Impact of acidic catalyst to coat superparamagnetic magnesium ferrite nanoparticles with silica shell via sol-gel approach
Impact of acidic catalyst to coat superparamagnetic magnesium ferrite nanoparticles with silica shell via sol-gel approach
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DOI：
10.1016/j.apt.2016.02.009
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发表时间：
2016-03-01
影响因子：
5.2
通讯作者：
Wakiya, Naoki
中科院分区：
文献类型：
--
作者：
Das, Harinarayan;Arai, Takashi;Wakiya, Naoki
本文介绍了一种简单的方法，在超顺磁性铁酸镁（MgFe 2 O 4）纳米粒子表面包覆一层无定形二氧化硅。首先，核MgFe 2 O 4纳米粒子的合成从金属硝酸盐前驱体水溶液的超声喷雾热解（USP）技术。之后，通过溶胶-凝胶方法在所获得的颗粒表面上涂覆二氧化硅。在该反应中，正硅酸乙酯（TEOS）被用作二氧化硅的前体和HCl作为催化剂，并且已经发现酸性催化剂在纳米颗粒表面形成无定形二氧化硅层而不形成任何无核二氧化硅颗粒方面起重要作用。采用X射线衍射（XRD）、场发射电子显微镜（FESEM）、透射电子显微镜（TEM）、能谱仪（EDS）、电泳散射光度计、傅里叶变换红外光谱（FT-IR）和热重分析（TGA）等分析手段对产物的组成、形貌和结构进行了表征。结果表明，产物具有核壳结构，通过Fe-O-Si的化学键结合。二氧化硅厚度在30-50 nm的范围内，所得纳米球的总尺寸为200-300 nm。在振动样品磁强计（VSM）上进行了磁性测量，测量结果表明，MgFe 2 O 4纳米粒子在包覆SiO2后仍保持超顺磁性，但其Ms值明显小于未包覆样品。这种核/壳纳米复合材料由于具有核的超顺磁性和二氧化硅的独特性质，可用于多种应用，特别是在生物医学领域。(C)2016年日本粉末技术学会。由Elsevier B. V.和日本粉末技术协会出版。All rights reserved.
This paper describes a simple way for the coating of superparamagnetic magnesium ferrite (MgFe2O4) nanoparticles with amorphous silica layer. First, core MgFe2O4 nanoparticles were synthesized by ultrasonic spray pyrolysis (USP) technique from the aqueous metal nitrate precursor solution. Afterward, silica was coated on the obtained particles surface by a sol-gel approach. In this reaction, tetraethyl orthosilicate (TEOS) were used as precursor of silica and HCl as a catalyst, and it has been found that acidic catalyst plays an important role to form amorphous silica layer on nanoparticle surface without formation any core-free silica particles. The composition, morphology and structure of the products were characterized using different analysis technique such as X-ray diffraction (XRD), field emission electron microscopy (FESEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), electrophoretic scattering photometer, Fourier transform infrared (FT-IR) spectroscopy and thermogravimetric analysis (TGA), respectively. The results indicate that the product has a core-shell structure, which is combined through the chemical bond of Fe-O-Si. The silica thickness lies in the range of 30-50 nm with overall dimension of the resulting nanospheres 200-300 nm. Magnetic measurement were carried out on a vibrating sample magnetometer (VSM), and the measurement results indicate that MgFe2O4 nanoparticles remain superparamagnetic after coating with silica although their Ms values is significantly less than uncoated samples. This core/shell nanocomposite can be used for several applications especially in the biomedical field due to having superparamagnetic property of core and unique properties of silica. (C) 2016 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.