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1.
采用扫描电镜(SEM)、热重分析(TG)、傅里叶变换红外光谱(FTIR)及白度测试对三角帆蚌贝壳与其养殖的珍珠研磨粉进行了对比研究。结果表明:1珍珠粉的υ2谱带较于贝壳粉的该谱带存在约1~3cm-1的蓝移,两者文石中的υ1与υ4谱带具有较好的一致性;2 SEM观察下,粉体的颗粒粒径大小与形貌特征并不能作为贝壳粉与珍珠粉区分鉴别的依据。3随煅烧温度的升高,贝壳粉与珍珠粉的白度先下降后升高,珍珠粉白度降低的速率高于贝壳粉,且煅烧后珍珠粉的白度最低值低于煅烧贝壳粉的白度最低值。 相似文献
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Infrared and Raman spectra of CO[dbnd] 3 ions are different in the two crystallographic forms of CaCO3 Calcite and Aragonite owing to their different site symmetries. Due to this fact, i.r. has been used to assess the reversible Calcite ← → Aragonite transformation which occurs upon grinding of CaCO3, and much work has been done in this field in the last few years(1-4). In the present paper data are reported on Raman spectra of Calcite and Aragonite forms of CaCO3 produced by the above mechanical procedure. 相似文献
4.
Abstract Stable isotope (13C, 18O, 34S) and trace element (Sr2+, Mg2+, Mn2+, Ba2+, Na+) investigations of elemental sulfur, primary calcites and mixtures of aragonite with secondary, post-aragonitic calcite from sulfur-bearing limestones have provided new insights into the geochemistry of the mineral forming environment of the native sulfur deposit at Machów (SE-Poland). The carbon isotopic composition of carbonates (δ13C = ?41 to ?47‰ vs. PDB) associated with native sulfur (δ34S = + 10 to + 15‰ vs. V-CDT) relates their formation to the microbiological anaerobic oxidation of methane and the reduction of sulfate derived from Miocene gypsum. From a comparison with experimentally derived fractionation factors the element ratios of the aqueous fluids responsible for carbonate formation are estimated. In agreement with field and laboratory observations, ratios near seawater composition are obtained for primary aragonite, whereas the fluids were relatively enriched in dissolved calcium during the formation of primary and secondary calcites. Based on the oxygen isotope composition of the carbonates (δ18O = ?3.9 to ?5.9‰ vs. PDB) and a secondary SrSO4 (δ18O = + 20‰ vs. SMOW; δ34S = + 59‰ vs. V-CDT), maximum formation temperatures of 35°C (carbonates) and 47°C (celestite) are obtained, in agreement with estimates for West Ukraine sulfur ores. The sulfur isotopic composition of elemental sulfur associated with carbonates points to intense microbial reduction of sulfate derived from Miocene gypsum (δ34S ≈ + 23‰) prior to the re-oxidation of dissolved reduced sulfur species. 相似文献
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利用金刚石压腔结合拉曼光谱分析技术,研究了文石在18~388 ℃,71~2 014 MPa,以及方解石在19~351 ℃,96~1 823 MPa条件下的拉曼光谱特征,并得到文石和方解石的拉曼位移与温度、 压力三者之间的关系式。研究结果表明,文石和方解石的拉曼位移随温度压力的变化规律相似,都随压力升高向高频移动,除文石的704 cm-1外均随温度升高向低频移动。二者的晶格振动νi/T值均大于[CO3]基团内振动的值,说明CaO6八面体的热膨胀性大于[CO3]基团的热膨胀性。二者的对称伸缩振动ν/T及ν/P值不同,由于该振动拉曼位移和C—O键的键长有关,方解石的C—O键的热膨胀性比文石小而可压缩性比文石大。另外升温升压过程中文石和方解石可以相互转化,伴随该过程发生的[CO3]基团旋转变形等动力学因素也可以造成二者νi/T和νi/P值差异。 相似文献
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Butterfly-like calcium carbonate(CaCO3) particles were successfully prepared via a facile precipitation reaction of Na2CO3 with CaCl2 in the presence of sodium polyacrylate(PAAS). The as-prepared samples were characterized with field emission scanning electron microscopy(FESEM), X-ray diffraction(XRD) and Fourier transform infrared spectroscopy(FTIR). Butterfly-like CaCO3 particles composed of three segment rods were obtained. Rod aggregates would act as the template for butterfly-like CaCO3 crystals consisted of regular shaped crystallites with 150―200 nm in diameter. The influences of reaction temperature, the amount of PAAS and reaction time on the nucleation and growth of CaCO3 crystals were investigated. The possible growth mechanism of CaCO3 crystals was discussed. This research can not only make us further understand the general principles of the reaction, but also open up a new avenue of industrial production of CaCO3 particles with exquisite and unique morphologies. 相似文献
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翡翠贻贝珍珠层的XRD和FTIR光谱特征 总被引:3,自引:0,他引:3
对翡翠贻贝贝壳的珍珠层、棱柱层进行了XRD和FTIR光谱检测,对文石的ν1,ν2及ν4三个内振动模式的频率进行了分析。文石的ν1和ν4带在所有的样品中不存在频率位移现象,与洞穴文石的相关谱带的频率一致;ν2带频率却存在较大差异,珍珠层、棱柱层的ν2带存在频率位移,初步推测生物合成文石与热效应有关,内部储存有过剩的能量,可作为研究生物矿化机理的实验依据。 相似文献
8.
天然文石质陶瓷-三角帆蚌贝壳的FTIR光谱研究 总被引:2,自引:1,他引:1
三角帆蚌贝壳珍珠层及韧带经粉末XRD分析证实均由文石组成。对珍珠层及韧带的FTIR光谱进行了测量和对比分析。结果表明:(1)文石的ν2,ν3带显示了较大的变化,相对韧带而言,珍珠层文石的ν2带频率蓝移6.5 cm-1,而ν3带却红移22.7 cm-1;(2)珍珠层文石的ν2,ν3带半高宽分别比韧带文石宽1倍左右。相比之下,珍珠层及韧带文石的ν1,ν4带的特征基本没有发生变化。文石红外光谱的这种各向异性的变化可能是由文石的粒径效应引起的。 相似文献
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Michael E. Böttcher Nadja Neubert Katja von Allmen Elias Samankassou Thomas F. Nägler 《Isotopes in environmental and health studies》2018,54(3):324-335
In this study, we present the experimental results for stable barium (Ba) isotope fractionation (137Ba/134Ba) during the transformation of aragonite (CaCO3) and gypsum (CaSO4·2H2O) in Ba-bearing aqueous solution to witherite (BaCO3) and barite (BaSO4), respectively. The process was studied at three temperatures between 4 and 60?°C. In all cases, the transformation leads to a relative enrichment of the lighter 134Ba isotope in the solid compared to the aqueous solution, with 137/134Ba enrichment factors between –0.11 and ?0.17?‰ for BaCO3, and –0.21 and –0.26?‰ for BaSO4. The corresponding mass-dependent 138/134Ba enrichment factors are ?0.15 to –0.23?‰ for BaCO3, and –0.28 to –0.35?‰ for BaSO4. The magnitude of isotope fractionation is within the range of recent reports for witherite and barite formation, as well as trace Ba incorporation into orthorhombic aragonite, and no substantial impact of temperature can be found between 4 and 80?°C. In previous studies, ion (de)solvation has been suggested to impact both the crystallization process of Ba-bearing solids and associated Ba isotope fractionation. Precipitation experiments of BaSO4 and BaCO3 using an methanol-containing aqueous solution indicate only a minor effect of ion and crystal surface (de)solvation on the overall Ba isotope fractionation process. 相似文献
10.
Jolivet A Bardeau JF Fablet R Paulet YM de Pontual H 《Analytical and bioanalytical chemistry》2008,392(3):551-560
It is generally accepted that the formation of otolith microstructures (L- and D-zones) and in particular the organic and
mineral fractions vary on a daily basis. Raman microspectrometry provides a nondestructive technique that can be used to provide
structural information on organic and mineral compounds. We applied it to thin otolith sections of hake in order to address
the following issues: (1) the simultaneous characterization of variations in the organic and mineral fractions both in the
core area and along successive otolith microstructures; (2) elucidation of significant differences between these fractions;
(3) quantification of the effects of etching and staining protocols on otolith structures. The primordium appeared as a punctual
area depicting higher luminescence and greater concentrations in organic compounds containing CH groups. Sulcus side showed
similar composition suggesting that the contact of the otolith with the macula and its orientation in otosac occur rapidly
(about 10 days). The characterization of L- and D-zones in the opaque zones indicated that both structures contained organic
and aragonitic fractions with cyclic and synchronous variations. Contrary to the results obtained after EDTA etching, L-zones
depicted greater concentrations in organic compounds containing CH groups, whereas D-zones appear richer in aragonite. This
organic fraction seemed to be revealed by Mutvei’s staining and was affected by EDTA etching which suggests that it corresponds
to the soluble fraction of organic matrix. Such results indicate that L- and D-zones differ in their respective organic constituents.
Raman microspectrometry thus appears as a powerful technique to acquire quantitative information that is required for a better
understanding of otolith biomineralization.
Figure Raman microspectrometry is a powerful technique for studying otolith biomineralization 相似文献