Island Days (Part 1)- Geologic and Historical Constraints (GHC) on Glacial Advance and Retreat

text and images by Victoria Fitzgerald

 

As I face the glossy orange wall of the Louisiana born ship, the Nathaniel B. Palmer, I prepare to step off the deck and take my first step down the iced over rope ladder. I am getting off the ship to provide technical assistance and optically stimulated luminescence (OSL) field expertise to PhD student Scott Braddock and Master’s student Meghan Spoth, representatives of the Geologic and Historical Constraints (GHC) team. My mind races from fear to focusing on helping them accomplish their mission: collect organic material (e.g. bones, algae, fur, seashells) for radiocarbon dating of raised beaches on multiple islands in the Amundsen Sea. Their efforts will provide glacial-geology modelers with data to determine if modern Thwaites Glacier retreat rates have occurred in the recent past and if it was able to recover. This information will help us better predict sea level change. I quickly absorb the importance of the project before my mind jumps to the excitement in thinking that I will touch Antarctic land and not just sail near it for 8 weeks. I take a deep breath from beneath five layers of heavy winter clothing and bury my fear of small boats and the ocean. I think: Just step down, away from the comfort of the ship, and get on the Zodiak.

 

 

After we arrive, we stumble across a frozen rocky surface carrying shovels, survival bags, and other sampling equipment, looking for a place that won’t interfere with the wildlife, and is above the tides which could wash our gear out to sea. We find a high spot on some rocks and quickly change out of our float coats, the loud orange life vest parkas that (hypothetically) would save our lives if we fall out of the boat into the freezing water. We shimmy into additional dry layers for the long haul of beach combing and hole digging.

 

To say the wind hurts is an understatement. It’s -10°F outside and the wind chill is around -20°F; I look around and take in what will be the next 12 hours of my day. This isn’t an island for relaxing and drinking margaritas. It’s a stone desert filled with ice, penguin poop, and Adélie penguin parents who are running in all directions away from their tenacious chicks who are begging for another snack. I immediately identify with their struggle, having three kids of my own with insatiable appetites and the energy of a thousand Suns.

 

 

 

 

 

 

Oh, and there are Skuas, the equivalent of angry giant seagulls who dive bomb your head anytime you are near their chicks…which is often. They are everywhere and nowhere. The chicks are the same color as the rocks and it is difficult to see them until you train your eyes for their movement. This is my new priority.

 

 

 

I take a selfie in true millennial fashion and cover up my face. No time to correct my reflection in my sunglasses: my hands have started burning and my phone isn’t recognizing my finger anymore. We make our way to the beaches that Scott has recon’d using what we think of in the U.S. as old satellite imagery, thanks to the internet’s ease of access. Out here we are using two to three-week-old data.  Every now and then we receive new ice imagery, but with limited bandwidth on our satellite internet comms and the ice constantly moving, we rely heavily on our experienced Captain and crew to steer us clear of danger and navigate us safely to our projects. We all hold our breath, hoping the beaches are ice free for sampling.

 

 

 

Good news! The imagery was fairly accurate. Even better news: we are further into summer and the beaches have even less ice than we expected. There are four of us, and Scott issues our marching orders plus a quick demonstration on what to look for before we split up into two teams on the hunt for organics. I’m with Scott, while Meghan wanders across the ridge line with Dr. Kelly Hogan, a British Antarctic Survey Geophysicist who has experience in this type of sampling.

As we start, I feel like we are playing a game, a great scavenger hunt, only here it is literal (and littoral!). Surface material can be difficult to find as the islands are littered with penguin remains. The bones of the recently deceased penguins or seals are not good samples, we need hundred to thousand-year-old bones, the ones that are bleached white, growing algae, and spongey looking instead of smooth nonporous surfaces you might find in that piece of chicken from last night’s dinner. After a few minutes of beach combing with little luck, Scott announces he will start digging and I should prepare sample bags.

 

Photos by Linda Welzenbach

 

We make quick work of all the loose cobbles and start using them to hold our gear and samples in place as the wind just won’t stop.  Soon we have around 15 samples from at least 2 raised beaches. We are pretty proud of ourselves and decide we should check on the other team and have a hot drink break.  Meghan’s side of the island wasn’t as productive and she has about half the number of samples collected, which is ok, because that in itself is new information about the islands in this remote part of the world.

 

These islands don’t have traditional windward and leeward sides. The land-based glaciers that provide us with a surreal background for our field work are causing harsh winds to push down the sides of the ice and across us. On the opposite side, the island deals with currents and tidal action from the Amundsen Sea.  It’s rough, and so is my instant latte.  We forgot stir sticks and all my powder is at the bottom of the cup. I gulp it down anyway so that I can put my gloves back on and get back to work.  My romanticized notion of touching Antarctica has quickly morphed into reality: Antarctica is cold and desolate and I’m pretty sure it wants to kill us. We all finish, pack up our garbage, and go back to our respective beaches.

 

 

 

At around 9:30pm the Zodiak returns and we make our way back to our home away from home, our little bunk beds awaiting us on the ship.  Our bags are successfully filled with penguin bones, seal fur, algae, and seashells. Scott and Meghan have another three days to collect their samples. I help out for two more days with similar results on other islands, but the wind is stronger, the penguin rookeries are more expansive, and Skua attacks increase. On the last day I remain on the ship. I want to help the “science”, but the previous day was bitter, and I discovered that I enjoy having feeling in my fingers! I traded out with another member of our THOR team, PhD student James Kirkham, who was just as excited as I was when stepping on the ladder the first day.

 

 

 

Completing island field work in Antarctica is difficult and requires a level of unwavering dedication to the cause. Scott and Meghan carried on and completed their portion of the International Thwaites Glacier Collaboration without complaint. I have a new appreciation for the GHC team’s dedication to unravel the mystery of glacier retreat in the Amundsen Sea.

We never did find a good spot to take samples using my OSL dating expertise, but we sure did try. A crew member, Joee Patterson, even made us a blacked-out tent from several tarps and some PVC pipe, just for the purpose of taking an OSL sample in complete darkness. If you’d like to know more about our continuing work at Thwaites, check out Thwaiterglacier.org or Thwaitesglacieroffshoreresearch.org.

 

Victoria Fitzgerald is a National Science Foundation Graduate Research Fellow and geology PhD student at the University of Alabama.  She is a mother of three, Army veteran, and a first-generation college graduate. She likes science communication, rocks, and food, but not in that order. If you want to know more about her and OSL, check her out on Twitter @fitzofscience and at fitzofscience.com coming this summer!

 

 

The “Iceberg” Correction

text and images by Linda Welzenbach

 

Since leaving the Chilean coastline, the THOR team has been exploring the sea floor… with sound.  Similar to the way that sea mammals communicate with each other over long distances and submarines avoid obstacles, scientists use sound to “see” the bed surface and ultimately map the ocean bottom.   Sound waves are generated from beneath the ship from an instrument called a multibeam echo sounder which, in effect, is a giant loudspeaker pointing downwards and away from the vessel on either side.

Here’s how it works: the multibeam sends a “ping” (like you hear in the movies with submarines), a pulse of high-pitched sound that moves down and away from the bottom of the ship.  It’s called multibeam because each ping contains 432 individual depth soundings that go out in the shape of a fan. The angle and trajectory of each sounding, the time traveled and distance away from the source of sound, combined with the properties of the ocean, (temperature and salinity) are used to calculate the velocity of sound through water.  The result is a swath “image” of sound velocity, where the width of the swath is the maximum angle the outermost depth soundings have achieved as they travel some distance to the seafloor and back.

Each “ping” is displayed as a line of points. This image shows multiple pings. Each “ping” line is composed of 432 depth soundings – you may even be able to see the individual points.

For deeper water, the swath will be wider; for shallower water, the swath will narrow.  Each of the reflected soundings are then processed to show a continuous colorful ribbon, or snail trail, of the seafloor below the ship. (example snail trail image) The colors are equivalent to the distance the sound wave has travelled through the depth of the water, where the longest distances, which are blue, represent the deepest parts and the red colors are shallower features.  Collectively they “paint” a picture of the seafloor’s surface in 3-dimensions.

Most oceanographic research vessels employ the multibeam echo sounder whenever they can, the combined results of which can paint a detailed picture of processes that we could never witness ourselves through the depths of the ocean. Marine geologists, oceanographers, and glaciologists studying Thwaites Glacier will use this information to unravel the processes operating between the ocean and the ice shelves.  Features such as furrows and plough marks indicate past movement of the ice shelf and icebergs dragging along the sea floor, channels show where water flowed beneath past ice sheets, and high ridges or peaks may have been places where ice was once “grounded” (or resting on) the sea bed, a situation which may act to stabilize an ice shelf or glacier, and allay or even stop its’ backwards retreat.

The science team also use these echo sounders to make decisions about where to gather samples from the sea floor by producing an image of the layers of muds, sands, and rocks just below the surface. The samples help to decipher a longer history of how ice interacted with the ocean, and ultimately how the ice will behave in the future.  The accuracy of the data is critical to ensuring that the location where those samples are taken will not be in a place that might damage the instruments (coring devices) used to collect the samples.

An important part of collecting accurate multibeam data is accounting for a variety of physical parameters. On the ship, we are effectively a bobbing cork in the ocean. Combined with the echo sounder, a set of reference points are made with each “ping” to account for this unpredictable motion.  Similar to how a gyroscope works, the reference point data accounts for real time conditions such as roll (side to side) pitch (forward and backward motion), heave (the up and down motion) and yaw (the horizontal or side to side motion). The data processing software then applies clever corrections to make sure that the data accurately represent the true position and orientation of each sea floor sounding.

Two days after the ship’s passage through rough seas, THOR team members Kelly Hogan and Ali Graham noticed that the seafloor bathymetry data output suggested that the seafloor had a tilt when they knew it should have been flat.  In order to understand if the tilt was real, they needed to do an experiment.  They would have to go back over an area that had already been scanned, but in the opposite direction.  The difference in the two data sets would show an equal and opposite tilt (if they were right that the tilt was in error) and it would help them calculate the degree of that error.   In order to accomplish this, the seafloor would have to be flat and they would need about an hour’s worth of backtrack scanning of the same flat seafloor.

Icebergs are made of freshwater ice and compacted snow. They typically originate from the breakup of glaciers and ice shelves that terminate in the ocean.

 

Enter the icebergs.  The first significant iceberg that appeared was close enough to provide a terrific photo opportunity for the passengers, and the crew of Nathaniel B. Palmer made a spontaneous viewing loop around the iceberg.  (pic of the first berg) The ship had also entered the Bellingshausen Abyssal Plain in the Southeast Pacific Basin, the flattest area of the transit before reaching the Antarctic continental shelf, so the sea floor conditions were optimum.

Turn captured on the multibeam swath image.

Another iceberg on the horizon looked to provide the appropriate distance and time it would take to conduct the necessary scan.   Using that iceberg as a goal post, they made the first multibeam swath, rounded the second target iceberg (which was as photogenic as the first), and retraced the initial snail trail long enough to determine the degree of error and apply the correction.

These icebergs originated from Antarctica. They may be at least a year old, but their location in warmer waters will melt them very quickly, as much of their rounded surfaces are already showing.

Two icebergs later, the problem was solved and the colorful ribbon of seafloor bathymetry was returned to its horizontal self. These kinds of corrections are not uncommon and ensure that the data is good for when the THOR team reaches Thwaites itself, where the accuracy of the sea floor measurements will be important for selecting the best sea floor to sample and interpreting its history.

OTHER Icebergs…

Here are some of the other icebergs we have seen on our traverse through the Amundsen Sea. They have been categorized by shape, age, and how they formed.

This is classified as a blocky multi- year freshwater iceberg because of its steep sides and flat top.

 

 

 

 

 

 

 

 

 

 

 

 

Drift sea ice is young flat ice floes formed from sea water at the sea surface that can move with current or winds.

 

 

 

 

 

 

 

 

 

 

 

 

 

Landfast ice or “Fast” ice is multi-year flat, solid ice made of both seawater and fresh water (from snow) that is attached to the far continental margin and can include grounded icebergs such as the one in the background.

The J-Team

text and images by Linda Welzenbach

 

All field-based science conducted on board and beyond the Nathaniel B. Palmer would not be possible without the support of the Marine technicians.  They are in charge of on-board deck operations, ship to shore operations, and the safe deployment and recovery of scientists, scientific tools and equipment.

Within a day after leaving Punta Arenas, marine technicians Jennie Mowatt and Joee Patterson were tasked with the recovery of a state-of-the-art Autonomous Underwater Vehicle (AUV) that was being field tested in the Straits of Magellan prior to its deployment in the Amundsen Sea.

Jennie Mowatt will celebrate 4 years in her position in May; Joee Patterson, 3 years in May. They love their jobs and the great opportunity to problem solve. The work is always different, sometimes hugely frustrating but also hugely satisfying. They appreciate seeing Antarctica in ways most people never do. “We have seen the entire profile of the ocean around Antarctica- from the top to deepest depths. I have put my hands on creatures from 1,500 meters deep below the surface,” says Joee Patterson.

The pressure is on for the successful launch and retrieval of this “torpedo of science” that can accommodate up to 20 different sensors, including an obstacle detection sonar instrument in the nose cone.  The design is based on devices used by the petroleum industry and for national defense purposes; it takes advantage of the AUV’s ability to dive deep (up to 1,000 meters) but with payloads that will measure a variety of characteristics of the ocean, map the seafloor under Thwaites Glacier, and collect information on what is happening at the interface of both—something that was not possible until now.  Much was riding on this early test.

The morning of the test was perfect.  Cloudless skies were mirrored by the nearly still water of a small cove in the Straits of Magellan. The Hugin, built by the Kongsberg company (who also happen to provide the technology for multibeam bathymetry), is named for one of Odin’s ravens that travel the world to gather information.

 

 

 

 

 

 

 

Prior to launch, the science team meets with the entire Marine technician support group to go over safety and thesequence of activities. (pic of the big group) Jonas Andersson, one of the TARSAN scientists that manages the Hugin, rolls out the AUV from a specially made garage.

Once the bridle was attached and rigging set to lift Hugin off the ship, Joee and Jennie hopped in the zodiac to prepare for the AUV’s deployment.

With the Hugin in the water, the ship moves away and Jennie and Joee move in to watch over the AUV as it takes on water (shedding buoyancy) in preparation for diving.  Once it disappears, they return to ship.  Four hours later, the weather has turned ominous.  The skies are heavy, dark and spitting rain.  The winds have picked up and the sea surface is rough and rolling.  Hugin’s bright orange skin is spotted and Joee and Jennie are off in the zodiac to begin the process of bringing Hugin home.

Unbeknownst to those of us observing on deck, the marine technicians (known as the MT’s) had met and devised a plan, to include several contingencies for the AUV’s retrieval based on changes in the environment or equipment condition.  The first unplanned situation was the unexpected presence of a South American fur seal who found the AUV interesting.

“The seal was doing acrobatics while we were out there, and I thought it might jump in the zodiac. He came at us quickly and so I scooted the boat away, and then he just disappeared”, said Joee.

South American fur seal torpedoing through the air

Their first step was to attach the bridle system using the hooks on top that would be used to hoist the AUV onto the ship.  The plan was that one person would be in charge of maneuvering the lighter weight and buoyant zodiac while the other wrangled the two-ton AUV.

Assuming that the AUV would move more slowly and that the wind and the swells would impact the zodiac, their plan would take advantage of the zodiac’s maneuverability. The goal would be to tie the AUV to the side of the zodiac, which is a typical way of using a smaller thing to tow a larger thing. “Once we got out there, we figured out that our plan where one person did the maneuvering and one person to do the wrangling was not the optimum situation. The contingency was then to tow it astern of the zodiac. This presented other challenges.  The Hugin acts an anchor so we have to put a lot of power on the zodiac to get the Hugin to move at all.  Then once you get the Hugin moving you don’t want to get it moving so fast that it moves past you.  Add to that the swell and wind working against us as we try to keep a heading and keep it trapped behind us.”

 

Jennie summarized the complexity of the situation, “It was our first time working with the bridle system and we didn’t know how well the zodiac would travel with the AUV.  I definitely would not have predicted its hydrodynamic behavior as we tried to tow it behind the zodiac.  That was the thing that we couldn’t have predicted until we were actually doing it.”

 

 

 

 

Following the successful delivery of the Hugin to the deck, Jennie and Joee discussed adding a third person for next retrieval even if the conditions are calmer.  “It would be good to have more hands to pull the lines, and to use extra slip lines on the vehicle itself.  The weight of the bridal makes it want to sink, so keeping that in the boat will enable better control of the AUV.”

 

I was amazed at their perseverance and their calm under what was obviously difficult environmental conditions.  Yet for the J-Team, it was just another Friday at the office, and problem solving is why they are MT’s for science.

 

 

 

 

NBP’s Current Path Approaches the Second of Two Low Pressure Systems

text and images by Linda Welzenbach

Waves approaching 15 feet are regularly inundating both the lower and the main deck (where our berth is located).  Viewing the maelstrom from the large windows of the aft winch control room where I’m sitting, I can forget the sea sickness for a bit as I watch the incredible power and beauty of the sea, eyes fixed on the distant horizon as a rocking and rolling NBP slowly but very steadily works its way south.

Large wave on the starboard side of the aft deck.

It is after 12, and I realize I have missed lunch, when a message suddenly comes from the radio telling everyone outside to come in due to heavy seas.  Feeling somewhat normal, and wanting to know how fast or how close the ship is moving into the outer reaches of the severe weather (very cyclonic looking in my opinion), I head to the bridge.  To watch us float about with all the ease of a cork in a bathtub, you wouldn’t know that the NBP is a 6,800-long-tons (15,232,000 pounds) ship with 3,000 (10’ x 40’) steel plates (the bow plates are 1 9/16 inches thick) carrying 425,000 gallons of gas.

 

The image on the left is a computer model of the low-pressure system. The NBP is the red target between 1016 and 1012 pressure contours. Right image shows the ship’s traverse to the Amundsen sea.

 

Meanwhile, below deck, science planning and activities persevere.

 

The monitors show the depth from the multibeam generated sound wave to the seafloor, 4426 meters (13,278 feet) and the reflected signal from two views. The range of color indicate depth-blues are deepest and reds are shallowest. Chris Linden, the NBP multibeam manager and expert, points out the location of the transducers that generate the sound waves and the instruments that will receive the signals that have been reflected off the seafloor.

 

The THOR team and NBP multibeam specialist Chris Linden set up the EM122 multibeam echo sounder to start gathering bathymetry information. As soon as the ship passed beyond the legal border of Chile, they would take advantage of the adjusted ship traverse to gather high resolution seafloor bathymetry from an area that hasn’t been mapped previously. There will be some challenges to acquiring the return signal: the slow ship speed combined with the rough seas that impact the ship’s hull create interference around the receivers (bubbles, for example), affecting the quality of the data.

Other ITGC scientists, whose constitutions are more stalwart than mine, sit at workstations and tabletops that are festooned with pieces of anti-slide fabric (much like rubber carpet pads) utilizing predrilled holes for eye-screws to which bungee cords are tied; these go over top of valued electronics to hold them in place.

 

Author Elizabeth Rush is ready for the rough sea crossing!

 

Tilt-o-meter and barometer on the bridge of the NBP.

 

Back on the bridge of the NBP, I stumble around still developing my sea legs as the motion of the ship is amplified due to its height off the water. The near 360-degree view of the waves is both captivating and hypnotic, helping to subdue some of the seasickness.  In fact, sitting on one of the control chairs is like having an unlimited ticket on the earth’s most incredible amusement park ride.

But as we roll upwards of 20 degrees each way, knowing that the larger sea is coming, the amusement fades for a few moments.  THOR team member and PhD student Victoria Fitzgerald adds, “There is no getting off this ride.” According to Chief Mate Rick Wiemken, there is a buoy in the area that has measured a wave height of 80+ feet. The highest wave ever recorded!

 

 

 

 

NBP pitches forward into a large wave.

One would think TARSAN’s successful deployment of the Hugin AUV would appease Ran (the AUV’s unofficial name), the Nordic goddess of the seas.   The crew of the ship are reassuring: the storm will still pass in front of us.  And while we will see a couple more days of rough seas, the Palmer (with 80 research cruises since coming into service in 1992) will handle it, and we will have gained a deep appreciation and respect for the amazing people who are taking care of us, and the forces of nature around us that we hope to better understand.

GCA: Core-mantle fractionation of carbon in Earth and Mars: The effects of sulfur

Tsuno, K., Grewal, D.S., Dasgupta, R. (2018). Core-mantle fractionation of carbon in Earth and Mars: The effects of sulfur. Geochimica et Cosmochimica Acta 238: 477-495.

 

Abstract: Constraining carbon (C) fractionation between silicate magma ocean (MO) and core-forming alloy liquid during early differentiation is essential to understand the origin and early distribution of C between reservoirs such as the crust-atmosphere,
mantle, and core of Earth and other terrestrial planets. Yet experimental data at high pressure (P)-temperature (T) on the
effect of other light elements such as sulfur (S) in alloy liquid on alloy-silicate partitioning of C and C solubility in
Fe-alloy compositions relevant for core formation is lacking. Here we have performed multi-anvil experiments at
6–13 GPa and 1800–2000 °C to examine the effects of S and Ni on the solubility limit of C in Fe-rich alloy liquid as well
as partitioning behavior of C between alloy liquid and silicate melt (Dc). The results show that C solubility in the alloy
liquid as well as Dc decreases with increasing in S content in the alloy liquid. Empirical regression on C solubility in
alloy liquid using our new experimental data and previous experiments demonstrates that C solubility significantly increases
with increasing temperature, whereas unlike in S-poor or S-free alloy compositions, there is no discernible effect of Ni on C
solubility in S-rich alloy liquid.
Our modelling results confirm previous findings that in order to satisfy the C budget of BSE, the bulk Earth C undergoing
alloy-silicate fractionation needs to be as high as those of CI-type carbonaceous chondrite, i.e., not leaving any room for
volatility-induced loss of carbon during accretion. For Mars, on the other hand, an average single-stage core formation at
relatively oxidized conditions (1.0 log unit below IW buffer) with 10–16 wt% S in the core could yield a Martian mantle with
a C budget similar to that of Earth’s BSE for a bulk C content of 0.25–0.9 wt%. For the scenario where C was delivered to
the proto-Earth by a S-rich differentiated impactor at a later stage, our model calculations predict that bulk C content in the
impactor can be as low as ~0.5 wt% for an impactor mass that lies between 9 and 20% of present day Earth’s mass. This value
is much higher than 0.05–0.1 wt% bulk C in the impactor predicted by Li et al. (Li Y., Dasgupta R., Tsuno K., Monteleone B.,
and Shimizu N. (2016) Carbon and sulfur budget of the silicate Earth explained by accretion of differentiated planetary
embryos. Nat. Geosci. 9, 781–785) because C-solubility limit of 0.3 wt% in a S-rich alloy predicted by their models is significantly
lower than the experimentally derived C-solubility of 1.6 wt% for the relevant S-content in the core of the impactor.

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

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

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

Nature Nanotechnology, volume 13pages602–609 (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, 13pages 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

ACS: Ratiometric Gas Reporting: A Nondisruptive Approach To Monitor Gene Expression in Soils

JGR-Biogeosciences: Short-Term Changes in Physical and Chemical Properties of Soil Charcoal Support Enhanced Landscape Mobility