Energy is constantly around people in its many forms - in sunlight, warmth in a room, and even the movements of the people themselves. All this energy is usually simply “wasted” for human civilization, but it can potentially be used to power mobile and wearable gadgets - from biometric sensors to smart watches. Researchers from the University of Oulu (Finland) have found a mineral with a perovskite crystal structure, the properties of which allow it to extract energy from many different sources simultaneously.
Perovskites are a family of minerals, many of which have shown themselves to be promising due to their ability to simultaneously extract one or two types of energy. One of the members of this family, for example, may be good for converting solar energy into electricity. The other is better at extracting energy from the changes in temperature and pressure that can occur during movement. They are called, respectively, pyroelectric and piezoelectric materials.
At times, of course, one type of energy is not enough as a source. A certain form of energy may not always be available - in cloudy weather or when a person is not moving. Therefore, researchers have developed devices that can extract multiple forms of energy. But these devices require different materials that make them too bulky for use in compact devices.
The Applied Physics Letters has published the results of a study by Yang Bai and colleagues at the University of Oulu. Researchers have studied a specific type of perovskite called KBNNO, which is likely capable of extracting various forms of energy. Like all perovskites, KBNNO is a ferroelectric material filled with tiny electrical dipoles, like the little compass arrows in a magnet.
When a KBNNO-like ferroelectric material undergoes temperature changes, its dipoles are displaced and thus an electric current is induced. Electric charge is also accumulated according to the direction of the dipole moment. The deformation of the material leads to the fact that certain fragments of it attract or repel a charge, which again leads to the generation of current.
Researchers have previously studied the photovoltaic and general ferroelectric properties of KBNNO, but this study was conducted at 200 degrees below freezing, and they did not focus on the material's temperature and pressure properties. In the new study, Yang Bai notes, for the first time, all of these properties of the material, which appear at room temperature, were evaluated.
Experiments have shown that while KBNNO is good for generating energy from heat and pressure, it is not as good as other perovskites. Perhaps the most impressive discovery by the researchers was the ability to modify the KBNNO composition to improve its pyroelectric and piezoelectric properties. Thus, it is possible to "customize" all these properties and use them as efficiently as possible. Young Bai and his colleagues are exploring the possibility of improving KBNNO using sodium.
Yang Bai also said that he hopes to create a prototype device that extracts energy from various sources next year. Its manufacturing process is simple, so the technology could be commercialized within a few years after researchers have identified the best material.
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According to Yang Bai, this technology can lead to accelerated development in the areas of the Internet of Things and smart cities, where energy-consuming sensors and devices can have constant access to energy.
Such material is likely to be used in device batteries, increasing their energy efficiency and reducing the need for frequent charges. Someday, Yang Bai complements his narration, the user will never need to put his gadget on charge at all. Batteries of compact devices in the modern sense can generally remain in the past.
But the fact that a theoretical way has been found to dispense with batteries in gadgets does not mean either that products using this technology will soon appear, or that the technology will ever be implemented.
Will there ever be wearable devices and even smartphones without batteries, which are quite enough for the energy that is in the space around, but is lost, because there is no effective method of extracting it?
Based on materials from sciencedaily.com
OLEG DOVBNYA