Measuring diffraction data during the application of electric fields has provided useful insight into the mechanisms that give rise to strain in thin film and bulk ferroelectric materials (field-induced phase transitions, domain realignment, and lattice strain). However, such experiments are primarily conducted at synchrotron facilitates (e.g. APS and ESRF). Researchers at North Carolina State University have developed a new technique that enables the acquisition of diffraction data during the application of electric fields using a lab X-ray diffractometer.

Experimental Setup/Capability

• A custom made in situ electric field cell constructed from high-density polyethylene is shown in the below figure. Bottom side of the testing sample will be connected to a high voltage input, and a ground wire will connect to top side of the sample. The in situ cell was machined for use in the PANalytical Empyrean in the AIF at NCSU.

• In situ cell has been validated for measuring:
• Bulk polycrystalline (± 10 kV)
• Thin film (± 230V)
• PANalytical Empyrean X-ray diffractometer equipped with a PIXcel1D detector which enables fast data acquisition

Picture of PANalytical Empyrean (left) during the measurement of in situ diffraction during application of electric fields, and (right) top down view of a bulk sample in the stage after complementing an in situ diffraction experiment.

Demonstration Experiment: 111 oriented PZT thin film

• In situ XRD of a 111 oriented PZT 70-30 (PbZr0.7Ti0.3O3) thin film was measured during eclectic loading from 0→30→0 volts in 6V increments
• Intensity interchange between the 112/211 reflections suggests that ferroelectric/ferroelastic domain wall motion is induced in the randomly oriented volume fraction
• The fraction of domains switched was quantified using:

$\Delta\eta_{112}&space;=&space;\frac{I_{112}/I'_{112}}{I_{112}/I'_{112}&space;+&space;2*I_{211}/I'_{211}}&space;-&space;1/3$

where Ihkl and I’hkl represent the measured and randomly oriented intensities of the hkl reflection.

• The measured η112 is in good agreement with results from a synchrotron experiment

Demonstration Experiment: Bulk PZT

• In situ XRD of PZT (Karamos 350) was measured during application of a bipolar triangular waveform with 2kV/mm amplitude (1200s period)
• Measured diffraction data shows a strong 002/200 intensity interchange associated with ferroelectric/ferroelastic domain wall motion
• The in situ XRD data measured using the PANalytical Empyrean is in good agreement with XRD data measured in a synchrotron experiment
• Comparing the measured data at during application of similar applied fields demonstrates that the laboratory and synchrotron results are in good agreement
• The prolonged period of measurement waveform used in the laboratory experiment induces a stronger 002/200 intensity interchange than the synchrotron experiment (160s).

References

1. Pramanick, D. Damjanovic, J.E. Daniels, J.C. Nino, and J.L. Jones, J. Am. Ceram. Soc. 94, (2011).
2. R.L. Johnson-Wilke, et al., IEEE Trans Ultrason Ferroelectr Freq Control, 62, 1, (2015)

Acknowledgement

Thin Films were provided by the Troiler-McKinstry research group at Penn State University.  This material is based upon work supported by the National Science Foundation, as part of the Center for Dielectrics and Piezoelectrics under Grant Nos. IIP-1361571 and IIP-1361503

Disclaimer

Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation