Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userComposition-dependent polarization switching behaviors of (111)-preferred polycrystalline Pb(Zr_{x}Ti_{1-x})O_{3} thin films
209
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We investigated the time-dependent polarization switching behaviors of (111)-preferred polycrystalline Pb(ZrxTi1-x)O3 thin films with various Zr concentrations. We could explain all the polarization switching behaviors well by assuming Lorentzian distributions in the logarithmic polarization switching time [Refer to J. Y. Jo et al., Phys. Rev. Lett. (in press)]. Based on this analysis, we found that the Zr ion-substitution for Ti ions would induce broad distributions in the local field due to defect dipoles, which makes the ferroelectric domain switching occur more easily.
rate research
Read More
In a systematic study we investigate the effect of dopant level and hydration on the short-range structure of the proton conducting perovskite-type oxide BaIn_{x}Zr_{1-x}O_{3-x/2} (x = 0-0.75), using infrared and Raman spectroscopy. The results show that doping leads to significant local distortions of the average cubic structure of these materials. By increasing the In concentration from x = 0 to x = 0.75 new bands appear and grow in intensity in both the IR and Raman spectra, showing that the local distortions become successively more and more pronounced. The structural distortions are largely uncorrelated to the presence of oxygen vacancies, but instead are mainly driven by the size difference between the In^{3+} and Zr^{4+} ions, which leads to displacements of the cations and to tilting of the (In/Zr)O_{6} octahedra. Based on our results, we suggest that there is a threshold between x = 0.10 and x = 0.25 where the local structural distortions propagate throughout the whole perovskite structure. Comparison of our spectroscopic data with the proton conductivity reported for the same materials indicates that the presence of extended structural distortions are favorable for fast proton transport.
High-temperature (T) and high-electric-field (E) effects on Pb[(Zn_{1/3} Nb_{2/3})_{0.92} Ti_{0.08}]O_3 (PZN-8%PT) were studied comprehensively by neutron diffraction in the ranges 300 <= T <= 550 K and 0 <= E <= 15 kV/cm. We have focused on how phase transitions depend on preceding thermal and electrical sequences. In the field cooling process (FC, E parallel [001] >= 0.5 kV/cm), a successive cubic (C) --> tetragonal (T) --> monoclinic (M_C) transition was observed. In the zero field cooling process (ZFC), however, we have found that the system does not transform to the rhombohedral (R) phase as widely believed, but to a new, unidentified phase, which we call X. X gives a Bragg peak profile similar to that expected for R, but the c-axis is always slightly shorter than the a-axis. As for field effects on the X phase, we found an irreversible X --> M_C transition via another monoclinic phase (M_A) as expected from a previous report [Noheda et al. Phys. Rev. Lett. 86, 3891 (2001)]. At a higher electric field, we confirmed a c-axis jump associated with the field-induced M_C --> T transition, which was observed by strain and x-ray diffraction measurements.
We present the electronic structure of Sr_{1-(x+y)}La_{x+y}Ti_{1-x}Cr_{x}O_{3} investigated by high-resolution photoemission spectroscopy. In the vicinity of Fermi level, it was found that the electronic structure were composed of a Cr 3d local state with the t_{2g}^{3} configuration and a Ti 3d itinerant state. The energy levels of these Cr and Ti 3d states are well interpreted by the difference of the charge-transfer energy of both ions. The spectral weight of the Cr 3d state is completely proportional to the spin concentration x irrespective of the carrier concentration y, indicating that the spin density can be controlled by x as desired. In contrast, the spectral weight of the Ti 3d state is not proportional to y, depending on the amount of Cr doping.
We have studied magnetism in Ti_[1-x]Co_xO_[2-delta] thin films with various x and delta by soft x-ray magnetic circular dichroism (XMCD) measurements at the Co L_[2,3] absorption edges. The estimated ferromagnetic moment by XMCD was 0.15-0.24 mubeta/Co in the surface, while in the bulk it was 0.82-2.25 mubeta/Co, which is in the same range as the saturation magnetization of 1.0-1.5 mubeta/Co. Theseresults suggest that the intrinsic origin of the erromagnetism. The smaller moment of Co atom at surface is an indication of a magnetically dead layer of a few nm thick at the surface of the thin films.
Recently, materials exhibiting colossal dielectric constant ($CDC$) have attracted significant attention because of their high dielectric constant and potential applications in electronic devices, such as high dielectric capacitors, capacitor sensors, random access memories and so on.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
