A new technique for growing single-crystal nanorods and controlling their shape using biomolecules could enable the development of smaller, more powerful heat pumps and devices that harvest electricity from heat.
Researchers at Rensselaer Polytechnic Institute have discovered how to direct the growth of nanorods made up of two single crystals using a biomolecular surfactant. The researchers were also able to create “branched” structures by carefully controlling the temperature, time, and amount of surfactant used during synthesis.
“Our work is the first to demonstrate the synthesis of composite nanorods with branching, wherein each nanorod consists of two materials — a single-crystal bismuth telluride nanorod core encased in a hollow cylindrical shell of single-crystal bismuth sulfide,” said G. Ramanath, professor of materials science and engineering at Rensselaer and director of the university’s Center for Future Energy Systems, who led the research project. “Branching and core-shell architectures have been independently demonstrated, but this is the first time that both features have been simultaneously realized through the use of a biomolecular surfactant.”
Most nanostructures comprised of a core and a shell generally require more than one step to synthesize, but these new research results demonstrate how to synthesize such nanorods in only one step.
“Our single-step synthesis is an important development toward realizing large-scale synthesis of composite nanomaterials in general,” said Arup Purkayastha, who worked on the project as a postdoctoral researcher at Rensselaer and is now a scientist with Laird Technologies in Bangalore, India.
Because of their attractive properties, core-shell nanorods are expected to one day enable the development of new nanoscale thermoelectric devices for power generation, as well as nanoscale heat pumps for cooling hot spots in nanoelectronics devices.
“Our discovery enables the realization of two very important attributes for heat dissipation and power generation from heat,” Ramanath said. “First, the core-shell junctions in the nanorods are conducive for heat removal upon application of an electrical voltage, or generating electrical power from heat. Second, the branched structures open up the possibility of fabricating miniaturized conduits for heat removal alongside nanowire interconnects in future device architectures.”
The researchers discovered that synthesis at high temperatures or with low amounts of the biomolecular surfactant L-glutathonic acid (LGTA) yields branched nanorod structures in highly regulated patterns. In contrast, synthesis at low temperatures or with high levels of LGTA results in straight nanorods without any branching. It is interesting to note that at the point of branching, atoms in the branch resemble a mirror image of the parent crystal – a finding that reinforces Ramanath’s conclusion that LGTA is able to induce branching through atomic-level sculpture.
“Since LGTA is similar to biological molecules, our discovery could be conceivably used as a starting point to explore the use of proteins and enzymes to atomically sculpt such nanorod architectures through biological processes,” said Ramanath
Results of the study, titled “Surfactant-Directed Synthesis of Branched Bismuth Telluride/Sulfide Core/Shell Nanorods,” were recently published online and will be featured in an upcoming issue of the journal Advanced Materials.
The full study may be viewed at: http://dx.doi.org/10.1002/adma.200702572
Along with Ramanath and Purkayastha, co-authors of the paper include: Theodorian Borca-Tasciuc, associate professor of mechanical, aerospace and nuclear engineering at Rensselaer; Rensselaer materials science and engineering postdoctoral researcher Huafang Li; Rensselaer graduate students Makala S. Raghuveer and Darshan D. Gandhi; as well as materials science and engineering professor Raju V. Ramanujan, assistant professor Qingyu Yan, and postdoctoral researcher Zhong W. Liu of Nanyang Technological University in Singapore.
The research project was supported by the Interconnect Focus Center New York through MARCO, DARPA and New York state. The National Science Foundation and Honda Motor Co. also supported this project through research grants.About Rensselaer
Michael Mullaney | Newswise Science News
Researchers measure near-perfect performance in low-cost semiconductors
18.03.2019 | Stanford University
Robot arms with the flexibility of an elephant’s trunk
18.03.2019 | Universität des Saarlandes
DESY and MPSD scientists create high-order harmonics from solids with controlled polarization states, taking advantage of both crystal symmetry and attosecond electronic dynamics. The newly demonstrated technique might find intriguing applications in petahertz electronics and for spectroscopic studies of novel quantum materials.
The nonlinear process of high-order harmonic generation (HHG) in gases is one of the cornerstones of attosecond science (an attosecond is a billionth of a...
Nano- and microtechnology are promising candidates not only for medical applications such as drug delivery but also for the creation of little robots or flexible integrated sensors. Scientists from the Max Planck Institute for Polymer Research (MPI-P) have created magnetic microparticles, with a newly developed method, that could pave the way for building micro-motors or guiding drugs in the human body to a target, like a tumor. The preparation of such structures as well as their remote-control can be regulated using magnetic fields and therefore can find application in an array of domains.
The magnetic properties of a material control how this material responds to the presence of a magnetic field. Iron oxide is the main component of rust but also...
Due to the special arrangement of its molecules, a new coating made of corn starch is able to repair small scratches by itself through heat: The cross-linking via ring-shaped molecules makes the material mobile, so that it compensates for the scratches and these disappear again.
Superficial micro-scratches on the car body or on other high-gloss surfaces are harmless, but annoying. Especially in the luxury segment such surfaces are...
The Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope (LBT) in Arizona released its first image of the surface magnetic field of another star. In a paper in the European journal Astronomy & Astrophysics, the PEPSI team presents a Zeeman- Doppler-Image of the surface of the magnetically active star II Pegasi.
A special technique allows astronomers to resolve the surfaces of faraway stars. Those are otherwise only seen as point sources, even in the largest telescopes...
Researchers at Chalmers University of Technology and the University of Gothenburg, Sweden, have proposed a way to create a completely new source of radiation. Ultra-intense light pulses consist of the motion of a single wave and can be described as a tsunami of light. The strong wave can be used to study interactions between matter and light in a unique way. Their research is now published in the scientific journal Physical Review Letters.
"This source of radiation lets us look at reality through a new angle - it is like twisting a mirror and discovering something completely different," says...
11.03.2019 | Event News
01.03.2019 | Event News
28.02.2019 | Event News
22.03.2019 | Life Sciences
22.03.2019 | Life Sciences
22.03.2019 | Information Technology