Syntheses and crystal structures of two pentaborates, Na 3CaB 5O 10 and Na 3MgB 5O 10

• Published in: Solid state sciences Vol. 9; no. 8; pp. 678 - 685
• Main Authors: Chen, Xuean, Li, Ming, Zuo, Jianlong, Chang, Xinan, Zang, Hegui, Xiao, Weiqiang
• Format: Journal Article
• Language: English
• Published: Elsevier Masson SAS 2007
• Subjects: Borate; Crystal structure; Na 3CaB 5O 10; Na 3MgB 5O 10; Synthesis; Na 3MgB 5O 10; Synthesis; Na 3CaB 5O 10; Borate; Crystal structure
• ISSN: 1293-2558; 1873-3085
• DOI: 10.1016/j.solidstatesciences.2007.05.013

Two ternary borates, Na 3CaB 5O 10 and Na 3MgB 5O 10, have been prepared by solid-state reactions at temperature below 750 °C. Single-crystal X-ray structural analyses showed that Na 3CaB 5O 10 crystallizes in the triclinic space group P 1 ¯ with a = 7.4403(6) Å, b = 9.7530(10) Å, c = 12.9289(9) Å, α = 90.972(7)°, β = 90.073(7)°, γ = 109.656(6)°, Z = 4 and Na 3MgB 5O 10 in the orthorhombic group Pbca with a = 7.838(1) Å, b = 12.288(1) Å, c = 18.180(2) Å, Z = 8. Na 3CaB 5O 10 has a superstructure, with the cell volume being two times of that reported previously. The crystal structure consists of discrete [B 5O 10] 5− anions separated by six-coordinated Ca 2+ as well as five-, six- and seven-coordinated Na + cations. Na 3MgB 5O 10 contains [B 5O 10] 5− groups that are bridged by MgO 4 tetrahedra through common O atoms to form 2D [ MgB 5 O 10 ] 3 − ∞ 2 layers, with Na + cations situated between and within the layers. The IR spectra further confirmed the presence of BO 3 and BO 4 groups in both compounds. [Display omitted] Na 3CaB 5O 10 has a superstructure, with the cell volume being two times of that reported previously. The crystal structure consists of discrete [B 5O 10] 5− anions separated by six-coordinated Ca 2+ as well as five-, six- and seven-coordinated Na + cations. Na 3MgB 5O 10 contains [B 5O 10] 5− groups that are bridged by MgO 4 tetrahedra through common O atoms to form 2D [ MgB 5 O 10 ] 3 − ∞ 2 layers, with Na + cations situated between and within the layers.