Recoverable Self-Polarization in Lead-Free Bismuth Sodium Titanate Piezoelectric Thin Films.

Title Recoverable Self-Polarization in Lead-Free Bismuth Sodium Titanate Piezoelectric Thin Films.
Authors J. Zhao; W. Ren; G. Niu; N. Zhang; G. Dong; L. Wang; M. Liu; P. Shi; Z.G. Ye
Journal ACS Appl Mater Interfaces
DOI 10.1021/acsami.7b04033
Abstract

Bismuth sodium titanate, Bi0.5Na0.5TiO3 (BNT), is a promising lead-free ferroelectric material. However, its potential applications have not been fully explored, mainly because of the complex domain structure arising from its intricate phase transitions. A deep and thorough study of its domain structure and polarization switching behavior will greatly help with understanding the polarization nature and with promoting future applications. In this work, we demonstrate that BNT polycrystalline films possess a highly ordered out-of-plane polarization (self-polarization) and randomly oriented in-plane polarizations. Interestingly, the inherent nature of polarization in the BNT films does not allow for the nonvolatile domain writing, as the switched polarization spontaneously and rapidly reverses to the initial orientation state once the external poling electric field is removed, making the self-polarization recoverable. Such a stable self-polarization vanishes gradually with temperature increasing over 150 °C but starts to recover to its initial state upon cooling down to 250 °C, and entirely recovers once the temperature is reduced to below 200 °C. Such interesting properties of BNT films are attributed to the combined effects of the free charges at the Pt electrode, (detected) cation vacancies at the oxide/Pt interface and the defects in oxide lattices. Our results make a step closer to fully understand the nature of polarization and related piezoelectricity in BNT. Such films with recoverable self-polarization are of great interest for applications as sensors, actuators, and transducers that can operate particularly under high temperatures and high electric field conditions.

Citation J. Zhao; W. Ren; G. Niu; N. Zhang; G. Dong; L. Wang; M. Liu; P. Shi; Z.G. Ye.Recoverable Self-Polarization in Lead-Free Bismuth Sodium Titanate Piezoelectric Thin Films.. ACS Appl Mater Interfaces. 2017. doi:10.1021/acsami.7b04033

Related Elements

Bismuth

See more Bismuth products. Bismuth (atomic symbol: Bi, atomic number: 83) is a Block P, Group 15, Period 6 element with an atomic radius of 208.98040. The number of electrons in each of Bismuth's shells is 2, 8, 18, 32, 18, 5 and its electron configuration is [Xe] 4f14 5d10 6s2 6p3. Bismuth Bohr ModelThe bismuth atom has a radius of 156 pm and a Van der Waals radius of 207 pm. In its elemental form, bismuth is a silvery white brittle metal. Bismuth is the most diamagnetic of all metals and, with the exception of mercury, its thermal conductivity is lower than any other metal. Elemental BismuthBismuth has a high electrical resistance, and has the highest Hall Effect of any metal (i.e., greatest increase in electrical resistance when placed in a magnetic field). Bismuth is found in bismuthinite and bismite. It is also produced as a byproduct of lead, copper, tin, molybdenum and tungsten extraction. Bismuth was first discovered by Early Man. The name Bismuth originates from the German word 'wissmuth,' meaning white mass.

Sodium

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Titanium

See more Titanium products. Titanium (atomic symbol: Ti, atomic number: 22) is a Block D, Group 4, Period 4 element with an atomic weight of 47.867. The number of electrons in each of Titanium's shells is [2, 8, 10, 2] and its electron configuration is [Ar] 3d2 4s2. Titanium Bohr ModelThe titanium atom has a radius of 147 pm and a Van der Waals radius of 187 pm. Titanium was discovered by William Gregor in 1791 and first isolated by Jöns Jakob Berzelius in 1825. In its elemental form, titanium has a silvery grey-white metallic appearance. Titanium's properties are chemically and physically similar to zirconium, both of which have the same number of valence electrons and are in the same group in the periodic table. Elemental TitaniumTitanium has five naturally occurring isotopes: 46Ti through 50Ti, with 48Ti being the most abundant (73.8%). Titanium is found in igneous rocks and the sediments derived from them. It is named after the word Titanos, which is Greek for Titans.

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