6 MeV and 15 MeV carbon ion beams modified the structure and optical properties of KTiOAsO4 crystals

Ion irradiation is a pivotal technique for tailoring material properties. This study investigates 6 MeV and 15 MeV carbon (C) ion irradiation effects on potassium titanyl arsenate (KTiOAsO 4 , KTA) crystals. Experimental analyses reveal that irradiation induced lattice damage on the crystal surface, with surface roughness increasing with ion energy. Furthermore, C ion irradiation enhances absorption in 350–500 nm. Concurrently, the optical bandgap narrows from 3.41 eV (virgin) to 3.36 eV (6 MeV) and 3.31 eV (15 MeV). X-ray photoelectron spectroscopy (XPS) measurements and Density functional theory (DFT) calculations indicate that the bandgap narrowing stems from irradiation-induced increases in oxygen vacancies. This study demonstrates that ion energy can precisely control the optical absorption through controlled microstructural changes of KTA, providing important insights for ion beam modification of nonlinear optical materials.