Large thermal hysteresis of ferroelectric transition in HfO2-based ferroelectric films

Microstructure of epitaxial ferroelectric/conductive oxide heterostructures on LaAIO3(LAO) and Si substrates have been studied by conventional and high resolution transmission electron microscopy. The epitaxial films have a wide range of potential applications in areas such as non-volatile memory devices, electro-optic devices and pyroelectric detectors. For applications such as electro-optic devices the films must be single crystal and for applications such as nonvolatile memory devices and pyroelectric devices single crystal films will enhance the performance of the devices. The ferroelectric films studied are Pb(Zr0.2Ti0.8)O3(PLZT), PbTiO3(PT), BiTiO3(BT) and Pb0.9La0.1(Zr0.2Ti0.8)0.975O3(PLZT).Electrical contact to ferroelectric films is commonly made with metals such as Pt. Metals generally have a large difference in work function compared to the work function of the ferroelectric oxides. This results in a Schottky barrier at the interface and the interfacial space charge is believed to responsible for domain pinning and degradation in the ferroelectric properties resulting in phenomenon such as fatigue.

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Local atomic structure of relaxor ferroelectric solids studied by pulsed neutron scattering

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100170505 ◽

1994 ◽

Vol 52 ◽

pp. 554-555

Author(s):

T. Egami ◽

H. D. Rosenfeld ◽

S. Teslic

Keyword(s):

Neutron Scattering ◽

Atomic Structure ◽

Argonne National Laboratory ◽

Relaxor Ferroelectrics ◽

Relaxor Ferroelectric ◽

Crystallographic Structure ◽

Chemical Inhomogeneity ◽

Distribution Analysis ◽

Ferroelectric Transition ◽

Pulsed Neutron

Relaxor ferroelectrics, such as Pb(Mg1/3Nb2/3)O3 (PMN) or (Pb·88La ·12)(Zr·65Ti·35)O3 (PLZT), show diffuse ferroelectric transition which depends upon frequency of the a.c. field. In spite of their wide use in various applications details of their atomic structure and the mechanism of relaxor ferroelectric transition are not sufficiently understood. While their crystallographic structure is cubic perovskite, ABO3, their thermal factors (apparent amplitude of thermal vibration) is quite large, suggesting local displacive disorder due to heterovalent ion mixing. Electron microscopy suggests nano-scale structural as well as chemical inhomogeneity.We have studied the atomic structure of these solids by pulsed neutron scattering using the atomic pair-distribution analysis. The measurements were made at the Intense Pulsed Neutron Source (IPNS) of Argonne National Laboratory. Pulsed neutrons are produced by a pulsed proton beam accelerated to 750 MeV hitting a uranium target at a rate of 30 Hz. Even after moderation by a liquid methane moderator high flux of epithermal neutrons with energies ranging up to few eV’s remain.

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Spin-crossover in an iron(iii) complex showing a broad thermal hysteresis

Dalton Transactions ◽

10.1039/d0dt03610b ◽

2021 ◽

Author(s):

Cyril Rajnák ◽

Romana Mičová ◽

Ján Moncoľ ◽

Ľubor Dlháň ◽

Christoph Krüger ◽

...

Keyword(s):

Schiff Base ◽

Schiff Base Ligand ◽

Spin Crossover ◽

Thermal Hysteresis ◽

Mononuclear Complex ◽

Hysteresis Width ◽

Thermally Induced

A pentadentate Schiff-base ligand 3,5Cl-L2− and NCSe− form a iron(iii) mononuclear complex [Fe(3,5Cl-L)(NCSe)], which shows a thermally induced spin crossover with a broad hysteresis width of 24 K between 123 K (warming) and 99 K (cooling).

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