Three Dimensional (3D) Electron Paramagnetic Resonance Imaging Technique For Mapping Porosity in Ceramics

ABSTRACTA three dimensional (3D) Electron Paramagnetic Resonance Imaging (EPRI) method has been developed to probe the structure and size of pores in ceramic materials. A computer control current source and magnetic field gradient coil assembly were added on the conventional EPR instrument as imaging devices. This added-on facility was tested using a phantom sample having cavities filled with DPPH (2,2-diphenyl-1-picrylhydrazyl) particles. Pumice was then used to demonstrate the feasibility of the technique. Porous pumice stone was immersed in a 0.5mM 15N-PDT-water solution to introduce the spin labels into the open volume of the sample. A two-dimensional image was reconstructed from a set of 1-D projections using a filtered back-projection technique. A three-dimensional image was derived from 22 2-D images each constructed by 22 1-D projections. At present, the facility allows a resolution of 69 and 46 μm for 2-D and 3-D imaging.