N. ChaikumR. M. CarrMahidol UniversityUniversity of Otago2018-06-142018-06-141989-01-01Solid State Ionics. Vol.32-33, No.PART 1 (1989), 389-393016727382-s2.0-0024613055https://repository.li.mahidol.ac.th/handle/20.500.14594/15740Kaolinite exhibits two principal ESR resonances centred at g∼4 and g∼2. Following heat treatment at 500°C, the low-field resonance collapses with a simultaneous increase in intensity of the central line. Similar results were obtained from dry-ground kaolinite and this change is attributed partly to oxidation of Fe 2+ . X-irradiation resulted in new paramagnetic species on the clay surfaces and a corresponding intense signal at g=2, while treatment with solutions of a strong acid and a strong base produced no significant change in the spectrum. © 1989.Mahidol UniversityChemistryMaterials SciencePhysics and AstronomyArticleSCOPUS10.1016/0167-2738(89)90245-2