Formation of intrinsic and silicon defects in MoO<sub>3</sub> under varied oxygen partial pressure and temperature conditions: an <i>ab initio</i> DFT investigation

Lambert, Daniel; Murphy, Samuel T.; Lennon, Alison; Burr, Patrick A.

doi:10.1039/c7ra10690d

Cited by 18 publications

(16 citation statements)

References 89 publications

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“…We find these Poisson ratios to be negative, contradicting computational predictions. 35 It is quite common for anisotropic materials and especially 2D layered materials to exhibit negative Poisson's ratios in some directions due to their overall structure. 37,38 All other Poisson ratios are positive, as predicted, and the elastic stability conditions for an orthorhombic crystal 39 are satisfied for all four stiffness tensors, verifying that these are physically realizable solutions.…”

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confidence: 57%

“…Modification of the tensor properties themselves is a separate question, expected to be important for thicknesses roughly on the order of 100 nm or less. MoO 3 is expected to have large elastic anisotropy, 35 with 9 distinct elastic constants (c ij ; Table 1) and 3 distinct refractive indices. Errors in the last displayed digit in each value are shown in parentheses.…”

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confidence: 99%

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Chemically Tuning Quantized Acoustic Phonons in 2D Layered MoO₃ Nanoribbons

et al. 2019

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Molybdenum trioxide (α-MoO 3 ) is a 2D layered metal oxide that can be altered in color from transparent white to dark blue with reversible intercalation of zerovalent metals, and whose mechanical properties can be controlled through intercalation. Here, we use Brillouin laser light spectroscopy to map the entire angular dispersion curves of multiple acoustic phonon branches of 2D layered MoO 3 , directly probing the effects of phonon quantum confinement when the phonon wavelength is comparable to the material thickness. Since acoustic phonons dictate elasticity, we thereby determine the full elastic stiffness tensor and the thickness of each nanoribbon to a statistical precision (derived from standard error propagation) corresponding to less than a monolayer. We show how intercalation of metallic Sn, Co, and Cu can chemically tune the quantized acoustic phonons and elasticity of MoO 3 nanoribbons. This work provides the methodology to extract precise elastic constants from complex Brillouin scattering of 2D materials, taking advantage of phonon confinement to capture the complete elastic response with a single scattering geometry.

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confidence: 57%

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confidence: 99%

Chemically Tuning Quantized Acoustic Phonons in 2D Layered MoO₃ Nanoribbons

et al. 2019

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“…Indeed, research using the disappearing text paradigm (Rayner, Liversedge, White, & Vergilino-Perez, 2003), in which text is masked or disappears during a fixation, has shown that words can be encoded in as little as 50–60 ms. However, in the disappearing text paradigm, the eyes remain fixated on the word location even after it has disappeared, with this duration being modulated by word frequency (Blythe, Liversedge, Joseph, White, & Rayner, 2009; Liversedge et al, 2004; Rayner, Liversedge, & White, 2006). Furthermore, Rayner et al (2006) show that initial encoding of the word in parafoveal preview is vital in combination with the 60-ms foveal presentation.…”

Section: Introductionmentioning

confidence: 99%

Return sweeps in reading: Processing implications of undersweep-fixations

Slattery

Parker

2019

Psychon Bull Rev

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Models of eye-movement control during reading focus on reading single lines of text. However, with multiline texts, return sweeps, which bring fixation from the end of one line to the beginning of the next, occur regularly and influence ~20% of all reading fixations. Our understanding of return sweeps is still limited. One common feature of return sweeps is the prevalence of oculomotor errors. Return sweeps, often initially undershoot the start of the line. Corrective saccades then bring fixation closer to the line start. The fixation occurring between the undershoot and the corrective saccade (undersweep-fixation) has important theoretical implications for the serial nature of lexical processing during reading, as they occur on words ahead of the intended attentional target. Furthermore, since the attentional target of a return sweep will lie far outside the parafovea during the prior fixation, it cannot be lexically preprocessed during this prior fixation. We explore the implications of undersweep-fixations for ongoing processing and models of eye movements during reading by analysing two existing eye-movement data sets of multiline reading.

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“…The dipole nature of the α-MoO 3 layers is at the origin of its relatively high work function (WF) of about 6.5 eV [1,5]. Moreover, despite its insulator nature and high WF, previous studies pointed out that thin MoO 3 films may exhibit a conductive behavior in the presence of defects and oxygen vacancies [6][7][8][9][10] or via interaction with a metallic substrate such as copper [7].…”

Section: Introductionmentioning

confidence: 99%

Structural Evolution of MoO3 Thin Films Deposited on Copper Substrates upon Annealing: An X-ray Absorption Spectroscopy Study

et al. 2019

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Structural changes of MoO3 thin films deposited on thick copper substrates upon annealing at different temperatures were investigated via ex situ X-Ray Absorption Spectroscopy (XAS). From the analysis of the X-ray Absorption Near-Edge Structure (XANES) pre-edge and Extended X-ray Absorption Fine Structure (EXAFS), we show the dynamics of the structural order and of the valence state. As-deposited films were mainly disordered, and ordering phenomena did not occur for annealing temperatures up to 300 °C. At ~350 °C, a dominant α-MoO3 crystalline phase started to emerge, and XAS spectra ruled out the formation of a molybdenum dioxide phase. A further increase of the annealing temperature to ~500 °C resulted in a complex phase transformation with a concurrent reduction of Mo6+ ions to Mo4+. These original results suggest the possibility of using MoO3 as a hard, protective, transparent, and conductive material in different technologies, such as accelerating copper-based devices, to reduce damage at high gradients.

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Formation of intrinsic and silicon defects in MoO₃ under varied oxygen partial pressure and temperature conditions: an ab initio DFT investigation

Abstract: DFT simulations predict how varied MoO3 preparation conditions could change intrinsic defect concentrations and avoid silicon contamination in photovoltaic applications.

Cited by 18 publications

References 89 publications

Chemically Tuning Quantized Acoustic Phonons in 2D Layered MoO₃ Nanoribbons

Chemically Tuning Quantized Acoustic Phonons in 2D Layered MoO₃ Nanoribbons

Return sweeps in reading: Processing implications of undersweep-fixations

Structural Evolution of MoO3 Thin Films Deposited on Copper Substrates upon Annealing: An X-ray Absorption Spectroscopy Study

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Formation of intrinsic and silicon defects in MoO3 under varied oxygen partial pressure and temperature conditions: an ab initio DFT investigation

Abstract: DFT simulations predict how varied MoO3 preparation conditions could change intrinsic defect concentrations and avoid silicon contamination in photovoltaic applications.

Cited by 18 publications

References 89 publications

Chemically Tuning Quantized Acoustic Phonons in 2D Layered MoO3 Nanoribbons

Chemically Tuning Quantized Acoustic Phonons in 2D Layered MoO3 Nanoribbons

Return sweeps in reading: Processing implications of undersweep-fixations

Structural Evolution of MoO3 Thin Films Deposited on Copper Substrates upon Annealing: An X-ray Absorption Spectroscopy Study

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Product

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Formation of intrinsic and silicon defects in MoO₃ under varied oxygen partial pressure and temperature conditions: an ab initio DFT investigation

Chemically Tuning Quantized Acoustic Phonons in 2D Layered MoO₃ Nanoribbons

Chemically Tuning Quantized Acoustic Phonons in 2D Layered MoO₃ Nanoribbons