Quantitative Effects of Preferred Orientation and Impurity Phases on Ferroelectric Properties of SrBi₂(Ta_1-xNb_x)₂O₉Thin Films Measured by X-Ray Diffraction Reciprocal Space Mapping

Abstract

Intense heavy ion beams from the Gesellschaft für Schwerionenforschung (GSI-Darmstadt) accelerator facilities are investigated for their potential to drive inertial fusion targets and are currently used to generate and probe high-energy-density (HED) matter. The existing heavy ion synchrotron facility SIS-18 delivers intense uranium beam pulses for experiments with up to 4 × 10 9 ions per bunch at a charge state of q = 73+. Higher intensities are potentially available at lower charge states, when related loss mechanisms can be overcome. We have observed intensity-dependent beam losses in SIS-18. The origin of these beam losses is attributed to processes changing the charge state of ions, which is predominantly due to collisions with rest gas atoms. The resulting change in the mass over charge ratio m/q leads to modified trajectories in dispersive beam transport elements, and finally to the loss of the particle at the vacuum tube wall. At the impact position secondary particles are produced by ion-induced desorption and as a result the pressure in the vacuum tube is increased locally. This local rise in pressure in turn leads to increased charge changing processes starting an avalanche process that may eventually lead to a complete loss of the beam during a few turns in the synchrotron. In this paper, we discuss a method to control the problem of desorbed gases with specifically designed beam catchers at critical positions. We have further developed a program package to calculate the most important beam loss mechanisms and to couple them to the dynamic vacuum problem. The basis of this simulation is an ion-optics routine where relevant atomic processes and the effects of dynamic vacuum are implemented.

Ferroelectric thin films: Review of materials, properties, and applications

“…The ferroelectric thin film community's ability to synthesize both polycrystalline and epitaxial ferroelectric thin films has advanced considerably in the last decade, with continued progress in chemical solution deposition, [226][227][228] physical vapor deposition including pulsed laser ablation, 229-232 sputtering [233][234][235][236][237][238] and molecular beam epitaxy, 208,239,240 and metal-organic chemical vapor deposition. [241][242][243][244][245][246][247][248][249][250][251][252][253] Additionally, fundamental insight into thin film behavior is becoming increasingly important as technologies utilizing ferroelectric thin films continue to push towards smaller and smaller dimensions. 88 Because of these continued improvements in ferroelectric film quality, significant advances have been made in exploring the impact of film thickness on ferroelectric behavior both in polycrystalline and in epitaxial films.…”

A Thin Film Approach to Engineering Functionality into Oxides

“…These physical vapor deposition techniques yielded high‐quality oxide superconductor films just a few nanometers in thickness, 115–117 superlattices of superconducting oxides with atomic‐scale thickness control and abrupt interfaces, 110,118–126 and the construction of new oxide superconducting phases with atomic layer precision 76,127 . Chemical techniques including metal‐organic chemical vapor deposition (MOCVD) 128–143 and chemical solution deposition (CSD) 144–148 have also been adapted and applied to functional oxides, particularly ferroelectrics. In recent years, a growing cadre of researchers has applied these physical and chemical techniques with increasing precision to the growth of an ever‐broadening set of functional oxide materials.…”

Controlled crystal growth of layered-perovskite thin films as an approach to study their basic properties

“…Saito et al applied x-ray reciprocal space mapping performed using a 2-scan at a wide range of ͑sample inclination angle normal to the scattering plane͒ to the SBT films deposited on the ͑111͒Pt layer to distinguish the SBT phase with incorporated pyrochlore and fluorite phases and to quantify the volume fraction of each film orientation. 76,77 Figure 7 shows the x-ray 2-patterns of a BLT thin film prepared using MOCVD at 600°C on a ͑111͒Pt/ Ti/ SiO 2 /Si substrate. Figure 8 shows the x-ray reciprocal space mappings measured for the film shown in Fig.…”