A new tetragonal structure type for Li2B2C

2015 ◽  
Vol 71 (1) ◽  
pp. 39-43 ◽  
Author(s):  
Volodymyr Pavlyuk ◽  
Viktoriya Milashys ◽  
Grygoriy Dmytriv ◽  
Helmut Ehrenberg
Keyword(s):  
Electronic Structure ◽  
Electronic Structure Calculations ◽  
Structure Type ◽  
Tetragonal Structure ◽  
Vertex Polyhedron ◽  
Coordination Polyhedra ◽  
Space Group ◽  
Nearest Neighbours ◽  
Structure Calculations ◽  
Lateral Facet

The ternary dilithium diboron carbide, Li2B2C (tetragonal, space groupP\overline{4}m2,tP10), crystallizes as a new structure type and consists of structural fragments which are typical for structures of elemental lithium and boron or binary borocarbide B13C2. The symmetries of the occupied sites are .m. and 2mm. for the B and C atoms, and \overline{4}m2 and 2mm. for the Li atoms. The coordination polyhedra around the Li atoms are cuboctahedra and 15-vertex distorted pseudo-Frank–Kasper polyhedra. The environment of the B atom is a ten-vertex polyhedron. The nearest neighbours of the C atom are two B atoms, and this group is surrounded by a deformed cuboctahedron with one centred lateral facet. Electronic structure calculations using the TB–LMTO–ASA method reveal strong B...C and B...B interactions.

LiBC3: a new borocarbide based on graphene and heterographene networks

2017 ◽  
Vol 73 (11) ◽  
pp. 984-989 ◽  
Author(s):  
Viktoria Milashius ◽  
Volodymyr Pavlyuk ◽  
Karolina Kluziak ◽  
Grygoriy Dmytriv ◽  
Helmut Ehrenberg
Keyword(s):  
Crystal Structure ◽  
Electronic Structure ◽  
Tight Binding ◽  
Lithium Ion ◽  
Electronic Structure Calculations ◽  
Structure Type ◽  
Coordination Polyhedra ◽  
Carbon Networks ◽  
Structure Calculations ◽  
Potential Use

Li–B–C alloys have attracted much interest because of their potential use in lithium-ion batteries and superconducting materials. The formation of the new compound LiBC3 [lithium boron tricarbide; own structure type, space group P\overline{6}m2, a = 2.5408 (3) Å and c = 7.5989 (9) Å] has been revealed and belongs to the graphite-like structure family. The crystal structure of LiBC3 presents hexagonal graphene carbon networks, lithium layers and heterographene B/C networks, alternating sequentially along the c axis. According to electronic structure calculations using the tight-binding linear muffin-tin orbital-atomic spheres approximations (TB–LMTO–ASA) method, strong covalent B—C and C—C interactions are established. The coordination polyhedra for the B and C atoms are trigonal prisms and for the Li atoms are hexagonal prisms.

Li4Ge2B as a new derivative of the Mo2B5and Li5Sn2structure types

2016 ◽  
Vol 72 (7) ◽  
pp. 561-565 ◽  
Author(s):  
Volodymyr Pavlyuk ◽  
Wojciech Ciesielski ◽  
Beata Rozdzynska-Kielbik ◽  
Grygoriy Dmytriv ◽  
Helmut Ehrenberg
Keyword(s):  
Electronic Structure ◽  
Ternary System ◽  
Electrode Materials ◽  
Tight Binding ◽  
Lithium Ion ◽  
Electronic Structure Calculations ◽  
Structure Type ◽  
Space Group ◽  
Rhombic Dodecahedra ◽  
Structure Calculations

Binary and multicomponent intermetallic compounds based on lithium andp-elements of Groups III–V of the Periodic Table are useful as modern electrode materials in lithium-ion batteries. However, the interactions between the components in the Li–Ge–B ternary system have not been reported. The structure of tetralithium digermanium boride, Li4Ge2B, exhibits a new structure type, in the noncentrosymmetric space groupR3m, in which all the Li, Ge and B atoms occupy sites with 3msymmetry. The title structure is closely related to the Mo2B5and Li5Sn2structure types, which crystallize in the centrosymmetric space groupR\overline{3}m. All the atoms in the title structure are coordinated by rhombic dodecahedra (coordination number = 14), similar to the atoms in related structures. According to electronic structure calculations using the tight-binding–linear muffin-tin orbital–atomic spheres approximation (TB–LMTO–ASA) method, strong covalent Ge—Ge and Ge—B interactions were established.

The New Ternary Silicide ErCo3Si2

2014 ◽  
Vol 69 (3) ◽  
pp. 369-372
Author(s):  
Mariya Dzevenko ◽  
Inna Bigun
Keyword(s):  
Structure Type ◽  
Vertex Polyhedron ◽  
Coordination Polyhedra ◽  
Space Group ◽  
Type Space ◽  
Ternary Silicide

The new ternary silicide ErCo3Si2 adopts the ErRh3Si2 structure type (space group Imma, Pearson code oI24, Z = 4, a = 6:950(1), b = 9:020(2), c = 5:230(1) Å, R1 = 0:0565, wR2 = 0:0355, 253 F2 values, 23 variables). It is a deformation derivative of the CeCo3B2 structure type. The coordination of the Er atom shows a normal 20- vertex polyhedron [Er(Si6Co12Er2)]. The two similar coordination polyhedra of Co are a distorted icosahedron [Co(Si4Co4Er4)], and a distorted icosahedron with one capped face [Co(Si4Co5Er4)]. The Si atom is surrounded by the polyhedron [Si(Co6Si2Er3)]

ErNi2.23Al2.77 and YbNi2.31Al2.69 – i3 superstructures of the CaCu5 type

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Nazar Zaremba ◽  
Ihor Muts ◽  
Volodymyr Pavlyuk ◽  
Viktor Hlukhyy ◽  
Rainer Pöttgen ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Single Crystal ◽  
Crystal Structures ◽  
Electronic Structure Calculations ◽  
Crystal Chemical ◽  
Muffle Furnace ◽  
Space Group ◽  
X Ray ◽  
Structure Calculations

Abstract The title compounds have been synthesized by reaction of the elements in sealed tantalum crucibles in a muffle furnace using special annealing sequences. The crystal structures of YbNi2.31Al2.69 (R1 = 0.0100 for 212 F 2 values and 18 variables) and for ErNi2.23Al2.77 (R1 = 0.0154 for 255 F 2 values and 18 variables) were refined from single crystal X-ray data. They belong to the YNi2Al3 type (i3 superstructure of CaCu5) with the following crystallographic parameters: space group P 6 / m m m $P6/mmm$ , Pearson’s symbol hP18, Z = 3, a = 8.2723(12), c = 4.0672(8) Å, V = 241.03(8) Å3 for YbNi2.31Al2.69 and a = 8.9109(13), c = 4.0669(8) Å, V = 279.66(8) Å3 for ErNi2.23Al2.77. The crystal chemical discussion is supported by electronic structure calculations.

scholarly journals Thulium nickel/lithium distannide, TmNi1−xLixSn2(x= 0.035)

2013 ◽  
Vol 69 (11) ◽  
pp. i76-i76 ◽  
Author(s):  
Andrij Stetskiv ◽  
Ivan Tarasiuk ◽  
Renata Misztal ◽  
Volodymyr Pavlyuk
Keyword(s):  
Electronic Structure ◽  
Three Dimensional ◽  
Electronic Structure Calculations ◽  
Structure Type ◽  
Trigonal Prism ◽  
Interatomic Distances ◽  
Tricapped Trigonal Prism ◽  
Pentagonal Prism ◽  
Structure Calculations ◽  
Positively Charged

The quaternary thulium nickel/lithium distannide, TmNi1−xLixSn2(x= 0.035), crystallizes in the orthorhombic LuNiSn2structure type. The asymmetric unit contains three Tm sites, six Sn sites, two Ni sites and one Ni/Li site [relative occupancies = 0.895 (8):0.185 (8)]. Site symmetries are .m. for all atoms. The 17-, 18- and 19-vertex distorted pseudo-Frank–Kasper polyhedra are typical for all Tm atoms. Four Sn atoms are enclosed in a 12-vertex deformed cubooctahedron, and another Sn atom is enclosed in a pentagonal prism with three added atoms. A tricapped trigonal prism is typical for a further Sn atom. The coordination number for all Ni atoms and Ni/Li statistical mixtures is 12 (fourcapped trigonal prism [Ni/LiTm5Sn5]). Tm atoms form the base of a prism and Ni/Li atoms are at the centres of the side faces of an [SnTm6Ni/Li3] prism. These isolated prisms are implemented into three-dimensional-nets built out of Sn atoms. Electronic structure calculations using TB-LMTO-ASA suggest that the Tm and Ni/Li atoms form positively chargedn[TmNi/Li]m+polycations which compensate the negative charge of 2n[Sn]m−polyanions. Analysis of the interatomic distances and electronic structure calculations indicate the dominance of a metallic type of bonding.

SmPt2In2 – a new ternary indide with a Pt–In polyanionic framework

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Nazar Zaremba ◽  
Ihor Muts ◽  
Volodymyr Pavlyuk ◽  
Viktor Hlukhyy ◽  
Rainer Pöttgen ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Electronic Structure ◽  
Single Crystals ◽  
High Frequency ◽  
Electronic Structure Calculations ◽  
Structure Type ◽  
Argon Atmosphere ◽  
Crystal Chemical ◽  
X Ray ◽  
Structure Calculations

Abstract Single crystals of a new samarium platinum indide have been synthesized in a high-frequency furnace under flowing argon atmosphere. The crystal structure of SmPt2In2 was determined from single-crystal X-ray data (R1 = 0.0416 for 1049 F values and 63 variables). It belongs to the CePt2In2 structure type with the following crystallographic parameters: P21/m, mP20, Z = 4, a = 10.0561(8), b = 4.4214(2), c = 10.1946(8) Å, β = 116.492(5)°, V = 405.68(5) Å3. Physical properties were studied and the crystal chemical discussion is supported by electronic structure calculations.

Message Passing Neural Networks for Partial Charge Assignment to Metal-Organic Frameworks

2020 ◽  
Author(s):  
Ali Raza ◽  
Arni Sturluson ◽  
Cory Simon ◽  
Xiaoli Fern
Keyword(s):  
Electronic Structure ◽  
Message Passing ◽  
Gas Adsorption ◽  
Metal Organic Frameworks ◽  
Computational Cost ◽  
Electronic Structure Calculations ◽  
High Fidelity ◽  
Partial Charges ◽  
Metal Organic ◽  
Structure Calculations

Virtual screenings can accelerate and reduce the cost of discovering metal-organic frameworks (MOFs) for their applications in gas storage, separation, and sensing. In molecular simulations of gas adsorption/diffusion in MOFs, the adsorbate-MOF electrostatic interaction is typically modeled by placing partial point charges on the atoms of the MOF. For the virtual screening of large libraries of MOFs, it is critical to develop computationally inexpensive methods to assign atomic partial charges to MOFs that accurately reproduce the electrostatic potential in their pores. Herein, we design and train a message passing neural network (MPNN) to predict the atomic partial charges on MOFs under a charge neutral constraint. A set of ca. 2,250 MOFs labeled with high-fidelity partial charges, derived from periodic electronic structure calculations, serves as training examples. In an end-to-end manner, from charge-labeled crystal graphs representing MOFs, our MPNN machine-learns features of the local bonding environments of the atoms and learns to predict partial atomic charges from these features. Our trained MPNN assigns high-fidelity partial point charges to MOFs with orders of magnitude lower computational cost than electronic structure calculations. To enhance the accuracy of virtual screenings of large libraries of MOFs for their adsorption-based applications, we make our trained MPNN model and MPNN-charge-assigned computation-ready, experimental MOF structures publicly available.<br>

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