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  • richardmitnick 7:09 am on March 22, 2021 Permalink | Reply
    Tags: "Nano-mapping phase transitions in electronic materials", , “Phase transitions” are a central phenomenon in physical sciences., Behind this behaviour is a strong interaction between the electronic properties of these compounds and their “lattice” structure., , , , , Solid; liquid; and gas are three well known “phases” and when one turns into another that is a phase transition., STEM- scanning transmission electron microscopy   

    From EPFL (Swiss Federal Institute of Technology in Lausanne) [École polytechnique fédérale de Lausanne](CH)and From University of Geneva [Université de Genève](CH): “Nano-mapping phase transitions in electronic materials” 


    From EPFL (Swiss Federal Institute of Technology in Lausanne) [École polytechnique fédérale de Lausanne](CH)

    and

    From University of Geneva [Université de Genève](CH)

    18.03.21
    Nik Papageorgiou

    1
    Schematic illustration of a STEM probe scanning across the interface of two nickelate compounds, with the nature of the scattered electrons changing as the electronic phase of the material goes from being metallic to insulating. Credit: Duncan T.L. Alexander. Atomic structure model rendered using VESTA.

    “Phase transitions” are a central phenomenon in physical sciences. Despite being technical-sounding, they are actually something we all experience in everyday life: ice melting into liquid water, or hot water evaporating as steam. Solid; liquid; and gas are three well known “phases” and when one turns into another that is a phase transition.

    Rare-earth nickelate oxides, also called nickelates, have attracted a lot of interest from researchers because they display an electronic phase transition, which may be exploited in future electronic devices. This particular phase transition consists of turning from a metallic state that conducts electricity into an electrically-insulating state as temperature drops.

    Behind this behaviour is a strong interaction between the electronic properties of these compounds and their “lattice” structure – the well-ordered arrangement of atoms that forms a crystal. However, uncovering the true nature of this metal to insulator phase transition in nickelates, and being able to control it for potential electronic devices, requires knowing how each characteristic phase emerges and evolves across the transition.

    Now, scientists from EPFL and the University of Geneva [Université de Genève](CH) have combined two cutting-edge techniques to achieve nanoscale mapping of each distinct electronic phase. Published in the journal Nano Letters, the study was led by Dr Duncan Alexander at EPFL’s School of Basic Sciences and the group of Professor Jean-Marc Triscone at the University of Geneva.

    The study’s first author, Dr Bernat Mundet, says: “To fully understand the physics displayed by novel electronic materials and to control them in devices, new atomic-scale characterization techniques are required. In this regard, we have been able for the first time to precisely determine the metallic and insulating regions of atomically engineered devices made from two nickelate compounds with near atomic resolution. We believe that our methodology will help to better understand the physics of this important family of electronic materials.”

    The researchers combined aberration-corrected scanning transmission electron microscopy (STEM) with monochromated electron energy-loss spectroscopy (EELS).

    In STEM, images are formed by scanning a beam of electrons, focused to a spot of about 1 Ångstroms in size, across a sufficiently thin specimen – in this case a sliver of nickelate – and collecting the transmitted and scattered electrons with the use of annular detectors. Though technically demanding, this technique allows researchers to precisely visualise a crystal’s lattice structure, atomic row by atomic row.

    For the second technique, EELS, those electrons passing through the central hole of the annular detector are instead collected. Some of these electrons have previously lost some energy due to their interaction with the Ni atoms of the nickelate crystal. By measuring how this energy difference changes, we can determine the metallic or insulating state of the nickelate compound.

    Since all electrons are scattered and collected simultaneously, the researchers were able to correlate the electronic state changes with the associated lattice positions in the different nickelate compounds. This approach allowed them to map, for the first time, the spatial configuration of their metallic or insulating regions, reaching a very high spatial resolution of around 3.5 Ångstroms (0.35 nanometers). The technique will be a valuable tool for studying and guiding the atomic engineering of these novel electronic materials.

    2
    Atomic resolution STEM image showing the perfect crystal structure of a nickelate thin film, coloured to represent the two compounds. Credit: Bernat Mundet.

    “The latest electron microscopes give us an amazing ability to measure a variety of materials physical properties with atomic or nanometric spatial resolution,” says Duncan Alexander. “Here, by pushing the capabilities of EPFL’s Titan Themis microscope to the limits, we take an exciting step forward in this domain, by proving that we can measure the changes in electronic state across a thin film structure precisely made from two different nickelates.

    3
    FEI Titan Themis 200 TEM. Credit:FEI.

    Our approach opens up new avenues for investigating the physics of these nickelate compounds, which have sparked research interest worldwide.”

    “The combination of amazing artificial materials that display a metal to insulator transition and very advanced electron microscopy has allowed unprecedented detailed investigations of their electronic properties,” adds Jean-Marc Triscone. “In particular, it revealed, at the atomic scale, whether the material is conducting or insulating – an important question for better understanding these materials that may be used in future computing approaches.”

    Other contributors

    University of Zurich [Universität Zürich]

    See the full article here .

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    EPFL bloc

    EPFL campus

    The EPFL-École polytechnique fédérale de Lausanne(CH) is a research institute and university in Lausanne, Switzerland, that specializes in natural sciences and engineering. It is one of the two Swiss Federal Institutes of Technology, and it has three main missions: education, research and technology transfer.

    The QS World University Rankings ranks EPFL(CH) 14th in the world across all fields in their 2020/2021 ranking, whereas Times Higher Education World University Rankings ranks EPFL(CH) as the world’s 19th best school for Engineering and Technology in 2020.

    EPFL(CH) is located in the French-speaking part of Switzerland; the sister institution in the German-speaking part of Switzerland is the Swiss Federal Institute of Technology in Zürich(CH) (ETH Zürich(CH). Associated with several specialized research institutes, the two universities form the Swiss Federal Institutes of Technology Domain (ETH(CH) Domain) which is directly dependent on the Federal Department of Economic Affairs, Education and Research. In connection with research and teaching activities, EPFL(CH) operates a nuclear reactor CROCUS; a Tokamak Fusion reactor; a Blue Gene/Q Supercomputer; and P3 bio-hazard facilities.

    The roots of modern-day EPFL(CH) can be traced back to the foundation of a private school under the name École spéciale de Lausanne in 1853 at the initiative of Lois Rivier, a graduate of the École Centrale Paris and John Gay, the then professor and rector of the Académie de Lausanne. At its inception it had only 11 students and the offices was located at Rue du Valentin in Lausanne. In 1869, it became the technical department of the public Académie de Lausanne. When the Académie was reorganised and acquired the status of a university in 1890, the technical faculty changed its name to École d’ingénieurs de l’Université de Lausanne. In 1946, it was renamed the École polytechnique de l’Université de Lausanne (EPUL). In 1969, the EPUL was separated from the rest of the University of Lausanne and became a federal institute under its current name. EPFL(CH), like ETH Zürich(CH), is thus directly controlled by the Swiss federal government. In contrast, all other universities in Switzerland are controlled by their respective cantonal governments. Following the nomination of Patrick Aebischer as president in 2000, EPFL(CH) has started to develop into the field of life sciences. It absorbed the Swiss Institute for Experimental Cancer Research (ISREC) in 2008.

    In 1946, there were 360 students. In 1969, EPFL(CH) had 1,400 students and 55 professors. In the past two decades the university has grown rapidly and as of 2012 roughly 14,000 people study or work on campus, about 9,300 of these being Bachelor, Master or PhD students. The environment at modern day EPFL(CH) is highly international with the school attracting students and researchers from all over the world. More than 125 countries are represented on the campus and the university has two official languages, French and English.

     
  • richardmitnick 12:47 pm on January 16, 2021 Permalink | Reply
    Tags: "Conductive nature in crystal structures revealed at magnification of 10 million times", , , , MBE-molecular beam epitaxy, Metallic lines in a perovskite crystal, STEM- scanning transmission electron microscopy,   

    From University of Minnesota Twin Cities: “Conductive nature in crystal structures revealed at magnification of 10 million times” 

    u-minnesota-bloc

    From University of Minnesota Twin Cities

    January 15, 2021

    Media Contacts
    Main Line
    University Public Relations
    (612) 624-5551
    unews@umn.edu

    Rhonda Zurn
    College of Science and Engineering, Twin Cities
    612-626-7959
    rzurn@umn.edu

    1
    Using advanced analytical scanning transmission electron microscopy (STEM) at a magnification of 10 million times, University of Minnesota researchers were able to isolate and image the structure and composition of the metallic line defect in a perovskite crystal BaSnO3. This image shows the atomic arrangement of both the BaSnO3 crystal (on the left) and the metallic line defect.

    In groundbreaking materials research, a team led by University of Minnesota Professor K. Andre Mkhoyan has made a discovery that blends the best of two sought-after qualities for touchscreens and smart windows—transparency and conductivity.

    The researchers are the first to observe metallic lines in a perovskite crystal. Perovskites abound in the Earth’s center, and barium stannate (BaSnO3) is one such crystal. However, it has not been studied extensively for metallic properties because of the prevalence of more conductive materials on the planet like metals or semiconductors. The finding was made using advanced transmission electron microscopy (TEM), a technique that can form images with magnifications of up to 10 million.

    The research is published in Science Advances, a peer-reviewed scientific journal published by the American Association for the Advancement of Science (AAAS).

    “The conductive nature and preferential direction of these metallic line defects mean we can make a material that is transparent like glass and at the same time very nicely directionally conductive like a metal,” said Mkhoyan, a TEM expert and the Ray D. and Mary T. Johnson/Mayon Plastics Chair in the Department of Chemical Engineering and Materials Science at the University of Minnesota’s College of Science and Engineering. “This gives us the best of two worlds. We can make windows or new types of touch screens transparent and at the same time conductive. This is very exciting.”

    Defects, or imperfections, are common in crystals—and line defects (the most common among them is the dislocation) are a row of atoms that deviate from the normal order. Because dislocations have the same composition of elements as the host crystal, the changes in electronic band structure at the dislocation core, due to symmetry-reduction and strain, are often only slightly different than that of the host. The researchers needed to look outside the dislocations to find the metallic line defect, where defect composition and resulting atomic structure are vastly different.

    “We easily spotted these line defects in the high-resolution scanning transmission electron microscopy images of these BaSnO3 thin films because of their unique atomic configuration and we only saw them in the plan view,” said Hwanhui Yun, a graduate student in the Department of Chemical Engineering and Materials Science and a lead author of the study.

    For this study, BaSnO3 films were grown by molecular beam epitaxy (MBE)—a technique to fabricate high-quality crystals—in a lab at the University of Minnesota Twin Cities. Metallic line defects observed in these BaSnO3 films propagate along film growth direction, which means researchers can potentially control how or where line defects appear—and potentially engineer them as needed in touchscreens, smart windows, and other future technologies that demand a combination of transparency and conductivity.

    “We had to be creative to grow high-quality BaSnO3 thin films using MBE. It was exciting when these new line defects came into light in the microscope,” said Bharat Jalan, associate professor and Shell Chair in the Department of Chemical Engineering and Materials Science, who heads up the lab that grows a variety of perovskite oxide films by MBE.

    Perovskite crystals (ABX3) contain three elements in the unit cell. This gives it freedom for structural alterations such as composition and crystal symmetry, and the ability to host a variety of defects. Because of different coordination and bonding angles of the atoms in the line defect core, new electronic states are introduced and the electronic band structure is modified locally in such a dramatic way that it turns the line defect into metal.

    “It was fascinating how theory and experiment agreed with each other here,” said Turan Birol, assistant professor in the Department of Chemical Engineering and Materials Science and an expert in density functional theory (DFT). “We could verify the experimental observations of the atomic structure and electronic properties of this line defect with first principles DFT calculations.”

    Members of the research team include University of Minnesota Ph.D. students and postdoctoral fellows Hwanhui Yun, Mehmet Topsakal (now associate scientist at Brookhaven National Laboratory), and Abhinav Prakash (postdoc researcher Argonne National Laboratory); and University of Minnesota faculty members K. Andre Mkhoyan, Bharat Jalan, Turan Birol, and Jong Seok Jeong.

    This research was supported in part by SMART, one of seven centers of nCORE, a Semiconductor Research Corporation program, sponsored by National Institute of Standards and Technology, and by the National Science Foundation (NSF) through the University of Minnesota Materials Research Science and Engineering Center (MRSEC). The team also worked with the University of Minnesota Characterization Facility. The MBE growth work was supported partially by the NSF and the Air Force Office of Scientific Research.

    See the full article here .

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    u-minnesota-campus-twin-cities

    The University of Minnesota, Twin Cities (often referred to as the U of M, UMN, Minnesota, or simply the U) is a public research university in Minneapolis and Saint Paul, MN. The Twin Cities campus comprises locations in Minneapolis and St. Paul approximately 3 miles (4.8 km) apart, and the St. Paul location is in neighboring Falcon Heights. The Twin Cities campus is the oldest and largest in the University of Minnesota system and has the sixth-largest main campus student body in the United States, with 51,327 students in 2019-20. It is the flagship institution of the University of Minnesota System, and is organized into 19 colleges, schools, and other major academic units.

    The University was included in a list of Public Ivy universities in 2001. Legislation passed in 1851 to develop the university, and the first college classes were held in 1867. The university is categorized as a Doctoral University – Highest Research Activity (R1) in the Carnegie Classification of Institutions of Higher Education. Minnesota is a member of the Association of American Universities and is ranked 14th in research activity, with $881 million in research and development expenditures in the fiscal year ending June 30, 2015.

    University of Minnesota faculty, alumni, and researchers have won 26 Nobel Prizes and three Pulitzer Prizes. Notable University of Minnesota alumni include two vice presidents of the United States, Hubert Humphrey and Walter Mondale.

     
  • richardmitnick 5:30 pm on April 18, 2019 Permalink | Reply
    Tags: , Handedness, , , , Skyrmions – quasiparticles akin to tiny magnetic swirls, STEM- scanning transmission electron microscopy   

    From Lawrence Berkeley National Lab: “Electric Skyrmions Charge Ahead for Next-Generation Data Storage” 

    Berkeley Logo

    From Lawrence Berkeley National Lab

    April 18, 2019
    Theresa Duque
    tnduque@lbl.gov
    (510) 495-2418

    Berkeley Lab-led research team makes a chiral skyrmion crystal with electric properties; puts new spin on future information storage applications.


    VIDEO: Simulation of a single polar skyrmion. Red arrows signify that this is a left-handed skyrmion. The other arrows represent the angular distribution of the dipoles. (Credit: Xiaoxing Cheng, Pennsylvania State University; C.T. Nelson, Oak Ridge National Laboratory; and Ramamoorthy Ramesh, Berkeley Lab)

    When you toss a ball, what hand do you use? Left-handed people naturally throw with their left hand, and right-handed people with their right. This natural preference for one side versus the other is called handedness, and can be seen almost everywhere – from a glucose molecule whose atomic structure leans left, to a dog who shakes “hands” only with her right.

    Handedness can be exhibited in chirality – where two objects, like a pair of gloves, can be mirror images of each other but cannot be superimposed on one another. Now a team of researchers led by Berkeley Lab has observed chirality for the first time in polar skyrmions – quasiparticles akin to tiny magnetic swirls – in a material with reversible electrical properties. The combination of polar skyrmions and these electrical properties could one day lead to applications such as more powerful data storage devices that continue to hold information – even after a device has been powered off. Their findings were reported this week in the journal Nature.

    “What we discovered is just mind-boggling,” said Ramamoorthy Ramesh, who holds appointments as a faculty senior scientist in Berkeley Lab’s Materials Sciences Division and as the Purnendu Chatterjee Endowed Chair in Energy Technologies in Materials Science and Engineering and Physics at UC Berkeley. “We hadn’t planned on making skyrmions. So for us to end up making a chiral skyrmion is exciting.”

    1

    When the team of researchers – co-led by Ramesh and Lane Martin, a staff scientist in Berkeley Lab’s Materials Sciences Division and a professor in Materials Science and Engineering at UC Berkeley – began this study in 2016, they had set out to find ways to control how heat moves through materials. So they fabricated a special crystal structure called a superlattice from alternating layers of lead titanate (an electrically polar material, whereby one end is positively charged and the opposite end is negatively charged) and strontium titanate (an insulator, or a material that doesn’t conduct electric current).

    But once they took STEM (scanning transmission electron microscopy) measurements of the lead titanate/strontium titanate superlattice at the Molecular Foundry, a U.S. DOE Office of Science User Facility at Berkeley Lab that specializes in nanoscale science, they saw something strange that had nothing to do with heat: Bubble-like formations had cropped up all across the device.

    Bubbles, bubbles everywhere

    So what were these “bubbles,” and how did they get there?

    Those bubbles, it turns out, were polar skyrmions – or textures made up of opposite electric charges known as dipoles. Researchers had always assumed that skyrmions would only appear in magnetic materials, where special interactions between magnetic spins of charged electrons stabilize the twisting chiral patterns of skyrmions. So when the Berkeley Lab-led team of researchers discovered skyrmions in an electric material, they were astounded.

    3
    Simulation of the cross-section in the middle of the polar-skyrmion bubble. (Credit: Berkeley Lab)

    Through the researchers’ collaboration with theorists Javier Junquera of the University of Cantabria in Spain, and Jorge Íñiguez of the Luxembourg Institute of Science and Technology, they discovered that these textures had a unique feature called a “Bloch component” that determined the direction of its spin, which Ramesh compares to the fastening of a belt – where if you’re left-handed, the belt goes from left to right. “And it turned out that this Bloch component – the skyrmion’s equatorial belt, so to speak – is the key to its chirality or handedness,” he said.

    While using sophisticated STEM at Berkeley Lab’s Molecular Foundry and at the Cornell Center for Materials Research, where David Muller of Cornell University took atomic snapshots of skyrmions’ chirality at room temperature in real time, the researchers discovered that the forces placed on the polar lead titanate layer by the nonpolar strontium titanate layer generated the polar skyrmion “bubbles” in the lead titanate.

    “Materials are like people,” said Ramesh. “When people get stressed, they respond in unpredictable ways. And that’s what materials do too: In this case, by surrounding lead titanate by strontium titanate, lead titanate starts to go crazy – and one way that it goes crazy is to create polar textures like skyrmions.”

    Through the researchers’ collaboration with theorists Javier Junquera of the University of Cantabria in Spain, and Jorge Íñiguez of the Luxembourg Institute of Science and Technology, they discovered that these textures had a unique feature called a “Bloch component” that determined the direction of its spin, which Ramesh compares to the fastening of a belt – where if you’re left-handed, the belt goes from left to right. “And it turned out that this Bloch component – the skyrmion’s equatorial belt, so to speak – is the key to its chirality or handedness,” he said.

    While using sophisticated STEM at Berkeley Lab’s Molecular Foundry and at the Cornell Center for Materials Research, where David Muller of Cornell University took atomic snapshots of skyrmions’ chirality at room temperature in real time, the researchers discovered that the forces placed on the polar lead titanate layer by the nonpolar strontium titanate layer generated the polar skyrmion “bubbles” in the lead titanate.

    Custom-designed scanning transmission electron microscope at Cornell University by David Muller/Cornell University

    LBNL THEMIS scannng transmission electronic micsoscope

    “Materials are like people,” said Ramesh. “When people get stressed, they respond in unpredictable ways. And that’s what materials do too: In this case, by surrounding lead titanate by strontium titanate, lead titanate starts to go crazy – and one way that it goes crazy is to create polar textures like skyrmions.”

    Shining a light on crystal chirality

    To confirm their observations, senior staff scientist Elke Arenholz and staff scientist Padraic Shafer at Berkeley Lab’s Advanced Light Source (ALS), along with Margaret McCarter, a physics Ph.D. student from the Ramesh Lab at UC Berkeley, probed the chirality by using a spectroscopic technique known as RSXD-CD (resonant soft X-ray diffraction circular dichroism), one of the highly optimized tools available to the scientific community at the ALS, a U.S. DOE Office of Science User Facility that specializes in lower energy, “soft” X-ray light for studying the properties of materials.

    LBNL ALS

    3
    Simulations of skyrmion bubbles and elongated skyrmions for the lead titanate/strontium titanate superlattice. (Credit: Berkeley Lab)

    Light waves can be “circularly polarized” to also have handedness, so the researchers theorized that if polar skyrmions have handedness, a left-handed skyrmion, for example, should interact more strongly with left-handed, circularly polarized light – an effect known as circular dichroism.

    When McCarter and Shafer tested the samples at the ALS, they successfully uncovered another piece to the chiral skyrmion puzzle – they found that incoming circularly polarized X-rays, like a screw whose threads rotate either clockwise or counterclockwise, interact with skyrmions whose dipoles rotate in the same direction, even at room temperature. In other words, they found evidence of circular dichroism – where there is only a strong interaction between X-rays and polar skyrmions with the same handedness.

    “The theoretical simulations and microscopy both revealed the presence of a Bloch component, but to confirm the chiral nature of these skyrmions, the last piece of the puzzle was really the circular dichroism measurements,” McCarter said. “It is amazing to observe this effect in materials that typically don’t have handedness. We are excited to explore the implications of this chirality in a ferroelectric and how it can be controlled in a way that could be useful for storing data.”

    Now that the researchers have made a single electric skyrmion and confirmed its chirality, they plan to make an array of dozens of electric skyrmions – each one with a diameter of just 8 nm (for comparison, the Ebola virus is about 50 nm wide) – with the same handedness. “In terms of applications, this is exciting because now we have chirality – switching a skyrmion on or off, or between left-handed and right-handed – on top of still being able to use the charge for storing data,” Ramesh said.

    The researchers next plan to study the effects of applying an electric field on the polar skyrmions. “Now that we know that polar/electric skyrmions are chiral, we want to see if we can electrically manipulate them. If I apply an electric field, can I turn each one like a turnstile? Can I move each one, one at a time, like a checker on a checkerboard? If we can somehow move them, write them, and erase them for data storage, then that would be an amazing new technology,” Ramesh said.

    Also contributing to the study were researchers from Pennsylvania State University, Cornell University, and Oak Ridge National Laboratory.

    The work was supported by the DOE Office of Science with additional funding provided by the Gordon and Betty Moore Foundation’s EPiQS Initiative, the National Science Foundation, the Luxembourg National Research Fund, and the Spanish Ministry of Economy and Competitiveness.

    See the full article here .

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    Bringing Science Solutions to the World

    In the world of science, Lawrence Berkeley National Laboratory (Berkeley Lab) is synonymous with “excellence.” Thirteen Nobel prizes are associated with Berkeley Lab. Seventy Lab scientists are members of the National Academy of Sciences (NAS), one of the highest honors for a scientist in the United States. Thirteen of our scientists have won the National Medal of Science, our nation’s highest award for lifetime achievement in fields of scientific research. Eighteen of our engineers have been elected to the National Academy of Engineering, and three of our scientists have been elected into the Institute of Medicine. In addition, Berkeley Lab has trained thousands of university science and engineering students who are advancing technological innovations across the nation and around the world.

    Berkeley Lab is a member of the national laboratory system supported by the U.S. Department of Energy through its Office of Science. It is managed by the University of California (UC) and is charged with conducting unclassified research across a wide range of scientific disciplines. Located on a 202-acre site in the hills above the UC Berkeley campus that offers spectacular views of the San Francisco Bay, Berkeley Lab employs approximately 3,232 scientists, engineers and support staff. The Lab’s total costs for FY 2014 were $785 million. A recent study estimates the Laboratory’s overall economic impact through direct, indirect and induced spending on the nine counties that make up the San Francisco Bay Area to be nearly $700 million annually. The Lab was also responsible for creating 5,600 jobs locally and 12,000 nationally. The overall economic impact on the national economy is estimated at $1.6 billion a year. Technologies developed at Berkeley Lab have generated billions of dollars in revenues, and thousands of jobs. Savings as a result of Berkeley Lab developments in lighting and windows, and other energy-efficient technologies, have also been in the billions of dollars.

    Berkeley Lab was founded in 1931 by Ernest Orlando Lawrence, a UC Berkeley physicist who won the 1939 Nobel Prize in physics for his invention of the cyclotron, a circular particle accelerator that opened the door to high-energy physics. It was Lawrence’s belief that scientific research is best done through teams of individuals with different fields of expertise, working together. His teamwork concept is a Berkeley Lab legacy that continues today.

    A U.S. Department of Energy National Laboratory Operated by the University of California.

    University of California Seal

    DOE Seal

     
    • Arushi 6:58 am on April 19, 2019 Permalink | Reply

      Your blog seems pretty informative. Instead of just NASA can you write about the discoveries of other organizations as well so that the science lovers can get every aspect of physics in your blog? BTW love your blog💝

      Like

      • richardmitnick 3:31 pm on April 19, 2019 Permalink | Reply

        I cover much more than NASA. I cover universities and science institutions all over the world. There is a concentration on Astronomy and Physics, but I also cover volcanology, earthquake science, ASD, HPC, . What you need to do is read the blog or access the Facebook Fan page, http://facebook.com/sciencesprings which is a pretty rich experience if you do not want to bother seeing the blog posts in full.

        Like

  • richardmitnick 8:16 am on March 19, 2019 Permalink | Reply
    Tags: , , , , Janus nanocrystal platform, MSE-Material Science and Engineering, Nanoparticle self-assembly, , STEM- scanning transmission electron microscopy   

    From Iowa State University: “Engineered nanoparticle discovery led by MSE’s Jiang makes cover of Nano Letters” 

    Iowa State University

    March 13, 2019
    Cyclone Engineering

    1

    Shan Jiang, assistant professor of material science and engineering [MSE], led a research group that created a novel Janus nanocrystal platform to control nanoparticle self-assembly.

    Janus particles are fundamental new materials, and Jiang’s discovery opens opportunities in different areas including energy, drug delivery, disease diagnosis and therapy. The results appear on the cover of the March issue of Nano Letters.

    Key to the team’s discoveries were a multidisciplinary approach and the powerful high-resolution scanning transmission electron microscopy available at U.S. Department of Energy’s Ames Laboratory’s Sensitive Instrument Facility.

    Ames Lab’s Matt Kramer with the Tecnai transmission electron microscope at the new Sensitive Instrument Facility

    The collaborative research effort is led by Jiang with Eric Cochran, professor of chemical and biological engineering, and Lin Zhou, scientist at Ames Laboratory. Fei Liu, a postdoctoral researcher in materials science and engineering, is the first author. Shailja Goyal and Michael Forrester, graduate students in chemical and biological engineering, contributed to the synthesis and Tao Ma, a postdoctoral researcher at Ames Laboratory contributed to the electron microscopy characterization. Undergraduates in materials science and engineering Yasmeen Mansoorieh and John Henjum also contributed to the work.

    Jiang’s research team’s technique is inexpensive, scalable to commercial production. The group demonstrated their synthesis approach in the form of Au-Fe3O4 nanocrystals, particularly important materials because the particles are biocompatible and have enhanced magnetic and surface plasmon resonance properties.

    “We had the right people and the right facilities to demonstrate for the first time that we can make these particles that show unique structures. The work was all completed here on the Iowa State University campus, and I’m very proud of that,” said Jiang.

    See the full article here .

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    Iowa State University is a public, land-grant university, where students get a great academic start in learning communities and stay active in 800-plus student organizations, undergrad research, internships and study abroad. They learn from world-class scholars who are tackling some of the world’s biggest challenges — feeding the hungry, finding alternative fuels and advancing manufacturing.

    Iowa Agricultural College and Model Farm (now Iowa State University) was officially established on March 22, 1858, by the legislature of the State of Iowa. Story County was selected as a site on June 21, 1859, and the original farm of 648 acres was purchased for a cost of $5,379. The Farm House, the first building on the Iowa State campus, was completed in 1861, and in 1862, the Iowa legislature voted to accept the provision of the Morrill Act, which was awarded to the agricultural college in 1864.

    Iowa State University Knapp-Wilson Farm House. Photo between 1911-1926

    Iowa Agricultural College (Iowa State College of Agricultural and Mechanic Arts as of 1898), as a land grant institution, focused on the ideals that higher education should be accessible to all and that the university should teach liberal and practical subjects. These ideals are integral to the land-grant university.

    The first official class entered at Ames in 1869, and the first class (24 men and 2 women) graduated in 1872. Iowa State was and is a leader in agriculture, engineering, extension, home economics, and created the nation’s first state veterinary medicine school in 1879.

    In 1959, the college was officially renamed Iowa State University of Science and Technology. The focus on technology has led directly to many research patents and inventions including the first binary computer (the ABC), Maytag blue cheese, the round hay baler, and many more.

    Beginning with a small number of students and Old Main, Iowa State University now has approximately 27,000 students and over 100 buildings with world class programs in agriculture, technology, science, and art.

    Iowa State University is a very special place, full of history. But what truly makes it unique is a rare combination of campus beauty, the opportunity to be a part of the land-grant experiment, and to create a progressive and inventive spirit that we call the Cyclone experience. Appreciate what we have here, for it is indeed, one of a kind.

     
  • richardmitnick 7:38 am on March 2, 2018 Permalink | Reply
    Tags: , , , CFNCenter for Functional Nanomaterials, , Converting CO2 into Usable Energy, HER-hydrogen evolution reaction or “water splitting", , , STEM- scanning transmission electron microscopy   

    From BNL: “Converting CO2 into Usable Energy” 

    Brookhaven Lab

    March 1, 2018

    Stephanie Kossman
    skossman@bnl.gov
    (631) 344-8671

    Peter Genzer
    genzer@bnl.gov
    (631) 344-3174

    Scientists show that single nickel atoms are an efficient, cost-effective catalyst for converting carbon dioxide into useful chemicals.

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    Brookhaven scientists are pictured at NSLS-II beamline 8-ID, where they used ultra-bright x-ray light to “see” the chemical complexity of a new catalytic material. Pictured from left to right are Klaus Attenkofer, Dong Su, Sooyeon Hwang, and Eli Stavitski.

    Imagine if carbon dioxide (CO2) could easily be converted into usable energy. Every time you breathe or drive a motor vehicle, you would produce a key ingredient for generating fuels. Like photosynthesis in plants, we could turn CO2 into molecules that are essential for day-to-day life. Now, scientists are one step closer.

    Researchers at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory are part of a scientific collaboration that has identified a new electrocatalyst that efficiently converts CO2 to carbon monoxide (CO), a highly energetic molecule. Their findings were published on Feb. 1 in Energy & Environmental Science.

    “There are many ways to use CO,” said Eli Stavitski, a scientist at Brookhaven and an author on the paper. “You can react it with water to produce energy-rich hydrogen gas, or with hydrogen to produce useful chemicals, such as hydrocarbons or alcohols. If there were a sustainable, cost-efficient route to transform CO2 to CO, it would benefit society greatly.”

    Scientists have long sought a way to convert CO2 to CO, but traditional electrocatalysts cannot effectively initiate the reaction. That’s because a competing reaction, called the hydrogen evolution reaction (HER) or “water splitting,” takes precedence over the CO2 conversion reaction.

    A few noble metals, such as gold and platinum, can avoid HER and convert CO2 to CO; however, these metals are relatively rare and too expensive to serve as cost-efficient catalysts. So, to convert CO2 to CO in a cost-effective way, scientists used an entirely new form of catalyst. Instead of noble metal nanoparticles, they used single atoms of nickel.

    “Nickel metal, in bulk, has rarely been selected as a promising candidate for converting CO2 to CO,” said Haotian Wang, a Rowland Fellow at Harvard University and the corresponding author on the paper. “One reason is that it performs HER very well, and brings down the CO2 reduction selectivity dramatically. Another reason is because its surface can be easily poisoned by CO molecules if any are produced.”

    Single atoms of nickel, however, produce a different result.

    “Single atoms prefer to produce CO, rather than performing the competing HER, because the surface of a bulk metal is very different from individual atoms,” Stavitski said.

    Klaus Attenkofer, also a Brookhaven scientist and a co-author on the paper, added, “The surface of a metal has one energy potential—it is uniform. Whereas on a single atom, every place on the surface has a different kind of energy.”

    In addition to the unique energetic properties of single atoms, the CO2 conversation reaction was facilitated by the interaction of the nickel atoms with a surrounding sheet of graphene. Anchoring the atoms to graphene enabled the scientists to tune the catalyst and suppress HER.

    To get a closer look at the individual nickel atoms within the atomically thin graphene sheet, the scientists used scanning transmission electron microscopy (STEM) at Brookhaven’s Center for Functional Nanomaterials (CFN), a DOE Office of Science User Facility.

    Scanning transmission electron microscope Wikipedia

    BNL Center for Functional Nanomaterials

    By scanning an electron probe over the sample, the scientists were able to visualize discrete nickel atoms on the graphene.

    “Our state-of-art transmission electron microscope is a unique tool to see extremely tiny features, such as single atoms,” said Sooyeon Hwang, a scientist at CFN and a co-author on the paper.

    “Single atoms are usually unstable and tend to aggregate on the support,” added Dong Su, also a CFN scientist and a co-author on the paper. “However, we found the individual nickel atoms were distributed uniformly, which accounted for the excellent performance of the conversion reaction.”

    To analyze the chemical complexity of the material, the scientists used beamline 8-ID at the National Synchrotron Light Source II (NSLS-II)—also a DOE Office of Science User Facility at Brookhaven Lab. The ultra-bright x-ray light at NSLS-II enabled the scientists to “see” a detailed view of the material’s inner structure.

    BNL NSLS-II

    “Our state-of-art transmission electron microscope is a unique tool to see extremely tiny features, such as single atoms,” said Sooyeon Hwang, a scientist at CFN and a co-author on the paper.

    “Single atoms are usually unstable and tend to aggregate on the support,” added Dong Su, also a CFN scientist and a co-author on the paper. “However, we found the individual nickel atoms were distributed uniformly, which accounted for the excellent performance of the conversion reaction.”

    To analyze the chemical complexity of the material, the scientists used beamline 8-ID at the National Synchrotron Light Source II (NSLS-II)—also a DOE Office of Science User Facility at Brookhaven Lab. The ultra-bright x-ray light at NSLS-II enabled the scientists to “see” a detailed view of the material’s inner structure.

    “Photons, or particles of light, interact with the electrons in the nickel atoms to do two things,” Stavitski said. “They send the electrons to higher energy states and, by mapping those energy states, we can understand the electronic configuration and the chemical state of the material. As we increase the energy of the photons, they kick the electrons off the atoms and interact with the neighboring elements.” In essence, this provided the scientists with an image of the nickel atoms’ local structure.

    Based on the results from the studies at Harvard, NSLS-II, CFN, and additional institutions, the scientists discovered single nickel atoms catalyzed the CO2 conversion reaction with a maximal of 97 percent efficiency. The scientists say this is a major step toward recycling CO2 for usable energy and chemicals.

    “To apply this technology to real applications in the future, we are currently aimed at producing this single atom catalyst in a cheap and large-scale way, while improving its performance and maintaining its efficiency,” said Wang.

    This study was supported in part by the Rowland Institute at Harvard University. Operations at CFN and NSLS-II are supported by DOE’s Office of Science. For a full list of collaborating institutions and facilities, please see the scientific paper [link is above].

    See the full article here .

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    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world. Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.
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