种用于表征氧化铁纳米颗粒的多功能磁力计组件。该磁力计可在室温下运行，也可在温度低至6 K的低温冷却器内运行。磁力计的传感器可轻松更换，并且可以使用不同的检测电子设备。我们在四线电阻测量方案中使用非低温商用霍尔传感器和台式万用表对该组件进行了测试。通过这种配置获得了8.5×10(-8) Am(2)的磁矩灵敏度。为了说明该组件的能力，我们合成了涂覆有不同量三嵌段共聚物Pluronic F-127的氧化铁纳米颗粒，并对其磁性能进行了表征。我们确定聚合物涂层在室温下不会影响颗粒的磁化，并证明可以通过测量样品的磁场来估计涂层的平均尺寸。
