Araujo, J.F.D.F.; Reis, A.L.A.; Oliveira, V.C., Jr.; Santos, A.F.; Luz-Lima, C.; Yokoyama, E.; Mendoza, L.A.F.; Pereira, J.M.B.; Bruno, A.C. Characterizing Complex Mineral Structures in Thin Sections of Geological Samples with a Scanning Hall Effect Microscope. Sensors2019, 19, 1636.
Araujo, J.F.D.F.; Reis, A.L.A.; Oliveira, V.C., Jr.; Santos, A.F.; Luz-Lima, C.; Yokoyama, E.; Mendoza, L.A.F.; Pereira, J.M.B.; Bruno, A.C. Characterizing Complex Mineral Structures in Thin Sections of Geological Samples with a Scanning Hall Effect Microscope. Sensors 2019, 19, 1636.
We improved a magnetic scanning microscope for measuring the magnetic properties of minerals in thin sections of geological samples at submillimeter scales. The microscope is comprised of a 200 µm diameter Hall sensor that is 142 µm from the sample; an electromagnet capable of applying to the sample up to 500 mT dc magnetic fields over a 40 mm diameter region; a second Hall sensor arranged in a gradiometric configuration to cancel the background signal applied by the electromagnet and reduce overall noise in the system; a custom-designed electronics to bias the sensors and provide adjustment for background signal cancelation; and a scanning XY stage with micrometer resolution. Our system achieves a spatial resolution of 220 µm with noise at 6.0 Hz of »300 nTrms/(Hz)1/2 in an unshielded environment. The magnetic moment sensitivity is 1.3 × 10−11 Am2.1/2 We successfully measured the representative magnetization of a geological sample using an alternative model that takes into account the sample geometry and identified different micrometric characteristics in the sample slice.
magnetic scanning microscope; hall sensor; magnetic materials; geological sample
PHYSICAL SCIENCES, Applied Physics
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.