Magnetic moments and ESR spectra of Co 2+ ions in alkali borate glasses

Abstract

Measurements of magnetic moments and ESR spectra at room temperature and at 4.2 K, respectively, have been made on the R 2OB 2O 3 glasses containing Co 2+ (RLi,K). For purposes of comparison the measurements of ESR spectra have also been made on the high alkali-borate glass (70Na 2O30B 2O 3) and the sodium-borosilicate glass (10Na 2O60SiO 230B 2O 3), both of which contain Co 2+. The magnetic moments calculated from the susceptibility data in this paper are considerably smaller in comparison with those of Juza et al.; this finding also indicates that the dependences of the magnetic moments on the glass composition differ from the result of Juza et al. The ESR spectra indicate that Co 2+ is predominantly octahedral in low alkali-borate glasses, whereas in high alkali-borate glasses Co 2+ is located in distorted tetrahedral sites.