Epitaxial Growth of Chromium Oxynitride Thin Films on Magnesium Oxide (100) Substrates and Their Oxidation Behavior

Abstract

Epitaxially grown Cr(N,O) thin films were prepared on MgO substrates, with a misfit of ¹1.7% with respect to CrN, using pulsed laser deposition. X-ray diffraction patterns showed the peak for the (200) reflection of Cr(N,O) around the peak for the (200) reflection of MgO. The X-ray diffraction pattern of the ¤ scan for the (111) reflection of Cr(N,O) showed a narrow peak appearing every 90 degrees. From microstructural observations, grain boundaries in the thin films could not be confirmed. In order to evaluate the oxidation behavior of Cr(N,O) thin films, oxidation tests in air were carried out. After the oxidation tests, a Cr 2 O 3 phase was formed at 873 K and the B1 (NaCl-type) phase disappeared at 1173 K. In the thin film oxidized at 1073 K, a Cr 2 O 3 layer on the surface of the thin film as well as a compositional gradient of oxygen were observed. This indicates that Cr(N,O) hard coatings can form oxidation barrier layers to extend the lifetime of cutting tools.

Preparation of B1-(Cr,Ga)N thin films by pulsed laser deposition

“…[28][29][30][31] Pure gallium cannot be used as the target because it has a low melting point (303 K) and thus no resistance against the heat is produced during deposition. Therefore, a Cr-10 at.…”

“…CrN and Cr(N,O) thin films on (100)-oriented MgO single-crystal substrates were epitaxially grown by pulsed laser deposition (PLD). [27][28][29][30] Suzuki et al successfully demonstrated a solid solution of Si in B1-CrN by the same approach, through the epitaxial growth of a Cr-Si-N thin film on a (100)-oriented MgO substrate. 31) In the present work, B1-(Cr,Ga)N thin films were prepared through epitaxial growth on (100)-oriented MgO singlecrystal substrates by PLD and the resulting films were characterized.…”

Nanotwin hardening in a cubic chromium oxide thin film

“…We expected that B1-CrO would have a high hardness because of our previous results involving chromium oxynitride Cr(N,O) thin films. [11][12][13][14] Cr(N,O) thin films, which can be considered as a solid solution of B1-CrO and B1-CrN, were synthesized by pulsed laser deposition (PLD). Oxygen atoms were dissolved in CrN to 37 mol.…”

“…MgO has been used as a substrate material for the epitaxial growth of chromium compounds that have a B1 structure, such as CrN [20][21][22][23] and Cr(N,O), 14 because the lattice constant of MgO is close to those of these epitaxial materials. No atypical conditions such as high pressures or temperatures were required.…”

“…13,14 The chamber was evacuated to a pressure of 1.0 × 10 −6 Pa, and then filled with oxygen gas (>99.99995 vol. % purity) to a pressure of 4.0 × 10 −5 Pa through a variable leak valve.…”