scholarly journals Influence of CNTs, ZnO, Gd2O3 and SiO2 on Calcium Silicate Hydrate: A Raman spectroscopic study

Author(s):  
Muhammad Azeem

Abstract Raman spectra are collated from the cement paste matrices of CNTs, ZnO, Gd2O3, and SiO2. The spectra show that CNTs do not take part in hydration process and therefore concentration of calcium silicate hydrate (CSH) is unchanged in CNT-OPC matrix. The metal oxides, on the other hand, have shown significant effects on the CSH concentration. The CSH concentration increases with the increase of ZnO weight percent in the matrix whereas spectra collected from Gd2O3 matrix shows the strongest CSH vibrational bands. Moreover, vibrational bands of CaCO3 also become weak in the matrices with Gd2O3. The addition of SiO2 however had opposite effects that is by increasing the weight percent of SiO2 in the matrix, the CSH concentration is decreased. Since CSH acts a glue in a binder, the study shows that its concentration can be controlled by adding foreign elements. Such binders are expected to show improved strength and durability.

2021 ◽  
Vol 33 (3) ◽  
pp. 283-297
Author(s):  
Evgeniy Nikolaevich Kozlov ◽  
Ekaterina Nikolaevna Fomina ◽  
Vladimir Nikolaevich Bocharov ◽  
Mikhail Yurievich Sidorov ◽  
Natalia Sergeevna Vlasenko ◽  
...  

Abstract. Raman spectra of three natural carbonophosphates (sidorenkite, bonshtedtite, and bradleyite) with the general formula Na3MCO3PO4 (M is Mn, Fe, and Mg) were studied and compared. These spectra showed from 21 to 24 vibrational bands, of which the two most intense (964±5 and 1074±3 cm−1) correspond to the υ1(P–O) and υ1(C–O) modes. These two bands split into doublet peaks due to the occurrence of isomorphic impurities. It was found that the crystallographic orientation of the sample influences the intensity of most bands. Most bands assigned to the same vibrations showed a regular shift (the smallest in sidorenkite spectra, an intermediate in bonshtedtite, and the largest in bradleyite). We propose an algorithm that allows for diagnostics of carbonophosphates in inclusions by their Raman spectra, providing a reliable result even in the absence of energy-dispersive X-ray spectroscopy (EDX) data.


2021 ◽  
Author(s):  
Ekaterina Fomina ◽  
Evgeniy Kozlov ◽  
Mikhail Sidorov ◽  
Vladimir Bocharov

<p>Along with some other Na-minerals, carbonophosphates indicate a high initial Na activity in carbonatite and kimberlite melts, which is beneficial for petrological reconstructions. Because carbonophosphates are capable of incorporating large-ion lithophile and rare earth elements (REEs) in their structure, they can participate in the transport of these elements. Moreover, due to the presence of both [PO<sub>4</sub>]<sup>3−</sup> and [CO<sub>3</sub>]<sup>2− </sup>groups in carbonophosphates, these mineral phases play an important role in the Earth's global carbon and phosphate cycles. With all these properties, carbonophosphates have long attracted the attention of geologists. Raman spectroscopy appears to be one of the most suitable tools for their diagnosis, since they commonly present in rocks as small inclusions in other mineral grains. Despite this profit, only a few publications contain Raman characteristics of either natural or synthetic carbonophosphates.</p><p>We studied and compared Raman spectra of three natural carbonophosphate phases (sidorenkite, bonshtedtite, and bradleyite) with the general formula Na<sub>3</sub>MCO<sub>3</sub>PO<sub>4</sub> (M = Mn, Fe, and Mg, correspondingly). These spectra showed from 21 to 24 vibrational bands, of which the two most intense (963±5 cm<sup>-1</sup> и 1074±3 cm<sup>-1</sup>) correspond to the ν1(P–O) and ν1(C–O) modes. These two bands split due to the occurrence of isomorphic impurities. It was found that the crystallographic orientation of the sample influences the intensity of most bands. A natural increase in the Raman shift was observed for most bands assigned to the same vibrations (the smallest shift in the spectrum is characteristic of sidorenkite, an intermediate - of bonshtedtite, and the largest - of bradleyite).</p><p>We propose the following algorithm for the diagnosis of carbonophosphates:</p><ul><li>Checking minerals for belonging to the group of carbonophosphates by the main bands and the characteristic profile of the spectrum;</li> <li>Testing the hypothesis that the mineral of question is bradleyite based on the analysis of the estimated shift of the main bands;</li> <li>Diagnosis of a mineral species by peaks located between the main bands;</li> <li>Validation of the diagnostics by considering the position of the bands at 185±9 cm<sup>-1</sup>, 208±7 cm<sup>-1</sup>, 255±5 cm<sup>-1</sup>, and 725±6 cm<sup>-1</sup>.</li> </ul><p>The proposed algorithm allows one to perform Raman diagnostics of carbonophosphates in inclusions even in the absence of EPMA data. In the study of carbonatites, kimberlites, and other rocks, the diagnostics of the mineral species of the carbonophosphate group can be important in the petrological aspect.</p><p>This research was funded by the Russian Science Foundation, grant number 19-77-10039.</p>


1987 ◽  
Vol 65 (3) ◽  
pp. 491-496 ◽  
Author(s):  
Serge Alex ◽  
Rodrigue Savoie

A systematic Raman spectroscopic investigation of the complexation of CH3Hg+ by the standard amino acids is reported. It is shown that the vibrational bands due to the ligand—Hg and Hg—CH3 stretching modes and to the symmetric —CH3 bending mode of the —HgCH3 unit are well suited to characterize the extent of complexation and the sites of attachment of the cation. Coordination, which occurs mostly on sulfur and nitrogen atoms by substitution of a proton on the thiol group of cysteine or on amino groups in general, is best identified by the frequency of the ligand—Hg stretching vibration in the 250–550 cm−1 region of the spectrum.


2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Felipe Basquiroto de Souza ◽  
Ezzatollah Shamsaei ◽  
Shujian Chen ◽  
Kwesi Sagoe-Crentsil ◽  
Wenhui Duan

AbstractOptimising the mesoscale structure of calcium-silicate-hydrate (C-S-H) is critical to achieving durable and sustainable infrastructure using Portland cement concrete. However, control of its intricate formation process, which comprises spatially disordered growth of poorly-crystalline sheets, remains a challenge. Here, through combination of experimental and computer simulation techniques, we report a promising mechanism to control this complex growth process and thereby optimise the C-S-H nanostructure. The pivotal step was utilizing graphene oxide (GO) to restrain the inherent spatial deformations of the C-S-H sheets and guide their concurrent 2D growth and layer-by-layer ordering. Accordingly, we designed a layered GO–C-S-H composite that exhibits 1–2 orders of magnitude improvement in strength and durability compared with C-S-H formed without control. Our findings open a window for nano-engineering of cements and other complex layered materials for ceramic, pharmaceutical and energy applications.


2014 ◽  
Vol 6 (2) ◽  
pp. 46-51
Author(s):  
Galang Amanda Dwi P. ◽  
Gregorius Edwadr ◽  
Agus Zainal Arifin

Nowadays, a large number of information can not be reached by the reader because of the misclassification of text-based documents. The misclassified data can also make the readers obtain the wrong information. The method which is proposed by this paper is aiming to classify the documents into the correct group.  Each document will have a membership value in several different classes. The method will be used to find the degree of similarity between the two documents is the semantic similarity. In fact, there is no document that doesn’t have a relationship with the other but their relationship might be close to 0. This method calculates the similarity between two documents by taking into account the level of similarity of words and their synonyms. After all inter-document similarity values obtained, a matrix will be created. The matrix is then used as a semi-supervised factor. The output of this method is the value of the membership of each document, which must be one of the greatest membership value for each document which indicates where the documents are grouped. Classification result computed by the method shows a good value which is 90 %. Index Terms - Fuzzy co-clustering, Heuristic, Semantica Similiarity, Semi-supervised learning.


2021 ◽  
Vol 118 (13) ◽  
pp. 133101
Author(s):  
Sanghyun Kim ◽  
Donghyeon Lee ◽  
Binbin Wang ◽  
Shang-Jie Yu ◽  
Kenji Watanabe ◽  
...  

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