Prof. Manivannan et al.,and his research collaboration team have been investigated the discovery of carbon nanotubes in sixth century BC potteries that have obtained from Keeladi, Tamilandu, India. This investigation has reported in Nature publication journal of “Scientific Reports” on 13th November 2020 [1]. This is one of the most interesting reports and scientific research from Keeladi excavation located in the southern part of India.
Keeladi Excavation: The excavation was first started in Pallisanthai Thidal which is in the north of Manalur, about a kilometer east of the town of Keeladi in Sivagangai district, Tamilnadu, India. Number of various archaeological residues were found in this excavation, when plowing the land around the site. The first survey was conducted in 2013 in the vicinity of the Vaigai river, 293 sites were identified during the study including Keeladi, and all this sites have an archaeological residues [2]. A part of excavation, researchers found carbon nanotubes in sixth century BC potteries.
During the eighth–nineth century, 0-D metal nanoparticles were found to be used for the improvement of the lustre of the potteries. Carbon Nanotubes (CNTs) first observation in ancient objects was found to be from the back of the sixteenth–eighteenth century [3, 4].
The Indian Scientists have reported the evidence for the presence of CNTs with black coating used along with the inner walls of pottery shards that have been found at Keeladi, Tamilnadu, India. The Keeladi settlement’s fall of period at the range of sixth–third century BC has indicated the radiocarbon dating. As per the author’s knowledge from the ancient artifacts elsewhere, the discovery of CNTs at the Keeladi shards was found to be the oldest among all the nanostructures that have been reported elsewhere [1].
The images of shards from Keeladi site have been excavated and the inner portion of pottery shards are comprised of black coating. The black coatings of the inner portion is shown in Figure 1(a,c) with the appearance of shiny, hard and exhibited with endurance. Further it can be seen that the inner black coating was separated, fractionated and drop-casted on a surface with a separate analysis. The shard of the coating was up to 1 mm and was removed with a surgical knife.
Archaeological excavations includes mainly of Metal pieces, Pottery shards, and Fossil remnants. But the main excavation of Keeladi shards was its uniqueness of the black coating of the shards with its inner portion which remained under the earth for more than two thousand years. However, the main interesting factor was found to be its smoothness was preserved for many years with less degradation rate. It can be seen that some of the pieces (pottery shards) were still remains of smooth shiny surface of coating for more than 2000 years old. Also, the coating possess robust mechanical and chemical stability to resist against with different environmental conditions. Hence, it has become one of the most practically impossible of being stable to retain for such a long time period.
It is an very interesting factor to know that the presence of CNTs from these samples were been date backs with the sixth-third century BC. From our modern era, the main synthesis route that have been found was CNTs to act as a nucleation site and the main essential elements that contain in CNTs are Fe, Si and Al.
The major research finding that have been observed at the Keeladi region was mainly composed of the coatings with two carbon forms viz., CNTs and Graphene. However the authors have raised these following questions:
1. How the Ancient peoples at Keeladi have known the importance of these properties and whether they have been adapted it intentionally?
2. How they have used the potteries for the edible preparation or preservation with the black coating of inner portion of the shard observation, since the ancients would be aware of the cytotoxicity nature of CNT and Graphene sheets!
Dispute of Tamil Nadu peoples (in India) ancient cultural activities is announced proudly by Keeladi research perspectives or scenarios. As it can be seen that an surprising fact that 1D and 2D carbon based nanomaterials usage was continued until 600 BC. Moreover, the diameter was found to be closer than its theoretical limit and its stability were retained until 2600 years!
Our SNB team have focused on this research article to enrich our viewer’s knowledge to know mainly about the discovery of carbon nanotubes in sixth century BC potteries at Keeladi, Tamilnadu, India by various Indian researchers. They found various forms of CNTs which include are single-wall CNTs, multiwall CNTs, in the form of sheet like structures as identified to be graphene oxide. Particularly, the graphene oxide was identified in the inner black coating of the pottery shards at the regions of Keeladi and found to be the oldest nanostructures as per the updated current available reports. Also it is a known fact that CNTs and Graphene possess excellent mechanical strength than the bulk materials. Tamil language is a well known and announced oldest language during the ancient time period. Now again it's a scientific proof, and the knowledge of Tamilian in olden culture is established in Keeladi research pathway. However, the main question raised was how the ancient peoples can make it this one possible and retain its structure for so many years? Still its an mystery and unanswerable question! Nature made some time miracle than the humans, especially our existing scientists! We should accept it.
References
- K. Manivannan et al., Scientific Reports, 10, 19786(2020).
- The Hindu Net Desk (13 June 2017). "Keezhadi excavation: what was found and what they mean". The Hindu.
- J. Pérez-Arantegui, et al., J. Am. Ceram. Soc. 84, 442 (2004).
- S. Padovani, et al., J. Appl. Phys. 93,10058 (2003).
--- Dr. Y. Sasikumar
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