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article imageThree-pronged approach to electrical power generation

By Tim Sandle     Feb 20, 2017 in Technology
Much of the energy around us is wasted, such as the sunlight around us or the movements we make. What if this could be harnessed to create power to drive wearable devices and portable systems? Researchers have been looking into this.
The study of surrounding sources of energy has been the focus of University of Oulu in Finland scientists and this centers on a mineral with the perovskite crystal structure. This mineral possesses remarkable properties that allow it to extract energy from several sources simultaneously.
Perovskite is a calcium titanium oxide mineral composed of calcium titanate. Perovskite materials exhibit many interesting and intriguing properties, which include strong magnetoresistance, superconductivity, and high thermopower. One use for the mineral is with a class of solar cells where they convert solar energy into electricity.
Naturally occurring perovskites can only harness one form of energy at time; while this is useful, it is not as efficient as two forms of energy. This is where the new research comes in. The research has looked into a special form of perovskite called KBNNO (named after the chemical formula of the mineral - (1-x)KNbO3-xBaNi1/2Nb1/2O3-δ). This structure appears to be able to harness many forms of energy. It is a ferroelectric material, meaning that it is filled with tiny electric dipoles. These are a little like tiny compass needles in a magnet.
The KBNNO material, when it undergoes a change in temperature, produces an electric current. This happens as the dipoles alter their alignment. Depending on the placement of the dipoles, current is either attracted or repelled. Similar effects happen when the mineral is exposed to light. More recent research shows that the mineral also produces current in response to pressure, which occurs when the structure is deformed. This means that power can be produced in response to temperature, light and pressure. Somewhat remarkably, electrical power can be produced from all three sources at the same time.
The researchers aim next to modify the KBNNO material in order to boost electrical efficiency. This involves a form of ‘fine tuning’ the material to reach its maximum point. To do this, sodium is being added to the crystal structure to form a type of hybrid energy harvester.
The research has been published in the journal Applied Physics Letters under the title “Ferroelectric, pyroelectric and piezoelectric properties of a photovoltaic perovskite oxide.”
More about Power, Solar power, Electricity, perovskite
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