Structural and Optical Characterization of Pure and Lanthanum Substituted Nd_1-xLa_xAlO₃ Prepared by Sol-Gel Method

Area of Science:

• Materials Science
• Solid State Chemistry
• Rare Earth Chemistry

Background:

• Neodymium Aluminum Oxide (NdAlO3) is a perovskite material with potential applications in various fields.
• Understanding the influence of aliovalent substitution on its structural and optical properties is crucial for material design.
• Crystal-field parameters dictate the electronic and optical behavior of rare earth ions in host lattices.

Purpose of the Study:

• To investigate the effect of lanthanum (La) substitution on the crystal-field parameters of the Neodymium (Nd) rare earth ion in NdAlO3.
• To synthesize and characterize pure and La-substituted NdAlO3 polycrystalline samples.
• To correlate structural modifications with changes in optical properties.

Main Methods:

• Polycrystalline samples of Nd1-xLaxAlO3 (x = 0 to 0.5) were prepared using the sol-gel synthesis method.
• X-ray diffraction (XRD) was employed to confirm phase purity and analyze structural parameters.
• Optical absorption spectroscopy was used to study crystal-field transitions.

Main Results:

• La substitution systematically increased lattice parameters (a, b, and c) and bond lengths (Nd/La-O).
• Structural distortion improved, indicated by shifts in bond angles (Nd-O-Nd, Al-O-Al) and an increased tolerance factor.
• Optical absorption spectroscopy revealed a shift in the 4F9/2 transition peak of the Nd ion from 676.99 nm to 675.44 nm with increasing La content.

Conclusions:

• Lanthanum substitution effectively tunes the crystal-field environment of Nd ions in NdAlO3.
• Structural changes induced by La substitution directly influence the optical transitions of Nd.
• The study provides insights into tailoring the properties of rare earth aluminates through controlled substitution.