From The Pennsylvania State University: “Ultrahigh piezoelectric performance demonstrated in ceramic materials” 

Penn State Bloc

From The Pennsylvania State University

May 17, 2022
Jamie Oberdick
jco11@psu.ed
814-865-0285


Ultra-high performing ceramic materials could lead to improved electronics, such as a future version of this robotic vision sensor camera system. Credit: Adobe stock images. All Rights Reserved.

The ability of piezoelectric materials to convert mechanical energy into electrical energy and vice versa makes them useful for various applications from robotics to communication to sensors. A new design strategy for creating ultrahigh-performing piezoelectric ceramics opens the door to even more beneficial uses for these materials, according to a team of researchers from Penn State and Michigan Technological University.

“For a long time, piezoelectric polycrystalline ceramics have shown limited piezoelectric response in comparison to single crystals,” said Shashank Priya, associate vice president for research and professor of materials science and engineering at Penn State and co-author of the study published in the journal Advanced Science. “There are many mechanisms that limit the magnitude of piezoelectricity in polycrystalline ceramic materials. In this paper, we demonstrate a novel mechanism that allows us to enhance the magnitude of the piezoelectric coefficient several times higher than is normally expected for a ceramic.”

The piezoelectric coefficient, which describes the level of a material’s piezoelectric response, is measured in picocoulombs per Newton.

“We achieved close to 2,000 picocoulombs per Newton, which is a significant advance, because in polycrystalline ceramics, this magnitude has always been limited to around 1,000 picocoulombs per Newton,” Priya said. “2,000 was considered an unreachable target in the ceramics community, so achieving that number is very dramatic.”

The path to discovering the new mechanism began with a question: What factors control the magnitude of piezoelectric constant? The piezoelectric constant is the charge generated by a unit of applied force, picocoulomb per Newton, which in turn is dependent on effects occurring at atomic to mesoscale.

“We wondered what are some basic effects, almost at the atomic scale, of the fundamental parameters that limit or control the response?” Priya said. “Using the multiscale model developed at Michigan Tech, which is a combination of different modeling techniques to bridge the length scale, we carried out a very detailed investigation on two phenomena.”

One was chemical heterogeneity, which describes how atoms of different elements in a material are distributed at the nanoscale. This is important because the different atomic positions and the sites that they occupy are critical to piezoelectric response. The second is anisotropy, the influence of crystallographic orientation. This is important because piezoelectric properties in a material are higher along a certain crystallographic direction.

“Imagine the material is like a cube — a cube has different axes, a face diagonal, and a body diagonal, and so piezoelectric response changes across all these different directions,” Yu U. Wang, professor in materials science and engineering, Michigan Technical University, said. “And so, we show that by aligning all the grains in a ceramic material along certain crystallographic axes, we can get a very high piezoelectric response. We created a very high amount of local heterogeneity and a very high grain orientation in the ceramic material, and the combination of these two basic controlling parameters led to high piezoelectric response in ceramics.”

The researchers discovered if you add a small amount of the rare earth element europium to the ceramic, the europium will occupy the corner of the cubic lattice. This creates the chemical heterogeneity in the material that is necessary for a high piezoelectric response. The researchers were able to further amplify the response by getting 99% of the crystal grains oriented.

The combination of these two effects has not been explored before, according to Yongke Yan, associate research professor in materials science and engineering and lead author in this study.

“I think this mechanism that we were able to identify not only leads to enhancement but leads to dramatic enhancement, and pushes it close to ideal value, which is much higher than what many people would expect,” Yan said.

To collect the necessary data to prove their concept, Priya and his team worked with Dabin Lin, formerly a visiting scholar with Penn State’s Materials Research Institute (MRI) and currently a lecturer in photoelectrical engineering at Xi’an Technological University in China, and Ke Wang, MRI staff scientist in MRI’s Materials Characterization Lab. This included gathering transmission electron microscope data by scanning the ceramic materials, which they combined with energy-dispersive X-ray spectroscopy (EDS) techniques. EDS can determine what chemical elements are present and enables researchers to “see” at the single atom level that the europium is present in the ceramic in a way that gives it the heterogeneity necessary for high piezoelectric response.

These findings have the potential to lead to improved and even novel piezoelectric materials, with a variety of new actuator and transducer applications. This could mean better robotics, sensors, transformers, ultrasonic motors and medical technologies. In addition, since the ultrahigh piezoelectric ceramics in the study can be processed using traditional multilayer manufacturing processes, the materials would be cost-effective and scalable.

“People benefit from electronics, and they are present in so many things, such as robots, microscopes, transportation systems, any personal device with a screen such as a phone, medical devices such as body imaging or scanning tools, and even things used in space exploration like robots that might operate outside a spacecraft,” Priya said. “All of these things can be improved with ultrahigh piezoelectric ceramics.”

Along with Priya, Ke, Yang, Yan and Lin, other co-authors of the study from Penn State include Li-Feng Zhu, visiting scholar, Haoyang Leng, doctoral candidate materials science and engineering; Xiaotian Li, assistant research professor in materials science and engineering; and Hairui Liu, postdoctoral researcher in materials science and engineering. Liwei Geng, instructor in materials science and engineering at Michigan Technological University, was also a co-author.

Support for the study was provided by the Department of Defense’s Defense Advanced Research Projects Agency and the National Science Foundation.

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Penn State Campus

The The Pennsylvania State University is a public state-related land-grant research university with campuses and facilities throughout Pennsylvania. Founded in 1855 as the Farmers’ High School of Pennsylvania, Penn State became the state’s only land-grant university in 1863. Today, Penn State is a major research university which conducts teaching, research, and public service. Its instructional mission includes undergraduate, graduate, professional and continuing education offered through resident instruction and online delivery. In addition to its land-grant designation, it also participates in the sea-grant, space-grant, and sun-grant research consortia; it is one of only four such universities (along with Cornell University, Oregon State University, and University of Hawaiʻi at Mānoa). Its University Park campus, which is the largest and serves as the administrative hub, lies within the Borough of State College and College Township. It has two law schools: Penn State Law, on the school’s University Park campus, and Dickinson Law, in Carlisle. The College of Medicine is in Hershey. Penn State is one university that is geographically distributed throughout Pennsylvania. There are 19 commonwealth campuses and 5 special mission campuses located across the state. The University Park campus has been labeled one of the “Public Ivies,” a publicly funded university considered as providing a quality of education comparable to those of the Ivy League.
The Pennsylvania State University is a member of The Association of American Universities an organization of American research universities devoted to maintaining a strong system of academic research and education.

Annual enrollment at the University Park campus totals more than 46,800 graduate and undergraduate students, making it one of the largest universities in the United States. It has the world’s largest dues-paying alumni association. The university offers more than 160 majors among all its campuses.

Annually, the university hosts the Penn State IFC/Panhellenic Dance Marathon (THON), which is the world’s largest student-run philanthropy. This event is held at the Bryce Jordan Center on the University Park campus. The university’s athletics teams compete in Division I of the NCAA and are collectively known as the Penn State Nittany Lions, competing in the Big Ten Conference for most sports. Penn State students, alumni, faculty and coaches have received a total of 54 Olympic medals.

Early years

The school was sponsored by the Pennsylvania State Agricultural Society and founded as a degree-granting institution on February 22, 1855, by Pennsylvania’s state legislature as the Farmers’ High School of Pennsylvania. The use of “college” or “university” was avoided because of local prejudice against such institutions as being impractical in their courses of study. Centre County, Pennsylvania, became the home of the new school when James Irvin of Bellefonte, Pennsylvania, donated 200 acres (0.8 km2) of land – the first of 10,101 acres (41 km^2) the school would eventually acquire. In 1862, the school’s name was changed to the Agricultural College of Pennsylvania, and with the passage of the Morrill Land-Grant Acts, Pennsylvania selected the school in 1863 to be the state’s sole land-grant college. The school’s name changed to the Pennsylvania State College in 1874; enrollment fell to 64 undergraduates the following year as the school tried to balance purely agricultural studies with a more classic education.

George W. Atherton became president of the school in 1882, and broadened the curriculum. Shortly after he introduced engineering studies, Penn State became one of the ten largest engineering schools in the nation. Atherton also expanded the liberal arts and agriculture programs, for which the school began receiving regular appropriations from the state in 1887. A major road in State College has been named in Atherton’s honor. Additionally, Penn State’s Atherton Hall, a well-furnished and centrally located residence hall, is named not after George Atherton himself, but after his wife, Frances Washburn Atherton. His grave is in front of Schwab Auditorium near Old Main, marked by an engraved marble block in front of his statue.

Early 20th century

In the years that followed, Penn State grew significantly, becoming the state’s largest grantor of baccalaureate degrees and reaching an enrollment of 5,000 in 1936. Around that time, a system of commonwealth campuses was started by President Ralph Dorn Hetzel to provide an alternative for Depression-era students who were economically unable to leave home to attend college.

In 1953, President Milton S. Eisenhower, brother of then-U.S. President Dwight D. Eisenhower, sought and won permission to elevate the school to university status as The Pennsylvania State University. Under his successor Eric A. Walker (1956–1970), the university acquired hundreds of acres of surrounding land, and enrollment nearly tripled. In addition, in 1967, the Penn State Milton S. Hershey Medical Center, a college of medicine and hospital, was established in Hershey with a $50 million gift from the Hershey Trust Company.

Modern era

In the 1970s, the university became a state-related institution. As such, it now belongs to the Commonwealth System of Higher Education. In 1975, the lyrics in Penn State’s alma mater song were revised to be gender-neutral in honor of International Women’s Year; the revised lyrics were taken from the posthumously-published autobiography of the writer of the original lyrics, Fred Lewis Pattee, and Professor Patricia Farrell acted as a spokesperson for those who wanted the change.

In 1989, the Pennsylvania College of Technology in Williamsport joined ranks with the university, and in 2000, so did the Dickinson School of Law. The university is now the largest in Pennsylvania. To offset the lack of funding due to the limited growth in state appropriations to Penn State, the university has concentrated its efforts on philanthropy.

Research

Penn State is classified among “R1: Doctoral Universities – Very high research activity”. Over 10,000 students are enrolled in the university’s graduate school (including the law and medical schools), and over 70,000 degrees have been awarded since the school was founded in 1922.

Penn State’s research and development expenditure has been on the rise in recent years. For fiscal year 2013, according to institutional rankings of total research expenditures for science and engineering released by the National Science Foundation , Penn State stood second in the nation, behind only Johns Hopkins University and tied with the Massachusetts Institute of Technology , in the number of fields in which it is ranked in the top ten. Overall, Penn State ranked 17th nationally in total research expenditures across the board. In 12 individual fields, however, the university achieved rankings in the top ten nationally. The fields and sub-fields in which Penn State ranked in the top ten are materials (1st), psychology (2nd), mechanical engineering (3rd), sociology (3rd), electrical engineering (4th), total engineering (5th), aerospace engineering (8th), computer science (8th), agricultural sciences (8th), civil engineering (9th), atmospheric sciences (9th), and earth sciences (9th). Moreover, in eleven of these fields, the university has repeated top-ten status every year since at least 2008. For fiscal year 2011, the National Science Foundation reported that Penn State had spent $794.846 million on R&D and ranked 15th among U.S. universities and colleges in R&D spending.

For the 2008–2009 fiscal year, Penn State was ranked ninth among U.S. universities by the National Science Foundation, with $753 million in research and development spending for science and engineering. During the 2015–2016 fiscal year, Penn State received $836 million in research expenditures.

The Applied Research Lab (ARL), located near the University Park campus, has been a research partner with the Department of Defense since 1945 and conducts research primarily in support of the United States Navy. It is the largest component of Penn State’s research efforts statewide, with over 1,000 researchers and other staff members.

The Materials Research Institute was created to coordinate the highly diverse and growing materials activities across Penn State’s University Park campus. With more than 200 faculty in 15 departments, 4 colleges, and 2 Department of Defense research laboratories, MRI was designed to break down the academic walls that traditionally divide disciplines and enable faculty to collaborate across departmental and even college boundaries. MRI has become a model for this interdisciplinary approach to research, both within and outside the university. Dr. Richard E. Tressler was an international leader in the development of high-temperature materials. He pioneered high-temperature fiber testing and use, advanced instrumentation and test methodologies for thermostructural materials, and design and performance verification of ceramics and composites in high-temperature aerospace, industrial, and energy applications. He was founding director of the Center for Advanced Materials (CAM), which supported many faculty and students from the College of Earth and Mineral Science, the Eberly College of Science, the College of Engineering, the Materials Research Laboratory and the Applied Research Laboratories at Penn State on high-temperature materials. His vision for Interdisciplinary research played a key role in creating the Materials Research Institute, and the establishment of Penn State as an acknowledged leader among major universities in materials education and research.

The university was one of the founding members of the Worldwide Universities Network (WUN), a partnership that includes 17 research-led universities in the United States, Asia, and Europe. The network provides funding, facilitates collaboration between universities, and coordinates exchanges of faculty members and graduate students among institutions. Former Penn State president Graham Spanier is a former vice-chair of the WUN.

The Pennsylvania State University Libraries were ranked 14th among research libraries in North America in the 2003–2004 survey released by The Chronicle of Higher Education. The university’s library system began with a 1,500-book library in Old Main. In 2009, its holdings had grown to 5.2 million volumes, in addition to 500,000 maps, five million microforms, and 180,000 films and videos.

The university’s College of Information Sciences and Technology is the home of CiteSeerX, an open-access repository and search engine for scholarly publications. The university is also the host to the Radiation Science & Engineering Center, which houses the oldest operating university research reactor. Additionally, University Park houses the Graduate Program in Acoustics, the only freestanding acoustics program in the United States. The university also houses the Center for Medieval Studies, a program that was founded to research and study the European Middle Ages, and the Center for the Study of Higher Education (CSHE), one of the first centers established to research postsecondary education.