February8, 1967 Dear Enclosed is a short Progress Repoft of our work to date pursuant to-- Very truly yours, AMk ol Agri. I January to 31 January 1967 PROGRIESS REPOR'R r. PREZOELECTRIC CRYSTALS Several PZT 5-B series connected ceramic birnorphs have been obtained from Clevite. A test rig was built to a-Uow electrical and mechanical measurements on these cer amic crystals. The test rig allo%vs a thin rectalngular crystal to be mounted cantilever fashion; i.e., clamped at one end with the rest of the element suspended in air. A stop was machined to allow the free far end of the crystal to be de- p.-essed only .020". Foz the 1. 7" by . 7" crystal which has been slubjected to test this amount of deformation re-)resents a strain of about 2 x 10 -4 which is 209,lo of the e' ec@ted fiacture strain and sufficieat XP to produce a peak voltage transient of 13 volts. The experimentation with this crystal has bten c2oncerned vn"th estabushing the transient or rin" characteristics. Electrical voltage output is monitored on an oscilloscope. and the crystal is set in (decaying) oscillation.by depressing the end to the stc-p with a piece of plastic and then slidin,c the plastic off the end of the crystal. Oscillation at 150 cps occurs with an approximately ecpo- nential- amplitude Zecay at a tir@e constant of 83 milliseconds (with a 10 meg electrical load). This ti@ae constant can be interpreted as equivalent to saying that the system has a Q of 39 with am electrical open circuit. As the resistance connected to crystal is decreased the Q is, lowered and the 2 oscillation dies out faster. A lumped const,--nt electromechanical model of the crystal was used to de%,-clop expressions for total system Q and total electrical power delivered to the load resistor as functions of e.\-ternal load resistance. The optimurn resistance was thus calctilated and when a resist-or of this value is connected to the test crystal, Q and voltage de- creas3 to values within the e.\porimental error 517,)) of the calculated values. According to our calculations the marimum efficiency of enerery -2 - conversion is 50@'a with a pure resistive load of the optimum value and the quantity of power for a 2017a strain is 20 j2 Joule per square inch cf crystal area for each transient mechanical excitation. Since the actual load presented by an electronic packa2ge will not be a pure resistance the actual conversion efficiency will be.less than 501*. Our previously assumed value of 207* efficiency still appears a reasonable one. In the remaintng contract time work %vM continue to establish the desi-n requirements of a piezoelectric ener,7,y converter. 11. ENIG SOURCE RESISTANCE Our consultants have determi@ed that the most promising electrode materials a.@-e pla.tinum, gold, stainless steel, and tantalum. 3 mil diameter wires of all four metali@.,have been ordered. The stainless 0 PT I 00,'o rRi wires have been rec 2 steel and platinum (90T eived already Teflon coated. When the other wires'arrive they will be Teflon coated by a local compa@y. Ch@r animal experiinent consultant is expected to begln work immediately using the materials on hand with laboratory rats as the experimental 3stibjects.