Ferroelectricity's Discovery 100th Anniversary - Progress Knows No Boundaries

11:18, August 7, 2020

Read Vladimir Shur's on the properties and history of ferroelectric materials

2020 marks the 100th anniversary of the opening of the first material of the class of ferroelectrics - Rochelle Salt. The history of the scientific discovery and development of ferroelectricity was told by the director of the Ural Center for Shared Use "Modern Nanotechnologies" of the UrFU Vladimir Shur.

“Ferroelectric salt was synthesized from tartar in 1655 by French pharmacists from the city of La Rochelle - brothers Jen and Elie Seigner. For many years it has been used as a universal medicine, explains Vladimir Shur. - This is a double salt of tartaric acid - sodium potassium tartrate tetrahydrate. Colorless transparent crystals weighing more than a kilogram can be grown from an aqueous solution."

Over time, scientists discovered that Rochelle salt is a piezoelectric, pyroelectric, and optically active crystal. Its characteristics change under the influence of an electric field, temperature, and also depend on history and humidity.

“The piezoelectric effect was discovered by the Curie brothers in 1880 in quartz, tourmaline, Rochelle salt and a number of other crystals. During the First World War, starting in 1916, piezoelectric devices for detecting submarines and underwater communications were intensively developed in many countries. Rochelle's salt was also investigated, since it was known that its sensitivity is much higher than that of quartz. However, the instability of the characteristics greatly damaged its reputation,” says the physicist.

In 1920, Rochelle salt became the progenitor of a new class of substances. American physicist Joseph Walaszek was the first to discover its unique properties: a dielectric hysteresis loop similar to a magnetic one, as well as gigantic values ​​of dielectric constant and piezoelectric response in the temperature range from –18 to +24 ° C.

During World War II, Rochelle salt was used to make laryngophones, microphones, underwater locating and communication devices, piezoelectric fuses and loudspeakers. In the USSR, 54 tons of crystals were grown, from which millions of defense devices were made. Today, Rochelle salt is used in the food industry as a food additive (antioxidant) E337, an emulsifier in cheese making and a baking powder in baking powders.

Scientists from our country have played a significant role in the study of ferroelectrics. So, the term "ferroelectricity", used in Russian-language literature, was proposed by Igor Vasilyevich Kurchatov in 1933 in the world's first monograph of the same name.

During World War II, with an active search for new piezoelectrics, scientists from Japan, the USA and the USSR synthesized BaO-TiO2 ceramics with an abnormally high dielectric constant. Later, physicists of the USSR and the USA discovered a polarization switching in it and thus discovered a new ferroelectric barium titanate BaTiO3, which became the ancestor of a huge family of ferroelectrics with the perovskite structure CaTiO3. It is interesting to note that perovskite was found in the Urals and named after Count Perovsky.

To date, scientists have synthesized hundreds of ferroelectrics, which are actively studied and widely used in various fields. The laboratory of ferroelectrics IENiM under the leadership of Vladimir Shur is one of the world's recognized research centers.

“In recent years, micro- and nanodomain engineering has been actively developing all over the world as a new branch of science and technology associated with the fabrication of stable precision regular domain structures (RDS) in ferroelectrics. The advances in blast-furnace engineering have become an important step in the production of electro-optical and nonlinear-optical devices. The production of nonlinear optical crystals with RDS using the phase quasi-phase-matching effect has made it possible to develop coherent light sources with frequency conversion,” says Vladimir Shur.

With the help of domain engineering, integrated optics devices are created, and the dielectric and piezoelectric characteristics of ferroelectric crystals and ceramics are improved. In addition, the production of monocrystalline thin films of lithium niobate and lithium tantalate of submicron thickness has been mastered. Converters with such films are used in quantum communication (photon sources), telecommunications (highly efficient single-channel converters), and spectroscopy (laser sources without a resonator).From 17 to 19 August 2020, on the basis of the Institute of Natural Sciences and Mathematics of UrFU, an international online conference “Research of ferroelectric materials by Russian scientists. Centenary of the discovery of ferroelectricity (SE-100)”. Scientists from Russia, Israel, USA, Portugal, Germany and the Czech Republic will talk about the latest scientific achievements, as well as about the history of ferroelectric research in the leading research centers of the USSR and Russia.

About Ferroelectrics

According to the classical definition, a ferroelectric is a substance that has, in a certain temperature range, spontaneous polarization oriented in two or more directions, which can be changed under the action of an electric field.