Effect of partial substitution of Ce for La on the structural, magnetic and abnormal thermal expansion properties of La1-Ce Fe11.2Al1.8 alloys

Abstract

Abstract NaZn13-type La(Fe, M)13-based (M = Si, Al) intermetallic compounds find wide applications, ranging from microelectronics to space technology, because of their significant abnormal thermal expansion (ATE) associated with their huge magnetovolume effect. In this work, element La was partially substituted in LaFe11.2Al1.8 by element Ce to optimize the ATE characteristics of these alloys. The obtained average thermal expansion coefficient (CTE) of La0.8Ce0.2Fe11.2Al1.8 reaches as large as −21.7 × 10−6 K−1 in the temperature range of 100–200 K, which is nearly 25% larger than that of LaFe11.2Al1.8 (−17.31 × 10−6 K−1). Magnetic measurements confirmed that the improved negative thermal expansion (NTE) property is attributed to the enhanced magnetization originating from the magnetic coupling between Ce and Fe atoms. Additionally, smaller negative thermal expansion was observed in La0.4Ce0.6Fe11.2Al1.8 with an average CTE of −1.6 × 10−6 K−1 in a broad operating temperature window from 10 to 170 K. The enhanced NTE values of La(Fe, Al)13-based alloys with partial substitution of Ce for La demonstrated in this work show the potential of their practical applications.