May/June_AMP_Digital

A D V A N C E D M A T E R I A L S & P R O C E S S E S | M A Y / J U N E 2 0 1 8 1 1 A neutron interferometer can scan the interior of thick objects, such as this chunk of granite, providing enough detail to show the four types of rock that are mixed within it. Courtesy of Huber and Hanacek/NIST. object, which experts can easily inter- pret. The method was developed by a team of researchers from the National Institute of Standards and Technology, National Institutes of Health, and the University of Waterloo. nist.gov, nih.gov, www.uwaterloo.ca . NEW MATERIALS FOR BETTER ULTRASOUND Development of a theoretical basis for ultra-high piezoelectricity in ferro- electric materials led to a new mater- ial with twice the piezo response of tions within a host material created by doping a small amount of chemical species, in this case doping samarium in PMN-PT ceramics, as a way to mod- ify the thermodynamic energy land- scape of the material. This increases the dielectric properties and the piezo- electric effect. A needle transducer then uses a submillimeter piezoelectric ele- ment of the Penn State material fitted into a standard needle or catheter to perform minimally invasive procedures or to image or guide precision surgery inside the body. mri.psu.edu. any existing commercial ferro- electric ceramics, according to an international team of re- searchers from Penn State, China, and Australia. Adding small amounts of samarium to a high-performance piezoelectric ceramic called lead magnesium niobate-lead titanate (PMN-PT) dramatically increases its pie- zo performance. The team believes this materials-by-de- sign strategy will be useful in developing materials for other applications as well. Researchers first analyzed the impact of adding various chemical dopants on the local struc- ture of an existing ferroelectric ceramic. They were then able to select the most effective dopants by comparing the measured dielectric losses with the sig- natures obtained from phase-field sim- ulations. After the dopant screening, they focused on processing and compo- sition optimization to achieve the ultra- high piezoelectricity. Local structure heterogeneity re- fers to nanoscale-size structural distor- A long-range ferroelectric domain with nanoscale structure heterogeneity (4-8 nm) is evidenced by high-resolution TEM. Courtesy of Fei Li/Penn State.