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A possible paradigm shift within piezoelectricity by Staff Writers Copenhagen, Denmark (SPX) Feb 21, 2022
Piezoelectricity is used everywhere: Watches, cars, alarms, headphones, pickups for instruments, electric lighters and gas burners. One of the most common examples is probably the quartz watch, where the piezoelectric material quartz is a prerequisite for the watch's function. Piezoelectric materials have the particular property that their shape changes when applying an electrical voltage to the material. It also works the other way around: Exposing them to a mechanical impact will create an electrical voltage. Piezoelectricity is often used in sensors, actuators, and resonators. In small devices, they are known as MEMS (micro-electromechanical systems). Here, materials other than quartz must be used. These materials, however, often contain lead in the form of lead zirconate titanate (PZT). This may prove to be a barrier to the spread of technology in, for example, the biomedical field, as lead is harmful to the body. However, researchers assess an excellent potential for utilizing the piezoelectric effect in a wider range of diagnostics, prognosis and therapy technologies if lead could be removed. In a new, scientific article in the journal Science, Professor Nini Pryds and Professor Vincenzo Esposito from DTU Energy show that it is possible to create piezoelectric effects in materials where this is not ordinarily possible. It paves the way for designing piezoelectric materials that are lead-free and far more environmentally friendly. The research was conducted with colleagues from EPFL (Ecole Polytechnique Federale de Lausanne), Tel Aviv University and the University of Antwerp.
More environmentally friendly materials "Many micro-electromechanical systems already exist, but they often contain lead-containing materials that are harmful for human implantation. The BioWings project aims to develop biocompatible materials with properties similar to common lead-containing materials that do not contain lead or the other harmful materials," says Nini Pryds, adding: "The new development will provide a fundamental step towards environmentally friendly piezoelectric materials with high performance for use, e.g. in car technology and medical applications," says Nini Pryds. As a fundamental premise, piezoelectric materials depend on crystal symmetry. Typical piezoelectric materials have a so-called non-centrosymmetric crystal lattice. This means, for example, that when one presses on the material, an electrical voltage naturally arises across the material due to the movement of positive and negative ions relative to each other. This results in the symmetry of the crystal being broken. For over a century, this has been a significant obstacle to finding new piezoelectric materials because piezoelectricity can only be created with a non-centrosymmetric crystal lattice.
Possible paradigm shift According to Nini Pryds, this concept will also be possible with other materials with similar atomic defects. It can thus help pave the way for non-lead-based piezoelectricity in, for example, actuators and sensors. "For the time being, piezoelectric materials are limited to the non-centrosymmetric crystal structure. This entails a significant limitation in the number of materials that may be used. Our new results provide a paradigm shift towards inducing piezoelectricity in centrosymmetric crystals, thereby expanding the number of possible materials used. I expect it will have a significant effect on the design of new electromechanical devices with new biocompatible materials," says Nini Pryds. Piezoelectricity is used everywhere: Watches, cars, alarms, headphones, pickups for instruments, electric lighters and gas burners. One of the most common examples is probably the quartz watch, where the piezoelectric material quartz is a prerequisite for the watch's function. Piezoelectric materials have the particular property that their shape changes when applying an electrical voltage to the material. It also works the other way around: Exposing them to a mechanical impact will create an electrical voltage. Piezoelectricity is often used in sensors, actuators, and resonators. In small devices, they are known as MEMS (micro-electromechanical systems). Here, materials other than quartz must be used. These materials, however, often contain lead in the form of lead zirconate titanate (PZT). This may prove to be a barrier to the spread of technology in, for example, the biomedical field, as lead is harmful to the body. However, researchers assess an excellent potential for utilizing the piezoelectric effect in a wider range of diagnostics, prognosis and therapy technologies if lead could be removed. In a new, scientific article in the journal Science, Professor Nini Pryds and Professor Vincenzo Esposito from DTU Energy show that it is possible to create piezoelectric effects in materials where this is not ordinarily possible. It paves the way for designing piezoelectric materials that are lead-free and far more environmentally friendly. The research was conducted with colleagues from EPFL (Ecole Polytechnique Federale de Lausanne), Tel Aviv University and the University of Antwerp.
More environmentally friendly materials "Many micro-electromechanical systems already exist, but they often contain lead-containing materials that are harmful for human implantation. The BioWings project aims to develop biocompatible materials with properties similar to common lead-containing materials that do not contain lead or the other harmful materials," says Nini Pryds, adding: "The new development will provide a fundamental step towards environmentally friendly piezoelectric materials with high performance for use, e.g. in car technology and medical applications," says Nini Pryds. As a fundamental premise, piezoelectric materials depend on crystal symmetry. Typical piezoelectric materials have a so-called non-centrosymmetric crystal lattice. This means, for example, that when one presses on the material, an electrical voltage naturally arises across the material due to the movement of positive and negative ions relative to each other. This results in the symmetry of the crystal being broken. For over a century, this has been a significant obstacle to finding new piezoelectric materials because piezoelectricity can only be created with a non-centrosymmetric crystal lattice.
Possible paradigm shift According to Nini Pryds, this concept will also be possible with other materials with similar atomic defects. It can thus help pave the way for non-lead-based piezoelectricity in, for example, actuators and sensors. "For the time being, piezoelectric materials are limited to the non-centrosymmetric crystal structure. This entails a significant limitation in the number of materials that may be used. Our new results provide a paradigm shift towards inducing piezoelectricity in centrosymmetric crystals, thereby expanding the number of possible materials used. I expect it will have a significant effect on the design of new electromechanical devices with new biocompatible materials," says Nini Pryds.
Research Report: "Induced Giant Piezoelectricity in Centrosymmetric Oxides"
Chaining atoms together yields quantum storage Pasadena CA (SPX) Feb 18, 2022 Engineers at Caltech have developed an approach for quantum storage could help pave the way for the development of large-scale optical quantum networks. The new system relies on nuclear spins-the angular momentum of an atom's nucleus-oscillating collectively as a spin wave. This collective oscillation effectively chains up several atoms to store information. The work, which is described in a paper published on February 16 in the journal Nature, utilizes a quantum bit (or qubit) made from an ion of ... read more
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