Reduced Local Symmetry in Lithium Compound Li₂SrSiO₄ Distinguished by an Eu³⁺ Spectroscopy Probe

Research on lithium compounds has attracted much attention nowadays. However, to elucidate the precise structure of lithium compounds is a challenge, especially when considering the small ions that may be transferred between the interstitial voids. Here, the discovery of reduced local symmetry (symmetry breaking) in small domains of Li₂SrSiO₄ is reported by employing Eu³⁺ as a spectroscopic probe, for which X-ray, neutron, and electron diffraction have confirmed the average long-range structure with the space group P3₁21. However, luminescence shows a lower local symmetry, as confirmed by the extended X-ray absorption fine structure. By considering the reduced symmetry of the local structure, this work opens the door to a new class of understanding of the properties of materials.