Chromium nitride (CrN) is a well-known hard coating material that has found applications in abrasion and wear-resistant cutting tools, bearings, and tribology applications due to its high hardness, high-temperature stability, and corrosion-resistant properties. In recent years, CrN has also attracted significant interest due to its high thermoelectric power factor, and for its unique and intriguing metal-insulator phase transition. While CrN bulk single-crystals exhibit the characteristic metal-insulator transition accompanied with structural (orthorhombic-to-rocksalt) and magnetic (antiferromagnetic-to-paramagnetic) transition at ~260-280K, observation of such phase transition in thin-film CrN has been scarce and highly debated. In this work, the formation of the secondary metallic Cr2N phase during the growth is demonstrated to inhibit the observation of metal-insulator phase transition in CrN thin films. When the Cr-flux during deposition is reduced below a critical limit, epitaxial and stoichiometric CrN thin film is obtained that reproducibly exhibits the phase transition. Annealing of the mixed-phase film inside reducing NH3 environment converts the Cr2N into CrN, and a discontinuity in the electrical resistivity at ~ 277 K appears which supports the underlying hypothesis. A clear demonstration of the origin behind the controversy of the metal-insulator transition in CrN thin films marks significant progress and would enable its nanoscale device realization.
Contiguous Hetero-structures & Co-existing Morphological Derivatives of Preferentially Grown Carbo-nitrides in Long Term Aged SS 316LN with Varying Nitrogen Concentration
Optical properties of silicon rich silicon nitride (SixNyHz) from first principles
用密度泛函微扰理论计算了SixNyHz的复折射率的实部和虚部。光谱的反射率，吸收系数，能量损失函数（ELF），和折射率，得到。Si_3N_4的计算结果与已有的理论和实验结果一致。为了了解富硅氮化硅中电子能量损失的机理，研究了硅掺杂率、掺杂位置以及表面H对ELF的影响。已经发现，所有的缺陷，如悬挂键在体和表面，增加的ELF的强度在低能量范围内（低于10 eV）。体相和表面上的H具有愈合效应，其可以通过饱和悬挂键来降低损耗峰的强度。电子结构分析证实了ELF变化的原因。结果表明，ELF的变化不仅受材料成分的影响，而且受材料微观结构的影响。结果可用于调整光学性质，在这种情况下，ELF的富Si的Si 3 N 4，这是必不可少的次级电子发射应用。
Physical Properties and Thermal Stability of Zirconium Platinum Nitride Thin Films
ETH Zurich（苏黎世联邦理工学院）；Laboratory for Nanometallurgy, Department of Materials, ETH Zurich（苏黎世联邦理工学院材料系纳米冶金实验室）；Ion Beam Physics, Department of Physics, ETH Zurich（苏黎世联邦理工学院物理系离子束物理）
Equation of state of paramagnetic CrN from ab initio molecular dynamics
氮化铬的状态方程在文献中已经被争论，与在压力诱导从顺磁性立方相到反铁磁性正交相的转变之后其体积模量的建议崩溃有关[F. Rivadulla等人，Nat Mater 8，974（2009）; B. Alling等人，Nat Mater 9，283（2010）]。实验上的测量是复杂的，由于低的过渡压力，而理论上的磁无序的模拟是一个重大的挑战。本文提出了一种计算磁性材料高温顺磁相热力学性质的第一性原理方法。它是基于从头算分子动力学和同时重新分配的无序，但有限的本地磁矩。我们将这种无序局域矩分子动力学方法应用于CrN的情况，并模拟其状态方程。特别是有争议的体积模量计算在顺磁性立方相，并显示为非常相似的反铁磁性正交CrN相的所有考虑的温度。
Defect-controlled electrical and optical properties of CrN thin films: experiment and first-principles study
Institute of Physics of the Czech Academy of Sciences（捷克科学院物理研究所）；IT4Innovations, VSB - Technical University of Ostrava（俄斯特拉发理工大学IT4创新中心）；Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University（查理大学数学与物理学院凝聚态物理系）
