Lanthanides: The Key to Durable and Sustainable Corrosion Protection

Lanthanides (Ln), as an important class of materials, have recently generated global interest in modern technology due to their unique metallurgical, ceramic, catalytic, electronic, nuclear, and mechanical properties. Here, 12 Ln (La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Y, and Lu) elements are outlined based on their impacts on the structural and functional properties of alloys that have tremendous applications in both the chemical and industrial sectors. Owing to the particular position in the lanthanides series, although each element possesses similar oxidation state variation in the number of unpaired electrons in the outermost shell, it is responsible for imparting unique features such as electrochemical characteristics, mechanical strength, and improvement in magnetic properties. This review starts with an introduction of every Ln element, followed by a detailed description of the element-based conversion coatings, which includes the morphology and composition of these Ln-based coatings along with their mechanism of formation and competence for the corrosion control process.