ABSTRACT

Silica coated cobalt ferrite (CoFe₂O₄:SiO₂) nanocomposites were synthesized by co-precipitation technique using metal nitrates as precursors. The as-prepared samples were heat treated at different temperatures of 250⁰C, 500⁰C and 750⁰C for 24 hrs. Structural, thermal and morphological behaviour of nanocomposites are investigated by XRD, FTIR, TGA-DTG and SEM characterization results, useful in biomedical applications. With increasing calcinations temperature from250 ⁰C to 500 ⁰C and 750 ⁰C an increase in crystallite size of CoFe₂O₄:SiO₂ nanocomposites has been determined from 20.26nm to 28.95nm and 38.76 nm by Williamson-Hall method respectively. Furthermore, by increasing the temperature from 250 ⁰C to 750 ⁰C the lattice parameter and strain values have been found to increase from 8.0321 Å to 8.0691 Å and 1.01 x10⁻² to 3.75 x10⁻³ respectively. Analysis of TGA results found no weight loss when the sample was heated beyond 700⁰C and thus complete decomposition of precursors has led to the formation of stable nanocomposite structures at high temperatures. SEM analysis of synthesized samples at 750 ⁰C revealed well developed nanoparticles of CoFe₂O₄: SiO₂ with inter-granular porosity.

摘要

以金属硝酸盐为前驱体，通过共沉淀技术合成了二氧化硅包覆的钴铁氧体（CoFe ₂ O ₄：SiO ₂）纳米复合材料。将所制备的样品在250 ⁰ C，500 ⁰ C和750 ⁰ C的不同温度下热处理24小时。通过XRD，FTIR，TGA-DTG和SEM表征结果研究了纳米复合材料的结构，热学和形态学行为，这些结果可用于生物医学应用。随着煅烧温度从250 ⁰ C升高到500 ⁰ C和750 ⁰ C，CoFe ₂ O _4的微晶尺寸增加 通过Williamson-Hall法分别测定了：SiO ₂纳米复合材料的波长为20.26nm至28.95nm和38.76nm。此外，通过将温度从250 ⁰ C增加到750 ⁰ C，已发现晶格参数和应变值分别从8.0321Å增加到8.0691Å和从1.01 x10 ^-2增加到3.75 x10 ^-3。对TGA结果的分析发现，当样品加热到700 ⁰ C以上时，重量没有损失，因此前体的完全分解已导致在高温下形成稳定的纳米复合结构。合成样品在750 ⁰ C的SEM分析显示出CoFe _2的纳米颗粒发育良好 O ₄：具有粒间孔隙的SiO ₂。