Epitaxial growth of Al–Cr–N thin films on MgO(111)

Willmann, Herbert; Beckers, Markus; Birch, Jens; Mayrhofer, P.H.; Mitterer, Christian; Hultman, Lars

doi:10.1016/j.tsf.2008.07.003

Cited by 16 publications

(6 citation statements)

References 30 publications

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“…2 shows the dependence of the lattice parameter a of the cubic phase on the overall AlN content in comparison to the ab initio obtained dependence [11]. The lattice parameters of c-Cr 1 − x Al x N on cemented carbide substrates decrease with increasing AlN content and are 4.155, 4.153, 4.143, and 4.108 Å for x = 0, 0.21, 0.45, and 0.71, respectively, and correspond to earlier reports of c-Cr 1 − x Al x N coatings [6,[13][14][15][16][17][18][19].…”

Section: Resultssupporting

confidence: 87%

Structure and phase evolution of Cr–Al–N coatings during annealing

Mayrhofer

Willmann

Reiter

2008

Surface and Coatings Technology

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123

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Section: Resultssupporting

confidence: 87%

Structure and phase evolution of Cr–Al–N coatings during annealing

Mayrhofer

Willmann

Reiter

2008

Surface and Coatings Technology

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123

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“…For Ti 0.54 Al 0.46 N, a significant difference in the coherence length value is observed between 111 and 200 cubic domains, 258 Å and 140 Å , respectively. Those values are obviously five to ten times lower than for epitaxically grown metallic nitride layers of rock salt structure (Willmann et al, 2008). Fig.…”

Section: Characterization Methodsmentioning

confidence: 75%

The competitive growth of cubic domains in Ti_1–xAl_xN films studied by diffraction anomalous near-edge structure spectroscopy

Pinot

Tuilier

Pac

et al. 2015

J Synchrotron Radiat

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Titanium and aluminium nitride films deposited by magnetron sputtering generally grow as columnar domains made of oriented nanocrystallites with cubic or hexagonal symmetry depending on Al content, which are embedded in more disordered grain boundaries. The substitution of Al atoms for Ti in the cubic lattice of the films improves their resistance to wear and oxidation, allowing their use as protective coatings. Ti K-edge X-ray absorption spectroscopy, which probes both crystallized and more disordered grain boundaries, and X-ray diffraction anomalous fine structure, which is sensitive to short- and long-range order within a given crystallized domain, are carried out on a set of Ti(1-x)AlxN films deposited by magnetron sputtering on Si substrates. Attention is paid to the shape of the pre-edge region, which is sensitive to the symmetry of the site occupied by Ti atoms, either octahedral in face-centred-cubic Ti-rich (TiN, Ti0.54Al0.46N) samples or tetrahedral in hexagonal-close-packed Al-rich (Ti0.32Al0.68N) films. In order to obain information on the titanium environment in the well crystallized areas, subtraction of the smooth part of the energy-dependent structure factor for the Bragg reflections is applied to the pre-edge region of the diffraction anomalous data in order to restore their spectroscopic appearance. A flat pre-edge is related to the typical octahedral environment of Ti atoms for cubic reflections. The difference observed between pre-edge spectra associated with face-centred-cubic 200 and 111 Bragg reflections of Ti0.54Al0.46N is assigned to Ti enrichment of 111 large well ordered domains compared with the more disordered 200 ones. The sharp peak observed in the spectrum recorded from the hexagonal 002 peak of Ti0.32Al0.68N can be regarded as a standard for the pure tetrahedral Ti environment in hexagonal-close-packed nitride.

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“…is chosen which has shown that they can improve CrN thermal stability as well as mechanical properties. 136,147,[162][163][164][165][166][167][168][169] Despite the fact that the mechanical properties of CrN has been well studied. The electrical properties of CrN are still controversial with conclusion varying from report to report.…”

Section: Review Of Chromium Nitride (Crn)mentioning

confidence: 99%

Design of Transition-Metal Nitride Thin Films for Thermoelectrics

Kerdsongpanya

2015

Linköping Studies in Science and Technology. Dissertations

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Thermoelectric devices are one of the promising energy harvesting technologies, because of their ability to convert heat (temperature gradient) to electricity by the Seebeck effect. Furthermore, thermoelectric devices can be used for cooling or heating by the inverse effect (Peltier effect). Since this conversion process is clean, with no emission of greenhouse gases during the process, this technology is attractive for recovering waste heat in automobiles or industries into usable electricity. However, the conversion efficiency of such devices is rather low due to fundamental materials limitations manifested through the thermoelectric figure of merit (ZT ). Thus, there is high demand on finding materials with high ZT or strategies to improve ZT of materials.In this thesis, I discuss the basics of thermoelectrics and how to improve ZT of materials, including present-day strategies. Based on these ideas, I propose a new class of materials for thermoelectric applications: transition-metal nitrides, mainly ScN, CrN and their solid solutions. Here, I employed both experimental and theoretical methods to synthesize and study their thermoelectric properties. My study envisages ways for improving the thermoelectric figure of merit of ScN and possible new materials for thermoelectric applications.The results of my studies show that ScN is a promising thermoelectric material since it exhibits high thermoelectric power factor 2.5×10 −3 Wm −1 K −2 at 800 K, due to low metallic-like electrical resistivity while retained relatively large Seebeck coefficient. My studies on thermal conductivity of ScN also suggest a possibility to control thermal conductivity by tailoring the microstructure of ScN thin films. Furthermore, my theoretical studies on effects of impurities and stoichiometry on the electronic structure of ScN suggest the possibly to improve ScN ZT by stoichiometry tuning and doping. For CrN and Cr1−xScxN solid solution thin films, the results show that the power factor of CrN (8×10 −4Wm −1 K −2 at 770 K) can be retained for the solid solution Cr0.92Sc0.08N. Finally, density functional theory was used to enable a systematic predictionbased strategy for optimizing ScN thermoelectric properties via phase stability of solid solutions. Sc1−xGdxN and Sc1−xLuxN are stabilized as disordered solid solutions, while in the Sc-Nb-N and Sc-Ta-N systems, the inherently layered ternary structures ScNbN2 and ScTaN2 are stable. Svensk sammanfattningSedan den industriella revolutionen har fossila bränslen varit vår huvudkälla till energi i motorer för transport, elproduktion och uppvärmning av byggnader. Eftersom mänskligheten och vår teknik växer för varje år som går, fortsätter efterfrågan på fossila bränslen att öka. Med tanke på att fossila bränslen inte är förnybara, riskerar vi att de tar slut. Dessutom är resultatet av denna ständiga förbränning av fossila bränslen generering av växthusgaser, t.ex. kolmonoxid och koldioxid, som orsakar klimatförändringar, som ett ytterligare problem. Således finns det ett ökande behov...

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Epitaxial growth of Al–Cr–N thin films on MgO(111)

Cited by 16 publications

References 30 publications

Structure and phase evolution of Cr–Al–N coatings during annealing

Structure and phase evolution of Cr–Al–N coatings during annealing

The competitive growth of cubic domains in Ti_1–xAl_xN films studied by diffraction anomalous near-edge structure spectroscopy

Design of Transition-Metal Nitride Thin Films for Thermoelectrics

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Epitaxial growth of Al–Cr–N thin films on MgO(111)

Cited by 16 publications

References 30 publications

Structure and phase evolution of Cr–Al–N coatings during annealing

Structure and phase evolution of Cr–Al–N coatings during annealing

The competitive growth of cubic domains in Ti1–xAlxN films studied by diffraction anomalous near-edge structure spectroscopy

Design of Transition-Metal Nitride Thin Films for Thermoelectrics

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The competitive growth of cubic domains in Ti_1–xAl_xN films studied by diffraction anomalous near-edge structure spectroscopy