Temperature Dependent Energy Loss of Protons in Barium Titanate Single Crystals

The energy loss of 25 MeV protons in ferroelectric Barium Titanate [BT] single crystals was measured as a function of the temperature of BT with an accuracy of 0.06%. When the protons traversed the crystal along the ferroelectric axis energy loss showed broad fluctuations with a peak-to-peak variation of 5% from the value at room temperature and the energy losses in ferroelectric and paraelectric phases of BT appeared to be nearly the same. When protons traversed the crystal in a direction perpendicular to the ferroelectric axis energy loss in the crystal remained independent of the crystal temperature in the ferroelectric phase. However, the energy loss in paraelectric phase appeared to be about 1.5% lower than that in the ferroelectric state. It is suggested that the observed results are indicative of a new mode of energy loss and can be related to the fluctuations in polarization of cluster of unit cells and the dynamics of their short-range order.

Keywords:

• Ferroelectrics
• energy loss of charged particles
• stopping power

Acknowledgments

The authors would like to thank Prof. A. M. Umarji for the help in preparation and characterization of the ferroelectric samples. One of the authors (Khadke UdayKumar) is grateful to the CSIR for the financial assistance.

Paper originally presented at AMF-4, Bangalore, India, December 12-15, 2003.