Preparation and characterization of uniform coated particles (Cobalt compounds on cadmium compounds)

Uniformly dispersed particles of CdCO₃ were prepared by homogeneous precipitation from aqueous solutions of cadmium sulphate and urea at the elevated temperatures. These particles were then employed as cores for coating with 2CoCO₃·Co(OH)₂·H₂O from cobalt nitrate and urea solutions at 85°C. In the absence of cores, when heated under similar conditions, the coating solutions produced nearly uniform particles of 2CoCO₃·Co(OH)₂·H₂O. On calcination at 700°C, the core [CdCO₃], coated [CdCO₃/2CoCO₃·3Co(OH)₂], and coating precursor [2CoCO₃·Co(OH)₂·H₂O] particles transformed into CdO, CdO/Co₃O₄, and Co₃O₄, respectively. No sintering occurred during calcination and the particles preserved their morphological features to a significant extent.     

Synthesis and characterization of electroless Ni-P coated graphite particles

Electroless alkaline bath is used to coat Ni-P graphite particles of average size, 150 μm. Amorphous nickel and graphite phases are observed in X-ray diffraction of the coated particles. The crystallite size from diffraction peaks is found to be 9·56 nm. The microstructural studies are carried out with field emission scanning electron microscope (SEM) on the uncoated and coated graphite particles. Uncoated particles showed irregular and fractured surfaces while the surface of coated particles revealed the presence of Ni-P globules. Sizes of Ni-P globules are observed to be in the range 175–250 nm. The presence of Ni and P are confirmed by the energy dispersive spectrometer results. The effect of coating bath composition is studied and an increasing trend in deposition is observed up to 50 gl⁻¹ of stabilizer as well as up to 20 gl⁻¹ of the reducing agent, however, the trend reverses afterwards. The phenomena of nucleation and growth of the Ni-P layer over the graphite surface have been demonstrated through SEM studies and a model has been proposed to demonstrate the growth mechanism of Ni-P globules.     

Synthesis and characterization of uniform fine particles of copper oxalate

Copper oxalate particles were synthesized in various shapes and sizes by mixing appropriate volumes of known concentration of oxalic acid and copper nitrate at 25 and 85 °C. Temperature and reactants concentration had significant effect on the morphology of the precipitated particles and therefore extensive optimizations of the experimental parameters were carried out in order to obtain maximum uniformity in particles' morphological features. Selected batch of the copper oxalate particles was characterized by various physical methods.     

Synthesis and properties of a copper(I) cobalt(II) double sulfite

The Pourbaix diagrams of the Cu–H₂SO₄–H₂O and Co–H₂SO₄–H₂O systems have been refined and the stability regions of sulfite phases in the diagrams have been identified. Phase diagrams of copper(I) copper( II) and copper(I) cobalt(II) double sulfites have been mapped out. The double sulfites Cu₂SO₃ · СuSO₃ and Cu₂SO₃ · СoSO₃ have been isolated from an aqueous solution saturated with sulfur dioxide. We have obtained electron paramagnetic resonance spectra of the double sulfite Cu₂SO₃ · СoSO₃ and characterized it by X-ray diffraction, IR spectroscopy, particle size analysis, and thermogravimetry. A foundation has been laid for the thermodynamic prediction of the synthesis of the Cu₂SO₃ · MSO₃ (M = Cu, Co) double sulfites.     

Synthesis and characterization of the iron oxide magnetic particles coated with chitosan biopolymer

Magnetic particles are extremely interesting for several biomedical applications; amongst these are therapeutic applications, such as: hyperthermia and release of drugs. The use of magnetic particles to induce hyperthermia in biological tissues is an important factor in cancer therapy. The aim of this study was to prepare and characterize iron oxide magnetic particles coated with biopolymer chitosan, and also to produce ferrofluids from the magnetic particles. The iron oxide magnetic particles (IOMP) were coated with chitosan (CS) by spray-drying method using two IOMP/coating ratios (IOMP/CS = 1.6 and IOMP/CS = 4.5). The magnetic particles were characterized by way of scanning electronic microscopy and energy-dispersive X-ray. The analysis by energy-dispersive X-ray was carried out to determine the chemical composition of particles in samples. The size distribution the iron oxide magnetic particles uncoated and coated were evaluated by the laser diffraction analysis and image analysis, respectively. Amongst the prepared ferrofluids, the sample IOMP/CS = 1.6 proved to be the one that has brought about the best results in therapeutics applications, such as in hyperthermia treatment. This sample was placed within an alternating magnetic field during 40 min, it was observed that 1 °C heated in 3 min and underwent a temperature variation of 7 °C, since it varied from 25 °C to 32 °C. Considering that the experiment would be carried out at body temperature 37 °C, probably, the temperature variation would be very close to the one reported at 25 °C. In such a way, the cancerous cells would reach 44–45 °C and at such temperatures the cancer cells generally perish.     

Co链状结构的制备及其表征

以氯化钴，水合肼为起始原料，乙二醇为溶剂，采用溶剂热法制得链状结构的金属钴亚微米粒子。通过X射线衍射分析标定了获得样品的物相为六角堆积（hcp）结构，用透射及扫描电镜观察了样品的形貌，颗粒具有链状结构，长达数微米，构成长链结构的亚微米粒子为球形，粒径约为800hm左右。用振动样品磁强计表征了样品的静磁性能，测得的饱和磁化强度为163．76emu/g，矫顽力为104．20×79．6A/m。同时简要探论了链状结构的钴亚微米粒子形成机理，初步认为其形成过程是一个络合-还原-成核-组装的过程。     

Synthesis and characterization of ultrafine poly(vinylalcohol phosphate) coated magnetite nanoparticles

Nanosized magnetite (Fe3O4) particles showing superparamagnetism at room temperature have been prepared by controlled coprecipitation of Fe2+ and Fe3+ in presence of highly hydrophilic poly(vinylalcohol phosphate)(PVAP). The impact of polymer concentration on particle size, size distribution, colloidal stability, and magnetic property has been extensively studied. The aqueous suspension of magnetite, prepared using 1% PVAP solution is stable for four weeks at pH 5-8. X-ray diffractograms show the formation of nanocrystalline inverse spinel phase magnetite. Transmission Electron Microscopy confirmed well dispersed cubic magnetite particles of size of about 5.8 nm. Dynamic Light Scattering measurement shows narrow distribution of hydrodynamic size of particle aggregates. Infrared spectra of samples show strong Fe--O--P bond on the oxide surface. UV-visible studies show aqueous dispersion of magnetite formed by using 1% PVAP solution is stable at least for four weeks without any detoriation of particle size. Magnetization measurements at room temperature show superparamagnetic nature of polymer coated magnetite nanoparticles.     

Synthesis and characterization of zinc oxide fine particles coated with titania/PDMS hybrid

Zinc oxide nanoparticles were coated with titania/polydimethylsiloxane hybrid by co-hydrolysis and co-condensation of the sols prepared from titanium tetraisopropoxide and methoxy-functionalized polydimethylsiloxane to synthesize a new class of hierarchically designed composite materials. The successful formation of the shell, which is composed of titania/polydimethylsiloxane hybrid, was evidenced by SEM, TEM, IR, EDS and zeta potential data. The hydrophobicity and the dispersibility in decamethylcyclopentasiloxane changed dramatically by the shell formation.     

Synthesis and characterization of novel Ag-polypyrrole@poly(styrene-co-methacrylic acid) nanocomposite particles

Novel raspberry-like Ag-polypyrrole/poly(styrene-co-methacrylic acid) (Ag-PPy/P(St-co-MAA)) colloidal nanocomposite particles were prepared by aqueous oxidative polymerization of pyrrole using AgNO₃ as the oxidant. The polymerization was carried out in the pre-synthesized polymer-emulsion of P(St-co-MAA) with emulsifier-free P(St-co-MAA) latex particles serving as both the templates and the stabilizers. Without any extra surfactants or polymer stabilizers, the polymerization proceeded steadily with the in-situ produced Ag-PPy nanocomposites depositing on the surface of the template particles. The obtained product is typical of raspberry-like morphology, whose nanostructures and compositions were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), powder X-ray diffraction (XRD) and electron dispersive X-ray spectrometer (EDS), respectively. The results confirmed that the surface of the P(St-co-MAA) latex was coated by Ag-PPy nanocomposite particles with a size range from 2 nm to 50 nm. Most of Ag nanoparticles are encapsulated by the PPy sheath or dispersed in the PPy layer.     

碳包覆铁碳化合物的爆轰合成及表征

以Fe（NO3）3，CO（NH2）2和萘为原料，掺入一定量黑索金（RDX），在真空的爆炸容器中引爆，从而制备出碳包覆铁碳化合物的纳米材料。通过XRD，TEM以及Raman等检测手段对所得爆轰产物进行表征。结果表明，产物由碳包覆Fe2.5C以及富勒烯组成，其中，包覆结构以无定型碳作为外壳，将Fe2.5C内核完全包覆起来。利用爆轰法制备碳包覆材料，方法简单、迅速，节省能源。     

Synthesis and characterization of copper nanoparticles

Reduction of copper salt by sodium citrate/SFS and myristic acid/SFS leads to phase pure Cu nanoparticles. However, a similar reaction with hydrazine hydrate (HH) and sodium formaldehyde sulfoxylate (SFS) in polymer afforded only a mixture of Cu₂O and Cu. Copper nanoparticles so-prepared were characterized by UV-Visible spectroscopy, X-ray diffraction measurements (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Freshly prepared solutions showed an absorption band at about 600 nm due to surface plasmon resonance (SPR). XRD analysis revealed all relevant Bragg's reflection for fcc crystal structure of copper metal. The particle size by use of Scherrer's equation is calculated to be about 30 nm. TEM showed nearly uniform distribution of the particles in PVA.     

Synthesis and characterization of biocompatible hydroxyapatite coated ferrite

Ferrite particles coated with biocompatible phases can be used for hyperthermia treatment of cancer. We have synthesized substituted calcium hexaferrite, which is not stable on its own but is stabilized with small substitution of La. Hexaferrite of chemical composition (CaO)_0.75(La₂0₃)_0.20(Fe₂O₃)₆ was prepared using citrate gel method. Hydroxyapatite was prepared by precipitating it from aqueous solution of Ca(NO₃)₂ and (NH₄)₂HPO₄ maintaining pH above 11. Four different methods were used for coating of hydroxyapatite on ferrite particles. SEM with EDX and X-ray diffraction analysis shows clear evidence of coating of hydroxyapatite on ferrite particles. These coated ferrite particles exhibited coercive field up to 2 kOe, which could be made useful for hysteresis heating in hyperthermia. Studies by culturing BHK-21 cells and WBC over the samples show evidence of biocompatibility. SEM micrographs and cell counts give clear indication of cell growth on the surface of the sample. Finally coated ferrite particle was implanted in Kasaulli mouse to test its biocompatibility. The magnetic properties and biocompatibility studies show that these hydroxyapatite coated ferrites could be useful for hyperthermia.     

SiO2／Ag核壳复合粒子的制备与表征

首次引入活性SiO2微球作为核基，采用自组装液相还原技术，定向的在核基上沉积纳米银颗粒得到SiO2／Ag核壳复合粒子；并用红外、x射线衍射、场发射扫描电镜、能谱等分析表征该核壳复合粒子的形貌与结构。结果表明：利用活性SiO2作为核基，pH值为12．4，有表面活性剂参与的条件下，通过改变银前驱体浓度，可实现表面包覆致密、银壳厚度可控的核壳复合粒子化学制备技术。     

羟基磷灰石的可控制备及其研究

以CTAB为表面活性剂,利用模板技术水热反应合成了平均粒径为68 nm的近球形颗粒和宽为26～35 nm,长为790～960 nm的纳米羟基磷灰石.通过对合成粉体的X射线衍射、红外光谱和透射电镜分析,探讨了CTAB在水热反应中对羟基磷灰石合成的影响机理.结果表明:通过控制反应温度、pH值、反应时间和CTAB的浓度等工艺条件,可以实现纳米羟基磷灰石粒径大小和形貌的可控生长.     

Synthesis of uniformly porous NiO/ZrO2 particles

Porous NiO-ZrO₂ particles were successfully synthesized using a spray-drying method with polystyrene latex (PSL: 400 nm) as a template and starting materials that included NiO powder (7 nm) and ZrO₂ sol (1.2 nm). Porous particles with an average diameter of 4.5 μm and nearly spherical, narrow pores with an average size of ∼300 nm were obtained from the precursor at a pH of 3.7. The Brunauer, Emmett and Teller (BET) surface area of the prepared particles was relatively high—about 27 m²/g. When the solution pH was increased to 9.7, the particle morphology became completely spherical, indicating that the morphology of prepared particles can be controlled by adjusting the pH. Calcinations at 900 and 1200 °C were carried out to estimate the thermal stability of the prepared particles, which had shrinkage of less than 36%. The existence of these pores means that various applications, such as electrodes and catalysts, will be possible for the prepared particles.     

Synthesis and characterization of different nanostructures of cobalt phosphate

In this research, different nanostructures of cobalt phosphate were successfully prepared. Flowerlike cobalt phosphate and platelike ammonium cobalt phosphate were made by coprecipitation method without any use of surfactant or capping agent as structure directors. Reverse micelle route in water/CTAB/n-hexanol microemulsion system was used to synthesize cobalt phosphate nanoparticles. The synthesized nanostructures were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), chemical analysis, and BET. The SEM images showed that the flowerlike nanostructure is an arrangement of cobalt phosphate plates. TEM images revealed that the nanoparticles are spherical with the diameter of 30-50 nm. The purity of cobalt phosphate nanoparticles was confirmed by chemical analysis. Finally, the possible mechanisms which can describe the formation of these nanostructures were discussed.     

Synthesis and characterization of antimony-doped tin oxide (ATO) with nanometer-sized particles and their conductivities

This study focused on finding the optimum conditions for displaying higher conductivity in an ATO-PET film prepared using the solvothermal method. The conductivity of the ATO film with Sb1.5:Sn8.5 increased to 800 °C calcinations. It did not, however, increase further even though the calcinations were at a temperature above 1000 °C. The average grain size measured from the FESEM micrographs was distributed within a 5.0-nm (at 400 °C) to 50.0-nm (at 1000 °C) range. It was determined from the XRD results that the special peaks assigned to the SnO₂ tetragonal type dominated until 1000 °C in the ATO particles with Sb1.5:Sn8.5. It was also confirmed that the hydrophilicity (the T–OH/T–O ratio was larger) of the ATO nano-particle with Sb1.5:Sn8.5 was largest at 600 °C calcinations. Its binding energy remarkably increased at 1000 °C calcination. In various Sb:Sn mole ratios, the conductivity was at its best in ATO films (for Sb1.5:Sn8.5) with 600 °C calcinations, 9.0×10⁵ (Ω/□). When 1,4-butanediol was used as a solvent, the conductivity of the ATO film was enhanced and the ATO film exhibited higher distribution than the other solvents did. The conductivity of the ATO film prepared in basic conditions (pH=10.0) was enhanced compared to those in acidic conditions.     

Processing and characterization of activated carbon coated magnetic particles for biomedical applications

Synthesis and characterization of Magnetically Targeted Carrier (MTC) powders consisting of activated carbon coated iron particles were carried out. Powders with activated carbon content of 5% by weight (Fe5C) and 35% by weight (Fe35C) were studied. Powders were synthesized via the high energy ball milling route, and the influence of milling time on the morphology, magnetic properties and drug adsorption and desorption characteristics was investigated. Physical and structural characterization included electron microscopy, size analysis, and X-ray diffraction. The magnetic properties, and theophylline adsorption and desorption characteristics were studied. Fe35C milled for 10 h was found to be a suitable candidate for MTC applications with fine size, stable magnetic properties, and superior drug adsorption and desorption behavior.