Process Evolution and Green Innovation in Rare Earth Element Research: A 50-Year Bibliometric Assessment (1975–2024)

Rare earth elements (REE) are vital for renewable energy, electronics, and advanced technologies; however, the process-related evolution of REE research has not been systematically quantified. This study conducts the first large-scale bibliometric analysis of 76,768 REE-related publications (1975–2024) from Web of Science, using the Cross-Disciplinary Publication Index (CDPI) and Technology–Economic Linkage Model (TELM). Results reveal three development phases: publication growth from <300 (1975–1990) to >5000 after 2008, driven by China’s export restrictions and the global clean energy transition; China leads with 24.1% of publications, followed by the U.S. (11.7%) and Germany (6.4%). Interdisciplinary mapping identifies materials science as the central field (CDPI = 0.81) linked to nanotechnology (0.75) and environmental science (0.66). Four thematic clusters dominate: (i) deposit geology, (ii) material applications, (iii) green extraction technologies, and (iv) circular economy strategies. Recent emphasis on sustainable practices and unconventional sources—such as phosphorites, bauxite, coal fly ash, and urban mining—reflects a shift toward green innovation. The findings guide policies to diversify REE supply through unconventional deposits (~50 Mt coal-hosted REE), eco-friendly extraction, and recycling. Future priorities include AI-driven exploration, lifecycle assessment of secondary sources, and stronger global collaboration to secure resilient, sustainable REE supply chains.