Studies in PZT piezoelectrics By Adam Myers Advisor: Prof. Bowman

Piezoelectrics: PZT, [ ] A piezoelectric is a material that produces an electric field when subjected to a mechanical stress, and vice versa. PZT is shorthand for Lead Zirconate Titanate,

X-ray Diffraction Prof S.A.Nelson, Tulane University n  2d*sin(  Constructive interference Destructive interference Bragg’s Law:

X-ray Diffraction cont. Useful in finding planar orientations Show mechanical surface damages Show poling effects Poling Direction Away from poling Direction A A B B X-Rays

Poling Mechanism The central shifting ion in the tetragonal unit cell of PZT allows the material to be a dielectric and a piezoelectric. +4 a a c Poling Direction Since the central ion can only move in the c direction, the domains must align so this can occur. Poling direction domains effectively grow.

Polishing effects Sample was subjected to different polishing media and annealing temperatures in order to study crystal structure changes. It was found that the 0.05 micron alumina polishing produced a sample texture closest to the as-received sample texture. Longer annealing times may have produced a more random sample.

{002} Planes Decreasing mechanical damage Ferroelastic material: Mechanical poling or just surface damage.

Poling of thin K550 sample Thin K550 PZT was placed in a silicone oil bath at 120 degrees C. A 250 volt potential difference was applied across the electrodes for 2 minutes. Sample was washed with solvent to remove the silicone oil, and nitric acid to remove the electrodes.

Peaks of interest: {002} -Split peak caused by tetragonal unit cell. -Poling shown by higher (002) peak

Electro-optic effects The K550 is an electro-optic PZT. Electro-optic materials can transmit or block light according to different electric fields and poling conditions. Wanted to see if there was a difference in the index of refraction of a poled and unpoled sample.

Air N1 Water N2 light Index of Refraction: N1*sin(Theta1)=N2*sin(Theta2) Theta1 Theta2 Laser Top View Screen PZT: Poled Unpoled Light was scattered, no measurable data was obtainable Alternate method was considered, but not used because of inability to polish samples down to at least 50 microns and lack of prior knowledge of a close value.

Sample Thinning -Silver electrodes were removed from samples with nitric acid, leaving about 120 microns of PZT for the thin samples. -Polishing went slowly until 600 grit polishing paper was used. -Sample shattered due to epoxy expansion in acetone. Relatively large piece at 88 microns was recovered for transmission XRD. -Results were uncertain due to possibility of reflection from micro-cracks.

Multiples of a Random Distribution Shows exactly what it says: The multiple of times something occurs compared to its occurrence in a randomly distributed sample Data was normalized to 3, the number of orthogonal planes in the {002} family

MRD plot of Poled Navy II sample Produced with encouragement from Andy Smith 90 degrees 45 degrees25 degrees

Checked different Navy II and VI samples poled in different fields for increased poling. Results seem to show that the increased poling fields do not increase the poled texture.

d 33 measurements on the samples seem to confirm the MRD results. d 33 measurements are a measure of the efficiency of the piezo in converting mechanical to electrical energy.

Thanks to…. Profs. Slamovich and Bowman Purdue University Dave Roberts All of my fellow REU students * Pete, Jake, and Harry