title: Temperature-induced changes in the EPR spectrum of the magnetic center in kaolin.
abstract: Studies of kaolin have revealed an effect characterized by an unusual temperature-induced change of the EPR spectrum of the Fe3+ ion, which is the magnetic probe in kaolin-clay. At low temperature (T=4.2 K) a resonance line with an effective g-value g1=4.13 +/- 0.16 is observed. At high temperature (T=288 K) one observes a resonance line with the effective g-value g2=2.15 +/- 0.1. The transition from the low- to high-temperature spectrum is gradual and it is accompanied by a redistribution of the absorption intensity. The observed properties of the temperature dependence of the EPR spectrum are characteristic of systems with a multiminimum potential.
authors.affiliation: Donetsk Physical-Technical Institute of the National Academy of Sciences of Ukraine, 83114 Donetsk, Ukraine.
authors.forename: Vladimir N
authors.initials: VN
authors.lastname: Vasyukov
authors.forename: Vladimir V
authors.initials: VV
authors.lastname: Shapovalov
authors.forename: Steven A
authors.initials: SA
authors.lastname: Schwarz
authors.forename: Miriam H
authors.initials: MH
authors.lastname: Rafailovich
authors.forename: Jonathan C
authors.initials: JC
authors.lastname: Sokolov
authors.forename: Vladimir A
authors.initials: VA
authors.lastname: Shapovalov
authors.forename: Viktor A
authors.initials: VA
authors.lastname: Beloshenko
mesh_terms: D004578:Electron Spin Resonance Spectroscopy; D007616:Kaolin / Q000737:chemistry*; D008280:Magnetics; D013696:Temperature
chemical_list: D007616:Kaolin