DOPED PSN.91-PT.09 ELECTROSTRICTIVE SINGLE CRYSTALS

Requirements for high quality electrostrictive single crystals continue to be important because the polycrystalline PSN-PT materials have a lower coupling coefficient . Single crystal PSN-PT is an attractive transducer material because of its very high energy density and its capacity to undergo large electrostrictive strains. Foster-Miller has conceived of an innovative approach to grow PSN.91- PT.09 single crystal compositions, uniformly doped, large diameter PSN-PT single crystals either by itself or encapsulated in a porous single crystal sapphire skeleton. Our processing approach eliminates the following problems - small crystal size, high defect structure and cracking, high >42% PT compositions associated with limitations of the current state of the art crystal growth processes. Additionally, our "sapphire/PSN-PT composite" will have a high fracture toughness, thermal shock resistance, and light weight without much reduction in the PSN-PT electrostrictive properties. Foster-Miller's process has the capability of growing single crystals at relatively low temperatures not possible with current crystal growth processes. Also, being a isothermal constant temperature process, it will promote uniform distribution of dopants and constant PT concentration levels. Our approach will be an enabling technology for producing low cost, high efficiency, high strength electrostrictive single crystals that are stable at high temperatures. The process is versatile and has the potential to produce high quality piezoelectric and electrostrictive single crystal materials of other desired compositions. The Phase I program will involve the growth of PSN-PT single crystal specimens and characterization including X-ray diffraction, dielectric and piezoelectric measurements. The Phase I team includes Penn State University as a subcontractor who will evaluate these materials. Foster-Miller's process has the capability of growing single crystals at relatively low temperatures not possible with current crystal growth processes. Also, being a isothermal constant temperature process, it will promote uniform distribution of dopan The Phase I program will involve the growth of PSN-PT single crystal specimens and characterization including X-ray diffraction, dielectric and piezoelectric measurements. The Phase I team includes Penn State University as a subcontractor who will evaluat