Investigation of the structural, thermal, and spectroscopic properties of L-threonine crystal containing Eu3+ ions for use in visible light-emitting devices

In this study, L-threonine containing trivalent europium ions (LTHEu) was successfully grown through the slow evaporation method. The LTHEu single crystal exhibit well-defined facets, with dimensions around 5 × 13 × 4 mm. Structural, thermal, and spectroscopic properties were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy, X-ray fluorescence (XRF), thermogravimetric analysis, differential thermal analysis, ultraviolet–visible absorption spectroscopy, and photoluminescence spectroscopy. Rietveld refinement of XRD data showed that the LTHEu crystal crystallizes in an orthorhombic system with P212121-space group. The Eu3+ ions promote an expansion effect on the unit cell volume. XRF measurements confirm the presence of the Eu3+-impurities in the L-threonine matrix. In addition, the LTHEu crystal showed thermal stability for temperatures up to 483 K. Spectroscopic analysis revealed light emission with orange color due to the combination of high-intensity bands related to 5D0→7F1 (orange) and 5D0→7F2 (red) electronic transitions of Eu3+ ions. The new emission for L-threonine crystal doped with Eu3+ observed in this study expands the range of materials with potential for application in optical devices in the visible region.