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March 2017
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April 2017

A piece of suggestion for MRS

In an early post, our blogger John mentioned that as MRS members, you are qualified for a number of benefits:

MRS is surely doing an awesome job in providing us these services, but I don't know how many of you are aware all of them. My personal feeling is that MRS is a little bit "shy" in reaching out to its members. Personally I would like to receive emails notifying me anything that MRS is providing. As far as I know, researchers frequently check their emails because conversations in academia primarily utilize emails as the communication platform. 

I, as an MRS member, would like to hear what great works MRS is doing for us!

-Tianyu Liu UCSC

My Last Day in Spring '17 MRS

Time flies! Already five days have passed and officially today is the last day for the Spr '17 MRS meeting. In the morning I attended the ES2 sessions and learned a lot from fellows working both in batteries and supercapacitors. At the end of meeting, I met with a graduate student from UK. His team works on supercapacitor simulation works and published a high quality paper I just came across a few weeks ago. We talked about the current research in his group as well as challenges and opportunities for supercapacitor simulation works. It is always of great pleasure to talk to those people who are working on theoretical studies to guide our experimentalists to design novel materials.

Early this afternoon four bloggers met together for the first time (because we always scattered to capture the materials for our posts I guess), and took a photo together. Then I was approached by an engineer and shared me his valuable feedback about the past meeting. At 3 pm, I went to Sheraton and thanked Judy, who worked behind-the-scene and maintained this website, for  all her great effort! I returned from Sheraton and joined the last session of ES1, where people were talking about perovskite materials. The last session officially ended at 4:45 pm.

Looking forward, the first thing is to get back home. I will have an early fly (7 am) to San Jose, CA tomorrow. Will release myself for a work-free night to pack my things.

-Tianyu Liu UCSC

Bloggers for Spring '17 MRS Meeting

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In the final day, we four bloggers finally managed to gather together and had the photo above. We hope our posts have added values to your participation in this meeting. Sessions, plenary talks, award ceremony, career fair, we were always there with you. We hope you've enjoyed our posts and this MRS spring meeting.

Being an blogger trains me on how to extract useful information from talks and how to communicate information effective to general audience. It also enabled me to talk to the "big names" in my field and to learn their inspiring behind-the-door stories about their researches. I also met a number of peers who we have chatted together and I learned a lot from them.

Everyone, have a safe trip back home! Hope to see you in next MRS meetings!

-Tianyu Liu UCSC

SM2: Advanced Multifunctional Fibers and Textiles

Yan-qing Lu, Nanjing University, China

Microfiber-Based Microcavities and Miniaturized Fiber Stereo Devices

Written by Akshay Phadnis

Microcavities based on optical microfibers are significant in fiber electronics because of their strong confinement, large evanescent field, flexibility, low-loss connection, and configurability. The one-dimensional (1D) approach involves methods such as Bragg grating for producing micro-cavities on the microfiber surface. Yan-qing Lu of Nanjing University explains the importance of optical force in these fibers, wherein force due momentum change of photons is considered. As compared to 1D, the three-dimensional resonator can be developed by a 2D graphene sheet coiled and put inside a 3D cavity of spiral microfibers. These kinds of special resonators, miniaturized fiber stereo device (MFSD), result in increased interaction length, with high modulation efficiency and hence find applications in optical modulation for optical signal processing. This type of miniaturized fiber stereo, in-line, all-optical modulator has potential in fiber optical communications, in which there are demands for high-speed, wideband, low-cost, and integrated methods to modulate information.

ES14: Thin-Film Chalcogenide Semiconductor Photovoltaics

Chris Leighton, University of Minnesota

Potential Resolution to the “Doping Puzzle” in Pyrite FeS2: Carrier Type Determination by Hall Effect and Thermopower

Written by Ahmad R. Kirmani

As the race toward a cost-effective solar energy conversion technology heats up, the need to better understand the fundamental questions at the heart of these promising technologies takes center-stage. One such interesting technology is based on pyrite iron sulfide (FeS2) as the absorber. The interest and potential in this not-much-pursued photovoltaics lies in its earth-abundance, non-toxicity, low-cost, and optimal bandgap. However, since the metric of power-conversion efficiency (PCE) rules the photovoltaics sector, interest in FeS2 has declined owing to sub-standard PCEs, making it a failed photovoltaic technology. Low voltages are a scourge to these solar cells and an inability to effectively dope them has led to the downfall.

Chris Leighton and his team at the University of Minnesota hope to revert this trend. Leighton feels that an efficient control over doping requires a deeper understanding of the doping mechanism in this material that the community has so far lacked. Harkening back to the widely-held misunderstandings on doping of FeS2 single crystals and thin films, the team took a fresh look employing a suite of characterization techniques. The findings suggest a rethink on the widely-accepted notion that these thin films are predominantly p-type. Furthermore, the team suggests that sulfur vacancies might, in fact, be responsible for doping in this photovoltaic material. 

These key findings from the Leighton group are potentially game-changing and provide crucial design rules for a cost-effective and non-toxic pyrite FeS2-based photovoltaic technology.

The Trip Home

Hello MRS!  Well, this is it, the last half hour.  Like many of you, I am heading back home soon.  For me, home is New Orleans, where I will return to my lab full of the new knowledge and insights that I learned over the past week.  I will return to my friends, and especially to my fiancé, who has been patiently waiting for me for the past week.  I will get back to work to prepare results to present at next year's MRS meeting.  This is the cycle, and hopefully sooner or later I will graduate!  For now, my plan is simply to take the fantastic Phoenix Metro Light Rail back to the Sky Harbor airport, and fly to NOLA (with a brief stop in Las Vegas).  

I hope that you all enjoyed this spring MRS conference, and I also hope you enjoyed the blog posts here on the MRS Meeting Scene.  I give a big shout-out to my fellow bloggers and to the MRS staff that make the MRS meeting scene possible, especially Judy Meiksin.  

I wish you all a wonderful year, a pleasant summer, and a safe trip home.  

-John, your faithful blogger.

ES10: Frontiers in Oxide Interface Spintronics—Magnetoelectrics, Multiferroics and Spin-Orbit Effects

Masaki Uchida, University of Tokyo

Metallic Domain Wall at Antiferromagnetic Pyrochlore Iridate Heterointerface

Written by Trevor Clark

Iridates in the 5d family of alloys exhibit strong spin-orbit coupling and novel ground states. These ground states lead to anomalous properties, such as anomalous insulating in the Ba2IrO4. Pyrochlore iridates also demonstrate interesting physics. The archetypical lattice of Ln2Ir2O7 has a frustrated lattice, and experiences antiferromagnetic ordering when specific lanthanide elements are in the lattice. The 5d orbital elements are tetragonally coordinated and can either have their moments aligned all-in or all-out. There are new topological states between metal and insulator known as the Dirac semi-metal. These materials are made with solid phase epitaxy; however, the strict topological requirements result in polycrystalline samples with metallic domain walls separating them. This has interesting implications for selectively conductive applications. These materials magnetic and electronic ordering properties are investigated by patterning heterostructures. Magnetotransport, conductivity, and topological phases are investigated. These materials may have potential applications in edge current devices, topological quantum computation, and skyrmion memory; however, more materials development and study are required.

ED6: Nanostructured Quantum-Confined Materials for Advanced Optoelectronics

Joseph Luther, National Renewable Energy Laboratory

Solar Cells of Perovskite Quantum Dots—Stable Cubic CsPbI3 Films for High-Efficiency Photovoltaics

Written by Ahmad R. Kirmani

Hybrid perovskites have risen over the past few years to become a global phenomenon in the field of renewables research. The implications appear imminent—flexible solar cells, displays, and laser diodes—marking the arrival of the long-awaited flexible electronics. This can be taken to a higher tier by engineering quantum confinement in these materials by fabricating perovskite quantum dots (PQDs). PQDs are colloidal solutions that combine color-tunability and solution-processability, stretching the advantages of perovskites to the next level. These materials, however, suffer from a phase-stabilization problem that limits their utilization at room temperature and hence their practicability.

The research team led by Joseph Luther at the National Renewable Energy Laboratory has exploded on the PQD scene recently with their landmark discovery of phase-stabilized PQDs. These PQD inks are stable at room temperature and exhibit excellent optoelectronic properties. The vast potential of this breakthrough is getting realized in the form of high-performing solar cells. The group has recently reached >13% power-conversion efficiency (PCE) solar cells employing thin films of their stable PQDs as the solar power absorber. The devices feature unusually low voltage losses, an indication of the clean, trap-free surfaces of these nanocrystals. This new class of energy harvesters, Luther believes, is an ideal candidate as the top cell for next-generation stable, high-performance tandem solar cells that can maximize harvest of the solar spectrum.

MRS Membership Beyond the Meetings

As the MRS spring meeting is winding down, I am remembering that in some ways the meeting keeps going.  The physical conference is over, but hopefully we are all members of the Materials Research Society, and can enjoy the benefits year-round.  This includes another big meeting, MRS Fall, typically in Boston.  It also includes countless other smaller, more specialized meetings either hosted or co-hosted by MRS.  I encourage you all to keep track of these conferences, and use them as a way to deepen your relationship with MRS.  In addition, MRS puts out several publications; my personal favorite is the materials 360 Newsletter, which keeps us up-to-date on the latest news in the materials research world.  Finally, MRS as an organization has lots of resources to help with networking and job-hunting.  The point is, the MRS spring meeting ends today, but MRS does not; it is a valuable network of people and tools that greatly benefits all of its members.  

Until next time,


SM4: A Soft Future—From Electronic Skin to Robotics and Energy Harvesting

Iain Anderson, University of Auckland
Towards a Continuous Sensory Experience and Autonomic Nervous System for Soft Robots
Written by Akshay Phadnis
The new age robotics designs should seek to achieve continuous sensory feedback, coupling strain feedback to electrical activity and integrated local pace-making for controlling actuator groups. Multifunctional dielectric materials (DE) sandwiched between flexible, stretchable elastomers offers such designs. The change in thickness of elastomeric sheets due to stretching changes the capacitance of the dielectric medium. Based on this change in capacitance, motion can be estimated. However, these devices have limited scope due to large wiring requirements (more number of senors, more number of connections). Iain Anderson developed strain-based skin sensor systems that have combined multiple sensors through a single wiring via use of auxiliary resistors. A thin sheet of DE material sandwiched between elastomeric sensory layers in a two-dimensional (2D) array of parallel capacitor sets with a 2D transmission line. For these 2D sensory motions, the motion of a jellyfish is a source of inspiration. At the same time, the strain inside the polymeric layers can be used as a switch, a piezoresistive dielectric elastomer switch (DES). These switches can be used to influence the actuation of dielectric elastomer actuators (DEA). Grouping together the DES and DEA in the same structure can be used for the construction of autonomous self-controlling mechanisms. One of these is a mechano-electrical oscillator capable of mimicking the motions of the caterpillar and dragonfly.