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Main Orientation of Piezoelectric Materials
Ben Iverson
Purdue Doctoral Candidate.
Piezoelectricity is defined by two equations:

P_i = d_ijkα_jk

ε_jk = d_ijkE_i

In normal polycrystaline circumstances spontaneous polariation domains are cancelled by ramdom grain orientation for a net polarization of zero. Shock changes domains to leave some net polarization.

Our study will deal exclusively with lead metaniobate PbNb₂O₆ where polarization is confined to the a-b plane. X-ray diffraction was initially used applying an "MRD" scale of 1 to represent fully random and 2 to represent fully polar properties. Some results are presented [visually].

An object is to mimic single crystal behavior in a polycrystaline structure. Tape casting (using a Dr. Blade slurry technique) was applied to induce some HK zero texture to lead metaniobate. Neutron diffraction (using a neutron time-of-flight diffractometer (HIPPO) at Los Alamos Neutron Science Center) was used to look at the orentation space all at once and fit theoretical data to experimental on the tape casted material. Using a free Rietveld Material Analysis software (MAUD) it was possible to show that tape cast laminate got higher b-axis texture. This confirms that the Dr. blade technique can be used to obtain "closer to single crystal" properties of the lead metaniobate piezoelectric at considerably reduced cost.

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