溶胶—凝胶工艺制备二氧化钛超微细粉过程中的物相和显微结构的变化

用溶胶—凝胶工艺制备了不同晶型的TiO_2超微细粉,锐钛矿型TiO_2超微细粉呈分散的球形颗粒,平均粒径约为0.03μm;金红石型TiO_2超微细粉呈分散的圆柱状颗粒,平均粒径约为0.07μm。用FT-IR.XRD.DTA/TGA和TEM等手段研究了TiO_2凝胶在煅烧过程中物相和显微结构的变化。发现TiO_2凝胶在200℃以下呈非晶态,在300℃时结晶成锐钛矿,在700℃时,锐钛矿开始转变为金红石,在1000℃时,锐钛矿消失,全部转变为金红石。     

溶胶凝胶法制备（Eu^2＋，Dy^3＋）SrAl2O4

采用无机盐溶胶-凝胶法制备了颗粒均匀的形态为针状的(Eu2+,Dy3+)SrAl2O4纳米粉体.通过TG-DTA分析和X射线衍射和扫描电镜分析方法,对样品进行了微观结构和表面形态的表征.研究了纳米(Eu2+,Dy3+)SrAl2O4粉体在不同烧结温度下固相反应过程和成相规律.实验结果表明,当样品的烧结温度为500 ℃时是单一的Sr(NO3)2晶相;750 ℃左右生成了Sr3Al2O6,并伴有少量SrAl2O4晶体;1 100 ℃是生成了结晶度良好的针状纳米(Eu2+,Dy3+)SrAl2O4粉体.通过计算,样品粉体晶粒平均为80～100 nm.该晶体粒度随烧结温度升高而逐渐变大.     

膨润土尾矿复合陶粒制备与Cr(Ⅵ)吸附性能

膨润土提纯后的尾矿主要含石英、斜绿泥石和白云母等矿物,以尾矿为主原料制备了复合陶瓷颗粒,采用XRD,IR和SEM探讨了烧结工艺对结构变化的影响,研究了复合陶瓷颗粒的组分变化、烧结温度、pH、初始浓度、吸附时间和温度对Cr(Ⅵ)离子吸附效果的影响,探讨了动力学和热力学变化。结果表明,烧结温度对吸附影响不大,烧结适宜温度为1000℃,陶瓷颗粒的主晶相为石英和硅灰石,表面为不均匀多孔结构。吸附的最佳吸附条件是pH值1、陶瓷颗粒用量1 g、吸附时间12 h及铬离子初始浓度100 mg/L,吸附率达96.33%。吸附行为符合准二级动力学方程,属于单分子层化学吸附;热力学数据说明,吸附反应为自发吸热反应。     

锶掺杂的正铌酸镧超细粉体的合成与性能

采用溶胶低温燃烧法和高温固相反应法制备了锶掺杂的正铌酸镧（La0.95Sr0.05NbO4）超细陶瓷粉体。应用XRD、SEM和激光粒度分析仪等对陶瓷粉体的物相、粒度和粒度分布进行了表征,同时考察了两种方法制备的粉体的烧结性能。结果表明：采用溶胶低温燃烧法制备的La0.95Sr0.05NbO4（LSNb）为粒径〈100 nm、粒度分布范围窄的超细粉体;高温固相反应法制备的粒径为0.5-1.0μm、呈球形的LSNb超细陶瓷粉体。溶胶低温燃烧法制备的粉体在1 250℃烧结10 h形成致密的陶瓷片;高温固相反应法制备的粉体在1 400℃以上烧结10 h致密。两种LSNb致密膜均具有一定的透氢作用,900℃氢渗速率分别为1.96×10^-3mL·cm^-2·min^-1和1.67×10^-3mL·cm^-2·min^-1。     

水热法合成黄铁矿微观形貌和结构的观测与表征

模拟热液型金矿床中黄铁矿生成的地质条件,采用硫酸亚铁(FeSO4)和硫代乙酰胺(CH3CSNH2)为铁源和硫源,在Fe/S比为1∶3、温度180~200 ℃、加热时间24 h条件下考察黄铁矿的结晶情况。用SEM扫描电镜观察在不同水热条件下合成黄铁矿的形态及成分;用多晶X射线衍射仪(XRD)确定了产物物相组成;用透射电子显微镜(TEM)观测表征了黄铁矿晶体的形态和结构。结果表明：在200 ℃时黄铁矿为粒状,粒度较均匀,粒径1 μm左右。在180 ℃时黄铁矿除有尺寸在1 μm左右粒状黄铁矿外,还有不规则带状黄铁矿晶体,带宽为200 nm左右。认为水热条件中,随着结晶温度的逐步升高,黄铁矿的形貌逐步由不规则形状向规则形状的转变。所以在实验温度较高阶段,形成规则的粒状形貌;在低温阶段,则会出现不规则带状形貌。     

利用赤泥制备钙铝榴石微晶玻璃的实验研究

在1300℃下将赤泥和石英砂熔制成基础玻璃,经粉磨、筛选后,通过二次热处理工艺获得了以钙铝榴石为主晶相的微晶玻璃。采用XRD和SEM等研究赤泥和微晶玻璃后表明,赤泥主要由方解石和霰石等钙质成分组成;热处理温度对微晶玻璃性能和钙铝榴石晶体结构的影响较大。优化的制备条件为:核化900℃,1h,晶化1105℃,2h,该条件下所得的微晶玻璃晶相含量较高,晶体发育完整,性能良好,相应的体积密度为2.79g/cm3,显微硬度为6.52。     

油页岩提硅渣铝溶出实验研究

针对提取氧化硅后的油页岩灰渣,对改良碱石灰烧结法提取氧化铝过程中的铝溶出进行了实验研究,主要探讨了烧结温度、烧结时间、碱铝比及钙硅比对烧结熟料中的物相特点及铝溶出率的影响。运用X射线粉末衍射(XRD)对烧结熟料进行的物相分析结果显示,主要物相为铝酸钠(NaAlO₂)和硅酸钙钠(Na₂CaSiO₄)。烧结实验结果表明,当烧结温度为1 150℃,保温时间为1.5 h,碱铝比为1.0,钙硅比为1.0时,烧结熟料中氧化铝的标准溶出率可达94%。     

热液条件下锐钛矿晶体生长的实验

为了解金属离子生长成为热液矿石矿物的过程和机理,使用氟钛酸钾稀溶液在100 MPa和200~400℃条件下开展了一系列等温不等时和等时变温实验.结果显示该热液条件下形成了不同形貌的锐钛矿.随着反应时间和温度的增加,锐钛矿由几十纳米生长至十几微米;10 h以内的晶体生长速度远高于10 h以后,相对高温下的晶体生长速度则高于低温,表明锐钛矿的热液生长与温度、过饱和程度密切相关.综合来看,粒子成核生长、定向附着和奥氏熟化先后控制了热液锐钛矿的生长,而金属在流体中的过饱和程度和溶解-沉淀过程则决定了其生长速度.因而锐钛矿的形态特征可用于指示其形成的温度、世代关系甚至含氟流体的演化历史.      

吉林通化地区煤系高岭岩合成4沸石研究

以吉林通化地区煤系高岭岩为原料,采用水热法合成了4沸石,讨论了煅烧温度、用碱量、晶化时间和温度等对生成产物的影响。实验表明：合成4沸石的适宜条件为：煅烧温度650-850℃,用碱量Na2O/SiO2=2.80,晶化时间2 h,晶化温度80℃,胶化时间2 h,老化时间10 h,在此条件下合成的4沸石,其钙离子交换量为233.51 mg.CaCO3/g。     

利用高铝粉煤灰制备堇青石微晶玻璃的实验研究

以高铝粉煤灰为主要原料，制备了堇青石微晶玻璃。通过差热分析（DTA）和X射线粉末衍射分析（XRD）确定了合适的热处理条件：核化温度807℃，核化时间2h，晶化温度960℃，晶化时间3h。XRD分析显示，制得微晶玻璃的主晶相为堇青石。SEM分析表明，基础玻璃晶化完全，微晶玻璃中微晶体呈不规则柱状、棒状，微晶体长度为5～15μm，长径比为5～10。     

Hydrometallurgical processing and recovery of molybdenum trioxide from spent catalyst

Hydrometallurgical processing of spent hydrodesulphurisation (HDS) catalyst for the recovery of molybdenum using sodium carbonate and hydrogen peroxide mixtures was investigated. The results indicated that the recovery of molybdenum was largely dependent on the concentrations of Na₂CO₃ and H₂O₂ in the reaction medium, which controls the acidity of the leach liquor and carry over of impurities such as Al, Ni, P, Si and V. Leaching process was exothermic and leaching efficiency of molybdenum decreased with increasing solid to liquid ratio. Large scale leaching of spent catalyst, under optimum conditions: 20% pulp density, 85 g/L Na₂CO₃, 10 vol.% H₂O₂ and 1 h reaction, resulted a leaching efficiency of 84% Mo. The obtained leach liquor contained (g/L): Mo — 22.0, Ni — 0.015 and Al — 0.82, P — 1.1, Si — 0.094 and minor quantities of V — 8 mg/L, As and Co — < 1 mg/L. Recovery of Mo from leach solution as MoO₃ of 97.30% purity was achieved by ammonium molybdate precipitation method.     

硅酸盐玻璃中的Na和K含量电子探针分析条件设定探讨

含Ti硅酸盐玻璃在基础科学研究和应用技术开发上均有重要价值,亟需对其进行准确的成分分析,为进一步的科研工作提供重要的数据支撑.对玻璃进行电子探针分析时,由于样品的易损性和其中(Na和K)阳离子在电子束轰击下极易发生迁移和扩散,因此往往需要经过条件实验来确定合适的分析条件,确保样品在该条件下能够保持尽量稳定的状态,才能获...     

A computer simulation study of OH defects in Mg2SiO4 and Mg2GeO4 spinels

Classical atomistic simulation techniques have been used to investigate the energies of hydrogen defects in Mg₂SiO₄ and Mg₂GeO₄ spinels. Ringwoodite (γ-Mg₂SiO₄) is considered to be the most abundant mineral in the lower part of the transition zone and can incorporate large amounts of water in the form of hydroxyls, whereas the germanate spinel (γ-Mg₂GeO₄) corresponds to a low-pressure structural analogue for ringwoodite. The calculated defect energies indicate that the most favourable mechanisms for hydrogen incorporation are coupled either with the reduction of ferric iron or with the creation of tetrahedral vacancies. Hydrogen will go preferentially into tetrahedral vacancies, eventually leading to the formation of the hydrogarnet defect, before associating with other negatively charged point defects. The presence of isolated hydroxyls is not expected. The same trend is observed for germanate, and thus γ-Mg₂GeO₄ could be used as a low-pressure analogue for ringwoodite in studies of water-related defects and their effect on physical properties.     

Elastic and thermoelastic properties of synthetic Ca<Subscript>2</Subscript>MgSi<Subscript>2</Subscript>O<Subscript>7</Subscript> (åkermanite) and Ca<Subscript>2</Subscript>ZnSi<Subscript>2</Subscript>O<Subscript>7</Subscript> (hardystonite)

Elastic and thermoelastic constants of large single crystals of Ca₂MgSi₂O₇ and Ca₂ZnSi₂O₇ have been derived from ultrasonic resonance frequencies of plane-parallel plates and their shift upon variation of temperature, respectively. In addition, coefficients of thermal expansion and dielectric constants were determined. Both species possess quite similar properties. As observed in other isotypic magnesium and zinc compounds, the mean elastic stiffness and the deviation from the Cauchy relations are significantly larger in the zinc compound, due to a covalent contribution of the Zn–O bond. Positive thermoelastic constants T₄₄ and T₆₆ in Ca₂MgSi₂O₇ allow temperature-independent ultrasonic generators and oscillators to be manufactured.     

中国北方典型中小盆地城市大气颗粒物污染特征及趋势对比

分析了2014~2018年北方5个典型中小盆地城市(兰州、银川、临汾、太原、南阳)PM10与PM2.5的浓度变化特征和大致来源类型。除2018年银川PM2.5浓度外,各市PM10和PM2.5年均浓度均超标;兰州、银川和南阳PM10与PM2.5呈逐年下降趋势,南阳下降最明显;临汾PM10与PM2.5呈逐年上升趋势;太原PM10与PM2.5稳定维持在一个高浓度状态。5个城市颗粒物浓度的季节变化特征一致:冬春高、夏秋低。对PM2.5/PM10值而言,冬季和夏季该比值较高,分别受取暖和降水的影响;春季和秋季该比值较低,分别受沙尘和秸秆焚烧及高强度建筑施工的影响。5市PM2.5和PM10浓度具有良好的线性关系,细颗粒占比大小顺序为临汾>南阳>太原>银川>兰州。     

Low-temperature heat capacities of MgAl<Subscript>2</Subscript>O<Subscript>4</Subscript> and spinels of the MgCr<Subscript>2</Subscript>O<Subscript>4</Subscript>–MgAl<Subscript>2</Subscript>O<Subscript>4</Subscript> solid solution

We present results from low-temperature heat capacity measurements of spinels along the solid solution between MgAl₂O₄ and MgCr₂O₄. The data also include new low-temperature heat capacity measurements for MgAl₂O₄ spinel. Heat capacities were measured between 1.5 and 300 K, and thermochemical functions were derived from the results. No heat capacity anomaly was observed for MgAl₂O₄ spinel; however, we observe a low-temperature heat capacity anomaly for Cr-bearing spinels at temperatures below 15 K. From our data we calculate standard entropies (298.15 K) for Mg(Cr,Al)₂O₄ spinels. We suggest a standard entropy for MgAl₂O₄ of 80.9 ± 0.6 J mol⁻¹ K⁻¹. For the solid solution between MgAl₂O₄ and MgCr₂O₄, we observe a linear increase of the standard entropies from 80.9 J mol⁻¹ K⁻¹ for MgAl₂O₄ to 118.3 J mol⁻¹ K⁻¹ for MgCr₂O₄.     

碱处理对河北围场天然沸石结构和性能的影响及其机理研究

采用NaOH对围场地区天然沸石进行处理,采用X射线衍射仪、红外光谱仪、N_2吸附-脱附技术、扫描电子显微镜等对材料进行表征分析,采用水蒸气吸附法评价材料的亲水性,采用Cr~(3+)和Mn~(2+)评价材料的离子交换性能,探讨了碱处理对天然沸石的结构、亲水性和离子交换性能的影响及其机理。实验结果表明,围场地区天然沸石中主要含有斜发沸石、石英和伊利石;碱处理可降低天然沸石的硅铝比,且沸石的硅铝比随着碱处理浓度的提高而不断降低;碱处理对斜发沸石结构的影响较石英和伊利石更大;高浓度碱处理导致天然沸石的结构发生破坏,比表面积降低,孔体积提高;伴随着天然沸石硅铝比的降低,其亲水性和离子交换性能不断提高。     

High-T phase transition of synthetic ANaB(LiMg)CMg5Si8O22(OH)2 amphibole: an X-ray synchrotron powder diffraction and FTIR spectroscopic study

The synthetic amphibole Na_0.95(Li_0.95Mg_1.05)Mg₅Si₈O₂₂(OH)₂ was studied in situ at high-T, using IR OH-stretching spectroscopy and synchrotron X-ray powder diffraction. At room-T the sample has P2₁ /m symmetry, as shown by the FTIR spectrum. It shows in the OH region two well-defined and intense absorptions at 3,748 and 3,712 cm⁻¹, respectively, and two minor bands at 3,667 and 3,687 cm⁻¹. The main bands are assigned to the two independent O–H groups in the primitive structure. The two minor bands evidencing the presence of small amount of vacant A-site (^A□_0.05). With increasing T, these bands shift continuously and merge into a unique absorption at high temperature. A change as a function of increasing T is revealed by the evolution of the refined unit-cell parameters, whose trend shows a transition to C2/m at about 320–330°C. The spontaneous scalar strain, fitted with a tricritical 2–6 Landau potential, gives a T _c of 325(10)°C (β parameter = 0.27). Comparison with the second-order P2₁ /m ⇔ C2/m phase transition at 255°C for synthetic amphibole ^ANa_0.8^B(Na_0.8Mg_1.2)^CMg₅Si₈O₂₂(OH)₂ indicates that the substitution of Na with Li at the B-sites strongly affects the thermodynamic character and the T _c of the phase transition. The comparison of LNMSH amphiboles with cummingtonitic ones shows that the high-T thermodynamic behaviour is affected by A-site occupancy.     

流体包裹体盐度低温拉曼光谱测定方法研究

氯盐溶液作为流体包裹体中最普遍和最重要的盐水化合物,是测定包裹体盐水溶液含盐度的主要溶质,但由于其强离子键化合物的分子特性在常温、常压下没有拉曼效应,拉曼光谱测试无法获取氯盐的有效特征信息,使得利用拉曼光谱研究流体包裹体分子组分及含盐度的方法存在严重缺陷。本文联合利用激光拉曼光谱探针和冷热台,原位采集了不同盐度的NaCl-H₂O和CaCl₂-H₂O标准盐水溶液在低温下(-185℃)形成的冰、NaCl水合物和CaCl₂水合物的拉曼光谱,分析了不同盐度标准盐水溶液形成的水合物拉曼特征峰的变化规律,尝试建立流体包裹体盐度低温拉曼光谱测定方法。分析表明,NaCl水合物约3425 cm^-1拉曼特征峰与冰约3120 cm^-1拉曼特征峰峰面积比值和配制的NaCl-H₂O标准溶液盐度呈良好的正相关(r²=0.9995),CaCl₂水合物约3431 cm^-1拉曼特征峰与冰约3120 cm^-1拉曼特征峰峰面积比值也和配制的CaCl₂-H₂O标准溶液盐度呈较好的正相关(r²=0.9458)。利用愈合人工水晶法合成的NaCl-H₂O和CaCl₂-H₂O包裹体标样检验了用上述方法低温测定流体包裹体盐度的可靠性,结果表明该技术用于盐度大于0.5 mol/L的NaCl-H₂O体系流体包裹体时,数据精度好于20%;用于盐度大于0.5 mol/L的CaCl₂-H₂O体系流体包裹体时,数据精度最高可达5%,完全可达到半定量-定量测定的要求。研究还发现,包裹体内压可能对低温拉曼光谱测定流体包裹体盐度影响不大,分析中获得的冰拉曼特征峰的拉曼位移(约3120 cm^-1)与前人略有差异,可能与实验条件下获得的冰的多型不同有关。与国内外同行的研究结果比较,本研究更加注重该项实验技术的实际应用,通过对不同体系盐水溶液系列进行拉曼光谱实验分析,对实验条件和方法进行不断优化,在确定流体体系的同时实现了包裹体盐水溶液盐度半定量-定量测定,准确度优于传统方法,并且该方法具有很强的实用性。