Paramagnetic Species in Ion Implanted Phosphate Glasses

Abstract

By means of EPR and optical spectroscopy were investigated phosphate glasses in the system xCaO-(100-x)P₂O₅, where 37≤x≤57, implanted with Ti⁺, Cr⁺, V⁺, Co⁺ and Mo⁺ (E=150keV, fluences F=2x10¹⁶÷5x10¹⁷cm^-2). The EPR spectra of samples co-implanted with V⁺and O⁺as well as Mo⁺and O⁺ were also studied. Some samples were co-implanted with ⁹⁵Mo⁺ and O⁺. EPR spectra were recorded at room temperature, 77K, in the range from 100 to 450K and at 4.2K The results are discussed together with data obtained earlier in our laboratory for phosphate glasses implanted with transition metals (TM). It is shown that the ions of transition metals Ti³⁺, V³⁺, V⁴⁺, Cr³⁺, Mn²⁺ Co²⁺, Cu²⁺, Mo⁵⁺ can be present in isolated states in implantation layers of phosphate glasses at a rather low fluences (≤5x10¹⁶ cm^-2). The ions in high valences forms (V⁴⁺, Mo⁵⁺) are formed only in the case of co-implantation with O⁺. The ions Ti³⁺, V⁴⁺, Mo⁵⁺ are in tetragonally compressed octahedral and Ion Cu²⁺ is in tetragonally elongated octahedron, i. e. tire in their the most typical environments. However, spectral parameters for these ions differ from those obtained for them in glasses of corresponding compositions melted, from the batch. The isolated ions Cr³⁺ and Co²⁺ are in octahedral coordination. At high fluences(≥10¹⁷cm^-2) some TM ions can form in implanted phosphate glasses compounds with O or PO groups (for example, antiferromagnetic crystals MnO, compounds with phase transition at 340K VO₂, ferromagnetic crystals CrO₂ with temperature Curie, Tc=390K, non-stoichiometric compound TixPO₄).