Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · 2601.08935

Effect of Niobium Doping on the Crystal Structure and Hydrogen Sorption Properties of TiFe: Combined Synchrotron X-ray Diffraction and Extended X-ray Absorption Fine Structure Study

Abhishek Banerjee·Stefano Deledda·Olena Zavorotynska
View original source ↗Read source document ↗Export metadata ↓

Abstract

TiFe alloys are attractive compounds for solid-state stationary hydrogen storage. They can absorb hydrogen gas reversibly at near ambient temperatures and practical pressures with high volumetric capacities surpassing that of cryogenically liquified H2. The main drawback of TiFe-based storage systems is a costly activation procedure required due to the formation of oxide surface layer, which hinders hydrogen diffusion into the bulk. Doping the alloy with various additives is known to improve hydrogen diffusion softening the conditions of the activation procedure. Hydrogen sorption properties of the modified alloys have been the focus of most studies whereas less attention has been dedicated to the fundamental understanding of the effects of hydrogen sorption on the alloys' structure. The latter, however, is an important information in the knowledge-guided design of novel materials. In this work, we investigated effects of Nb-doping on crystallographic structure of TiFe metal-alloy compounds and their hydrogen sorption properties. TiFe samples with two different Nb stoichiometries were synthesized using arc-melting (AM) and characterised with synchrotron powder X-ray diffraction (SR-PXRD) and extended X-ray absorption fine structure (EXAFS) analysis. Overall, H2 absorption measurements (at 50 +/- 2 degrees C and 40 +/- 2 bar), have shown that doping of TiFe with Nb can improve matrix activation and kinetics of hydrogen sorption without compromising the overall storage capacities. Refinement of SR-PXRD and EXAFS data showed significant Nb occupancy in secondary Ti phases, which improved the hydrogenation properties of the alloys.

Explore related subjects

cond-mat.mtrl-sci

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Abhishek Banerjee, Stefano Deledda, Olena Zavorotynska. 2026-01-13. Effect of Niobium Doping on the Crystal Structure and Hydrogen Sorption Properties of TiFe: Combined Synchrotron X-ray Diffraction and Extended X-ray Absorption Fine Structure Study. https://doi.org/10.1016/j.matdes.2026.116242

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

KEEP EXPLORING

Related papers

arXiv2026

Incommensurate structural and magnetic modulations in potassium-rich cryptomelane, K$_x$Mn$_8$O$_{16}$ ($x\approx1.45$)

Cryptomelane is a hollandite-like material consisting of K$^+$ cations in an $α$-MnO$_2$ tunnel-like crystallographic motif. Cryptomelane with stoichiometry K$_x$Mn$_8$O$_{16}$ ($x\approx1.45$) has been synthesized and its magnetic properties investigated using variable-temperature magnetic susceptibility, heat capacity, and neutron powder diffraction. Three distinct transitions at $T_1=184$\,K, $T_2=54.5$\,K, and $T_3=24$\,K are observed. At $T_1$ there is a subtle tetragonal$\rightarrow$monoclinic transition associated with emergence of a set of non-magnetic superstructure peaks indexable to a $\vec{k}_\mathrm{struc}\approx0.74\vec{c^*}$ incommensurate modulation parallel to the $α$-MnO$_2$ tunnels. Our findings are consistent with a relation previously reported in titanate hollandites, that $x\approx2|\vec{k}_\mathrm{struc}|$. Magnetic Bragg peaks emerge below $T_2=54.5$\,K, and their positions indicate an incommensurate modulated magnetic structure. The model consistent with the data is a dual-$\vec{k}_\mathrm{mag}$ structure with a ferromagnetic $|\vec{k}_\mathrm{mag}|=0$ component and an incommensurate $\vec{k}_\mathrm{mag}\approx0.37\vec{c^*}$, with the latter most likely to be helical. The period of oscillation of the incommensurate magnetic component is in line with predictions based on a Heisenberg spin Hamiltonian [Mandal \textit{et al}. Phys. Rev. B 90, 104420 (2014)]. Below $T_3=24$\,K, there is a magnetic transition, which gives rise to a different set of magnetic Bragg peaks indicative of a highly complex magnetic structure.

cond-mat.mtrl-sci↗
arXiv2026

An anisotropic functional for two-dimensional material systems

Density function theory is the workhorse of modern electronic structure theory. However, its accuracy in practical calculations is limited by the choice of the exchange-correlation potential. In this respect, two-dimensional materials pose a special challenge, as all these materials and their heterostructures have a crucial similarity. The underlying atomic structures are strongly spatially inhomogeneous, implying that current exchange-correlation functionals, that in almost all cases are isotropic, are ill-prepared for an accurate description. We present an anisotropic screened-exchange potential, that remedies this problem and reproduces the band-gap of 2D materials as well as the piecewise linearity of the total energy with fractional occupation number.

cond-mat.mtrl-sci↗
arXiv2026

Thermally-driven reorientation of the Néel vector in altermagnetic MnTe

Altermagnets are novel magnetic systems that possess a spin-polarized electronic band structure without a net magnetic moment, making them promising for device applications. Hexagonal MnTe, a prototypical altermagnet, arguably exhibits the most properties consistent with theoretical predictions, including an anomalous Hall effect despite a vanishing net magnetization, and altermagnetinduced electronic band splitting. However, fundamental questions remain, including why some effects only appear significantly below the magnetic ordering temperature. Here, we resolve this discrepancy by revealing a reorientation of the Néel vector in single-crystalline MnTe. The Néel vector points 30° from the a-axis at low $T$, before aligning directly with the a-axis around $T\simeq 260$ K. We attribute this to single-ion anisotropy, which depends on temperature-dependent lattice parameters. We obtained these results using muon-spin spectroscopy, magnetization measurements, and X-ray diffraction; we show that the findings are consistent with neutron diffraction. Manipulating this effect, for example through strain, could unlock sensitive electronic detection schemes for external stimuli, paving the way for functional altermagnetic devices.

cond-mat.mtrl-sci↗