Structural and ferroelectric properties of epitaxial BaZr_xTi_1−xO₃thin films

BaZrxTi1−xO3 Epitaxial Thin Films for Electrocaloric Investigations

“…In general, the standard X‐ray diffraction (XRD) patterns of the grown BT thin films exhibit only (00 ℓ ) peaks related to the STO substrate and the perovskite BT phase for p ≤0.0375 mbar. They are similar to our films reported previously and are therefore not shown here. Additional maxima, which are mainly identified with the (110) or (211) planes of the BT crystal structure, appear in the XRD patterns by using a higher background pressure of p =0.05 mbar during deposition.…”

“…Similar reduced T m values were also found for films deposited with 0.01 mbar O 2. In these cases, the temperature shift might be attributed to the ferroelectric relaxor behavior. Catalan et al.…”

“…Based on our previous studies, we carried out a fine‐tuning of the oxygen background pressure p between 0.01 mbar and 0.05 mbar as a first step because it is known from literature that p greatly influences the BT film structure . In general, the standard X‐ray diffraction (XRD) patterns of the grown BT thin films exhibit only (00 ℓ ) peaks related to the STO substrate and the perovskite BT phase for p ≤0.0375 mbar.…”

“…The epitaxial relationship between the single crystalline STO substrate and the BT layer was analyzed by (220) pole figure measurements for about 230 nm thick films grown at various p . Peaks connected to a 60° twinning along the [111] axis were only found for films deposited in p =0.05 mbar (compare also the results in our previous studies). For all other samples, the desired epitaxial cube‐on‐cube growth was confirmed without any sign for additional texture components.…”

“…Pure BT thin films grown with the same PLD parameters, but with a thickness of 400 nm, exhibit even rougher surfaces that are almost completely covered with the larger grains visible in Figure b. As mentioned before, twinning was proven by texture measurements for these thicker samples; therefore we assume that the twin formation is connected to the occurrence of these large preferentially growing grains . Consequently, the irregular grains shown for the BT film in Figure b might already indicate the start of a twin formation even though they are not detected with integral X‐ray measurements due to the small volume content.…”