Elastic moduli of η‐Ta₂N₃, a tough self‐healing material, via laser ultrasonics

The elastic moduli of the dense polycrystalline oxygen‐bearing η‐Ta 2 N 3 , a novel hard and tough high‐pressure (HP) material, were measured using the laser ultrasonic technique. The bulk modulus was determined to be B 0 = 281(15) GPa which is only ∼11% below that from HP compression measurements. Our value of the shear modulus G 0 = 123(2) GPa is below those ones predicted theoretically for model structures. The discrepancies in G 0 could be due to a substitution of an‐ ions and the formation of cation vacancies in η‐Ta 2 N 3 . Self‐healing behaviour of η‐Ta 2 N 3 by mechanical polishing was observed and confirmed by two independent experimental methods. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)