Science | July 31st, 2018
Materials for Light-Controlled Nanoelectronics

Research investigates the control of electric polarization in ferroelectric ceramics by the incidence of light

Materials called ferroelectrics have the property of maintaining a spontaneous electric polarization, reversible by the application of an external electric field. These materials are additionally piezoelectric – inducing the accumulation of electrical charges by the application of mechanical stress – and pyroelectric – inducing a temporary voltage by heating or cooling. These properties make ferroelectric materials useful in a variety of applications, such as mechanical vibration sensors, medical ultrasound machines, or fire sensors.

The ferroelectric materials have a structure divided into domains of different polarizations oriented in certain permitted symmetry directions. These domains are formed in the material by the equilibrium between electrostatic depolarization, elastic tension and the energy of the domain walls, which are the interface regions between different domains.

The domain walls can have properties radically different from the domains themselves. By manipulating the domain walls, it is possible to control the polarization of the adjacent domains, which makes them promising candidates for future active elements in nanoelectronic circuits.

In this context, Fernando Rubio-Marcos et al. [1] showed that it is possible to control, in a reversible and non-invasive way, the ferroelectric domains in ceramic materials, by the incidence of polarized light.

Ceramic, or polycrystalline, materials are more versatile, cheaper and easier to manufacture than monocrystalline materials. Thus, the methodology developed by the researchers has potential for application in the next generation of nanoelectronics.

The group used the XRD1 x-ray diffraction beamline of the Brazilian Synchrotron Light Laboratory (LNLS) to identify the crystalline structure of the ceramic material, which is related both to the domain structure and the functional response.

Source: [1] Fernando Rubio-Marcos, Adolfo Del Campo, Rocío E. Rojas-Hernandez, Mariola O. Ramírez, Rodrigo Parra, Rodrigo U. Ichikawa, Leandro A. Ramajo, Luisa E. Bausá and Jose F. Fernández. Experimental evidence of charged domain walls in lead-free ferroelectric ceramics: light-driven nanodomain switching, Nanoscale, 2018,10, 705-715. DOI: 10.1039/C7NR04304J

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