Atomic ordering in binary <i>A</i>l5-type phases

Reuth, E.C. van; Waterstrat, R.M.

doi:10.1107/s0567740868001937

Cited by 131 publications

(26 citation statements)

References 8 publications

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“…A more recent investigation of Cr72Ru28 and Cr12Os28 alloys with A 15 type structure and compositions deviating from stoichiometry has shown that the occupancies of sites lying along linear chains are mixed (Reuth & Waterstrat, 1968). The Cr atoms, however, show in both cases a marked preference for those sites (~85 at.% Cr); the same marked preference is evidenced by the present results for a-Cr2Ru and tT-Cr2Os.…”

Section: Discussionsupporting

confidence: 67%

“…Furthermore, binary alloys possessing the A 15 type of structure might be expected to be completely ordered, the occupancies of the A and B atomic sites being dictated by a definite stoichiometric composition A 3 B. This has been observed in a number of cases; however, some degree of disorder has been found in some phases (Reuth & Waterstrat, 1968;Waterstrat & Dickens, 1974).…”

Section: Discussionmentioning

confidence: 95%

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The ordering of the σ phases Cr₂Ru and Cr₂Os

Veiga¹,

Costa²,

Almeida³

et al. 1980

Acta Crystallogr Sect B

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Two a-phase structures, Cr2Ru and Cr2Os, have been studied using X-ray single-crystal diffraction techniques. The ordering determined has been compared with those of other a phases and A15 structures. Although atoms of both kinds occupy every atomic position, a significant departure from complete disorder was detected. This is particularly important in the 14-fold J atomic positions which are associated with bond angles of 180°: the marked preference of the smaller Cr atoms for these sites indicates that their occupancy appears to be determined by the electronic A.]

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Section: Discussionsupporting

confidence: 67%

Section: Discussionmentioning

confidence: 95%

The ordering of the σ phases Cr₂Ru and Cr₂Os

Veiga¹,

Costa²,

Almeida³

et al. 1980

Acta Crystallogr Sect B

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“…This is in agreement with results obtained for other Cr alloys with group-8 diluents that also show SC, such as in the case of Cr-Ir, Cr-Ru and Cr-Rh [1,5,10]. However, Cr alloys with high diluent concentrations of group-8 metal does not exclusively show a body centered cubic (bcc) structure, but also include binary phases such as Cr 3 X with a cubic A15 phase, shown to be SC [11][12][13][14]. * corresponding author; e-mail: alettap@uj.ac.za…”

Section: Introductionsupporting

confidence: 80%

Superconductivity and Quantum Critical Behavior in Cr_100-zOs_z

2017

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The magnetic phase diagrams of Cr alloys with group-8 metals, such as Re and Ru, show interesting properties. These include quantum critical and superconducting behavior. In order to extend these investigations this paper reports on the physical properties and the magnetic phase diagram of the Cr100−zOsz system, investigated in a concentration range of 2 ≤ z ≤ 30.6. Structural analysis indicate that samples with z < 22 have a bcc structure, while those with z > 22 include a cubic A15-type structure. Transport and magnetic property measurements indicate that the antiferromagnetic phase disappears at z ≈ 14 and that samples with concentrations z ≥ 12.2 show superconducting behavior. The magnetic phase diagram of Cr100−zOsz is constructed from the Néel and superconducting transition temperatures obtained from various measurements. The commensurate spin-densitywave to paramagnetic phase line decreases sharply for z > 4. Fitting parameters of a power law fit to the commensurate spin-density-wave to paramagnetic phase line indicate possible quantum critical behavior. Present results suggest that this phase line terminates in a superconducting dome near a magnetic quantum critical point, similar to that observed in certain heavy fermion systems, but not previously reported for other Cr alloys.

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“…Any structure in the library can be predicted and there are no preconceived biases as to the symmetry or underlying superlattice of the structure as is the case for methods that work with lattice model approaches. For example, in the Ti-Pt alloy, our method correctly finds the A15 [18,19] structure to be a ground state for Ti 3 Pt after only 20 steps in the algorithm, even though this structure is not a superstructure of fcc (the structure of Pt) or hcp (the structure of Ti), and is therefore not an obvious structure to investigate for this system. To study in a more statistically significant way how this iterative scheme converges we tested how well the library minus one alloy can perform predictions on the alloy left out.…”

mentioning

confidence: 99%

Predicting Crystal Structures with Data Mining of Quantum Calculations

et al. 2003

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Predicting and characterizing the crystal structure of materials is a key problem in materials research and development. It is typically addressed with highly accurate quantum mechanical computations on a small set of candidate structures, or with empirical rules that have been extracted from a large amount of experimental information, but have limited predictive power. In this letter, we transfer the concept of heuristic rule extraction to a large library of ab-initio calculated information, and demonstrate that this can be developed into a tool for crystal structure prediction.Ab-initio methods, which predict materials properties from the fundamental equations of quantum mechanics, are becoming a ubiquitous tool for physicists, chemists, and materials scientists. These methods allow scientists to evaluate and pre-screen new materials "in silico", rather than through time-consuming experimentation, and in some cases, even make suggestions for new and better materials [1][2][3][4][5]. One inherent limitation of most ab-initio approaches is that they do not make explicit use of results of previous calculations when studying a new system. This can be contrasted with datacentered methods, which mine existing data libraries to help understand new situations. The contrast between data-centered and traditional ab-initio methods can be seen clearly in the different approaches used to predict the crystal structure of materials. This is a difficult but important problem that forms the basis for any rational materials design. In heuristic models, a large amount of experimental observations are used in order to extract rules which rationalize crystal structure with a few simple physical parameters such as atomic radii, electronegativities, etc.. The Miedema rules for predicting compound forming [6], or the Pettifor maps [7] which can be used to predict the structure of a new binary material by correlating the position of its elements in the periodic table to those of systems for which the stable crystal structure is known, are excellent examples of this. Abinitio methods differ from these data-centered methods in that they do not use historic and cumulative information about previously studied systems, but rather try to determine structure by optimizing from scratch the complex quantum mechanical description of the system, either directly (as in ab-initio Molecular Dynamics), or in coarse-grained form (as in lattice models [8][9][10]). Here, we merge the ideas of data-centered methods with the predictive power of ab-initio computation. We propose a new approach whereby ab-initio investigations on new systems are informed with knowledge obtained from results already collected on other systems. We refer to this approach as Data Mining of Quantum Calculations (DMQC), and demonstrate its efficiency in increasing the speed of predicting the crystal structure of new and unknown materials. Using a Principal Component Analysis on over 6000 ab-initio energy calculations, we show that the energies of different crystal structures in ...

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Atomic ordering in binary Al5-type phases

Cited by 131 publications

References 8 publications

The ordering of the σ phases Cr₂Ru and Cr₂Os

The ordering of the σ phases Cr₂Ru and Cr₂Os

Superconductivity and Quantum Critical Behavior in Cr_100-zOs_z

Predicting Crystal Structures with Data Mining of Quantum Calculations

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Atomic ordering in binary Al5-type phases

Cited by 131 publications

References 8 publications

The ordering of the σ phases Cr2Ru and Cr2Os

The ordering of the σ phases Cr2Ru and Cr2Os

Superconductivity and Quantum Critical Behavior in Cr100-zOsz

Predicting Crystal Structures with Data Mining of Quantum Calculations

Contact Info

Product

Resources

About

The ordering of the σ phases Cr₂Ru and Cr₂Os

The ordering of the σ phases Cr₂Ru and Cr₂Os

Superconductivity and Quantum Critical Behavior in Cr_100-zOs_z