Channeling of Protons in Thin BaTiO3Crystals at Temperatures above and below the Ferroelectric Curie Point

The channeling of 3.8-MeV protons in thin (3-20-$\mu$-thick) BaTi${\mathrm{O}}_3$ crystals has been studied at 140 °C (i.e., in the cubic paraelectric phase) and at room temperature (i.e., in the tetragonal ferroelectrically polarized phase). The influence of channeling on backscattering yields, on characteristic x-ray production, and on the transmitted protons, has been determined. For the purpose of fitting the data for the cubic phase, the formulas that Barrett found to fit a large range of data on channeling in monatomic crystals were extended to the polyatomic case. The quality of the fit thus obtained is fair, but not as good as those obtained in monatomic lattices. Data are also presented on dechanneling and on the influence of radiation damage on the channeling properties of BaTi${\mathrm{O}}_3$. In the polarized tetragonal phase it is found that the channeling properties are strongly affected by the relative orientations of the crystal planes and the polarization of the crystal. The effect of polarization is attributed to the associated high internal electric fields.