Synthesis, crystal structure and thermal behavior of Rb3B7O12, a new compound

R. S. Bubnova, I. G. Polyakova, S. V. Krivovichev, I. P. Shakhverdova, S. K. Filatov, M. G. Krzhizhanovskaya, P. C. Burns

Research output

19 Citations (Scopus)

Abstract

A new compound, Rb3B7O12, has been synthesized using solid state reaction and glass crystallization methods. It is triclinic, space group P-1, a = 6.603(1), b = 6.632(1), c= 30.085(6), Å, α = 91.183(4), β = 91.781(4), γ = 119.293(3)°, V = 1147.5(5) Å3, Z =4. The crystal structure of the compound has been solved by direct methods and refined to R1 = 0.068 (ωR = 0. 142) on the basis of 1840 unique observed reflections (|Fo| > 4σ |Fo|). The structure is based upon a novel [B7O12] layered anion. The layer is parallel to (0 0 1) and is composed of four types of rigid boron-oxygen groups: two [B5O8.5]2- pentaborate groups, [B3O5]- triborate groups and BO4 single tetrahedra. There are six symmetrically independent Rb atoms in the structure, of which four are located in voids within the borate layer and two are between the layers. High-temperature X-ray powder diffraction studies showed that the new compound forms above 620 °C as a result of the solid state reaction Rb2B4O7 + α-RbB3O5 ↔ Rb3B7O12. The compound melts at ∼ 700°C according to the peritectic reaction Rb3B7O12 ↔ βRbB3O5 + liquid. Thermal expansion of the structure of Rb3B7O12 is highly anisotropic (α11 = 34, α22 = 9, α33 = 2 × 10-6°C-1). The thermal expansion is maximal in the direction perpendicular to the plane of the layer (α11 = 34 × 10-6°C-1).

Original languageEnglish
Pages (from-to)985-992
Number of pages8
JournalSolid State Sciences
Volume4
Issue number7
DOIs
Publication statusPublished - 1 Jan 2002

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Solid state reactions
Thermal expansion
Crystal structure
Borates
crystal structure
Boron
synthesis
Crystallization
X ray powder diffraction
Anions
thermal expansion
Negative ions
Oxygen
solid state
Glass
Atoms
Liquids
borates
tetrahedrons
voids

Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

Cite this

Bubnova, R. S. ; Polyakova, I. G. ; Krivovichev, S. V. ; Shakhverdova, I. P. ; Filatov, S. K. ; Krzhizhanovskaya, M. G. ; Burns, P. C. / Synthesis, crystal structure and thermal behavior of Rb3B7O12, a new compound. In: Solid State Sciences. 2002 ; Vol. 4, No. 7. pp. 985-992.
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title = "Synthesis, crystal structure and thermal behavior of Rb3B7O12, a new compound",
abstract = "A new compound, Rb3B7O12, has been synthesized using solid state reaction and glass crystallization methods. It is triclinic, space group P-1, a = 6.603(1), b = 6.632(1), c= 30.085(6), {\AA}, α = 91.183(4), β = 91.781(4), γ = 119.293(3)°, V = 1147.5(5) {\AA}3, Z =4. The crystal structure of the compound has been solved by direct methods and refined to R1 = 0.068 (ωR = 0. 142) on the basis of 1840 unique observed reflections (|Fo| > 4σ |Fo|). The structure is based upon a novel [B7O12] layered anion. The layer is parallel to (0 0 1) and is composed of four types of rigid boron-oxygen groups: two [B5O8.5]2- pentaborate groups, [B3O5]- triborate groups and BO4 single tetrahedra. There are six symmetrically independent Rb atoms in the structure, of which four are located in voids within the borate layer and two are between the layers. High-temperature X-ray powder diffraction studies showed that the new compound forms above 620 °C as a result of the solid state reaction Rb2B4O7 + α-RbB3O5 ↔ Rb3B7O12. The compound melts at ∼ 700°C according to the peritectic reaction Rb3B7O12 ↔ βRbB3O5 + liquid. Thermal expansion of the structure of Rb3B7O12 is highly anisotropic (α11 = 34, α22 = 9, α33 = 2 × 10-6°C-1). The thermal expansion is maximal in the direction perpendicular to the plane of the layer (α11 = 34 × 10-6°C-1).",
author = "Bubnova, {R. S.} and Polyakova, {I. G.} and Krivovichev, {S. V.} and Shakhverdova, {I. P.} and Filatov, {S. K.} and Krzhizhanovskaya, {M. G.} and Burns, {P. C.}",
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Synthesis, crystal structure and thermal behavior of Rb3B7O12, a new compound. / Bubnova, R. S.; Polyakova, I. G.; Krivovichev, S. V.; Shakhverdova, I. P.; Filatov, S. K.; Krzhizhanovskaya, M. G.; Burns, P. C.

In: Solid State Sciences, Vol. 4, No. 7, 01.01.2002, p. 985-992.

Research output

TY - JOUR

T1 - Synthesis, crystal structure and thermal behavior of Rb3B7O12, a new compound

AU - Bubnova, R. S.

AU - Polyakova, I. G.

AU - Krivovichev, S. V.

AU - Shakhverdova, I. P.

AU - Filatov, S. K.

AU - Krzhizhanovskaya, M. G.

AU - Burns, P. C.

PY - 2002/1/1

Y1 - 2002/1/1

N2 - A new compound, Rb3B7O12, has been synthesized using solid state reaction and glass crystallization methods. It is triclinic, space group P-1, a = 6.603(1), b = 6.632(1), c= 30.085(6), Å, α = 91.183(4), β = 91.781(4), γ = 119.293(3)°, V = 1147.5(5) Å3, Z =4. The crystal structure of the compound has been solved by direct methods and refined to R1 = 0.068 (ωR = 0. 142) on the basis of 1840 unique observed reflections (|Fo| > 4σ |Fo|). The structure is based upon a novel [B7O12] layered anion. The layer is parallel to (0 0 1) and is composed of four types of rigid boron-oxygen groups: two [B5O8.5]2- pentaborate groups, [B3O5]- triborate groups and BO4 single tetrahedra. There are six symmetrically independent Rb atoms in the structure, of which four are located in voids within the borate layer and two are between the layers. High-temperature X-ray powder diffraction studies showed that the new compound forms above 620 °C as a result of the solid state reaction Rb2B4O7 + α-RbB3O5 ↔ Rb3B7O12. The compound melts at ∼ 700°C according to the peritectic reaction Rb3B7O12 ↔ βRbB3O5 + liquid. Thermal expansion of the structure of Rb3B7O12 is highly anisotropic (α11 = 34, α22 = 9, α33 = 2 × 10-6°C-1). The thermal expansion is maximal in the direction perpendicular to the plane of the layer (α11 = 34 × 10-6°C-1).

AB - A new compound, Rb3B7O12, has been synthesized using solid state reaction and glass crystallization methods. It is triclinic, space group P-1, a = 6.603(1), b = 6.632(1), c= 30.085(6), Å, α = 91.183(4), β = 91.781(4), γ = 119.293(3)°, V = 1147.5(5) Å3, Z =4. The crystal structure of the compound has been solved by direct methods and refined to R1 = 0.068 (ωR = 0. 142) on the basis of 1840 unique observed reflections (|Fo| > 4σ |Fo|). The structure is based upon a novel [B7O12] layered anion. The layer is parallel to (0 0 1) and is composed of four types of rigid boron-oxygen groups: two [B5O8.5]2- pentaborate groups, [B3O5]- triborate groups and BO4 single tetrahedra. There are six symmetrically independent Rb atoms in the structure, of which four are located in voids within the borate layer and two are between the layers. High-temperature X-ray powder diffraction studies showed that the new compound forms above 620 °C as a result of the solid state reaction Rb2B4O7 + α-RbB3O5 ↔ Rb3B7O12. The compound melts at ∼ 700°C according to the peritectic reaction Rb3B7O12 ↔ βRbB3O5 + liquid. Thermal expansion of the structure of Rb3B7O12 is highly anisotropic (α11 = 34, α22 = 9, α33 = 2 × 10-6°C-1). The thermal expansion is maximal in the direction perpendicular to the plane of the layer (α11 = 34 × 10-6°C-1).

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