CRYSTAL-FIELD TRANSITIONS IN CO-2[AL4SI5]O-18 CORDIERITE AND COAL2O4 SPINEL DETERMINED BY NEUTRON SPECTROSCOPY

Inelastic magnetic neutron scattering has been used to determine the e nergy of the (4)A(2)-->T-4(2) transition in CoAl2O4 spinel and the del ta(1) transition in CO2[Al4Si5]O-18 cordierite. The observed crystal f ield splitting in Co-spinel is 485 meV (3900 cm(-1)), which correspond s to a crystal field stabilization energy of 56.2, kJ mol(-1). The tra nsition energy of the delta(1) transition in Co-cordierite has been de termined to be 21 meV (170 cm(-1)). The present data demonstrate that magnetic neutron scattering can be used to measure crystal field trans itions at energies of interest in the study of 3d-containing silicates . It may be used to measure transition energies when the use of optica l spectroscopy is inappropriate.