共查询到20条相似文献,搜索用时 125 毫秒
1.
矿化剂对铝酸钙粉的结构与光谱性能的影响 总被引:2,自引:0,他引:2
研究了矿化剂对制备铝酸钙粉的结构与性能的影响.研究中以铝矾土和石灰石为原料,加入一定量的矿化剂,混合均匀,经高温煅烧制得铝酸钙粉.借助于红外光谱、X射线粉末衍射、差热-热重分析等手段对不同原料的铝酸钙粉的结构、组成及性能进行了表征和研究,并对矿化剂在合成铝酸钙中的矿化机理进行探讨.研究表明:加入矿化剂后,可在更低温度条件下煅烧制备出铝酸钙粉,有利于节能减排.红外光谱分析、XRD分析、DTA-TG分析显示:未加矿化剂煅烧时,生成的产物主要是Ca3Al10O18,CaAl2Si2O8.加入矿化剂后煅烧生成的产物主要是易浸出Al2O3的CaAl3BO7和Ca3Al10O18,而不易浸出Al2O3的CaAl2Si2O8的含量大大降低.同时显示,加入矿化剂后,原料中的方解石(CaCO3)分解更容易;CaCO3与铝矾土反应更充分;更有利于促使铝矾土中的Al-Si键断裂,将铝矾土中的Al释放出来;并可降低铝酸钙的煅烧温度.研究还显示:加入矿化剂后,可以改变原产物的晶体结构与成分,有利于降低煅烧反应温度. 相似文献
2.
以氧化钐和H3PO4为原材料,在无模板剂的情况下,用水热法通过调控pH、时间和温度制备了SmPO4·0.5H2O一维纳米材料,并提出其可能形成机理。用X射线粉末衍射(XRD)、透射电镜(TEM,HRTEM和SAED)、红外光谱(IR)和能谱(EDS)对产物的物相结构、微观形貌和组成进行了表征。用紫外-可见吸收光谱研究了产物的光学性质。研究结果表明,实验所制备的产物全部是六方晶系结构,形貌都为一维纳米线。反应体系的pH值、温度和时间的改变对纳米线的长径比有影响,但对其相结构基本都没有影响。分析得到最佳水热制备条件为pH=5、温度和时间分别为130℃和8 h,产物的结晶性、分散性和均匀性都达到最好。光学性质研究表明,该类产物在300~350 nm的紫外区域有吸收宽峰,是属于基质O2-→P5+、Sm3+的电荷迁移。在350~450 nm处的可见光区域内也有一组吸收峰,是属于Sm3+的4f内层电子间的f-f跃迁吸收。依据该类吸收峰,得到禁带宽度在4.67~5.50 eV之间。pH值和温度对产物光学性能均有影响。 相似文献
3.
4.
5.
羟自由基与水杨酸反应机理的初探 总被引:2,自引:0,他引:2
探讨羟自由基与水杨酸的反应动力学过程。水杨酸与Fenton反应产生的的羟自由基反应,采用紫外-可见分光光度法(UV)和质谱法(MS),考察反应物的浓度、反应时间、反应温度、溶剂pH值等对反应产物的浓度以及反应速率的影响。水杨酸与.OH反应生成的紫色产物在波长530nm处有最大UV吸收峰,但仅于pH=4.51的缓冲溶液和水中有吸收峰;且该产物的吸光度值,随着反应物浓度的增加而增加;随反应时间的延长而减少;随着反应温度的升高而减少。反应速率t=5s达到最大值,其后随着反应时间的延长而逐渐降低,1min时达到平衡。通过MS分析,可得到质荷比(m/Z)=153,248,249,288,289,304,328,329,344,345的离子峰。推测羟自由基与水杨酸反应的中间产物是紫色的大分子自由基,而最终产物为二羟基苯甲酸,该反应可能是加成反应和聚合反应同时进行。 相似文献
6.
7.
十六烷基三甲基溴化铵对脱水四环素和异四环素荧光增强作用研究 总被引:3,自引:0,他引:3
在不同pH值的标准缓冲溶液及不同表面活性剂十六烷基三甲基溴化铵(CTMAB)浓度的胶束溶液环境中,研究了CTMAB对盐酸四环素的降解产物脱水四环素和异四环素的荧光强度的影响。结果表明,CTMAB对脱水四环素和异四环素具有荧光增强作用,荧光增强幅度与介质的pH值和CTMAB浓度有关,在中性和碱性条件下对脱水四环素荧光增强作用较大,在pH=9.2的条件下可使异四环素的荧光强度达到最大值,CTMAB对脱水四环素和异四环素的这种荧光增强作用,为建立较灵敏的盐酸四环素及其降解产物的荧光定量方法提供了依据。 相似文献
8.
9.
基于单颗粒消溶的缩核模型,建立了酸消溶石灰石反应在液膜传质和化学反应共同控制条件下的颗粒群的液固反应模型。实验研究了五种石灰石样品在不同温度、不同pH值和不同粒径分布下的消溶过程,模型理论计算与实验进行了验证,得到了不同种类的石灰石在不同反应条件下的平均整体反应常数k_m,且k_m是一个与反应条件相关的特征数。通过实验数据和理论模型对反应过程中的整体反应常数进行反推,发现同一反应条件下k_m随时间不断缩小并趋于常数,但粒度分布不同和产地不同的样品在相同反应条件下的整体反应常数相差不大。 相似文献
10.
11.
Jianhong Peng Mirabbos Hojamberdiev Baowei Cao Juan Wang Yunhua Xu 《Applied Physics A: Materials Science & Processing》2011,103(2):511-516
Submicron BiFeO3 powders were successfully synthesized via a simple hydrothermal process with the assistance of mineralizer (NaOH) at 150–190°C,
using FeCl3 and Bi(NO3)3⋅5H2O as reactants. The effects of mineralizer concentration, reaction temperature and time on the phase evolution and crystal
morphology of the resulting samples were investigated. X-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetry
and differential scanning calorimetry (TG-DSC), and vibrating sample magnetometry (VSM) were used to characterize the as-synthesized
samples. The experimental results revealed that a pure BiFeO3 phase could be formed at a temperature ranging from 170 to 190°C for 4–20 h in the presence of 0.03–0.12 M NaOH. It was found
that the mineralizer concentration, reaction temperature and time played a key role in controlling the growing speed of nuclei
and formation of BiFeO3 crystallites. The possible formation mechanisms of submicron BiFeO3 powders with different morphologies were presented. The magnetization of BiFeO3 powders showed a weak ferromagnetic behavior at room temperature. 相似文献
12.
We report the preparation of cerium-containing nanoparticles by a simple yet efficient hydrothermal synthesis process using cerium resource and NaF mineralizer with no surfactant or template. We demonstrate that morphology and chemistry of the synthesized CeO2 and CeF3 nanomaterials can be manipulated via tuning concentration of the mineralizer NaF alone. The synthesis mechanism, chemical evolution, and optical properties of the harvested nanomaterials have also been investigated. The ceria and its hybrid system are found to exhibit an excellent UV-shielding capability, which provides further evidence that the mineralizer NaF is critical for governing the morphology and properties of the cerium-containing nanomaterials. Such a facile method to synthesize the functional nano-crystallites with tunable morphology and chemistry by tailoring the concentration of mineralizer alone should be applicable to other types of nanomaterials and relevant for a wide range of applications. 相似文献
13.
Rod-like hydroxyapatite (HAp) nanoparticles with various aspect ratios are synthesized by means of low-temperature hydrothermal method in the presence of a N-[(2-hydroxy-3-trimethylammonium) propyl]chitosan chloride (HTCC) template. The synthesized HAps were examined by X-ray diffraction (XRD), Fourier transform infrared spectrophotometer (FTIR) and transmission electron microscopy (TEM) techniques. The results reveal that HAps are rod-like monocrystals, where the size and morphology can be tailored by varying synthesis conditions, such as pH, hydrothermal synthesis temperature and the ratio of PO43− to the quaternary ammonium in HTCC. The mechanism of HTCC template on HAp nanorod preparation is analyzed. 相似文献
14.
Nanometric yttria (8 mol%)-stabilized zirconia powders were hydrothermally synthesized at 110 °C for 7 days in the presence of dilute (0.20 M) or concentrated (2.0 M) solutions of (KOH+K2CO3) mineralizer. Zirconia xerogel, crystalline Y(OH)3, crystalline Y2O3 and a xerogel of coprecipitated (Y–Zr) hydroxide were used as starting materials. Setting the content of yttria constant and equal to 8 mol%, three types of mixtures were tested. Zirconia xerogel in mixture with crystalline Y2O3, zirconia xerogel in mixture with crystalline Y(OH)3 and, finally, a xerogel of coprecipitated (Y–Zr) hydroxide were hydrothermally treated.The different characteristics of the resulting powders are discussed in terms of both the mineralizer concentration and the type of Y-based precursor used in the hydrothermal treatments, respectively.Weakly agglomerated cubic ZrO2 powders with primary particles bigger in size and without any preliminary treatment show better performances when they are directly sintered at 1500 °C. 相似文献
15.
Well-dispersed hydroxyapatite (HA) nanorods with different morphologies were synthesized by a hydrothermal method in oleic acid, ethanol and water reaction system, and the surfactant assisted modifications effect was also comparatively studied. The structure and morphology of samples were characterized using X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and transmission electron microscopy (TEM), respectively. The effect of reaction systems and surfactant additives on the morphology evolution of HA nanorods were discussed in detail. The results showed that the controlled experimental conditions in the systems, such as the content ratio of oleic acid/ethanol, pH value and the content ratio of Ca/P source had an significant effect on the morphology evolution of as-prepared HA nanorods. Further, the selected surfactant additives, such as cetyltriethylammnonium bromide (CTAB), sodium dodecyl sulfate (K12) also play an important role in the formation of the uniform morphology of HA nanorods. Some possible formation mechanisms of the HA nanorods in the present reaction systems is proposed. 相似文献
16.
Hai-bin Zhang Ke-chao Zhou Zhi-you Li Su-ping Huang 《Journal of Physics and Chemistry of Solids》2009,70(1):243-248
In this article, calcium nitrate (Ca(NO3)2) and disodium hydrogen phosphate (Na2HPO4) are used as calcium and phosphorous sources to prepare hydroxyapatite nanoparticles by the hydrothermal method. Plate-like nanocrystals of hydroxyapatite are synthesized with the aid of sodium tripolyphosphate. The results show that sodium tripolyphosphate increases the diameters of the hydroxyapatite nanoparticles during the hydrothermal process. When the concentration of sodium tripolyphosphate reaches 0.015 M, the average aspect ratio of those nanoparticles is close to 1. The strong surface adsorption caused by sodium tripolyphosphate may answer for the morphological change of hydroxyapatite crystal. 相似文献
17.
Morphology controllable hydroxyapatite (HA) nanoparticles were synthesized using reverse microemulsion (aqueous solution/TX-100/n-butanol/cyclohexane) systems under hydrothermal conditions. The concentration of cetyltrimethylammonium bromide (CTAB) contained in the aqueous solution and pH value had significant effect on the morphology and crystal phases of the final products. All the as-synthesized HA nanoparticles had a larger a value but smaller c value compared with the standard values of the JCPDs card. The existence of CTAB could be attributed to the growth of HA along an axis, but inhibit the growth along the c-axis to some extent. A proposed model was established to explain the change of the lattice parameters. 相似文献
18.
Delafossite CuFeO2 oxide was synthesized by a hydrothermal technique using Cu2O and FeOOH as precursors with the addition of fused NaOH as mineralizer. The amount of rhombohedral and hexagonal delafossite phase formed depends on the synthesis time lapses between 2 and 5 days and on the NaOH concentration. The compounds obtained were analyzed with Raman Spectroscopy, X-Ray Diffraction (XRD), X-Ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) in order to obtain their morphological and structural properties. Optical behavior was studied by UV–vis Spectroscopy and gas adsorption measured with a Quartz-Crystal Microbalance (QCM). Our results show that this type of hydrothermal synthesis is capable of recreating the delafossite-type structure of copper-iron oxide and produces a high yield of material with the right stoichiometry. The highest uptake of carbon dioxide is observed on the sample with the highest ratio between rhombohedral and hexagonal delafossite phase. 相似文献
19.
研究了矿化剂对中低品位铝矾土对所制备铝酸钙粉的结构及其光谱性能的影响。以中低品位铝钒土和碳酸钙为主要原料,矿化剂CaF2为添加剂,三者经充分混合、 高温煅烧和粉磨后,生产出的铝酸钙粉可直接用于制备聚合氯化铝、 聚合硫酸铝、 铝酸钠等水处理剂。通过调整原料中铝矾土和碳酸钙的质量比和矿化剂CaF2投加量的方法优化铝酸钙粉的制备工艺,采用红外光谱分析对铝酸钙粉和铝矾土进行表征,并对矿化剂的矿化机理进行研究。红外光谱分析结果表明:加入矿化剂CaF2,可促进铝矾土中硬水铝石、 三水铝石和高岭石的分解转化,使碳酸钙的分解完全,使原料中的铝矾土与碳酸钙进行更加充分的反应,不仅有助于碳酸钙中的Ca与铝矾土中的Si结合,还有助于促进铝矾土中的Si—O,Si—O—Al及Al—Si键的断裂,使铝矾土中的Al充分溶出,从而提高Al2O3的溶出率;矿化剂CaF2的投加量(质量比)为3%时,可有效促进Al2O3的溶出;矿化剂CaF2的投加量为1.5%时,不足以起到充分的矿化作用;中低品位铝矾土较高品位铝矾土更易于烧结制备铝酸钙粉;在1 250 ℃下制备铝酸钙粉的最佳物料配比是:原料中铝矾土与碳酸钙的质量比为1∶0.6,矿化剂CaF2的投加量为3%。 相似文献
20.
采用水热法,以CoCl2·6H2O为前驱物,KOH作为矿化剂合成了掺钴氧化锌稀磁半导体晶体。利用扫描电子显微镜(SEM)及X射线能谱仪(XREDS)对合成晶体的微观形貌、表面及内部掺杂元素Co的相对含量和分布的均匀性进行了研究。研究结果表明:水热法合成的掺Co氧化锌晶体具有多种微观形貌,较大的晶体具有极性生长特性。随晶体形貌不同,显露面也发生了相应改变。不同微观形貌的晶体其Co含量有所差异,较大的晶体掺杂Co元素相对含量大于较小的晶体,+c(1011)显露面Co元素的含量比+c(1010)面高,锥柱状晶体其区别尤为明显。大的晶体内部存在着少量的氧化钴团簇,晶体表面与晶体内部Co元素分布相对均匀。由于Co2+具有磁性,因此,氧化钴团簇的存在将对氧化锌稀磁半导体晶体的磁性产生一定的影响。 相似文献