Mg<Subscript>2</Subscript>(OH)<Subscript>2</Subscript>CO<Subscript>3</Subscript>·3H<Subscript>2</Subscript>O whiskers growth mechanism

From the perspective of growth units, the growth mechanism of Mg₂(OH)₂CO₃·3H₂O whisker is investigated in this paper. Results show that the growth morphology of Mg₂(OH)₂CO₃·3H₂O whisker is consistent with the model of anion coordination polyhedron growth units. The growth solution Raman shift of Mg₂(OH)₂CO₃·3H₂O was monitored using Raman spectroscopy. The growth units are [Mg-(OH)₄]^2- and H₂CO₃. The growth process of Mg₂(OH)₂CO₃·3H₂O whisker is as follows: growth unit [Mg-(OH)₄]^2- first incorporates into the larger dimension [Mg-(OH)₄] _n ^2- , then the [Mg-(OH)₄] _n ^2- combines with H₂CO₃ into a linear skeleton Mg₂(OH)₂CO₃ in the same line. Mg₂(OH)₂CO₃ combines with H₂O by hydrogen bonds and ultimately transforms into Mg₂(OH)₂CO₃·3H₂O whisker. Magnesium carbonate whiskers have a layered structure, each of which is made of magnesium, carbon, oxygen, with H₂O in between each layer. When skeletons are superimposed within the same plane as a parallelepiped one, they grow into solid cuboid-shaped whiskers. When the parallelepiped skeletons planes combine with each other through the cascading links, they grow into hollow cylindrical whiskers.     

The Mechanism of the Formation and Transformation of Ettringite

The formation and transformation of ettringite were studied by measuring the ion concentration in liquid phase and analyzing the composition in solid phase. The effects of C3A, gypsum lime and C-S-H gel on ettringite formation and transformation were also investigated. The experimental results shuw, that, when gypsum was presented in solid phase, the composition of liquid phase was in favor of ettringite formation. Ettringite formation consisted of three reactions including the formation of [ Al （OH）6 ]^3- octahedral, formation of Ca-Al polyhedra prism in which Ca and Al polyhedra arranged alternately, as well as entrance of SO4^2- into the channel of polyhedra. [ Al （OH）6 ]^3- formation, which was the slowest reaction, controlled ettringite formation. The concentration of AlO2^- was a main factor that influenced ettringite formation. After gypsum in solid phase was consumed, [ SO4^2- ] decreased quickly and [ AlO2^- ] increased, and it was possible that ettringite transformed into hydrated monsulfate calcium aluminate （ be called M in short） in thermodymanics. The rate of transformation was controlled by diffusion of AlO2^- .     

Simultaneous Effect of pH and Acidgroup on Chromium(Ⅵ)Species in Solution

Making a calculation of the effect of the acidderived anion Cl~-,F~- andHSO_4~-,the relative concentrations of five chromium(V1)species present inaqueous soluti on over the pH raoge 0-8 have been calculated,The results showthat acid-derived anions effect a large reduction in the percentage of H_2CrO_4present at low pH's,bringing it to essentially zeno in the case of F~-,theeffect was never considered before.therefore,it is necessary to make furtherrefinements for the calculation of these problems.     

反应温度和反应时间对三水碳酸镁晶须长径比的影响

为了扩大其作为增强补韧剂和阻燃剂的应用,以氯化镁和碳酸氢铵为原料,通过水热法成功合成了不同长径比的三水碳酸镁晶须. 采用X射线衍射、扫描电子显微镜、透射电子显微镜对所得三水碳酸镁晶须的物相和形貌进行分析. 结果表明:当反应时间为5 h时,随着反应温度（50 ℃~80 ℃）的升高,三水碳酸镁晶须长径比减小. 当温度为50 ℃,反应时间在4 h~5 h内时,晶须处于生长阶段,长径比增大;反应时间延长至7 h,由于发生相转变,晶须开始溶解,导致长径比减小. 通过对晶须尖端的分析,证实晶须属于台阶生长机制.     

以TiB2作为硼源制备硼酸铝晶须的合成机理

以TiB2作为硼源制备了硼酸铝晶须，对反应过程中的相转变以及晶须的生长机理进行了分析。结果表明，（NH4）2SO4分解释放活性[O]使TiB2氧化生成B2O3，为硼酸铝晶须的生长提供硼源。砧／B的配比对晶须的形态影响较大。在晶须的生长过程中，过量的液态B2O3作为一个载体可以把Al2O3输运到晶核的附近促进晶须的生长。     

硫酸钙晶须的制备及其在聚丙烯树脂中的应用

论述晶须及硫酸钙晶须的特性.以生石膏为原料,采用水热合成法,研究反应温度、反应时间、料浆浓度、Ca/Mg摩尔比等工艺条件对晶须形态的影响.在反应温度150℃、反应时间5 h、料浆质量分数为4%、n（Ca）/n（Mg）为10条件下,制备出了直径为1-5μm、长度为30-100μm的硫酸钙晶须.X-射线衍射分析表明,产品为无水硫酸钙晶须;同时对硫酸钙晶须的应用进行初步研究.根据实验结果,当晶须的填充量为5%时,聚丙烯的力学性能最佳,拉伸强度为39.18 MPa,断裂伸长率为125.41%.     

双核镁配合物[Mg2（μ-OH2）2（H2O）4（OPPh3）4]Br4的合成与分子结构

溴化镁与三苯基膦氧在乙醇溶液中反应生成新的可用于MgO粒子制备前驱体的双核镁化合物[Mg2（μ-OH2）2（H2O）4-（OPPh3）4]Br4.单晶X射线衍射分析表明：该双核镁配合物结构由一个均氧配位的双核镁阳离子基团与4个溴离子所组成,两对溴离子参与形成分子间的O-H…Br氢键,并组成了由[Mg2（μ-O）2（O）4]核所共享的高度扭曲立方烷构型,其中每个镁原子与2个μ-OH2、2个OH2和2个OPPh3中的6个氧原子组成了八面体的空间结构,Mg-O（PPh3）、Mg-O（OH2）和Mg-μ-O（OH2）的平均键长分别为198.3（2）,206.1（2）和226.0（2） pm.     

OH型强碱阴树脂有机物清除器

Cl型、SO_4强碱阴树脂有机物清除器去除有机物时,带来降低阴床和阳床出力、严重影响除盐水水质等问题。试验研究表明,采用OH型强碱阴树脂有机物清除器可解决上述存在的问题,具有较好的实用价值。     

碱性环境下二维纳米AlOOH聚集体形态及“生长基元”运动

通过构建酸性水热环境条件下的AlOOH"生长基元"模型,揭示了酸性环境下晶体一维成长的机理。构建碱性水热条件下的"生长基元"模型,从原子层面揭示AlOOH发生二维片状定向生长的机理。重点分析pH=10,13条件下的纳米AlOOH的"聚集体"特点以及生长基元运动方式。用实验样品直接验证所构建模型的合理性。并通过X衍射结果佐证不同pH条件下的聚集体形态的存在,并验证了纳米AlOOH的Al 3+双聚体[Al3(OH)4(OH2)9]5+﹑[Al3(OH)5(OH2)8]4+﹑[Al3(OH)6(OH2)7]3+的存在。     

Mechanical Properties and Microstructure of CaSO_4 Whisker Reinforced Cement Mortar

Calcium sulfate whisker(CaSO_4 whiskers), a new type of microfiber material, was used in cement matrix to increase the strength of the cement based composites. Effect of CaSO_4 whiskers on the mechanical properties of the resulting cement mortar was also studied. The results showed that the flexural strength and compressive strength of the mortar specimen was improved as high as 28.3% and 8.5% by incorporating 5 wt% CaSO_4 whiskers. Also, the chemical composition and structural transformation of the hardened cement matrix with CaSO_4 whiskers were identified by X-ray diffraction(XRD) and scanning electron microscope(SEM). Conclusion can be drawn that CaSO_4 whiskers can effectively retard the formation and restrict the coalescence of micro-crack expansion. The interaction mechanism of CaSO_4 whisker on the reinforcement is mainly on three aspects: whisker pullout, crack deflection, and crack bridging. Mercury intrusion porosimetry(MIP) tests have confirmed that for 28 d cement mortar, the harmless pores increased from 9.33% to 10.62%, and the harmful pores decreased from 2.08% to 1.90%. Therefore, the whisker can optimize the pore size distribution of the resulting cement mortar.     

四氯化铁合四丁基胺化合物的合成和晶体结构表征

合成了标题化合物[n-Bu4N]+[FeCl4]-,并通过元素分析和X-射线单晶衍射对其结构进行了表征。晶体属于正交晶系,空间群Pnna,晶胞参数为:a=1.851 0(4)nm,b=1.155 3(2)nm,c=1.144 2(2)nm,V=2.446 8(8)nm3,Z=8,Dc=1.195 g.cm-3,F(000)=932,μ=1.051 mm-1。化合物由一个独立的[FeCl4]-阴离子和一个独立的[n-Bu4N]+阳离子组成。在[FeCl4]-阴离子中,中心的铁原子与4个氯离子配位,形成一个扭曲的四面体构型,Fe Cl键键长分别为0.212 2(14)nm和0.218 07(17)nm。在[n-Bu4N]+阳离子中,氮原子同样处于一个扭曲的四面体构型。在固体状态下,独立的[FeCl4]-阴离子和[n-Bu4N]+阳离子通过弱的C H…Cl分子间相互作用力使晶体结构得以稳定。     

Preparation,Characterization, and Formation Mechanism of Calcium Sulfate Hemihydrate Whiskers

Calcium sulfate hemihydrate whiskers were synthesized successfully via one-step hydrothermal crystallization method using phosphogypsum at 130 °C for 240 min with an initial slurry mass fraction of 2.5 wt%. The phase compositions, microstructures, thermal properties and molecular structures of asprepared samples were analyzed by XRD, ESEM, EDS, TG-DTA, and FT-IR. The influence of raw materials' ball-milling time on the morphologies of whiskers was investigated. The effects of impurities on crystallization morphologies and length to diameter ratio(L/D) of calcium sulfate hemihydrate whiskers were studied. The results indicated that the calcium sulfate dihydrate crystalline could be translated directly into fibrous calcium sulfate hemihydrate whiskers. It was beneficial to form fine fiber structure when the ball-milling time of the raw material was 15 min. Aspect ratio of calcium sulfate hemihydrate whiskers decreased with increasing content of impurities. Moreover, the relative growth mechanism of whisker crystals via one-step hydrothermal crystallization method was discussed in detail.     

微波干燥硫酸钙晶须的研究

硫酸钙晶须是一种正在被广泛应用的添加组分,发挥着日益突出的作用。干燥是制备硫酸钙晶须工艺中的重要步骤。为了探究微波干燥方式对硫酸钙晶须干燥的可行性,首先阐述了微波干燥原理,并且通过以二水硫酸钙晶须为原料的实验,获得在多种主要影响因素条件下半水硫酸钙晶须的实验结果。优化干燥的实验条件为：硫酸钙晶须100g、微波干燥时间25min、微波功率700W,此条件下硫酸钙晶须的相对脱水率达到97%;对样品进行XRD检测,其成分全部为半水硫酸钙晶须,与样品在120℃常规电加热干燥下所得样品成分相同,而微波干燥时间仅为其的加热干1/5。同时,通过材料性能测试实验,证明微波处理的硫酸钙晶须性能得到增强。     

复合型表面活性剂对氢氧化镁改性的效果

以菱镁矿及尿素为原料制得氢氧化镁晶须,用硅烷偶联剂和钛酸酯的复合型表面活性剂对其进行表面改性,最后得到黏度好,分散性高的Mg(OH)2阻燃剂.通过钛酸酯和硅烷偶联剂对氢氧化镁进行表面改性的实验,阐述了钛酸酯和硅烷偶联剂的复合型表面活性剂与其单一成分对氢氧化镁晶须的表面改性效果.并进行活性指数、比表面积、抑烟效果等测定.结果表明:复合型表面活性剂改性后的活性指数、比表面积、抑烟效果都高于单一成分改性的程度.     

利用工业轻烧粉合成碱式氯化镁晶须的方法

采用盐酸和轻烧粉为原料合成碱式氯化镁晶须(MHCH).利用扫描电子显微镜(SEM)、X射线衍射仪(XRD)、红外光谱仪(IR)等手段对碱式氯化镁晶须进行表征.结果表明:所制备的碱式氯化镁的分子式为Mg2(OH)3Cl·4H2O,粒径约为100~300 nm,晶须长度大于20μm.轻烧粉中的MgO与盐酸的摩尔比在0.75∶1~0.5∶1可以得到形貌较好的碱式氯化镁晶须.合成碱式氯化镁的适宜条件为:轻烧粉中的MgO与盐酸的摩尔比为0.65∶1,反应温度50℃,反应时间2 h.此外,利用配位化学理论合理地解释了轻烧粉与盐酸的反应机理.     

钙矾石对Pb（Ⅱ）的化学俘获

为查明钙矾石对Pb（Ⅱ）能否产生化学俘获以及发生俘获所需的必要条件,在室温下试用Pb（NO3）2与Al2（SO4）3、NaOH等进行人工液相合成Ph类钙矾石,即Pb6[Al（OH）6]2·3SO4·26H2O,并用CaO、Pb（NO3）2、Al2（SO4）,和蒸馏水等人工合成Ca—Pb钙矾石[（Ca,Pb）6[Al（OH）6]2·3SO4·26H2O]。试验表明：Ph6[Al（OH）6]2·3SO4·26H2O不能形成,但Ca—Pb钙矾石却能合成。这说明利用溶液反应法合成钙矾石时,若液相中缺Ca^2＋,则Pb（II）不能被钙矾石所俘获,只有当液相中出现了Ca^2＋时,Pb（Ⅱ）才能被钙矾石所俘获。另外,所合成的Ca—Pb钙矾石与纯钙矾石相比,其X射线衍射图谱发生了明显的改变,表明钙矾石在俘获了Pb（Ⅱ）后其晶格发生了一些变异。掺Pb（Ⅱ）的水泥熟料净浆在水化龄期为7d时,其XRD图谱也发生了一些变化,有Ca—Pb钙矾石存在的迹象。     

Microstructural Probing of (1-x) GeS_(2-x)Ga_2S_3 System Glasses By Raman Scattering

1IntroductionFiber amplifiers are of technological interest for ap-plications in optical communications systems.Attentionshas been paidtothe chalcogenide glasses because of theirlower phonon energy and higher quantumefficiency[1-4].Galliumis an essential …     

镍系催化丁二烯聚合的行为

本文研究了以(简称Ni—Al—B)为催化体系,加氢汽油为溶剂的丁二烯聚合的动力学行为。实验结果表明,在本实验范围内,聚合速率与主催化剂浓度[Ni]无关,对单体浓度[Bd]呈一级关系。当Al/B<1时,聚合速率方程式可表示为当Al/B>1时,聚合速率方程式可表示为: 此结果和吉本、焦书科等得出的结论不同,较明确地给出了聚合活性与镍系催化剂各组分之间的定量关系。本催化体系聚合表现活化能为25.4KJ·mol~(-1)。     

镍系催化丁二烯聚合动力学研究——Ⅰ聚合速率方程

本文报道了 (BF_3·0Et_2+n—C_8H_(17)OH)(简称Ni—Al—B)体系催化丁二烯聚合动力学研究结果,得到聚合速率方程式为 -d[Bd]/dt=k[Ni]~0[A1]~(-1)[B]~0[Bd],A1/B≤1 -d[Bd]/dt=k′[Ni]~0[A1]~(-1)[B][Bd],A1/B>1 聚合表观活化能为49.2kJ·mol~(-1)。     

Comparative study on lattice parameters of HAP nanoparticles with those of HAP whiskers

Hydroxyapatite whiskers are used as reinforcement for biomaterials because of their needlelike morphology and strong strength of single crystal. HAP nanoparitcles are used in drug delivery system, protein separation and anticancer drug besides their implant applications. Many new properties arise from nanoeffects while nanoeffects come from specialty of nanostructure. The Ca（NO3）2·4H2O and （NH4）2HPO4 were used as starting reagents for preparation of HAP whiskers and nanoparticles. The whiskers are 100-200 μm long while nanoparticles are 30-80 nm in size. XRD is applied to characterize the lattice parameter difference of whisker and nanoparticle. Compared with those of HAP whiskers, the a-axis and b-axis of HAP nanocrystals are shortened while the c-axis is elongated. That makes nanoparticles capable of their non-needle-like morphology, higher reaction activity and special bioeffects.