Acta Materialia最新文献

{"title":"Twin nucleation at grain boundaries in Mg analyzed through in situ electron back-scatter diffraction and high-resolution digital image correlation","authors":"Maral Sarebanzadeh, Alberto Orozco-Caballero, Eugenia Nieto-Valeiras, Javier LLorca","doi":"10.1016/j.actamat.2024.120678","DOIUrl":"https://doi.org/10.1016/j.actamat.2024.120678","url":null,"abstract":"Nucleation of extension twins at grain boundaries in weakly textured pure Mg was investigated through <em>in situ</em> mechanical tests in combination with electron backscatter diffraction and high-resolution digital image correlation. The Mg alloy exhibited a weak basal texture in which the Schmid factor for twinning under tensile deformation was low (or even negative) in most grains. Over 150 twin nucleation events at grain boundaries were recorded and classified into different groups. The most important ones were single twin nucleation and twin co-nucleation at grain boundaries and triple junctions while the number of twin transfer events was very small. It was found that twin nucleation/co-nucleation began at large grains suitably oriented for basal slip and gradually occurred in smaller grains with lower basal SF as the applied deformation increased while the twinning SF was not able to predict extension twinning. Thus, basal slip leads to the creation of stress concentrations at the grain boundaries that trigger twin nucleation. The microstructural features that dictate each type of twin nucleation event were analyzed and provided novel information about the influence of the microstructure of twin variant selection in Mg. In particular, it was found that twin variant selection was dictated in many cases by the orientation of twin shear strain with respect to the grain boundaries and was independent of the twinning Schmid factor.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"15 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2024-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142867229","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unusually large oxygen non-stoichiometry and defect thermodynamics in Sr4Mn2–xFe1+xO10–δ Ruddlesden-Popper layered oxides","authors":"I.S. Grobovoy, A.Yu. Suntsov, V.L. Kozhevnikov","doi":"10.1016/j.actamat.2024.120675","DOIUrl":"https://doi.org/10.1016/j.actamat.2024.120675","url":null,"abstract":"The Ruddlesden-Popper oxides Sr₄Mn_2–xFe_1+xO_10–δ (x = 0, 0.5, and 1.0) with the layered tetragonal structure (SG <em>I</em>4<em>/mmm</em>) were synthesized at the heating of organometallic precursors to 1400 °C in air. The Rietveld refinement of the X-ray diffraction patterns indicates a disordered arrangement of Mn and Fe atoms in the crystal. The results of the electron density functional-based calculations of the total energy show noticeably larger oxygen vacancy formation enthalpy for O_O2 positions in the structural rock salt layers of strontium oxide compared to the apical O_O1 and equatorial O_O3 and O_O4 positions in perovskite slabs. The coulometric titration measurements show that the Sr₄Mn_2–xFe_1+xO_10–δ phases can endure harsh reducing conditions, staying stable even when up to two oxygen atoms are taken away from the structure. Simulations of equilibrium oxygen content data reveal that oxygen exchange is coupled with electron excitation processes involving <em>d</em>-cations and intrinsic anion disorder. It is suggested that this disorder may be caused by unequal vacancy formation energies at crystallographically different oxygen sites. The enthalpy and entropy changes in the defect formation reactions were derived from the fitting of the experimental plots for oxygen non-stoichiometry. The obtained thermodynamic parameters were applied to determine how the concentrations of electronic and ionic defects depend on variations in temperature and partial pressure of oxygen. The consistency of the thermodynamic analysis is supported by a good coincidence of the calculated and experimental plots of the partial thermodynamic functions of labile oxygen in Sr₄Mn_2-xFe_1+xO_10–δ.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"1 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2024-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142857771","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Grain size dependence of microscopic strain distribution in a high entropy alloy at the onset of plastic deformation","authors":"Biaobiao Yang, Xu Xu, David Lunt, Fan Zhang, Michael D. Atkinson, Yunping Li, Javier Llorca, Xiaorong Zhou","doi":"10.1016/j.actamat.2024.120682","DOIUrl":"https://doi.org/10.1016/j.actamat.2024.120682","url":null,"abstract":"The development and distribution of microscopic shear strain have been investigated using high-resolution digital image correlation at the onset of plastic deformation in face-centred cubic CoCrFeNi high entropy alloys with different grain sizes. Microscopic strain localisation increased with grain size as shown by the presence of planar slip traces at the grain level and transgranular bands at the meso-scale. Slip traces were also found within grains larger than a critical size in the fine-grained high entropy alloy, while most of smaller grains were free of slip traces, leading to a bi-modal deformation pattern. Slip traces within coarse grains were associated with the activation of multiple slip systems with lower Schmid factor values, indicating that the local stress state is different from the global one due to the grain-to-grain interactions within the polycrystalline aggregate. In addition, the CoCrFeNi high entropy alloy, -especially the fine-grained one-, exhibits substantially lower microscopic strain heterogeneity as compared to a range of conventional engineering alloys at the onset of plastic deformation.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"19 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2024-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142867225","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The grain boundary brittleness at intermediate temperature in a precipitation strengthened Ni-based polycrystalline alloy","authors":"Qian Zhou, Qingqing Ding, Dengyu Liu, Xia Yao, Xiao Wei, Ze Zhang, Hongbin Bei","doi":"10.1016/j.actamat.2024.120681","DOIUrl":"https://doi.org/10.1016/j.actamat.2024.120681","url":null,"abstract":"The intermediate temperature brittleness (ITB), sudden fracture with insufficient plasticity in the range around 600-900 °C in precipitation strengthened polycrystalline alloys, plays a serious threat on the failure of structural hot-components. To reveal the relationship between microstructure and ITB, a typical precipitation strengthened alloy GH4151 has been fabricated and differently processed, including single crystal (SX) growth and thermal-mechanical processing and their mechanical properties have been tensile tested. The SX GH4151 alloy fractures in a ductile manner with elongation to fracture (EF) exceeding 10 % at all test temperatures. In contrast, all polycrystalline alloys exhibit some degree of brittleness (EFs less than 5%) at the temperature range of 700-900 °C. Microstructural characterization by using advanced microscopy techniques and a high-temperature mechanical testing system in a transmission electron microscope, dynamically reveal the origin of the ITB in situ and find that the ITB is primarily caused by oxidation accelerated GB fracture. Moreover, the microstructural effect, mainly γ′ volume fraction and grain size on the plasticity of precipitation strengthened alloys is established. Our findings might provide guidelines for overcoming ITB of precipitation-strengthened polycrystalline alloys.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"31 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142848969","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mechanism and kinetics of sodium diffusion in Na-feldspar from neural network based atomistic simulations","authors":"Alexander Gorfer, Rainer Abart, Christoph Dellago","doi":"10.1016/j.actamat.2024.120657","DOIUrl":"https://doi.org/10.1016/j.actamat.2024.120657","url":null,"abstract":"Alkali diffusion is a first-order control for microstructure and compositional evolution of feldspar during cooling from high temperatures of primary magmatic or metamorphic crystallization, and knowledge of the respective diffusion coefficients is crucial for reconstructing thermal histories. Our understanding of alkali diffusion in feldspar is, however, hindered by an insufficient grasp of the underlying diffusion mechanisms. We performed molecular dynamics simulations of sodium feldspar (Albite) containing different point defects using a recently developed neural network potential. A high degree of agreement between the sodium self-diffusion coefficients obtained from model simulations and those determined experimentally in earlier studies motivated a detailed investigation into the interstitial and vacancy mechanisms, corresponding jump rates, correlation factors and anisotropy. We identified a dumbbell shaped double occupancy of an alkali site as an important point defect and a correlation effect originating from the orientation of the dumbbell as a possible cause for the &lt;span&gt;&lt;span style=\"\"&gt;&lt;/span&gt;&lt;span data-mathml='&lt;math xmlns=\"http://www.w3.org/1998/Math/MathML\"&gt;&lt;mrow is=\"true\"&gt;&lt;mo is=\"true\"&gt;&amp;#x22A5;&lt;/mo&gt;&lt;mspace width=\"-0.16667em\" is=\"true\" /&gt;&lt;mspace width=\"-0.16667em\" is=\"true\" /&gt;&lt;mrow is=\"true\"&gt;&lt;mo is=\"true\"&gt;(&lt;/mo&gt;&lt;mn is=\"true\"&gt;001&lt;/mn&gt;&lt;mo is=\"true\"&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;mo linebreak=\"goodbreak\" linebreakstyle=\"after\" is=\"true\"&gt;&amp;gt;&lt;/mo&gt;&lt;mspace width=\"0.16667em\" is=\"true\" /&gt;&lt;mo linebreak=\"goodbreak\" linebreakstyle=\"after\" is=\"true\"&gt;&amp;#x22A5;&lt;/mo&gt;&lt;mspace width=\"-0.16667em\" is=\"true\" /&gt;&lt;mspace width=\"-0.16667em\" is=\"true\" /&gt;&lt;mrow is=\"true\"&gt;&lt;mo is=\"true\"&gt;(&lt;/mo&gt;&lt;mn is=\"true\"&gt;010&lt;/mn&gt;&lt;mo is=\"true\"&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;/math&gt;' role=\"presentation\" style=\"font-size: 90%; display: inline-block; position: relative;\" tabindex=\"0\"&gt;&lt;svg aria-hidden=\"true\" focusable=\"false\" height=\"2.779ex\" role=\"img\" style=\"vertical-align: -0.812ex;\" viewbox=\"0 -846.5 7229.8 1196.3\" width=\"16.792ex\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"&gt;&lt;g fill=\"currentColor\" stroke=\"currentColor\" stroke-width=\"0\" transform=\"matrix(1 0 0 -1 0 0)\"&gt;&lt;g is=\"true\"&gt;&lt;g is=\"true\"&gt;&lt;use xlink:href=\"#MJMAIN-22A5\"&gt;&lt;/use&gt;&lt;/g&gt;&lt;g is=\"true\"&gt;&lt;/g&gt;&lt;g is=\"true\"&gt;&lt;/g&gt;&lt;g is=\"true\" transform=\"translate(722,0)\"&gt;&lt;g is=\"true\"&gt;&lt;use xlink:href=\"#MJMAIN-28\"&gt;&lt;/use&gt;&lt;/g&gt;&lt;g is=\"true\" transform=\"translate(389,0)\"&gt;&lt;use xlink:href=\"#MJMAIN-30\"&gt;&lt;/use&gt;&lt;use x=\"500\" xlink:href=\"#MJMAIN-30\" y=\"0\"&gt;&lt;/use&gt;&lt;use x=\"1001\" xlink:href=\"#MJMAIN-31\" y=\"0\"&gt;&lt;/use&gt;&lt;/g&gt;&lt;g is=\"true\" transform=\"translate(1891,0)\"&gt;&lt;use xlink:href=\"#MJMAIN-29\"&gt;&lt;/use&gt;&lt;/g&gt;&lt;/g&gt;&lt;g is=\"true\" transform=\"translate(3281,0)\"&gt;&lt;use xlink:href=\"#MJMAIN-3E\"&gt;&lt;/use&gt;&lt;/g&gt;&lt;g is=\"true\"&gt;&lt;/g&gt;&lt;g is=\"true\" transform=\"translate(4226,0)\"&gt;&lt;use xlink:href=\"#MJMAIN-22A5\"&gt;&lt;/use&gt;&lt;/g&gt;&lt;g is=\"true\"&gt;","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"22 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142857772","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"S-scheme MoSi2N4/AlN with a 2D heterojunction for photocatalytic water dissociation","authors":"Nana Zhao, Jiamin Wang, Zhen Cui","doi":"10.1016/j.actamat.2024.120655","DOIUrl":"https://doi.org/10.1016/j.actamat.2024.120655","url":null,"abstract":"Two-dimensional heterojunctions with higher carrier mobility and larger specific surface area exhibit numerous applications in photovoltaics and energy. In this work, the MoSi₂N₄/AlN heterojunction structure was established, and the first-principles calculations were performed on its electronic properties, photocatalytic properties and power conversion efficiency, oxygen and hydrogen evolution reaction, electronic and photovoltaic characteristics under electric fields and strains, along with the photogalvanic effect. The results reveal that the MoSi₂N₄/AlN heterojunction displays an indirect bandgap semiconductor with a bandgap of 1.91 eV, generating an intrinsic electric field at the interface from AlN to MoSi₂N₄. It conforms to the S-scheme carrier transfer mechanism and can completely cross the oxidation and reduction potentials of water at pH values of 0-14. The power conversion efficiency can reach up to 15.21%. Hydrogen precipitation reaction occurs at the AlN side, while oxygen precipitation reaction generates at the MoSi₂N₄ side. At the photon energy of 2.5 eV, the maximum current can be achieved for the MoSi₂N₄/AlN heterojunction. This research can provide a novel strategy for the design and manufacture of optoelectronic devices with better performance.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"31 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142848931","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Novel 3-3-like heterostructure engineering enables BaTiO3-based ferroelectric ceramics with superior electrocaloric performance","authors":"Xiaowei Wei, Xiang Lv, Anyang Cui, Chunlin Zhao, Yinchang Ma, Xi-xiang Zhang, Youyou Yuan, Jiagang Wu","doi":"10.1016/j.actamat.2024.120674","DOIUrl":"https://doi.org/10.1016/j.actamat.2024.120674","url":null,"abstract":"For environmentally benign lead-free ferroelectric ceramics, the trait of temperature-dependent phase boundary renders ceramics with intrinsic temperature sensitivity, obstructing them toward practical applications. Recently, laminated composite ceramics were widely implemented to solve temperature instability. However, such 2-2 type structure exhibits inherent limitations on properties promotion. Given this, the present work proposes a novel strategy of 3-3-like heterostructure engineering to tackle the problem. Compared to the laminated counterpart, 3-3-like ceramic shows boosted dielectric, ferroelectric and strain properties. Significantly, its electrocaloric (EC) operating range is expanded from 18 to 49 °C, two-fold wider than the laminated one, while a large EC temperature change of 0.66 K@30 kV/cm is maintained, which shows great property advantages to that of state-of-art lead-free ceramics. The superior performance benefits from the relatively uniform field dispersion of 3-3-like heterogeneity. As a contrast, sharp interface divergence causes abnormal field distribution and phase destabilization in laminated structure, which undermines the electrical properties and limits temperature stability. This work offers a favorable strategy for designing high-performance lead-free materials with desirable temperature reliability.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"82 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142848935","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Passivating oxidation behavior of Ti0.12Al0.21B0.67 coatings investigated by scanning transmission electron microscopy and chemical environment dependent density functional theory simulations","authors":"Sebastian Lellig, Amir Hossein Navidi Kashani, Peter Schweizer, Marcus Hans, Ganesh K. Nayak, Johann Michler, Jochen M. Schneider","doi":"10.1016/j.actamat.2024.120662","DOIUrl":"https://doi.org/10.1016/j.actamat.2024.120662","url":null,"abstract":"The oxidation behavior of stoichiometric Ti_0.12Al_0.21B_0.67 coatings is investigated by scanning transmission electron microscopy (STEM) after oxidizing for 1, 4 and 8 h at 700°C and at 800 and 900°C.In the as deposited state, a ∼4 nm thick, native, amorphous oxide layer covers the surface of the coating, while the magnitude of incorporated O along the column boundaries decreases with depth. During oxidation, the formation of scale layers consisting predominantly of Al, O and B is observed that appear to be amorphous at 700°C, while after oxidation at 900°C for 8 h, a (nano-)crystalline aluminoborate layer forms. Concurrently, within the unoxidized coating, the formation of Al- and Ti-rich boride regions, consistent with spinodal decomposition, is observed. Chemical environment dependent density functional theory (DFT) predictions of the energies required for mass transport on the metal sublattice indicate that Al diffusion is initiated before Ti diffusion. Hence, as the temperature is increased, the migration of Al is initiated first, leading to the formation of the oxide scale observed already after oxidation at 700°C for 1 h. Below the oxidized region, the formation of Al-rich and Ti-rich regions by spinodal decomposition require the concurrent migration of Al and Ti. The fact that decomposition takes place at 900°C and hence at larger temperatures than the Al diffusion mediated scale formation is consistent with DFT predictions as the average values of the predicted energies required for both, vacancy formation and migration for Ti, are larger than for Al.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"50 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2024-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142840749","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Design of High-Temperature NiCuTiHf Shape Memory Alloys with Minimum Thermal Hysteresis using Bayesian Optimization","authors":"J. Broucek, D. Khatamsaz, C. Cakirhan, S. Hossein Zadeh, M. Fan, G. Vazquez, K.C. Atli, X. Qian, R. Arroyave, I. Karaman","doi":"10.1016/j.actamat.2024.120651","DOIUrl":"https://doi.org/10.1016/j.actamat.2024.120651","url":null,"abstract":"Chemical composition and thermal processing parameters are used in a first-of-their-kind machine learning (ML) and batch Bayesian optimization (BBO) approach in an iterative fashion in the quaternary NiTiCuHf high-temperature shape memory alloy (HTSMA) composition space to minimize thermal hysteresis in a desired transformation temperature range. The first of three iterations exploited an existing SMA database of lower complexity alloys (binary and ternary) attempting to optimize quaternary NiCuTiHf chemistry and thermal processing for the given constraint and the objective. Alloy synthesis and characterization revealed that the initial ML model displays high error levels between the predicted and experimental values, indicating the need for high-fidelity data in the complex quaternary alloy design space for optimization. The second iteration used this conclusion to explore an expanded design space through tuning Gaussian process (GP) hyperparameters. Utilization of active learning enabled the enlargement of data present in the high-complexity space during the iterative process, improving model accuracy. The third iteration discovered NiTiCuHf HTSMAs with the lowest reported martensitic transformation thermal hysteresis with transformation temperatures between 250°C and 350°C to date without precious metals. The effects of optimized secondary heat treatments on the martensitic transformation characteristics were explored and compared to those achieved after the initial homogenization heat treatments to demonstrate the ability of the BBO framework to create optimal alloys with controlled chemistry and thermal processing. In Ni-rich compositions of the designed alloys, the secondary heat treatments suggested by the BBO framework resulted in significant increases in transformation temperatures, suggesting the formation of Ni-rich precipitates.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"14 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2024-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142848939","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Predicted aluminum monoxide phases and their structural evolution under pressure","authors":"Zhen Jiao, Zheng-tang Liu, Xing-han Li, Fu-sheng Liu, Qi-jun Liu","doi":"10.1016/j.actamat.2024.120667","DOIUrl":"https://doi.org/10.1016/j.actamat.2024.120667","url":null,"abstract":"To explore the stable crystal structure and structural evolution of aluminum monoxide (AlO), we predict four novel structures and investigate their stability, mechanical, electronic and Raman properties using particle-swarm optimization (PSO) technique and density functional theory (DFT) calculations. Depending on the symmetry and bonding characteristics, these novel structures exhibit various stability and properties under pressure. The <em>oP</em>-AlO (space group Imm2) is the most stable structure under ambient pressure, while the <em>h</em>-AlO (space group R<span><span style=\"\"></span><span data-mathml='&lt;math xmlns=\"http://www.w3.org/1998/Math/MathML\"&gt;&lt;mover accent=\"true\" is=\"true\"&gt;&lt;mn is=\"true\"&gt;3&lt;/mn&gt;&lt;mo is=\"true\"&gt;&amp;#xAF;&lt;/mo&gt;&lt;/mover&gt;&lt;/math&gt;' role=\"presentation\" style=\"font-size: 90%; display: inline-block; position: relative;\" tabindex=\"0\"><svg aria-hidden=\"true\" focusable=\"false\" height=\"2.202ex\" role=\"img\" style=\"vertical-align: -0.235ex;\" viewbox=\"0 -846.5 570.5 947.9\" width=\"1.325ex\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"><g fill=\"currentColor\" stroke=\"currentColor\" stroke-width=\"0\" transform=\"matrix(1 0 0 -1 0 0)\"><g is=\"true\"><g is=\"true\" transform=\"translate(35,0)\"><use xlink:href=\"#MJMAIN-33\"></use></g><g is=\"true\" transform=\"translate(0,197)\"><use x=\"-70\" xlink:href=\"#MJMAIN-AF\" y=\"0\"></use><use x=\"70\" xlink:href=\"#MJMAIN-AF\" y=\"0\"></use></g></g></g></svg><span role=\"presentation\"><math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mover accent=\"true\" is=\"true\"><mn is=\"true\">3</mn><mo is=\"true\">¯</mo></mover></math></span></span><script type=\"math/mml\"><math><mover accent=\"true\" is=\"true\"><mn is=\"true\">3</mn><mo is=\"true\">¯</mo></mover></math></script></span>m) structure becomes the most stable above 3 GPa and remains so up to 100 GPa. The <em>h</em>-AlO structure stands out due to distinct bonding interactions at different Wyckoff positions of aluminum atoms, particularly the rhombus arrangement formed by Al-II atoms, which gives rise to a Dirac cone in its electronic structure that is insensitive to pressure. In contrast, the <em>m</em>-AlO (space group C2/m), <em>oP</em>-AlO and <em>oD-</em>AlO (space group I/mmm) structures undergo first-order phase transitions, accompanied by significant structural changes and discontinuities in Al-O bonds. The <em>oP</em>-AlO and <em>oD-</em>AlO structures, in particular, exhibit unstable transformations during these transitions. Additionally, the vibrational characteristics of predicted structures are discussed, and the significant differences facilitate future experimental identification through Raman spectroscopy.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"87 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2024-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142848974","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}