Recently published research by scientists at the U.S. Department of Energy's National Renewable Energy Laboratory (NREL) and Argonne National Laboratory, and academic institutions has shed light on a semiconducting material with zero thermal expansion (ZTE). The research may play a role in the design of future generations of electronics and optoelectronics that can withstand a wide range of temperatures.
Traditional interests in ZTE materials have largely been in areas such as optics, heat-engine components and kitchenware. ZTE materials with applications in non-conventional areas such as electronics and optoelectronics are rare; most are glasses, which do not work well in electronics applications. The hybrid inorganic-organic semiconductor investigated in this work is a multifunctional semiconductor that has previously been shown to possess superior electronic and optical properties. The work also suggests an alternative route to designing materials with any desired positive or negative thermal expansion.
“It's a merger of inorganic and organic materials,” said Zahirul Islam, a physicist in Argonne's X-Ray Science Division, “which form a fully coherent, three-dimensionally ordered crystal. Normally inorganic and organic materials don't work very well together, but here they are working together to display these remarkable properties.”
The materials under study form alternating organic and inorganic layers that work together to produce these effects. One contracts while the other expands, and the net effect is zero.
“This work suggests a novel approach to design the thermal expansion — from positive to negative, including zero — in a nanoscopic scale by assembling nano-scale units in an ordered manner,” said principal investigator Yong Zhang of NREL. “The idea has only been demonstrated for tuning thermal expansion in one dimension and study was limited to one or two materials. Next, we would like to extend the idea to higher dimensions (i.e., ZTE in more than one dimension), and explore more inorganic-organic combinations.”
These hybrid materials hold promise for high-efficiency semiconductor lasers, ultrathin and flexible solar cells and light-emitting and detecting devices. It is possible to “dope” the materials (adding small amounts of other compounds) to form transparent conducting materials, Zhang said.
While chemical and thermal stability are two major problems for most hybrids, the hybrid nanostructures investigated in this work are found to be exceptionally stable in the air, even under the illumination of an ultraviolet laser.
“Not only do the crystal structures remain unchanged,” Zhang said, “but their electronic and optical properties remain after a few years of air exposure or upon heating to more than 200 degrees C, a feature attributed to the strong covalent bonding throughout the structure.”
This work involved multiple institutes with complementary strengths and capabilities. Scientists at NREL initiated and organized the project. The materials were synthesized by Jing Li's group at Rutgers University. Critical X-ray diffraction measurements to determine the ZTE effects were carried out at Argonne's Advanced Photon Source. Other key Argonne researchers are Yang Ren and Peter L. Lee. Theoretical modeling on the phonon (vibrational) spectrum, crucial to the understanding of the experimental findings, was performed by scientists at the University of Arkansas. Collaborators at the University of Colorado at Boulder also made important contributions to the work.
Argonne National Laboratory, a renowned R&D center, brings the world's brightest scientists and engineers together to find exciting and creative new solutions to pressing national problems in science and technology. The nation's first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America 's scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy's Office of Science.
Steve McGregor | EurekAlert!
New type of smart windows use liquid to switch from clear to reflective
14.12.2017 | The Optical Society
New ultra-thin diamond membrane is a radiobiologist's best friend
14.12.2017 | American Institute of Physics
MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.
Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...
Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...
Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.
To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...
The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.
Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...
With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong
Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...
11.12.2017 | Event News
08.12.2017 | Event News
07.12.2017 | Event News
14.12.2017 | Health and Medicine
14.12.2017 | Physics and Astronomy
14.12.2017 | Life Sciences