Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · 2609.31496

Crystallographic-orientation dependence of the early-stage oxidation of Zr single crystals: an XPS study of suboxide formation and in-depth distribution

Joaquin Sacanell·Flavio Conde
View original source ↗Read source document ↗Export metadata ↓

Abstract

The influence of crystallographic orientation on the early stages of the oxidation of pure Zr single crystals was studied by X ray photoelectron spectroscopy (XPS). Two samples, cut from the same a-Zr single crystal, were oxidized simultaneously at room temperature and O2 pressures of 1 X 10-8, 1 X 10-7 and 1 X 10-6 torr: one with its surface normal parallel to the c-axis (Z1, basal (0001) plane) and the other with its normal 12deg from that of a prismatic plane (Z2, near-prismatic orientation). At all three pressures the oxidation kinetics of both samples followed a three stage, logarithmic type behaviour, but the near prismatic sample (Z2) incorporated oxygen faster and to a greater extent than the basal sample (Z1) in every case. Deconvolution of the Zr 3d core level spectra resolved, in addition to metallic Zr and ZrO2, two sub-stoichiometric Zr O compounds, denoted (ZrO)a and (ZrO)b, with binding-energy shifts of 1.3 and 2.3 eV with respect to metallic Zr, consistent with sub oxides previously reported for polycrystalline Zr. Angle resolved XPS showed that ZrO2 is the outermost compound in both orientations, while the two sub-oxides are distributed nearly homogeneously through the film. Oxide thicknesses, calculated from the attenuation of the metallic Zr 3d signal, ranged from 10 to 13 A for Z1 and from 14 to 19 A for Z2 depending on the oxidation pressure, in close agreement with earlier measurements on cold worked polycrystalline Zr, whose surface texture is dominated by prismatic-oriented grains.

Explore related subjects

cond-mat.mtrl-sci

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Joaquin Sacanell, Flavio Conde. 2026-09-25. Crystallographic-orientation dependence of the early-stage oxidation of Zr single crystals: an XPS study of suboxide formation and in-depth distribution. https://arxiv.org/abs/2609.31496

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Crystal Dislocations as Atomic Scale Ratchets

The symmetry of a system's response to external stimuli is a fundamental concept in physics and materials science. At the microscopic scale, breaking this symmetry to achieve a rectified response is exceptionally difficult to engineer and remains rare in nature. Conventional micromechanics models of crystalline solids often assume a symmetric response to applied stress, where reversing the load simply inverts the direction of defect velocity without altering its magnitude. In this work, we report an atomic-scale, geometry-rooted mechanism that breaks this symmetry. Molecular dynamics simulations of face-centered cubic nickel reveal that dislocations containing atomic-scale jogs exhibit asymmetric mobility under opposite applied stresses: reversing the loading direction triggers significantly higher drag. This asymmetry arises from the coupling of two internal variables with different transformation parity: a non-affine displacement of an atom at the jog core, and a strain-like tensor associated with the advance of the dislocation. Because jogs are ubiquitous structures in plastic deformation, this discovery challenges classical descriptions of plastic deformation mechanisms, with direct implications for cyclic creep, and opens new pathways for defect engineering to enhance fatigue resistance.

cond-mat.mtrl-sci↗
arXiv2026

The WEST code for large-scale excited-state materials simulations

We present WEST, an open-source plane-wave pseudopotential code for large-scale excited-state materials simulations, and describe its theoretical foundations, software architecture, and capabilities. WEST implements full-frequency GW, quantum defect embedding theory, the Bethe-Salpeter equation, and time-dependent density functional theory within a common algorithmic framework that avoids the explicit computation of virtual electronic states. By combining density functional and density matrix perturbation theory, low-rank representations of the dielectric screening and exact exchange, and localization techniques, WEST achieves favorable computational scaling with system size. The code supports the calculation of quasi-particle and neutral excitation energies, optical and photoluminescence spectra, excited-state forces, and non-adiabatic couplings, with interoperable workflows connecting to quantum chemistry, vibronic coupling, and quantum computing packages. A hierarchical parallelization strategy and GPU acceleration deliver near-ideal strong scaling to thousands of GPUs, enabling accurate excited-state simulations of systems with more than a thousand atoms. Representative applications, spanning the full optical cycle of solid-state spin defects, self-trapped excitons in metal-halide perovskites, and the optical response of liquid water and ice, demonstrate the accuracy and versatility of the code across diverse material classes. The capabilities implemented in WEST establish the code as a scalable platform for predictive excited-state simulations, high-throughput materials discovery, and the generation of high-fidelity datasets for machine learning in computational materials science.

cond-mat.mtrl-sci↗
arXiv2026

Symmetry-Based Design Rules for Second-Harmonic Generation in Stacked and Twisted MoS2 Bilayers

Understanding how stacking controls the nonlinear optical response of two-dimensional materials is key to designing van der Waals heterostructures with tailored functionalities. Here, we establish a comprehensive symmetry-based framework mapping the structural configuration of MoS2 bilayers across four point groups (D3h, D3d, C3v, C3) to their second-order susceptibility tensor chi^(2). Using group-theory arguments benchmarked against first-principles response-function calculations, we demonstrate how symmetry breaking controls the activation and suppression of individual tensor elements in these systems. We show that the emergence of the in-plane component chi_xxx in twisted configurations (C3 group) induces a rigid azimuthal rotation of the second-harmonic generation polar lobes, which remains frequency-independent across the entire optical spectrum, locking to half of the structural twist angle. Our findings establish a direct, wavelength-independent optical route for twist-angle determination and provide a clear roadmap for engineering nonlinear optical responses in two-dimensional materials.

cond-mat.mtrl-sci↗