Giant Negative Thermal Expansion in NaZn13-Type La(Fe, Si, Co)13 Compounds

• Published in: Journal of the American Chemical Society Vol. 135; no. 31; pp. 11469 - 11472
• Main Authors: Huang, Rongjin, Liu, Yanying, Fan, Wei, Tan, Jie, Xiao, Furen, Qian, Lihe, Li, Laifeng
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 07-08-2013
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja405161z

La(Fe, Si)13-based compounds are well-known magnetocaloric materials, which show a pronounced negative thermal expansion (NTE) around the Curie temperature but have not been considered as NTE materials for industrial applications. The NaZn13-type LaFe13–x Si x and LaFe11.5–x Co x Si1.5 compounds were synthesized, and their linear NTE properties were investigated. By optimizing the chemical composition, the sharp volume change in La(Fe, Si)13-based compounds was successfully modified into continuous expansion. By increasing the amount of Co dopant in LaFe11.5–x Co x Si1.5, the NTE shifts toward a higher temperature region, and also the NTE operation-temperature window becomes broader. Typically, the linear NTE coefficient identified in the LaFe10.5Co1.0Si1.5 compound reaches as much as −26.1 × 10–6 K–1, with an operation-temperature window of 110 K from 240 to 350 K, which includes room temperature. Such control of the specific composition and the NTE properties of La(Fe, Si)13-based compounds suggests their potential application as NTE materials.