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Advanced Materials Interfaces: Chromiteen: A New 2D Oxide Magnetic Material from Natural Ore

July 19, 2018/0 Comments/in Research/by Gelu Costin

Chromiteen: A New 2D Oxide Magnetic Material from Natural Ore

Advanced Materials Interfaces, 2018, 1800549. Posted by Gelu Costin

Thakur Prasad Yadav,* Sharmila N. Shirodkar, Narumon Lertcumfu, Sruthi Radhakrishnan, Farheen N. Sayed, Kirtiman Deo Malviya, Gelu Costin, Robert Vajtai, Boris I. Yakobson,* Chandra Sekhar Tiwary,* and Pulickel M. Ajayan*

The absence of inherent magnetism in the family of 2D materials limits its application in magnetoelectric and magnetic storage media. Here, a simple scalable route for the synthesis of magnetic 2D material chromite (chromiteen) via sonication-assisted liquid-phase exfoliation is demonstrated. The (111) plane of the exfoliated chromite is found to be the most stable which is confirmed by its common occurrence in exfoliation. Further, the stability and dispersion are verified by ab initio density functional theoretical simulations. Magnetic measurements over a large temperature range of 4 K ≤ T ≤ 300 K confirm ferromagnetic/superparamagnetic order with nearly 40 times higher magnetic moment saturation in chromiteen compared to chromite. The results reveal that 2D chromiteen causes a change in the magnetic behavior with respect to chromite which could be ascribed to the increase in the lattice strain as well as a magnetic strain due to high ferromagnetic
fraction in 2D plane.

Yadav, T. P., Shirodkar, S. N., Lertcumfu, N., Radhakrishnan, S., Sayed, F. N., Malviya, K. D., … Ajayan, P. M. (2018). Chromiteen: A New 2D Oxide Magnetic Material from Natural Ore. Advanced Materials Interfaces, 1800549.

https://doi.org/10.1002/admi.201800549

Nature Nanotechnology: Exfoliation of a non-van der Waals material from iron ore hematite

July 19, 2018/0 Comments/in Research/by Gelu Costin

Exfoliation of a non-van der Waals material from iron ore hematite

Nature Nanotechnology, volume 13, pages602–609 (2018), posted by Gelu Costin

Aravind Puthirath Balan 1,2,11, Sruthi Radhakrishnan1,11, Cristiano F. Woellner 3, Shyam K. Sinha4,
Liangzi Deng5, Carlos de los Reyes6, Banki Manmadha Rao7, Maggie Paulose7, Ram Neupane7,
Amey Apte1, Vidya Kochat1, Robert Vajtai 1, Avetik R. Harutyunyan8, Ching-Wu Chu5,9, Gelu Costin10,
Douglas S. Galvao3, Angel A. Martí6, Peter A. van Aken4, Oomman K. Varghese7, Chandra Sekhar Tiwary1*,
Anantharaman Malie Madom Ramaswamy Iyer1,2* and Pulickel M. Ajayan1*

Abstract
With the advent of graphene, the most studied of all two-dimensional materials, many inorganic analogues have been synthesized
and are being exploited for novel applications. Several approaches have been used to obtain large-grain, high-quality
materials. Naturally occurring ores, for example, are the best precursors for obtaining highly ordered and large-grain atomic
layers by exfoliation. Here, we demonstrate a new two-dimensional material ‘hematene’ obtained from natural iron ore hematite
(α -Fe2O3), which is isolated by means of liquid exfoliation. The two-dimensional morphology of hematene is confirmed by
transmission electron microscopy. Magnetic measurements together with density functional theory calculations confirm the
ferromagnetic order in hematene while its parent form exhibits antiferromagnetic order. When loaded on titania nanotube
arrays, hematene exhibits enhanced visible light photocatalytic activity. Our study indicates that photogenerated electrons can
be transferred from hematene to titania despite a band alignment unfavourable for charge transfer.

Citation: Balan, A. P., Radhakrishnan, S., Woellner, C. F., Sinha, S. K., Deng, L., Reyes, C. D. L., … Ajayan, P. M. (2018). Exfoliation of a non-van der Waals material from iron ore hematite. Nature Nanotechnology, 13, pages 602–609.

https://doi.org/10.1038/s41565-018-0134-y

Hematene was nominated in “The Most Significant Material Science News of 2018”, at the category “Advances from Academia”.

https://www.printedelectronicsworld.com/articles/16136/the-most-significant-material-science-news-of-2018?fbclid=IwAR2yOyoNOFqb-cMzvhOBgBmhvRayt8kftvgYO8VHqC5iNzARSIi9bzpCchI