Reaction Process of Chromium Slag Reduced by Industrial Waste in Solid Phase

M, a particular industrial waste, was selected to detoxify chromium slag at a high temperature. The carbon remaining in M reduced Cr （ Ⅳ ） of Na2 CrO4 borne in the chromium slag to Cr （ Ⅲ ） in the solid phase reaction, and its thermodynamics and kinetics were studied. The reduction process of Na2CrO4 by carbon produced CO, whiCh＇was endothermic. Under the experimental condition, the apparent activation energy was 4. 41 kJ·mol^-1 , the＇apparent order of reaction for Na2 CrO4 was equal to one, and the partial pressure of CO was only 0.22 Pa at 1 330℃.

FORMATION OF MANGANESE SILICIDE THIN FILMS BY SOLID PHASE REACTION

Manganese silicide MnSi_(2-x) thin films have been prepared on n-type siliconsubstrates through solid phase reaction. The heterostructures were analyzed by X-ray diffraction,Rutherford backscattering spectroscopy, Fourier transform infrared transmittance spectroscopy andthe four-point probe technique. The results show that two manganese silicides have been formedsequentially via the reaction of thin layer Mn with Si substrate at different irradiation annealingstages, i.e., MnSi at 450 deg C and MnSi_(1.73) at 550 deg C. MnSi_(1.73) phase exhibits preferredgrowth after irradiation with infrared. In situ four-point probe measurements of sheet resistanceduring infrared irradiation annealing show that nucleation of MnSi and phase transformation of MnSito MaSi_(1.73) occur at 410 deg C and 530 deg C, respectively; the MnSi phase shows metallicbehavior, while MnSi_(1.73) exhibits semiconducting behavior. Characteristic phonon bands ofMnSi_(2-x) silicides, which can be used for phase identification along with conventional XRDtechniques, have been observed by FTIR spectroscopy.

Low-temperature phase transitions of sodium aluminate solutions

A series of low-temperature phase transitions of sodium aluminate solutions were studied by differential scanning calorimetry (DSC) and Raman spectroscopy. The results indicate that NaOH concentration is a primary impact factor for the binary eutectic point and ice melting temperature of sodium aluminate solutions with low NaOH concentration. In addition, the phase transition process of sodium aluminate solutions with low NaOH concentration from 123.15 to 283.15 K is divided into four steps: non-crystal to crystal, ternary eutectic reaction, binary eutectic reaction and ice melt. The projection phase diagram of NaOH-Al(OH)3-H2O system at low temperature was plotted, in which the ternary eutectic temperature for sodium aluminate solutions is 183.15 K.

Acting mechanism of F,K,and Na in the solid phase sintering reaction of the Baiyunebo iron ore

The effect of F,K,and Na on the solid phase reaction of the Baiyunebo iron ore was investigated by differential thermal analysis （DTA） and X-ray diffraction（XRD）.It has been identified that alkaline elements K and Na in the Baiyunebo ore instigate the formation of low melting point compounds Na2SiO3 and Na2O·Fe2O3 and the generation of molten state in the solid phase sintering.Element F in the Baiyunebo ore facilitates the formation of cuspidine compound 3CaO·2SiO2·CaF2 in the solid phase reaction.The cuspidine compound is kept in solid as one of the final products through the entire sintering process due to its high melting point.In the sintering process,CaF2and SiO2 react with CaO first and form 3CaO·2SiO2·CaF2 and 3CaO·2SiO2,so the formation of ferrites,Na2O·Fe2O3,and 2CaO·Fe2O3 is inhibited.

Thermal stability of Mg_2 Si epitaxial film formed on Si(111) substrate by solid phase reaction

A single crystalline Mg2Si film was formed by solid phase reaction （SPR） of a Si（111） substrate with an Mg overlayer capped with an oxide layer（s）,which was enhanced by post annealing from room temperature to 100℃ in a molecular beam epitaxy （MBE） system.The thermal stability of the Mg2Si film was then systematically investigated by post annealing in an oxygen-radical ambient at 300℃,450℃ and 650℃,respectively.The Mg2Si film stayed stable until the annealing temperature reached 450℃ then it transformed into amorphous MgOx attributed to the decomposition of Mg2Si and the oxidization of dissociated Mg.

Approaching Ultimate Synthesis Reaction Rate of Ni-Rich Layered Cathodes for Lithium-Ion Batteries

Nickel-rich layered oxide LiNi_(x)Co_(y)MnzO_(2)(NCM,x+y+z=1)is the most promising cathode material for high-energy lithium-ion batteries.However,conventional synthesis methods are limited by the slow heating rate,sluggish reaction dynamics,high energy consumption,and long reaction time.To overcome these chal-lenges,we first employed a high-temperature shock(HTS)strategy for fast synthesis of the NCM,and the approaching ultimate reaction rate of solid phase transition is deeply investigated for the first time.In the HTS process,ultrafast average reaction rate of phase transition from Ni_(0.6)Co_(0.2)Mn_(0.2)(OH)_(2) to Li-containing oxides is 66.7(%s^(-1)),that is,taking only 1.5 s.An ultrahigh heating rate leads to fast reaction kinetics,which induces the rapid phase transition of NCM cathodes.The HTS-synthesized nickel-rich layered oxides perform good cycling performances(94%for NCM523,94%for NCM622,and 80%for NCM811 after 200 cycles at 4.3 V).These findings might also assist to pave the way for preparing effectively Ni-rich layered oxides for lithium-ion batteries.

Solid-phase Synthesis of PNA Monomer by Ugi Four-component Condensation Reaction

Peptide nucleic acids (PNA) oligomers were synthesized in most cases by peptide synthesis from N-protected monomers. In this work a new method of obtaining PNA monomer by Ugi four-component condensation reaction was tested by solid-phase synthesis. The Fmoc protected PNA monomer was build up with thymin-1-yl acetic acid, 3-methylbutyl aldehyde, Fmoc protected aminoethyl isocyanide and Gly-Wang resin.

Effect of Annealing Temperature and Atmosphere to Surface Solid Phase Reaction of Sapphire Substrates and Spin-Coated Copper Nitrate Gel Films

The solid-phase reaction of sapphire (Al2O3) substrates and spin-coated copper nitrate films was studied. X-ray diffraction analysis revealed that a CuO fraction was observed by annealing at temperatures higher than 800℃. In addition, crystalline CuAlO2 was formed at annealing temperatures in the range of 900℃ – 1000℃ by solid-phase reaction of the spin-coated films and sapphire substrate. Crystalline CuAlO2 was formed by annealing at 1000℃ for 5 - 10 h, and CuAl2O4 was formed by annealing at 1000℃ for 15 h. When annealing under N2 flow, Cu2O was observed rather than CuAlO2. For a sample annealed in air at 1000℃ for 5 h, X-ray photoelectron spectroscopy measurements at various depths from surface revealed that Cu2+ ions are located around the surface, which suggests that the CuO fraction is present near the surface while the CuAlO2 fraction is located at greater depths from the surface of the samples. The depth profile of the sample suggests that there is no pure CuAlO2 layer in the sample, but that crystalline CuAlO2 is present in the sample as a mixture with CuO and Al2O3.

Solid Phase Synthesis of 1,4-Disubstituted 1,2,3-Triazole from Polystyrene-supported Selenium Resin

We report here a solid-phase synthesis of 1, 4-disubstituted 1, 2, 3-triazole using polystyrene-supported selenium resin. The resin used here not only works as a simple linker, but also assists the crucial α-alkylation reaction and selenoxide syn-elimimation, which ensures the purity of the products.

二硒化钴电催化剂的制备及氧还原性能测试

具有高附加值的绿色环保型氧化剂——过氧化氢(H_(2)O_(2))的需求日益增加,急需发展绿色且安全的H_(2)O_(2)合成新方法。两电子氧还原反应(2e-ORR)是一种制备H_(2)O_(2)的高效方法,其中催化剂的高效率和高选择性是2e-ORR的关键。对二硒化钴(CoSe_(2))电催化剂的制备和性能测试实验进行了探索。首先,通过联氨还原法制备钴纳米粒子;然后,通过简单的固相反应并在不同温度下退火制备CoSe_(2)电催化剂;最后,通过一系列的表征方法对CoSe_(2)电催化剂的表面形貌、晶型、电化学及其稳定性等进行了研究。为2e^(-)ORR电催化剂CoSe_(2)的进一步研究和应用开发提供借鉴。

Wittig反应实验的绿色化改进

传统的有机化学实验教学中,大多侧重实验技能的训练,设置实验内容时对实验安全性、经典性和可重复性等因素考虑较多,而对反应的绿色化、新方法和新技能等重视程度不够。为此,经典的有机反应也需要不断改进,本文将需要在大量有机溶剂中进行的传统Wittig反应改进为无溶剂的固相研磨反应,使得合成方法更加简单、绿色、安全和高效。设计合成了3个不同推拉型(D-π-A)二苯乙烯结构分子,优化了反应条件,测定了它们的光谱性质,并对其进行比较,讨论其构性关系,不仅引入绿色化学理念,而且对知识进行扩展,增加了实验的新颖性、探索性和趣味性,提升了学生创新能力。

Ni^(3+)抑制具有阴离子氧化还原活性钠离子电池正极材料的电压衰减

由于钠资源丰富,钠离子电池在大规模储能方面显示出巨大的潜力。随着近年来研究的深入,在正极材料中引入适量的阴离子氧化还原可以有效地提升钠离子电池的能量密度,同时减少高成本过渡金属元素如V、Co和Ni等的用量。有研究表明,材料循环过程中不可逆的氧损失以及Mn^(4+)/Mn^(3+)氧化还原的激活,导致了层状氧化物正极材料持续的电压衰减。本工作通过在Na_(x)[Li,Ni,Mn]O_(2)基钠离子电池正极材料中引入Ni^(3+)作为Mn^(4+)/Mn^(3+)氧化还原屏障,利用Ni^(3+)/Ni^(2+)的氧化还原代替Mn^(4+)/Mn^(3+)的氧化还原,成功抑制了材料的电压衰减。电化学测试结果显示,改性材料在不损失容量的前提下,循环稳定性得到明显提升。X射线光电子能谱结果也验证了Ni3^(+)的引入有利于维持材料多周循环后Mn价态的稳定。

天然石膏制备烧石膏晶须试验研究

基于我国天然石膏资源丰富、但产品附加值低的现状,根据溶解-再结晶理论,以天然石膏为原料、硝酸为助剂,采用常压酸化法开展了高附加值烧石膏晶须制备试验研究,考查了固液比、硝酸浓度和反应温度对所得产物物相与显微形貌的影响。研究结果表明:样品中烧石膏晶须的质量分数随着硝酸浓度和反应温度的升高而升高,样品中晶须的质量分数随着固液比的增大呈先升高后降低的趋势;优化条件下所得样品的物相主要为烧石膏相,另有极少量的石膏相和硬石膏相,样品中晶须的长度为509~650μm,长径比为43~62。研究成果可为天然石膏的高值化利用提供参考。

铪钛酸钡陶瓷制备及其压电性能的微观机制研究

采用传统固相反应法制备系列BaHf_(x)Ti_(1-x)O_(3)陶瓷,通过对陶瓷的压电、铁电、相组成、晶粒尺寸的测试和分析,发现:所有BaHf_(x)Ti_(1-x)O_(3)陶瓷样品均具有纯钙钛矿结构,室温均为铁电体具有压电性;在x<0.1时室温压电系数为195~327p C/N,x=0.02时,压电系数、剩余极化强度和平均晶粒尺寸最大,分别为327pC/N,13.3μC/cm^(2)和37.2μm,大晶粒尺寸和四方-正交-三方多相共存是其具有大压电系数的主要原因。

气固两相介质协同抑制瓦斯爆炸实验及分子动力学研究

针对传统单相抑爆介质效果不佳的问题,提出气固两相介质通过不同抑爆原理的协同作用,实现高效快速抑制瓦斯爆炸。研究使用NaHCO3粉体与CO_(2)气体协同抑制瓦斯爆炸的方法,选用标准20 L球形爆炸测试装置,并通过密度泛函理论对甲烷爆炸微观反应机理中各反应物、过渡态、产物进行构型优化,在此基础上进行后续计算。结果表明:体积分数为16%的CO_(2)和质量浓度为0.35 g/L的NaHCO3单相介质对瓦斯爆炸具有优良的抑制效果,但0.1 g/L粉体存在时会使最大升压速率提升17.9%;气固两相介质抑爆相较单相CO_(2)、单相NaHCO3粉体使最大爆炸压力降低,采用体积分数为8%的CO_(2)协同0.125 g/L粉体时,瓦斯爆炸最大爆炸压力降低72.42%,最大升压速率降至2.345 MPa/s,抑制效果达到最优;但当体积分数为4%的CO_(2)协同0.05 g/L粉体时会使最大爆炸升压速率上升93.68%,反应呈现出一定的加剧现象;量子化学计算表明,在气固两相介质协同抑制瓦斯爆炸的过程中,NaHCO3粉体裂解会吸收反应体系中的热量,其分解产物会与混合体系中的OH·、H·优先反应,阻碍O·的产生,将链式过程抑制在CH2O阶段,进而抑制链式反应的传递过程;NaHCO3粉体分解产生的CO_(2)与混合体系中的CO_(2)稀释了混合体系中甲烷的体积分数,减少甲烷与氧气分子之间碰撞发生的概率,对反应进程起到有效抑制作用。

锑系和钛系聚酯的固相缩聚研究

为了研究乙二醇钛对聚酯固相缩聚反应及聚酯切片性能的影响,采用小型固相缩聚装置研究了分别以乙二醇钛与乙二醇锑为催化剂制备聚酯的固相缩聚反应动力学,并对两种催化剂制备的增黏切片进行注塑试验。结果表明乙二醇钛制备的聚酯固相缩聚反应活化能为74.6 kJ/mol,高于乙二醇锑制备的聚酯的56.7 kJ/mol。采用乙二醇钛制备的增黏切片和注塑加工的瓶坯热稳性能都优于乙二醇锑制备的增黏切片和瓶坯。

温度在四氧化三钴制备中的影响分析

温度在四氧化三钴生产中是一个重要的控制因素,不稳定会导致粉末指标大的波动。采用两种温度工艺合成球形碳酸钴,利用XRD和TEM分析其生长机理,不同温度下呈现不同的优势生长面,高温下为多晶结构,低温单晶,通过SEM看高温碳酸钴表面颗粒呈棒状,低温为细颗粒堆叠。以低温合成的球形碳酸钴为原料,采用高温煅烧方法,制备球形四氧化三钴。系统研究了不同温度和不同升温速率下热性能、粒径、物相的变化。通过这些条件实验揭示了改变温度条件及不同升温速率下碳酸钴的生长规律及其内在分解原理。

全自动固相萃取-气相色谱-三重四级杆质谱法测定地表水中20种半挥发性有机物

建立全自动固相萃取-气相色谱-三重四级杆质谱联用仪测定地表水中20种半挥发性有机物的分析方法。用全自动固相萃取装置对半挥发性有机污染物进行提取、富集,经DB-5MS色谱柱(30 m×0.25 mm,0.25μm)分离,用全扫描模式定性,以多反应监测(MRM)模式联合内标法定量分析。20种半挥发性有机物的质量浓度在20~1000μg/L范围内与色谱峰面积具有良好的线性关系,相关系数均大于0.9990,方法检出限为0.010~0.023μg/L。样品加标平均回收率为83.5%~103.1%,测定结果的相对标准偏差为0.76%~3.08%(n=6)。该方法既可提高萃取效率,又具有灵敏度高、准确度高等优点,适用于地表水中微量半挥发性有机物的分析。

Phase Transformation of Nanosized Zirconia

The nanosized zirconia was synthesized via solid state reaction in the presence of surfactant. The results indicate that crystal phase of zirconia can be controlled by tuning the synthesis parameters such as OH^-/Zr molar ratio, crystallizing temperature and time. It can be transformed among amorphous, tetragonal and monoclinic phases. The transformation is driven by particle size. The research shows the nanocrystalline zirconia possesses the higher thermal stability compared with amorphous framework. The ＂glow exotherm＂ can be observed for the amorphous samples. Otherwise, it is in the absence for nanocrystalline samples. Herein, the reason for retention of tetragonal zirconia is demonstrated.

Reduction reaction in Al-CuO powder mixturedriven by mechanical alloying

The solid state reduction reaction of Al-10 % CuO mixed powders during mechanical alloying was investigated using XRD, DTA and TEM. The CuO is believed to be gradually reduced by Al, and controlled by diffusion of atoms and ions. Reduced Cu spontaneously reacts with Al to form a metastable equilibrium of Al (Cu) with Al4Cu9 phase during ball-milling, instead of CuAl2 and Al(Cu), which is only observed after annealing.