Thermal expansion anomalies in R 2Fe 17 compounds before and after nitrogenation (R: Y and Sm)

The lattice expansion of R ₂Fe ₁₇ and R ₂Fe ₁₇N ₃ compounds (R: Y and Sm) have been measured by X-ray diffractometry from 12 K up to 873 K. Upon nitrogenation, the low temperature anomalous expansion along the c-axis disappears; nevertheless, the spontaneous volume magnetostriction is larger.