Binary semiconducting oxide nanostructures, such as zinc oxide and titanium oxide, are widely used in sensors and catalysts.
However, ternary semiconducting oxide nanostructures, which show higher electrical conductivity and are more stable than the binary type, are increasingly in demand for specific applications due to their particular physical properties. In contrast to conventional ‘top-down’ processes involving physically breaking large macroscopic materials into nanoparticles, the chemically based ‘self-organization’ approach offers an inexpensive and flexible means of precisely controlling the size, crystal structure and optoelectronic properties of semiconducting oxide nanostructures, which is crucial for the use of ZTO in specific applications.
ZTO nanostructures can be produced using a variety of methods including thermal evaporation, high-temperature calcination, mechanical grinding, sol-gel synthesis, hydrothermal reaction, and ion-exchange reaction. Different methods produce different ratios of ZTO oxides and impurities, expressed in alternative crystal structures. The authors describe the pertinent features of the hydrothermal growth method for synthesizing ZTO, including high purity of the stable zinc orthostannate Zn2SnO4 and the accompanying ‘cubic spinel’ crystal structure. Moreover, hydrothermal growth is an attractive and relatively simple method since crystal growth occurs at mild temperatures in water.
Typical hydrothermal growth of ZTO nanostructures consists of using an aqueous mixture of a zinc salt, such as zinc nitrate or zinc chloride, and stannic chloride. This mixture is then reduced at 200-250 °C in sodium hydroxide or ammonium hydroxide in a high-pressure environment. Various methods for hydrothermal growth of ZTO nanostructures are detailed by the authors, with varying end products in terms of crystal structure and ‘phase composition’ – amounts of the particular oxides produced.
The physical properties of ZTO depend on the method used for their synthesis. ZTO is a ‘wide-gap’ semiconductor with a bandgap of around 3.6 eV, but the precise bandgap energy depends on the conditions of synthesis, which might result in quantum confinement effects arising from the small size of the nanostructures. Controlling the photoelectrochemical properties of ZTO has practical importance, and relating the optical and electronic properties of ZTO with the composition and crystal structure can pave the way for applications of other complex oxides.
Princeton-UPenn research team finds physics treasure hidden in a wallpaper pattern
20.07.2018 | Princeton University
Relax, just break it
20.07.2018 | DOE/Argonne National Laboratory
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences