The first investigation of europium silicate melilite for second-order nonlinear optical application: experimental and theoretical studies

Abstract

A europium pyrosilicate, Eu₂MgSi₂O₇ (1), is obtained using a high-temperature solid-state reaction. It crystallizes in the tetragonal noncentrosymmetric space group P2₁m, and its structure features a 2D structure built by SiO₄ and MgO₄ tetrahedra, resulting in interlayer cavities occupied by Eu²⁺ ions. It has a SHG intensity around 0.7 times that of KTP in the particle size range of 45–75 μm under 2.1 μm radiation, demonstrating a relatively strong effect among the silicates. A typical photoluminescence phenomenon of Eu²⁺ can be observed at 482 nm. Calculations on the electronic structure and optical properties of 1 are performed. Moreover, to discuss the potential of pyrosilicates and related compounds as NLO crystals, the theoretical analysis on other A₂BM₂O₇ compounds is also addressed.