Thermodynamic modeling of Cr and Cr–H systems up to high temperatures and high pressures

Dottor, Maxime; Crivello, Jean-Claude; Joubert, Jean-Marc

doi:10.1016/j.ijhydene.2022.04.245

Cited by 4 publications

(2 citation statements)

References 81 publications

(158 reference statements)

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“…35,36 However, not only steric arguments could be invoked to explain the thermodynamic destabilization but also the repulsive character of Cr−H interactions since Cr only forms a hydride phase at extremely high pressures (around 3−4 kbar at 150 °C). 42,43 Moreover, the enthalpies of hydride formation among the four elements constituting the studied alloys, Ti, V, Nb, and Cr, as calculated by first-principles calculations are ΔH formation = −121.6, −38.4, −47, and +3.3 kJ/mol per metal atom for Ti, V, and Nb hydrides with a cubic CaF 2 type structure and Cr hydride with NiAs prototype, respectively. 44 The structure prototypes chosen here (CaF 2 and NiAs) were observed experimentally.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Previous results on as-cast MPEAs/HEAs demonstrated the presence of two components in the positron lifetime spectra. 48,49 The shortlived component can be attributed to free positrons (not trapped at defects), while the longer one represents the contribution of positrons trapped in defects, either in dislocations introduced by cutting from ingots 43 or in vacancies introduced by quenching from elevated temperatures. 49 In contrast, the as-cast TiVNbCr alloy shows only one component from free positrons, indicating that this material contains a low density of defects and virtually all positrons are annihilated in the free state.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Elucidating Primary Degradation Mechanisms in High-Cycling-Capacity, Compositionally Tunable High-Entropy Hydrides

Strozi

Witman

Stavila

et al. 2023

ACS Appl. Mater. Interfaces

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The hydrogen sorption properties of single-phase bcc (TiVNb)100–x Cr x alloys (x = 0–35) are reported. All alloys absorb hydrogen quickly at 25 °C, forming fcc hydrides with storage capacity depending on the Cr content. A thermodynamic destabilization of the fcc hydride is observed with increasing Cr concentration, which agrees well with previous compositional machine learning models for metal hydride thermodynamics. The steric effect or repulsive interactions between Cr–H might be responsible for this behavior. The cycling performances of the TiVNbCr alloy show an initial decrease in capacity, which cannot be explained by a structural change. Pair distribution function analysis of the total X-ray scattering on the first and last cycled hydrides demonstrated an average random fcc structure without lattice distortion at short-range order. If the as-cast alloy contains a very low density of defects, the first hydrogen absorption introduces dislocations and vacancies that cumulate into small vacancy clusters, as revealed by positron annihilation spectroscopy. Finally, the main reason for the capacity drop seems to be due to dislocations formed during cycling, while the presence of vacancy clusters might be related to the lattice relaxation. Having identified the major contribution to the capacity loss, compositional modifications to the TiVNbCr system can now be explored that minimize defect formation and maximize material cycling performance.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

Elucidating Primary Degradation Mechanisms in High-Cycling-Capacity, Compositionally Tunable High-Entropy Hydrides

Strozi

Witman

Stavila

et al. 2023

ACS Appl. Mater. Interfaces

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Thermodynamic and Kinetic Regulation for Mg‐Based Hydrogen Storage Materials: Challenges, Strategies, and Perspectives

Wang,

Li,

Wei

et al. 2024

Adv Funct Materials

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Mg‐based hydrogen storage materials have drawn considerable attention as the solution for hydrogen storage and transportation due to their high hydrogen storage density, low cost, and high safety characteristics. However, their practical applications are hindered by the high dehydrogenation temperatures, low equilibrium pressure, and sluggish hydrogenation and dehydrogenation (de/hydrogenation) rates. These functionalities are typically determined by the thermodynamic and kinetic properties of de/hydrogenation reactions. This review comprehensively discusses how the compositeization, catalysts, alloying, and nanofabrication strategies can improve the thermodynamic and kinetic performances of Mg‐based hydrogen storage materials. Since the introduction of various additives leads the samples being a multiple‐phases and elements system, prediction methods of hydrogen storage properties are simultaneously introduced. In the last part of this review, the advantages and disadvantages of each approach are discussed and a summary of the emergence of new materials and potential strategies for realizing lower‐cost preparation, lower operation temperature, and long‐cycle properties is provided.

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Advances in CALPHAD Methodology for Modeling Hydrides: A Comprehensive Review

Palumbo,

Dematteis,

Fenocchio

et al. 2024

J. Phase Equilib. Diffus.

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Hydrides enable handling hydrogen at low pressure and near room temperature, offering higher volumetric densities than compressed or liquid hydrogen and enhancing safety. The CALPHAD method, rooted in the principles of thermodynamics, offers a systematic approach for predicting phase equilibria and thermodynamic properties in multicomponent materials. This comprehensive review paper aims to provide a detailed overview of the application of the CALPHAD method in the realm of metallic and complex hydrides. After an introduction to the fundamental thermodynamic aspects of hydrides, key elements of applying the CALPHAD method to model metal-hydrogen systems and complex hydrides are discussed. Subsequently, recent publications are reviewed, highlighting key findings and recent progresses in the field. Finally, the challenges that must be overcome to achieve further progress in this area are explored.

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Thermodynamic modeling of Cr and Cr–H systems up to high temperatures and high pressures

Cited by 4 publications

References 81 publications

Elucidating Primary Degradation Mechanisms in High-Cycling-Capacity, Compositionally Tunable High-Entropy Hydrides

Elucidating Primary Degradation Mechanisms in High-Cycling-Capacity, Compositionally Tunable High-Entropy Hydrides

Thermodynamic and Kinetic Regulation for Mg‐Based Hydrogen Storage Materials: Challenges, Strategies, and Perspectives

Advances in CALPHAD Methodology for Modeling Hydrides: A Comprehensive Review

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