In recent years, infrared radiation materials have received extensive attention. In this study, a kind of natural carbonate rock was highlighted and its radiation mechanism investigated, using a series of mineralogical and spectroscopy studies such as optical microscope, varying-temperature X-ray diffraction (XRD), Raman spectroscopy, X-ray fluorescence spectrometer (XRF), inductively coupled plasma mass spectrometry (ICP-MS), electron microprobe analysis (EMPA), thermogravimetry, differential thermal analysis (TG/DTA), environment scanning electron microscopy (ESEM) and infrared absorption and emission spectroscopy (IR). Results indicated that micro-nanoscale calcite (95%), graphite (3%) and pyrite (0.1%) were the primary components. Additionally, Sr 2+ and Mg 2+ were found to substitute Ca 2+ in calcite, whose content could reach 0.145% and 0.152% (wt%), respectively. On the basis of blackbody radiation theory and the radiation energy spectrum of samples from 400 to 2000 cm −1 , the average emissivity of this rock, pure calcite, pyrite and graphite was calculated as 1.007, 0.986, 0.899 and 0.488, respectively, in the temperature range of 50–140 °C. Notably, the radiation energy spectrum calculated emissivity and emission spectrum of calcite showed high consistency with the natural carbonate at all temperatures, indicating that the radiation performance of the rock was principally contributed to calcite. The heat capacity of three components presented a positive correlation with their infrared emissivity values within the temperature and wavelength of this study. The highest heat capacity of calcite benefited the enhancement of the whole thermal radiation performance of carbonate rock. The vibration of C–O bonds in the narrow absorption band of emission spectrum (1350–1500 cm −1 ) would lead to relatively high radiation energy and emissivity. In addition, the substitution of Mg 2+ and Sr 2+ for Ca 2+ improved the infrared radiation characteristics due to the 6–8% enhancement of average emissivity for pure MgCO 3 and SrCO 3 compared to CaCO 3 . This study can provide theoretical reference for infrared radiation material, using abundant and cheap natural minerals on the Earth as a source of raw materials for infrared functional materials.

中文翻译：

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一种天然碳酸盐的红外发射特性：矿物学分析解释

近年来，红外辐射材料受到广泛关注。本研究通过光学显微镜、变温 X 射线衍射 (XRD)、拉曼光谱、X 射线荧光光谱仪等一系列矿物学和光谱学研究，重点研究了一种天然碳酸盐岩，并研究了其辐射机制。 (XRF)、电感耦合等离子体质谱 (ICP-MS)、电子探针分析 (EMPA)、热重分析、差热分析 (TG/DTA)、环境扫描电子显微镜 (ESEM) 和红外吸收和发射光谱 (IR)。结果表明，微纳米级方解石（95%）、石墨（3%）和黄铁矿（0.1%）是主要成分。此外，发现Sr 2+ 和Mg 2+ 替代方解石中的Ca 2+ ，其含量可达0.145%和0。分别为 152% (wt%)。根据黑体辐射理论和400~2000 cm -1 样品的辐射能谱，计算出该岩石、纯方解石、黄铁矿和石墨的平均发射率分别为1.007、0.986、0.899和0.488。温度范围为 50–140 °C。值得注意的是，辐射能谱计算的发射率和方解石的发射光谱在所有温度下都与天然碳酸盐具有高度一致性，表明岩石的辐射性能主要由方解石贡献。在本研究的温度和波长范围内，三种成分的热容量与其红外发射率值呈正相关。方解石的最高热容有利于碳酸盐岩整体热辐射性能的增强。C-O 键在发射光谱的窄吸收带（1350-1500 cm -1 ）中的振动会导致相对较高的辐射能量和发射率。此外，由于纯 MgCO 3 和 SrCO 3 的平均发射率比 CaCO 3 提高了 6-8%，用 Mg 2+ 和 Sr 2+ 代替 Ca 2+ 改善了红外辐射特性。该研究可为红外辐射材料提供理论参考，利用地球上丰富而廉价的天然矿物作为红外功能材料的原料来源。由于纯 MgCO 3 和 SrCO 3 的平均发射率比 CaCO 3 提高了 6-8%，用 Mg 2+ 和 Sr 2+ 代替 Ca 2+ 改善了红外辐射特性。该研究可为红外辐射材料提供理论参考，利用地球上丰富而廉价的天然矿物作为红外功能材料的原料来源。由于纯 MgCO 3 和 SrCO 3 的平均发射率比 CaCO 3 提高了 6-8%，用 Mg 2+ 和 Sr 2+ 代替 Ca 2+ 改善了红外辐射特性。该研究可为红外辐射材料提供理论参考，利用地球上丰富而廉价的天然矿物作为红外功能材料的原料来源。