The electron density distribution in calcium metaborate, Ca(BO<sub>2</sub>)<sub>2</sub>

Kirfel, Α.

doi:10.1107/s0108768187097763

Cited by 22 publications

(7 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…5) or Ca(BO2)2 (Kirfel, 1987 , Fig. These features are quite typical for B--O bonds, as seen for instance in the studies of LiBO2 (Kirfel et al, 1983, Fig.…”

mentioning

confidence: 60%

Electron Density Distribution in LiB₃O₅ at 293 K

Hénaff¹,

Hansen²,

Protas³

et al. 1997

Acta Crystallogr Sect B

View full text Add to dashboard Cite

The electron density distribution in lithium triborate LiB30 5 has been studied at room temperature by X-ray diffraction using Ag Ka radiation up to 1.02 A -t [1439 unique reflections with I > 3o-(/)]. Conventional refinements with a free-atom model yield R(F) = 0.0223, wR(F) = 0.0299, S = 1.632. Atom charge refinements show that the lithium should be considered a monovalent ion. Multipolar refinements were undertaken up to fourth order, imposing local non-crystallographic symmetry constraints in order to avoid phase problems leading to meaningless multipole populations due to the noncentrosymmetry of the structure (space group: Pna21). The residual indices decreased to: R(F) = 0.0147, wR(F) = 0.0193, S = 1.106. The net charges are in good agreement with what can be expected in borate chemistry. Deformation density maps are analysed in terms of o. and rr bonding. The experimental electron distribution in the Pz orbitals of triangular B atoms and surrounding O atoms has been analysed by introducing idealized hybridized states. In parallel, the electron density has been determined from ab initio Hartree-Fock calculations on fragments of the structure. Agreement with the X-ray determination is very good and confirms the nature of bonding in the crystal. The amount of transfer of rr electrons from the oxygen to the triangular B atoms is estimated to be 0.22 electrons by theory.

show abstract

“…5) or Ca(BO2)2 (Kirfel, 1987 , Fig. These features are quite typical for B--O bonds, as seen for instance in the studies of LiBO2 (Kirfel et al, 1983, Fig.…”

mentioning

confidence: 60%

Electron Density Distribution in LiB₃O₅ at 293 K

Hénaff¹,

Hansen²,

Protas³

et al. 1997

Acta Crystallogr Sect B

View full text Add to dashboard Cite

show abstract

“…The available crystal structure data of a natural okayamalite were used for Rietveld refinement, but with the 20 mol% Al introduced at the boron site. Calcium metaborate was observed in the samples cf30 and c30b and in very small amount also in f11 annealed at 800°C. In cf30, it dominated over okayamalite and was the main boron phase in the fully recrystallized samples.…”

Section: Resultsmentioning

confidence: 90%

Commercial alkaline earth boroaluminosilicate glasses for sealing solid oxide cell stacks. Part II: Characterization of devitrification and glass‐ceramic phase assemblages

Agersted

Balić-Žunić

2017

Int J Applied Ceramic Tech

View full text Add to dashboard Cite

The devitrification process and formation of crystalline phases from commercial alkaline earth boroaluminosilicate glasses containing 48-61 mol% SiO 2 , 18-28 mol% CaO, 1-7 mol% MgO, 7-10 mol% Al 2 O 3 , 1-11 mol% B 2 O 3 plus minor amounts of Na 2 O, K 2 O, FeO, and TiO 2 were quantified through analysis of phase assemblages as function of heat treatments above the glass transition temperatures, using the electron microprobe and powder X-ray diffraction. Treatments at 800 and 850°C lasted up to 6 weeks. Results indicate that devitrification was strongly

show abstract

“…The crystal-growth and the crystal structure determination of CaB 2 O 4 (III) and CaB 2 O 4 (IV), along with a discussion of the polymorphism of CaB 2 O 4 , were reported in detail by Marezio et al in 1969 [1, 2]. The electron density distribution in Ca(BO 2 ) 2 at room temperature has been studied by X-ray diffraction experiments on two crystals I and II [5], for which the number of atoms in the unit cells is very small.…”

Section: Introductionmentioning

confidence: 97%

“…In this article, we focused on the orthorhombic Pna2 1 phase CaB 2 O 4 (III), including 84 atoms in the super cell [2] and calculated its electronic properties with SIESTA program. The B-O distances of CaB 2 O 4 I, II, III, and IV were summarized [1,2,5,6], and on the basis of the work of Wu and Zhang [7], we calculated the bond covalency and bond valence of Ca-O and B-O bonds, then analyzed their properties in detail, and compared to Mulliken population analysis.…”

Section: Introductionmentioning

confidence: 99%

Bond covalency and electronic structure of CaB2O4(III) crystal

2009

View full text Add to dashboard Cite

The electronic structure of CaB 2 O 4 (III) crystal obtained by using SIESTA program is reported in this article. It is observed that the band gap values are, respectively, 5.39 and 5.89 eV from our LDA and GGA calculations. The bond covalency and bond valence are calculated with a simplified method. For both Ca-O and B-O types of bond, the bond covalency has a decreasing trend with the increasing bond length. The result of bond covalency in explaining the interaction between atoms has been shown in good agreement with that of Mulliken population analysis. The ionic configuration for CaB 2 O 4 (III) in the fundamental state is estimated to be Ca ?1.808 B -0.68 O -0.112 . A summary of B-O distances for the four phases of CaB 2 O 4 crystal from several works is also presented.

show abstract

The electron density distribution in calcium metaborate, Ca(BO₂)₂

Cited by 22 publications

References 13 publications

Electron Density Distribution in LiB₃O₅ at 293 K

Electron Density Distribution in LiB₃O₅ at 293 K

Commercial alkaline earth boroaluminosilicate glasses for sealing solid oxide cell stacks. Part II: Characterization of devitrification and glass‐ceramic phase assemblages

Bond covalency and electronic structure of CaB2O4(III) crystal

Contact Info

Product

Resources

About

The electron density distribution in calcium metaborate, Ca(BO2)2

Cited by 22 publications

References 13 publications

Electron Density Distribution in LiB3O5 at 293 K

Electron Density Distribution in LiB3O5 at 293 K

Commercial alkaline earth boroaluminosilicate glasses for sealing solid oxide cell stacks. Part II: Characterization of devitrification and glass‐ceramic phase assemblages

Bond covalency and electronic structure of CaB2O4(III) crystal

Contact Info

Product

Resources

About

The electron density distribution in calcium metaborate, Ca(BO₂)₂

Electron Density Distribution in LiB₃O₅ at 293 K

Electron Density Distribution in LiB₃O₅ at 293 K