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• 作者：N. V. Kuratieva ; M. B脿nki ; A. A. Tsirlin ; J. Eckert ; H. Ehrenberg ; D. Mikhailova
• 刊名：Inorganic Chemistry
• 出版年：2013
• 出版时间：December 16, 2013
• 年：2013
• 卷：52
• 期：24
• 页码：13974-13983
• 全文大小：721K
• 年卷期：v.52,no.24(December 16, 2013)
• ISSN：1520-510X

文摘

Crystal structures of three new lithium copper borates, Li₃CuB₃O₇, Li₈Cu₇B₁₄O₃₂, and Li₂Cu₉B₁₂O₂₈, and a new Li₆CuB₄O₁₀ polymorph were solved by single-crystal X-ray diffraction. In all of the structures, the boron cations form BO₃ triangles, which are connected with each other and with copper polyhedra only via corners in Li₆CuB₄O₁₀ and Li₃CuB₃O₇ and via both corners and edges in Li₈Cu₇B₁₄O₃₂ and Li₂Cu₉B₁₂O₂₈. The Li₃CuB₃O₇ and Li₈Cu₇B₁₄O₃₂ compounds were synthesized as pure samples with only trace amounts of impurities; hence, their magnetic properties could be investigated and analyzed in terms of underlying magnetic couplings. Other compositions always represented multiphase mixtures. Li₃CuB₃O₇ features infinite Cu,O chains formed by Cu₂O₆ units consisting of edge-shared CuO₄ squares. Together with two apical oxygen atoms with long interatomic Cu鈥揙 distances of 2.7鈥?.8 脜, the Cu₂O₆ units form chains extended along the a axis. These pseudochains are responsible for strong anisotropic thermal expansion behavior. The temperature dependence of the magnetization between 4 and 380 K for Li₃CuB₃O₇ could be fit well by a spin-dimer model. The magnetic susceptibility of Li₈Cu₇B₁₄O₃₂ showed a more complex temperature dependence, with two different Curie鈥揥eiss regimes in the temperature range of 2鈥?80 K.