Raman Spectroscopy and Force–Field Calculations of Intrinsic Defects in LiNbO3 Nanocrystals
Year: 2025
Type: article
Abstract: High Resolution Image Download MS PowerPoint Slide The intrinsic defects in lithium niobate (LiNbO 3 ) bulk crystals have been investigated with experimental and theoretical methods for many years. According to the most widely accepted model for the intrinsic defects in LiNbO 3 bulk crystals, antisite niobium (Nb Li ) and lithium vacancy (V Li ) defects are present in the lattice in concentrations depending on the composition, i.e., the Li/Nb ratio of the crystal. But nowadays, scientific attention has turned to nanocrystals. One of the methods to produce nanosized LiNbO 3 crystals is the frequently used ball-milling procedure. In the present work, sintered lithium niobate with congruent composition was ground under wet conditions in a high-energy ball mill for different grinding times. After that, thermal treatments were performed on the powder samples at temperatures of 300 and 500 °C. The structural changes were monitored by Raman spectroscopic measurements. Atomistic computer simulations based on classical potential models have long been used for understanding intrinsic defect formation in various crystal lattices. In this work, a Li 245 Nb 245 O 735 unit, constructed from a 5 × 5 × 5 supercell with sharp corners cut away to achieve a size of about 24 × 24 × 52 Å 3, was chosen for GULP force–field calculations as the starting configuration. The relaxation of the unit was achieved by first using the conjugate gradient and then the Newton–Raphson optimization methods. This process was repeated for the relaxed nano-LiNbO 3 structure by placing one or two Nb Li + 4 V Li, or one LiNb 3 O 8 -type neutral intrinsic defect into the supercell. The total energies were compared in terms of both the defect positions and their relative locations.
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,500
Awards: G2044776484, G206414428, G285949800
OpenAlex ID: W4414517996