Impact of lanthanum doping on growth, thermal stability, linear and nonlinear optical properties of metal coordinated amino acid based single crystals of glycine copper chloride

Abstract

This study aimed to enhance various physicochemical characteristics of lanthanum doped glycine copper chloride single crystals, which includes crystal habits, thermal stability, nonlinear optical behaviour and electrical properties. Organometallic crystal complexes with molar stoichiometric formula (C₂H₅NO₂CuCl₂)_1−x [La(NO₃)₃]_x, where [x = 0.00, 0.05, 0.10, 0.20] have been grown successfully in the absence and presence of lanthanum nitrate at various concentrations using slow solvent evaporation technique (SSET). The morphology of crystals displayed noticeable differences and the impact of La³⁺ doping on growth, optical, thermal and electrical properties. The lattice parameters examined through single crystal X-ray diffraction (SCXRD) technique confirms the tetragonal crystal system. Powder X-ray diffraction (PXRD) revealed diffraction planes displaying sharp and strong peaks suggesting excellent crystallinity of the crystals. The Rietveld refinements of PXRD data further validate the results with low values of goodness factor (χ²). Ultraviolet–Visible (UV–Vis) spectroscopy demonstrated outstanding linear optical properties with a lower cut off wavelength ranging from 224 to 244 nm. The energy bandgap found to be increasing with La³⁺ doping and lies in the range of 5.43–5.56 eV. High thermal stability was observed across all the grown crystals, with an increase noted with the addition of lanthanum concentration. Dielectric studies conducted as a function of temperature revealed the electrical properties of the crystals. The value of frequency exponent ‘n’ is found to be less than 1 which suggests that the motion involved is characterized by translational movement with sudden hopping transitions. Z-scan analysis confirmed the third order nonlinear optical (TONLO) response of the crystals. The calculated parameters n₂, β, and χ⁽³⁾ showed large values, indicating that the grown compositions are suitable for practical nonlinear optical device applications.