共查询到15条相似文献,搜索用时 187 毫秒
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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。
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本文用差热分析和X射线衍射等方法研究了BaO-Na2O-B2O3三元系的两个截面:BaB2O4-Na2B2O4和BaB2O4-Na2O赝二元系的相平衡关系。BaB2O4-Na2B2O4属共晶体系,其共晶温度为826±3℃。在BaB2O4-Na2O体系中发现一个新化合物BaB2O4·Na2O,该化合物在846±3℃同成分熔化。BaB2O4·Na2O对BaB2O4和Na2O均为共晶体系,其共晶温度分别为755±3℃和573±3℃。并根据所得的结果,分别以15mol%Na2O和13mol%Na2B2O4为助熔剂,用提拉法培养出2×4×6mm3和2×4×8mm3的低温相BaB2O4单晶体。
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采用高温原位拉曼光谱技术,研究了Li2B4O7从常温至1 373 K温度范围内的拉曼光谱。在升温过程中,晶体的拉曼光谱出现展宽和红移现象,且强度降低。晶体熔化时,由2个[BO4]和2个[BO3]组成的[B4O9]环状结构转变成(B3O6)3- 六元环和[BO3]结构,[BO4]结构减少直至消失。基于密度泛函理论,计算了Li2B4O7晶体的拉曼光谱,对其振动模式进行了分析归属。利用量子化学从头计算法计算了由[B3O6-BO3]为基础相互连接形成的x(Li2B4O7)(x=2, 3, …, 9)的环状团簇模型的拉曼光谱,对Li2B4O7熔体的结构进行了模拟分析。计算结果表明Li2B4O7熔体的阴离子基元为三个(B3O6-BO3)组成的大三元环超级结构。 相似文献
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作者用水热法对TeO2-K3PO4-H2O体系作了初步的合成与结晶尝试。在给定的条件和组成范围内除了能形成TeO2晶体外,还能生成一种点阵参数为a=b=10.734?,c=21.041?,α=β=90°,γ=120°的三方晶系的化合物γ,其分子式为K2Te4O9·3H2O。结晶区的产物主要取决于原料的k=TeO2/K3PO4(克分子比:当k≤1.9时,仅生成γ晶体;k≥2.22时,单独生成TeO2晶体;而当1.92晶体出现,本文还给出了γ晶相的DTA曲线和X射线粉末衍射谱线的相对强度与相应面间距的详细数据。
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本文报道了非晶态离子导体Li2B2O4的7Li核磁共振研究。测量了7Li核磁共振谱与温度的关系。实验中发现,Li2B2O4的晶态、非晶态和部分晶化样品的7Li核磁共振谱有很大的不同,且在部分晶化样品的7Li核磁共振谱上有附加的小峰,它与LiCl(Al2O3)的7Li核磁共振谱上附加的小峰相类似。我们也对非晶态离子导体B2O3-0.7Li2O-0.7LiCl进行了7Li核磁共振研究,其结果与上面的类似。研究结果表明,它们都起因于非晶母体与微晶的界面效应。
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采用高温固相法合成Sr3B2O6:Eu3+,Li+红色荧光粉,考察了激活剂Eu3+和电荷补偿剂Li+浓度对Sr3B2O6:Eu3+,Li+荧光粉发光性能的影响。结果表明:适量掺杂Eu3+、Li+离子并不改变Sr3B2O6的结构。当Eu3+掺杂量为4%、Li+的掺杂量为8%时,在900 ℃下灼烧2 h可以得到发光性能最佳的Sr2.9B2O6:0.04Eu3+,0.08Li+红色荧光粉。以394 nm的近紫外光激发时,Sr3B2O6:Eu3+,Li+荧光粉发射出红光,对应于Eu3+的4f-4f 跃迁,其中以614 nm附近的5D0→7F2跃迁发光最强,是一种有潜力用于白光LED的红色荧光粉。 相似文献
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The subsolidus phase relations of a ZnO-V 2 O 5-K 2 O system are investigated by X-ray powder diffraction.There is 1 ternary compound,11 binary compounds and 14 three-phase regions in this system.The phase diagrams of V 2 O 5 K 2 O with the K 2 O content ranging from 0 to 71 mol% and pseudo-binary system of ZnO-K 2 ZnV 2 O 7 are also studied by X-ray powder diffraction and differential thermal analysis methods. 相似文献
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R.Z. Mehdiyeva Mir Hasan Yu. Seyidov I.B. Baykulov 《Journal of Physics and Chemistry of Solids》2006,67(12):2623-2627
Boundaries of morphotropic phase transitions region in the system of solid solutions K2Pb4Nb10O30-Na2Pb4Nb10O30-K6W4Nb6O30 with the structure of the tetragonal tungsten bronze have been specified. Presence of the second morphotropic phase transition, perpendicular to the first one has been revealed. The temperature dependences of the structural parameters of some compounds have been investigated. The compounds with high values of Curie temperatures and working temperatures have been obtained. 相似文献
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The heat capacity of LiClO4 · 3H2O was measured from 17 to 343 K, in order to determine the relationship between its phase diagram and the phase diagrams of divalent metal perchlorate hexahydrates The heat capacity curve of pure LiClO4 · 3H2O was found to be smooth, indicating an absence of polymorphism, although a small amount of excess perchloric acid in one sample gave rise to a eutectic point at 232 8 ± 0 3 K The absence of transitions in LiClO4 · 3H2O is discussed in terms of its known structure, and some conclusions are drawn concerning the differences in H-bonding in this salt and in divalent metal perchlorate hexahydrates. 相似文献
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The dielectric, optical and non-linear optical properties of Ba6Ti2Nb8O30 single crystals were examined from room temperature up to the Curie temperature of 245°C. The spontaneous polarization at room temperature was estimated as 0·22±0·01 C/m2. The linear electrooptic constants were measured as r33T=(1·17±0·02)×10?10 and r13T=(0·42±0·01)×10?10 m/V. The non-linear optical coefficients were d33=(15·1±2·0)×10?12 and d31=(11·0±2·0)×10?12 m/V, which are comparable to those of Ba4Na2Nb10O30. Temperature dependences of δ33 and δ31 (Miller's δ) were found to be proportional to that of Ps. 相似文献