Crystal structure of the layered arsenide Rb3Cu3As2

2018 ◽  
Vol 74 (12) ◽  
pp. 1715-1718 ◽  
Author(s):  
Alexander Ovchinnikov ◽  
Hua He ◽  
Svilen Bobev
Keyword(s):  
Crystal Structure ◽  
First Principles ◽  
First Principles Calculations ◽  
X Ray Diffraction ◽  
Zintl Phases ◽  
X Ray ◽  
Bonding Analysis ◽  
Electron Counting ◽  
Valence Electrons ◽  
Weak Attraction

The crystal structure of a new arsenide, Rb3Cu3As2 (trirubidium tricopper diarsenide), has been established from single-crystal X-ray diffraction data. This compound crystallizes in the K3Cu3P2 type, with layers of interlinked CuAs2 units. The partitioning of the available valence electrons yields the charge-balanced composition (Rb+)3(Cu+)3(As3–)2, placing this phase in a broad field of transition-metal-containing Zintl phases. First-principles calculations confirm a semiconducting ground state, in accordance with electron-counting considerations. Chemical bonding analysis reveals strong covalent Cu—As bonds and ionic Rb...As interactions. In addition, a weak attraction is found between the Cu atoms, possibly pointing toward cuprophilic interactions.

scholarly journals Crystal Structures of Al2Cu Revisited: Understanding Existing Phases and Exploring Other Potential Phases

Metals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1037 ◽  
Author(s):  
Sai Wang ◽  
Changzeng Fan
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Single Crystal ◽  
First Principles ◽  
First Principles Calculations ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structural Relationships ◽  
Al2cu Phase ◽  
High Pressure Sintering

When processing single crystal X-ray diffraction datasets for twins of Al2Cu sample synthesized by the high-pressure sintering (HPS) method, we have clarified why the crystal structure of Al2Cu was incorrectly solved about a century ago. The structural relationships between all existing Al2Cu phases, including the Owen-, θ-, θ’-, and Ω-Al2Cu phases, were investigated and established based on a proposed pseudo Al2Cu phase. Two potential phases have been built up by adjusting the packing sequences of A/B layers of Al atoms that were inherent in all existing Al2Cu phases. The mechanical, thermal, and dynamical stability of two such novel phases and their electronic properties were investigated by first-principles calculations.

scholarly journals Structure and Stability of the Stoichiometric Al3Fe Phase

Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1322
Author(s):  
Zheng Xia ◽  
Bin Wen ◽  
Changzeng Fan
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Enthalpy Of Formation ◽  
First Principles ◽  
First Principles Calculations ◽  
Structural Refinement ◽  
X Ray Diffraction ◽  
X Ray ◽  
Plasma Sintering ◽  
Spark Plasma

A disordered stoichiometric Al3Fe phase was obtained when synthesizing Al8Fe3 by the spark plasma sintering (SPS) approach and its crystal structure was determined by the single-crystal X-ray diffraction (SXRD) techniques. The refined structure is an isotype of the reported Al5Fe2 phase, only different in the site occupation factors (s. o. f.) of Al2 and Al3 atoms, which was refined to be 0.431 (13) and 0.569 (13), respectively. Stimulated by the structural refinement results, an ordered stoichiometric Al3Fe phase was established. First-principles calculations reveal that the ordered Al3Fe phase is mechanically and dynamically stable and has a much lower value of enthalpy of formation than any other proposed Al3Fe phases, although it is also metallic and metastable.

scholarly journals New Insights on the Reversible Lithiation Mechanism of TiO2(B) by Operando X-ray Absorption Spectroscopy and X-ray Diffraction Assisted by First-Principles Calculations

2014 ◽  
Vol 118 (47) ◽  
pp. 27210-27218 ◽  
Author(s):  
Marcus Fehse ◽  
Mouna Ben Yahia ◽  
Laure Monconduit ◽  
Frédéric Lemoigno ◽  
Marie-Liesse Doublet ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
First Principles ◽  
First Principles Calculations ◽  
X Ray Diffraction ◽  
X Ray ◽  
X Ray Absorption

Structural analysis of Gd6FeBi2 from single-crystal X-ray diffraction methods and electronic structure calculations

2019 ◽  
Vol 75 (5) ◽  
pp. 562-567 ◽  
Author(s):  
Jiliang Zhang ◽  
Yong-Mook Kang ◽  
Guangcun Shan ◽  
Svilen Bobev
Keyword(s):  
Electronic Structure ◽  
Single Crystal ◽  
First Principles ◽  
Earth Metal ◽  
Magnetic Ordering ◽  
Additional Contribution ◽  
First Principles Calculations ◽  
X Ray Diffraction ◽  
Magnetic Exchange ◽  
X Ray

The crystal structure of the gadolinium iron bismuthide Gd6FeBi2 has been characterized by single-crystal X-ray diffraction data and analyzed in detail using first-principles calculations. The structure is isotypic with the Zr6CoAl2 structure, which is a variant of the ZrNiAl structure and its binary prototype Fe2P (Pearson code hP9, Wyckoff sequence g f d a). As such, the structure is best viewed as an array of tricapped trigonal prisms of Gd atoms centered alternately by Fe and Bi. The magnetic-ordering temperature of this compound (ca 350 K) is much higher than that of other rare-earth metal-rich phases with the same or related structures. It is also higher than the ordering temperature of many other Gd-rich ternary phases, where the magnetic exchange is typically governed by Ruderman–Kittel–Kasuya–Yosida (RKKY) interactions. First-principles calculations reveal a larger than expected Gd magnetic moment, with the additional contribution arising from the Gd 5d electrons. The electronic structure analysis suggests strong Gd 5d–Fe 3d hybridization to be the cause of this effect, rather than weak interactions between Gd and Bi. These details are of importance for understanding the magnetic response and explaining the high ordering temperature in this material.

scholarly journals [UO2(NH3)5]Br2·NH3: synthesis, crystal structure, and speciation in liquid ammonia solution by first-principles molecular dynamics simulations

2015 ◽  
Vol 44 (16) ◽  
pp. 7332-7337 ◽  
Author(s):  
Patrick Woidy ◽  
Michael Bühl ◽  
Florian Kraus
Keyword(s):  
Crystal Structure ◽  
Molecular Dynamics ◽  
Bond Strength ◽  
Molecular Dynamics Simulations ◽  
First Principles ◽  
Liquid Ammonia ◽  
Ammonia Solution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dynamics Simulations

X-Ray diffraction and Car–Parrinello molecular dynamics simulations furnish insights into the speciation of uranyl(vi) in liquid ammonia, calling special attention to the effect of solvation on the U–N bond length and bond strength.

scholarly journals Structural and electronic properties of the spinel Li4Ti5O12

2019 ◽  
Vol 20 (46) ◽  
pp. 7-12 ◽  
Author(s):  
Sarantuya Lkhagvajav ◽  
Namsrai Tsogbadrakh ◽  
Enkhjargal Enkhbayar ◽  
Sevjidsuren Galsan ◽  
Pagvajav Altantsog
Keyword(s):  
Electronic Properties ◽  
First Principles ◽  
Density Functional ◽  
Experimental Studies ◽  
First Principles Calculations ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structural And Electronic Properties ◽  
Hubbard U ◽  
Uv Visible

In this study, the structure and electronic properties of the spinel compound Li4Ti5O12 (LTO) are investigated both theoretical and experimental methods. The experimental studies of structural and electronic properties were performed by X-ray diffraction and UV-visible spectroscopy. The first principles calculations allowed to establish the relationship between the structure and electronic properties. The spinel type structure of LTO is refined by the Rietveld analysis using the X-ray diffraction (XRD). The band gap of LTO was determined to be 3.55 eV using the UV-visible absorption spectra. The Density functional theory (DFT) augmented without and with the Hubbard U correction (GGA and GGA +U+J0) is used to elucidate the electronic structure of LTO. We have performed systematic studies of the first principles calculations based on the GGA and GGA+U for the crystal structure and electronic properties of spinel LTO. We propose that a Hubbard U correction improves the DFT results.

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