Crystal Structure of Lithium Yttrium Borate LiY_6O_5(BO_3)_3

Single crystals of LiY6O5（BO3）3 were obtained by the flux method and its structure was determined by a four-circle automatic diffractometer with a MoKα radiation. It crystallizes in monoclinic, space group P21/n with a = 8.330（3）, b = 15.444（4）, c = 8.780（3）°A,β = 91.85（3）°, V = 1129.0（6）°A^3, Z = 4, Mr= 796.83, F（000） = 1456, μ = 30.567 mm^-1, Dc= 4.688 g/cm^3, the final R = 0.0722 and wR = 0.1304. It exhibits a three-dimensional fiamework of yttrium-oxygen polyhedra interconnected by common edges and corners. B and Li atoms are located in the planes and cavities formed by oxygen atoms, respectively.

Effect of Y_2O_3 on the crystallization kinetics of TiO_2 nucleated LAS glass for the production of nanocrystalline transparent glass ceramics

Crystallization kinetics of metastable B-quartz solid solution as a desirable phase for the production of trans- parent lithium aluminosilicate （LAS） glass ceramics was investigated in the presence of Y203. Accordingly, differential thermal analysis scans were performed thoroughly to study the mechanism of crystallization kinetics. The aim of this investigation is to discover the complicated mechanism of crystallization process in the presence of co-additives and ac- cordingly find a way for increasing the transparency of glass ceramics. It is shown that the bulk （3D） growth is intensively increased by the enhancement of Y203. Then again, reducing nucleation and increasing growth mechanisms were recog- nized for the LAS system in the presence of Y2O3. Results of the investigation illustrate that when co-additives are added to glasses, it is necessary to nucleate the optical component separately before the growth process.

Synchrotron Radiation Topographic Study on the Dislocations in Lithium Tetraborate Crystal

The dislocations in lithium tetraborate crystal have been investigated by means of synchrotron radiation white beam topography in BSRL(Beijing Synchrotron Radiation Laboratory).The Burgers'vectors of these dislocations are determined by their vanishing conditions.Both screw and edge dislocations exist in the specimen.

Synthesis, Structure and Thermodynamic Property of a New Lithium Borate： Li4[B8O13（OH）2]·3H2O

A new hydrated lithium borate, Li4[B8O13（OH）2]·3H2O, has been hydrothermally synthesized and characterized by single crystal X-ray diffraction, FT-IR spectroscopy, simultaneous TGA-DTA and chemical analysis. It crystal- lizes in the triclinic, space group P]-, a=8.4578（5） A, b=8.7877（5） A, c= 10.8058（7） A, a=87.740（3）°, β= 71.819（3）°, γ=61.569（3）°, Z=2, V=665.26（7） A3, Dc=2.043 g/cm3. Its crystal structure features polyborate ani- onic layers with the larger odd 13-membered boron rings constructed by [B8O13（OH）2]4- FBBs. Through designing the thermochemical cycle, the standard molar enthalpy of formation of this borate was determined to be -（7953.8 ± 6.6） kJ·mol-1 by using a heat conduction microcalorimeter.

Chemistry of borate in salt lake brine (XXXIV) ——Phase diagram of thermodynamic nonequilibrium state of MgO-B_2O_3-18%MgCl_2-H_2O system at 20℃

The crystallization processes of hydrated Mg-borates, boric, magnesium hydroxide and Mg-oxychloride from MgO-B2O3-18%MgCl2-H2O supersaturated solution at 20℃ have been studied by kinetic method. The crystallization solid phases were characterized by X-ray powder diffraction, IR spectra, thermal analysis and chemical analysis. The liquid-solid phase diagram of ther-modynamic nonequilibrium state has been given. In this phase diagram, there exist eight crystallization fields, boric acid(H3BO3), trigomagneborite(MgO·3B2O3·7.5H2O, MgO·3B2O3·7H2O), hungchaoite(MgO·2B2O3·9H2O), inderite(2MgO·3B2O3·15H2O), chloropinnoite(2MgO·2B2O3·MgCI2·14H2O), magnesium hydroxide(Mg(OH)2) and magnesium oxychloride (5Mg(OH)2·MgCI2·8H2O).

Li_2O·2B_2O_3-H_2O过饱和溶液20℃结晶动力学研究

The supersaturated solution of Li2O·2B2O3-H2O containing 26.8% Li2O·2B2O3 were prepared and kept at 20℃ The crystallization processes of Li-borates from the solution has been studied with the kinetic method.Two Li-borates, Li2B4O7·3H2O and LiBO2·8H2O crystallized out from Li2O·2B2O3-H2O solution. With the aid of simplex method and digital integration as well as RungeKutta digital solution of differential equation system, the experimental data were fitted and the crystailization kinetic equation of the first solid phase was obtained. The crystallization reaction processes of the two Li-borates were also discussed.

Li_2O·nB_2O_3-20%LiCl-H_2O体系20℃过饱和溶液结晶动力学研究

用动力学方法对Ｌｉ２Ｏ·ｎＢ２Ｏ３－２０％ＬｉＣｌ－Ｈ２Ｏ体系（ｎ＝１，２，３）２０℃过饱和溶液结晶过程进行研究，结果表明每一种溶液只析出一种固相，Ｌｉ２Ｏ∶Ｂ２Ｏ３＝１∶１、１∶２和１∶３的氯化锂溶液分别结晶出Ｌｉ２Ｏ·Ｂ２Ｏ３·４Ｈ２Ｏ，Ｌｉ２Ｏ·２Ｂ２Ｏ３·３Ｈ２Ｏ和Ｌｉ２Ｏ·５Ｂ２Ｏ３·１０Ｈ２Ｏ，拟合并给出结晶动力学方程，同时对这三种固相的结晶反应机理进行了探讨。

硼酸盐化学(XXXI)MgO·2B_2O_3-18%MgSO_4-H_2O过饱和溶液结晶动力学研究

针对我国盐湖硼资源的特点 ,模拟合成 Mg O· 2 B2 O3-1 8% Mg SO4-H2 O过饱和溶液 ,分别在 0℃和2 0℃恒温静止跟踪结晶动力学过程 .拟合并给出结晶动力学方程 ,同时对结晶机制进行了探讨 .析出固相采用 X射线粉末衍射。

含氟和磷Li_2O-Al_2O_3-SiO_2系玻璃的析晶机理

以Li20-Al2O3-SiO2(LAS)三元系微晶玻璃为研究对象,采用差热、X射线衍射和扫描电镜等研究了含磷和含氟磷LAS玻璃的析晶动力学和晶化过程,分析了氟、磷化合物对LAS玻璃晶化过程的影响机制。结果表明:氟、磷化合物对LAS玻璃的析晶过程有不同的作用机制。磷化物能显著提高LAS玻璃的析晶温度、活化能和有效频率因子,并抑制了晶体生长,但存在α-锂辉石向β-锂辉石转变;氟化合物降低了析晶温度和活化能, 因而不存在晶相转变过程,但晶体生长速度加快;氟、磷化合物同存可以调整了玻璃的析晶动力学参数,改善玻璃的析晶能力,细化晶粒,能获得所需晶相及显微结构。

盐卤硼酸盐化学 ⅩⅪ.MgO-B_2O_3-MgCl_2(8％)-H_2O体系20℃热力学非平衡态液固相关系

用动力学方法对标题体系过饱和溶液的结晶过程进行了研究,MgO:B_2O_3(mol比)为1:2、1:5和1:7时的结晶固相分别为多水硼镁石、三方硼镁石和硼酸,与MgCl_2浓度为28％时的结果对比表明,MgCl_2浓度越低,该四元体系溶液过饱和度越小,因此,液固相关系也变得比较简单,在本文研究的浓度条件下出现了多水硼镁石固相,而MgCl_2浓度为28％时却没有,拟合出结晶动力学方程,对结晶机制进行了探讨。

硼酸盐化学XXXⅢ MgO·4B_2O_3-18%MgSO_4-H_2O过饱和溶液结晶动力学研究

针对我国盐湖硼资源的特点 ,模拟合成MgO·4B2 O3 18%MgSO4 H2 O过饱和溶液 ,在 2 0℃恒温静置 ,跟踪结晶动力学过程。析出固相采用X ray粉末衍射、红外光谱和热分析进行物相鉴定。拟合并给出结晶动力学方程 。

MgO·3B_2O_3-18%MgSO_4-H_2O过饱和溶液结晶动力学

针对我国盐湖硼资源的特点模拟合成MgO·3B2O318%MgSO4H2O过饱和溶液在20℃恒温静置跟踪结晶动力学过程.析出固相采用X射线粉末衍射、红外光谱和热分析进行物相鉴定.拟合并给出结晶动力学方程同时对结晶机制进行了探讨.结果表明该结晶过程分两个阶段第一阶段析出三方硼镁石(MgO·3B2O3·7.5H2O)第二阶段结晶析出章氏硼镁石(MgO·2B2O3·9H2O).

含有羧基配体的蝎型钒氧配合物的合成、结构及其热分解动力学

设计合成了两种新型的以聚吡唑硼酸盐、氨基酸为配体的钒氧配合物VO[phCH_2CH(NH_2)COO][HB(pz)_3] (1)和VO(3,5-Me_2pz)[HB(3,5-Me_2pz)_3](CH_3COO)(2).通过元素分析、红外光谱对配合物进行了表征,并利用单晶X射线衍射技术解析了它们的结构.非等温热分解动力学研究表明,配合物1和2的热分解反应都是分两步进行的.通过计算,配合物1热分解的第一步反应的可能机理为成核与生长(n=1/4);第二步反应的可能机理为化学反应.其非等温动力学方程分别为,dα/dT=(A/β)e^(-ElRY)(1/4)(1-α)[-ln(1-α)]^(-3)和dα/dT=(A/β)e^(-ElRT)(1-α)~2.分解反应的表观活化能分别是223.52和331.94 kJ·mol^(-1);指前因子ln(A/s^(-1))分别是49.67和57.50.配合物2热分解的第一步反应的可能机理为化学反应;第二步反应的可能机理为成核与生长(n=1/2).其非等温动力学方程分别为,dα/dT= (A/β)e^(-ElRT)(1-α)~2,和dα/dT=(A/β)e-^(-RlRT)(1/2)(1-α)[-ln(1-a)]^(-1).分解反应的表观活化能分别是300.56和444.72KJ·mol^(-1);指前因子ln(A/s^(-1))分别是75.53和92.50.

强酸性离子交换树脂催化下硼酸三甲酯合成反应的动力学研究

以自制的负载氯化锂强酸性离子交换树脂为催化剂,采用间歇法研究了硼酸和甲醇酯化可逆反应的动力学。对可逆反应动力学方程进行线性化处理,确定了积分法拟合可逆反应动力学参数的方法,并以幂函数形式表达了指前因子与催化剂浓度的关系。测定了不同反应温度和催化剂用量下硼酸三甲酯得率随时间的变化,对动力学数据采用线性拟合,得到硼酸三甲酯非均相催化合成反应动力学方程式为:rA=499.4 C0.38cat exp(-31920/RT)CACB-397.7C0.08 cat exp(-29780/RT)CRCS。

盐卤硼酸盐化学(非汉字字符)——MgO·nB_2O_3-18%MgCl_2-H_2O过饱和溶液20℃结晶动力学

用结晶动力学方法对不同摩尔比的 Mg O/B2 O3在摩尔分数为 1 8% Mg Cl2 -H2 O中的过饱和溶液在2 0℃的结晶动力学过程进行了研究 .n(Mg O) /n(B2 O3) =1 /1和 1 /1 .5时分别结晶析出 2 Mg O· 2 B2 O3·Mg Cl2 · 1 4H2 O和 2 Mg O· 3 B2 O3· 1 5 H2 O(多水硼镁石 ) .n(Mg O) /n(B2 O3) =1 /2时依次结晶析出 Mg O·3 B2 O3· 7.5 H2 O,Mg O· 2 B2 O3· 9H2 O和 2 Mg O· 3 B2 O3· 1 5 H2 O(多水硼镁石 ) 3种固相 .n(Mg O) /n(B2 O3)=1 /3时结晶析出不同结晶水的六硼酸镁 Mg O· 3 B2 O3· 7H2 O和 Mg O· 3 B2 O3· 7.5 H2 O.析出固相采用X射线粉末衍射、红外光谱和热分析进行物相鉴定 .拟合并给出结晶动力学方程 。

含Co、Ni、Fe锂铝硅玻璃的析晶机制

以Li2O-Al2O3-SiO2(锂铝硅)微晶玻璃为研究对象,采用DTA、XRD、IR和SEM等测试技术研究含Fe2O3、Co2O3、Ni2O3锂铝硅玻璃的析晶动力学和晶化过程,分析着色剂成分Co2O3、Ni2O3对锂铝硅玻璃晶化过程及结构的影响机制。结果表明:着色剂成分不仅决定锂铝硅微晶玻璃的着色度,而且还影响锂铝硅玻璃的析晶过程和显微结构;着色剂的加入可提高锂铝硅玻璃的析晶温度,但降低析晶动力学参数,且高Co2O3含量的降幅大于高Ni2O3含量的。着色剂对锂铝硅玻璃析晶能力的影响主要与着色离子的离子半径、电场强度及对断裂硅氧四面体联结能力有关。

大柴旦富硼浓缩盐卤中硼酸镁盐稀释结晶动力学（英文）

采用动力学法研究了富硼浓缩盐卤稀释过程硼酸镁盐的结晶动力学,重点探讨了温度、稀释比和硼浓度对结晶过程的影响。利用单纯形优化法配合Runge-Kutta微分方程组数值解法对实验数据进行拟合,给出了结晶动力学方程和结晶速率。结果表明,低温、高硼浓度和中间稀释比有利于硼酸镁盐的结晶析出,最优条件下析硼率(以B2O3计)高达88%;结晶速率随硼浓度的增加和温度的降低快速增大;反应级数表明稀释结晶过程硼酸镁盐结晶主要受多核表面反应控制,同时提出了结晶相转化机理。

PEO及其与LiClO_4复合体系的非等温结晶动力学

用示差扫描量热法(DSC)研究了聚氧化乙烯(PEO)及其与高氯酸锂(LiClO4)复合体系的非等温结晶过程。依次用Jeziorny方法、一种结合Avrami和Ozawa方程的方法分析了以上体系中PEO的非等温结晶过程,得到了PEO在不同体系中非等温结晶时的动力学参数。动力学参数表明LiClO4晶粒缩短了PEO的结晶时间,使复合体系中PEO的结晶速率大于PEO体系的,但PEO体系形成更完善晶体;为使二者达到相同的相对结晶度,PEO体系需要更大的冷却速率。结果表明,LiClO4晶粒能够有效地将PEO的结晶相转变成非晶相,即LiClO4可有效地抑制PEO的结晶过程。

盐卤硼酸盐化学

ＭｇＯ，２Ｂ２Ｏ３－１８％ＭｇＣｌ２－Ｈ２Ｏ过饱和溶液于２０℃恒温静置，其结晶过程分为两个阶段，第一阶段结晶析出三方硼镁石（ＭｇＯ，３Ｂ２Ｏ３，７．５Ｈ２Ｏ）。第二阶段析出章氏硼镁（ＭｇＯ．２Ｂ２Ｏ３．９Ｈ２Ｏ），未得到多水硼镁石和库水硼镁石，探讨了两种析出固相的结晶机理并拟事出结晶动力学方程，结果表明，两个种固相结晶机理场为多核表面反应控制生长。

碳酸锂结晶动力学与机理研究

本文对碳酸锂自碳酸氢锂溶液中结晶的过程动力学进行了研究。研究了碳酸锂的结晶速率,包括晶核生长速率、晶粒长大速率与温度和质量浓度之间的关系。实验表明:晶核生长和晶粒长大速率可用二级反应速率方程来描述,并计算出了不同温度、质量浓度下,碳酸锂的结晶速率常数和表观活化能;诱导期与过饱和度之间的关系符合经典的相生成的热力学理论,并以此为依据推导出了晶体表面自由能和临界晶核半径等临界状态的热力学参数。晶体的生长机制表明,Li2CO3自LiHCO3溶液中的结晶主要受扩散机制控制。