The thermal expansion and magnetostriction of Nd2Fe14Si3 polycrystalline intermetallic compound was measured, using the strain gauge method in the temperature range 77–590 K under applied magnetic fields up to 1.5 T. Results show that both linear thermal expansion and linear thermal expansion coefficient exhibit anomalies below Curie temperature. A pronounced positive spontaneous volume magnetostriction has been observed below the Curie temperature. The spontaneous volume magnetostriction decreases with Si substitution in Nd2Fe17 compound. The saturation trend of the anisotropic magnetostriction below 115 K depends on the saturation of the kc mode. In the low field region (l0H < 0.3 T), a minimum appears in the isothermal curves of the volume magnetostriction that may be attributed to the domain walls motion and rotation of the magnetic moments of domains toward the applied field direction. The results of the spontaneous and anisotropic magnetostriction are discussed based on the local magnetic moment model and irreducible magnetoelastic coupling modes, respectively.

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