Piezoelectric materials have long been an integral part of modern technology. Their ability to convert mechanical energy into electrical energy and vice versa is used in a wide range of fields—from medical devices to industrial sensors. Yet, until recently, it remained a mystery why some ceramics achieve record performance while others do not. A new study by Russian materials scientists sheds light on this question, revealing that the secret to these unique properties lies in the subtle details of atomic structure.
The focus was on lead zirconate titanate (PZT), a material considered the gold standard among piezoelectrics for decades. Its outstanding properties appear near the morphotropic phase boundary—an area where several crystal structures coexist within a single piece of ceramic. This ‘crossroads’ of phases delivers the highest response to external influences, but its underlying nature remained unclear for a long time due to structural similarities and analysis challenges.
Three Phases Instead of Two: Surprising Discoveries
A team of Russian scientists conducted a comprehensive study on four types of samples: pure CTS, its variant with strontium added, and two industrial grades — CTS-19 and CTS-23, doped with niobium and cobalt. They used the Rietveld method to analyze the structure, allowing for highly accurate determination of phase ratios within the material. It turned out that the classic pure sample consists not of two, but three crystalline phases: tetragonal, monoclinic, and rhombohedral. Moreover, the proportion of each phase significantly affects the electrical properties of the ceramic.
The addition of dopants changed the picture entirely. In CTS-19 and CTS-23 samples, the rhombohedral phase disappeared, and the material transformed into a mixture of tetragonal and monoclinic structures. Particularly interesting was the discovery that the best piezoelectric performance was observed when these two phases were present in nearly equal proportions, as in the case of CTS-19. Meanwhile, a dominance of the tetragonal structure, as seen in CTS-23, led to changes in the material’s electrophysical characteristics.
Structure determines functionality
Experimental data formed the basis for a theoretical analysis that established a direct link between atomic displacements in the crystal lattice and the Curie temperature—the point at which a material loses its piezoelectric properties. The study showed that not only the quantitative ratio of phases but also their structural characteristics determine the efficiency of the ceramics. This approach paves the way for the targeted creation of materials with specified parameters, which is especially important for high-precision technologies.
Mikhail Talanov, lead researcher at the Terahertz Spectroscopy Laboratory of the Center for Photonics and 2D Materials at MIPT, noted that the development of new piezoelectrics can now rely not on empirical methods, but on a deep understanding of the relationship between chemical composition, structure, and properties. This enables engineers and scientists to control phase balance, achieving optimal performance for specific tasks.
Practical importance and future prospects
The results obtained have not only fundamental but also practical significance. The scientific foundation built during this work now makes it possible to design piezoceramics for a wide range of applications—from medical sensors to actuators in robotics. Specialists can now select the chemical composition and synthesis conditions to achieve the desired combination of phases and, consequently, the required properties.
In the future, researchers plan to study how production parameters—such as temperature, pressure, and sintering duration—affect the formation of phase architecture. This will make it possible to create entire libraries of materials with pre-set characteristics, a crucial factor for the rapidly evolving high-tech industries.
By the way: Who is Mikhail Talanov
For reference, Mikhail Talanov is one of Russia’s leading experts in solid-state physics and materials science. He works at the Moscow Institute of Physics and Technology (MIPT), considered one of the country’s primary research centers. The Terahertz Spectroscopy Laboratory, where Talanov works, is engaged in advanced research in photonics, two-dimensional materials, and novel functional ceramics. In recent years, more than 50 scientific papers have been published under his leadership, many receiving international recognition. Talanov actively collaborates with foreign colleagues and participates in major scientific projects focused on developing new materials for electronics, medicine, and energy. His research has repeatedly laid the groundwork for introducing innovative technologies into industry and education.
