ABSTRACT

Natural pyrrhotites have gained significant attention due to their interesting electronic, antimicrobial, and chemical properties. The present work attempts to explore the morphology-induced modifications in the thermal characteristics of natural pyrrhotite due to ageing. The morphological, elemental, structure, optical, and thermal characterisations help in understanding the effect of ageing. The effects of five years of ageing of the sample are (i) Field Emission Scanning Electron Microscopic analysis reveals a morphological transformation from flakes to agglomerated powder, (ii) elemental analyses suggest the ageing induced compositional modification (iii) the Tauc plot analysis shows a bandgap energy modification from 1.46 eV to 1.92 eV, (iv) X-ray Diffraction (XRD), Fourier Transform Infrared, and X-ray photoelectron spectroscopic studies affirm the formation of oxy-hydroxides (v) the XRD data indicates an increase of dislocation density, and (vi) Photoluminescence study shows a deep violet emission evidenced through the CIE plot. The study by the thermal lens technique shows a lowering of thermal diffusivity study by 23%, due to the morphological modifications, adsorbed/chemisorbed hydroxyl groups, and the formation of secondary compounds due to oxidation and weathering. The phonon boundary scattering, weathering induced smaller grain size, reduced phonon mean free path, and point defects also account for the lowering of the thermal diffusivity value and thereby influencing its properties.

抽象的

天然黄铁矿由于其有趣的电子，抗菌和化学特性而受到了广泛的关注。目前的工作试图探索由于老化引起的天然黄铁矿的热特性的形态诱导的改性。形态，元素，结构，光学和热学特征有助于理解老化的影响。样品五年老化的影响是（i）场发射扫描电子显微镜分析揭示了从片状到团聚粉末的形态转变，（ii）元素分析表明了老化引起的成分变化（iii）Tauc图分析显示将带隙能量从1.46 eV修改为1.92 eV，（iv）X射线衍射（XRD），傅立叶变换红外，X射线光电子能谱研究证实了羟基氧化物的形成（v）XRD数据表明位错密度增加，（vi）光致发光研究表明深紫色发射通过CIE图得到证明。通过热透镜技术进行的研究表明，由于形态变化，吸附/化学吸附的羟基以及由于氧化和老化而形成的次级化合物，热扩散率研究降低了23％。声子边界散射，风化引起的晶粒尺寸减小，声子平均自由程减小以及点缺陷也导致热扩散率值降低，从而影响其性能。（vi）光致发光研究表明，通过CIE曲线可以证明有深紫色发射。通过热透镜技术进行的研究表明，由于形态变化，吸附/化学吸附的羟基以及由于氧化和老化而形成的次级化合物，热扩散率研究降低了23％。声子边界散射，风化引起的晶粒尺寸减小，声子平均自由程减小以及点缺陷也导致热扩散率值降低，从而影响其性能。（vi）光致发光研究表明，通过CIE曲线可以证明有深紫色发射。通过热透镜技术进行的研究表明，由于形态变化，吸附/化学吸附的羟基以及由于氧化和老化而形成的次级化合物，热扩散率研究降低了23％。声子边界散射，风化引起的晶粒尺寸减小，声子平均自由程减小以及点缺陷也导致热扩散率值降低，从而影响其性能。