Synthesis, crystal structure, and optical properties of a novel pentaborate, K₂NaZnB₅O₁₀

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• 作者：Xuean Chen ; Chunyan Yang ; Xinan Chang ; Hegui Zang ; Weiqiang Xiao
• 关键词：K₂NaZnB₅O₁₀ ; Borate ; Synthesis ; Crystal structure
• 刊名：Journal of Alloys and Compounds
• 出版年：2010
• 出版时间：4 March 2010
• 年：2010
• 卷：492
• 期：1-2
• 页码：543-547
• 全文大小：295 K

文摘

A novel quaternary borate, dipotassium sodium zinc pentaborate, K₂NaZnB₅O₁₀, has been prepared by high-temperature solution reaction at temperature below 780 °C. Single-crystal XRD analyses showed that it crystallizes in the monoclinic C2/c group with a = 7.9244 (16) Å, b = 12.805 (3) Å, c = 18.962 (4) Å, β = 99.39 (3)°, Z = 8. The crystal structure is composed of double ring [B₅O₁₀]⁵⁻ and tetrahedral ZnO₄ groups that are linked to form a two-dimensional [ZnB₅O₁₀]³⁻ layer by sharing O vertices. The layers are stacked along the c-axis, with the interlayer void spaces filled by K⁺ and intralayer open channels occupied by Na⁺ cations to balance charge. The IR spectrum further confirmed the presence of both BO₃ and BO₄ groups, UV–vis diffuse reflectance spectrum showed a band gap of about 3.1 eV. Solid-state fluorescence spectrum was also investigated exhibiting the maximum emission peak at around 387.4 nm. Band structure calculations indicated that the compound is an indirect semiconductor with the calculated band gap close to the observed one.