“Hi-Fi Stake” Piezoelectric Actuators and New Developments

“Hi-Fi Stake” piezoelectric actuators are constructed by bonding [011]-poled d₃₂-mode lead-based relaxor-PT single crystals with polycarbonate edge guides into a square-pipe structure. They contract under positive-polarity applied voltage due to d₃₂ values being negative for [011]-poled relaxor-PT single crystals. Under quasi-static loading conditions, “Hi-Fi Stake” single crystal actuators exhibit highly linear displacement response with negligible hysteresis. Over the years, we have successfully developed the following three versions of “Hi-Fi Stake (HFS)”actuators: cost-effective (CE), large-stroke (LS) and High-load (HL), all of maximum use temperature of up to 60 ^oC. Of which, the LS version, of 2-level construction, displays strokes of up to 50 mm @ 240 V and the HL version, of 2-layer construction, has maximum loads allowed of 14 kg-f at room temperature and 7 kg-f at 60 ^oC. Also described in this work are the developments Cryogenic Hi-Fi Stakes (HFS-CG) and High-Temperature Hi-Fi Stake (HFS-HT) piezoelectric actuators. The selection of suitable crystal compositions, recommended working conditions and measured performance of fabricated prototypes of these two new versions of Hi-Fi Stakes are presented and discussed.