Valence band modification of Cr<sub>2</sub>O<sub>3</sub>by Ni-doping: creating a high figure of merit p-type TCO

Arca, Elisabetta; Kehoe, Aoife B.; Veal, T. D.; Shmeliov, Aleksey; Scanlon, David O.; Downing, Clive; Daly, Dermot; Mullarkey, Daragh; Shvets, I. V.; Nicolosi, Valeria; Watson, Graeme W.

doi:10.1039/c7tc03545d

Cited by 40 publications

(15 citation statements)

References 70 publications

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“…Cr 2 O 3 finds applications in both functional and structural applications such as catalysis [1,2], electro-optics [3,4], magnetoelectronic [5,6], and corrosion protection [7]. It serves as a protective oxide coating on widely used hightemperature Ni and Fe alloys [8,9,10].…”

Section: Introductionmentioning

confidence: 99%

“…Cr 2 O 3 finds applications in both functional and structural applications such as catalysis, , electro-optics, , magnetoelectronic, , and corrosion protection . It serves as a protective oxide coating on widely used high-temperature Ni and Fe alloys. − Point defects play an important role in the effectiveness of Cr 2 O 3 for corrosion protection and other applications, and significant experimental effort has been devoted to understanding the nature of point defects and their diffusion mechanisms.…”

Section: Introductionmentioning

confidence: 99%

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Temperature Dependence of Self-Diffusion in Cr₂O₃ from First Principles

et al. 2019

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Understanding and predicting the dominant diffusion processes in Cr 2 O 3 is essential to its optimization for anticorrosion coatings, spintronics, and other applications. Despite significant theoretical effort in modeling defect mediated diffusion in Cr 2 O 3 the correlation with experimentally measured diffusivities remains poor partly due to the insufficient accuracy of the theoretical approaches. Here an attempt to resolve these discrepancies is made through high accuracy density functional theory simulations coupled with grand canonical formalism of defect thermochemistry. In this approach, point defect formation energies were computed using hybrid exchange correlation functional. This level of theory proved to be essential for achieving the agreement with experimental self-diffusion coefficients. The analysis of the resulting self-diffusion coefficients indicate that chromium has higher mobility at low temperatures and high oxygen partial pressures, in particular at standard temperature and pressure conditions. At high vacuum, high temperature conditions, oxygen diffusion becomes dominant. At Cr/Cr 2 O 3 interfaces O vacancies were found to be more mobile than Cr vacancies at all temperatures. Cr diffuses preferentially along the c-axis at low temperatures but switches to basal plane at higher temperatures. O diffusion is primarily bound to basal plane at all temperatures.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Temperature Dependence of Self-Diffusion in Cr₂O₃ from First Principles

et al. 2019

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“…Thus, the Ni 3p XPS spectrum was measured, as shown in Figure 3 c. It was deconvoluted into two peaks located at 66.90 eV and 68.60 eV, respectively, corresponding to the measured, as shown in Figure 3 c. It was deconvoluted into two peaks located at 66.90 eV and 68.60 eV, respectively, corresponding to the Ni 2+ and Ni 3+ ions, respectively [ 57 ]. That means the existence of dual chemical states of Ni ions, and the molar ratio of [Ni 2+ ] to [Ni 3+ ] is calculated to be 49%:51%.…”

Section: Resultsmentioning

confidence: 99%

Unraveling the Structural, Dielectric, Magnetic, and Optical Characteristics of Nanostructured La2NiMnO6 Double Perovskites

Tang

et al. 2022

Nanomaterials

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Double perovskite La2NiMnO6 (LNMO) nanoparticles and nanorods were synthesized via a hydrothermal process, where only aqueous inorganic solvents are used to regulate the microscopic morphology of the products without using any organic template. They crystallized in a monoclinic (P21/n) double perovskite crystal structure. The LNMO nanoparticles exhibited spherical morphology with an average particle size of 260 ± 60 nm, and the LNMO nanorods had diameters of 430 ± 120 nm and length about 2.05 ± 0.65 μm. Dual chemical oxidation states of the Ni and Mn ions were confirmed in the LNMO samples by X-ray photoelectron spectroscopy. Strong frequency dispersion dielectric behavior observed in the LNMO ceramics, is attributed to the space charge polarization and the oxygen vacancy induced dielectric relaxation. A ferroelectric—paraelectric phase transition appearing near 262 K (or 260 K) in the LNMO ceramics prepared from nanoparticles (or nanorods) was identified to be a second-order phase transition. The LNMO samples are ferromagnetic at 5 K but paramagnetic at 300 K. The LNMO nanoparticles had larger saturation magnetization (MS = 6.20 μB/f.u. @ 5 K) than the LNMO nanorods (MS = 5.68 μB/f.u.) due to a lower structural disorder in the LNMO nanorods. The semiconducting nature of the nanostructured LNMO with an optical band gap of 0.99 eV was revealed by the UV–visible absorption spectra. The present results enable the nanostructured LNMO to be a promising candidate for practical spintronic devices.

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“…This electronic structure allows p-type doping, capable of reaching conductivity of 28 S cm À1 when doped with Ni. 69 DFT calculations show that Mg-doping is also possible with relatively low formation energy (0.9 eV), however the acceptor level is quite deep, so conductivity levels are unlikely to surpass that of Ni-doped Cr 2 O 3 . 70 SnO is a curious transparent conductor with a fundamental indirect band gap of 0.7 eV but an optical band gap of 2.6 eV (Fig.…”

Section: Oxidesmentioning

confidence: 99%