TY - JOUR
T1 - Synthesis, Hardness, and Electronic Properties of Stoichiometric VN and CrN
AU - Wang, Shanmin
AU - Yu, Xiaohui
AU - Zhang, Jianzhong
AU - Wang, Liping
AU - Leinenweber, Kurt
AU - He, Duanwei
AU - Zhao, Yusheng
N1 - Publisher Copyright:
© 2015 American Chemical Society.
PY - 2016/1/6
Y1 - 2016/1/6
N2 - We report synthesis of single-crystal VN and CrN through high-pressure ion-exchange reaction routes. The final products are stoichiometric and have crystallite sizes in the range of 50-120 μm. We also prepared VN and TiN crystals using high-pressure sintering of nitride powders. On the basis of single-crystal indentation testing, the determined asymptotic Vickers hardness for TiN, VN, and CrN is 18 (1), 10 (1), and 16 (1) GPa, respectively. The relatively low hardness in VN indicates that the metallic bonding prevails due to the overfilled metallic σ bonds, although the cation-anion covalent hybridization in this compound is much stronger than that in TiN and CrN. All three nitrides are intrinsically excellent metals at ambient pressure. In particular, VN exhibits superconducting transition at Tc ≈ 7.8 K, which is slightly lower than the reported values for nitrogen-deficient or crystalline-disordered samples due to unsuppressed "spin fluctuation" in the well-crystallized stoichiometric VN. The magnetostructural transition in CrN correlates with a metal-metal transition at TN = 240(5) K and is accompanied by a ∼40% drop in electrical resistivity. In addition, more detailed electronic properties are presented with new insights into these nitrides.
AB - We report synthesis of single-crystal VN and CrN through high-pressure ion-exchange reaction routes. The final products are stoichiometric and have crystallite sizes in the range of 50-120 μm. We also prepared VN and TiN crystals using high-pressure sintering of nitride powders. On the basis of single-crystal indentation testing, the determined asymptotic Vickers hardness for TiN, VN, and CrN is 18 (1), 10 (1), and 16 (1) GPa, respectively. The relatively low hardness in VN indicates that the metallic bonding prevails due to the overfilled metallic σ bonds, although the cation-anion covalent hybridization in this compound is much stronger than that in TiN and CrN. All three nitrides are intrinsically excellent metals at ambient pressure. In particular, VN exhibits superconducting transition at Tc ≈ 7.8 K, which is slightly lower than the reported values for nitrogen-deficient or crystalline-disordered samples due to unsuppressed "spin fluctuation" in the well-crystallized stoichiometric VN. The magnetostructural transition in CrN correlates with a metal-metal transition at TN = 240(5) K and is accompanied by a ∼40% drop in electrical resistivity. In addition, more detailed electronic properties are presented with new insights into these nitrides.
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U2 - 10.1021/acs.cgd.5b01312
DO - 10.1021/acs.cgd.5b01312
M3 - Article
AN - SCOPUS:84954072563
SN - 1528-7483
VL - 16
SP - 351
EP - 358
JO - Crystal Growth and Design
JF - Crystal Growth and Design
IS - 1
ER -