(013005)EPR Study of the Mn-Doped Magnesium Titanate Ceramics

摘要

Manganese-doped magnesium titanate ceramic samples obtained by a solid-state reaction via sintering in the air from a mixture of MgO and TiO_2 powders of different molar ratios were analyzed by electron paramagnetic resonance (EPR) technique. The EPR signals of Mn~(2+) ions (S = 5/2, ? = 5/2) in crystal phases of MgO, Mg_2TiO_4, and MgTiO_3 were detected. We have obtained the following spin Hamiltonian parameters for Mn~(2+) ions: g = 2.0015, A ?81.0 × 10-4 cm~(-1) (in MgO phase); g = 2.0029, A ?73.8 × 10-4 cm~(-1), b_2~0 = 35 × 10-4 cm~(-1) (in Mg_2TiO_4 phase); g = 2.0040, A ?79.0 × 10-4 cm~(-1), b_2~0 = 165 × 10-4 cm~(-1) (in MgTiO_3 phase). Despite the presence of Mn4+ centers in both Mg_2TiO_4:Mn and MgTiO_3:Mn ceramics confirmed by previous optical studies, no EPR signals related to Mn4+ ions (S = 3/2, ? = 5/2) were found. The Mn2+ EPR signals are proposed as structural probes in manganese-doped magnesium titanate ceramics.