BaO-Li2O-B2O3三元系中BaB2O4-Li2B2O4和BaB2O4-Li2O截面相平衡关系的研究

本文用X射线和差热分析方法对BaO-Li₂O-B₂O₃三元系中的两个截面:BaB₂O₄-Li₂B₂O₄和BaB₂O₄-Li₂O作了研究。在BaB₂O₄-Li₂B₂O₄赝二元系中发现了一个新的化合物4BaB₂O₄·Li₂B₂O₄。化合物在930±3℃由包晶反应形成,并与Li₂B₂O₄形成共晶反应。共晶温度为797±3℃,共晶点组分为79mol％Li₂B₂O₄。在BaB₂O₄-Li₂O截面中也存在化合物4BaB₂O₄·Li₂B₂O₄,其包晶反应温度从930±3℃随Li₂O含量增加下降到908±3℃。在组分60mol％Li₂O处形成另一个新的化合物2BaB₂O₄·3Li₂O。该化合物在630±3℃也是由包晶反应形成,并与Li₂O和Li₂CO₃分别形成共晶反应,共晶温度分别为400±3℃和612±3℃。在BaB₂O₄-Li₂B₂O₄和BaB₂O₄-Li₂O体系中都没有观察到固溶体。用计算机程序分别对化合物4BaB₂O₄·Li₂B₂O₄和2BaB₂O₄·3Li₂O的X射线粉末衍射图案进行了指标化,其结果:4BaB₂O₄·Li₂B₂O₄的空间群为Pmma,a=13.033?,b=14.630?,c=4.247?,每个单胞包含两个化合式单位;2BaB₂O₄·3Li₂O的空间群为Pmmm,a=4.814?,b=9.897?,c=11.523?,每个单胞也含有两个化合式单位。 关键词：

PHASE EQUILIBRIUM RELATION OF BaB2O4-Li2B2O4 AND BaB2O4-Li2O SECTIONS IN THE TERNARY SYSTEM BaO-Li2O-B2O3

The pseudo-binary systems BaB₂O₄-Li₂B₂O₄ and BaB₂O₄-Li₂O in ternay system BaO-Li₂O-B₂O₃ have been studied by means of X-ray diffraction and thermal -analysis. A new compound 4BaB₂O₄ ·Li₂B₂O₄ which is formed by peritectic reaction at 930 ± 3℃ has been discovered in the BaB₂O₄-Li₂B₂O₄ system. There is a eutectic horizontal from 4BaB₂O₄ ·Li₂B₂O₄ to Li₂B₂O₄ at 797±3℃ with a eutectic point component of 79 mol% Li₂B₂O₄. In BaB₂O₄-Li₂O system, there also exists a compound of 4BaB₂O₄ ·Li₂B₂O₄, formed by peritectic reaction. But its peritectic reaction temperature dropped to 908±3℃ with increasing amount of Li₂O. Another new compound 2BaB₂O₄ ·3Li₂O is formed by peritectic reaction at 630±3℃ and eutectic reaction occur from 2BaB₂O₄ ·3Li₂O to Li₂O at 400±3℃ and from 2BaB₂O₄ ·3Li₂O to Li₂CO₃ at 612±3℃. No solid solution is observed in BaB₂O₄-Li₂B₂O₄ and BaB₂O₄-Li₂O systems.The X-ray powder diffraction pattens of 4BaB₂O₄ ·Li₂B₂O₄ and 2BaB₂O₄ ·3Li₂O have been indexed by computed programme. It is shown that the space group of 4BaB₂O₄·Li₂B₂O₄ is Pmma with lattice parameters α = 13.033?, b=14.630?, c = 4.247?. There are two formula units per unit cell. The space group of 2BaB₂O₄ ·3Li₂O is Pmmm. Lattice parameters are α = 4.814?, b = 9.897?, c=11.523?. There are two formula units per unit cell.
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