Search results for "Ferroelectric"

The behavior of the 180° domain walls in disordered dielectrics like KTaO3 : Li and KTaO3 : Nb

2003

We calculate the structure of 180° domain wall in disordered ferroelectrics with random site electric dipoles (i.e. those like K 1-x Li x TaO 3 , KTa 1-x Nb x O 3 , where Li + or Nb 5+ are off-center ions forming impurity dipoles). The calculation is performed on the base of the free energy functional of disordered dielectrics derived earlier [M. D. Glinchuk et al., Phase Transit., 2003 (to be published)] within the framework of a random field method. We obtain the domain wall thickness as a function of impurity dipole concentration n and temperature T. It is shown that in disordered ferroelectrics the domain wall is usually broader than in their ordered counterparts. The thickness increase…

Ab initio calculations of the atomic and electronic structure of layered Ba0.5Sr0.5TiO3 structures

2005

Abstract Understanding of the atomic and electronic structure of Ba c Sr 1 −  c TiO 3 (BST) solid solutions is important for several applications including the non-volatile ferroelectric memories (dynamic random access memory, DRAM). We present results of ab initio calculations of several spatial arrangements of Ba 0.5 Sr 0.5 TiO 3 solid solutions based on DFT-HF B3PW hybrid method. We calculate the atomic and electronic structure, the effective charges, interatomic bond populations, the electronic density distribution, and densities of states for three layered structures with the same composition. The suggested method reproduces experimental lattice parameters of both pure BaTiO 3 and SrTi…

Dielectric response of BaTiO electronic states under AC fields via microsecond time-resolved X-ray absorption spectroscopy

2021

This research was performed under the approval of the Photon Factory Program Advisory Committee (PF-PAC; Contract Numbers 2015G580, 2017G587, and 2019G614) and was financially supported by JSPS KAKENHI Grant Numbers 18H01153 , 19H02426 , and 18K19126 . The experiment for measuring spectra in Fig. 6 (b) was performed on beamline BM26A (proposal MA 2731) at the European Synchrotron Radiation Facility (ESRF), Grenoble, France. We are grateful to Local Contact at the ESRF for providing assistance in using beamline BM26A. Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPRE…

Spatial Simultons in 2D Photonic Crystals of Nonlinear Origin

2007

We observed for the very first time quadratic spatial solitons (simultons) in a two dimensional photonic lattice defined by periodic sign inversion of its susceptibilty. This is the first demonstration of quadratic self-confinement in a 2D purely nonlinear photonic crystal.

Generazione di Seconda Armonica per Quasi-Phase-Matching Random in Tantalato di Litio con Poling Periodico

2009

We experimentally observed and explained bulk Second Harmonic Generation via Random Quasi-Phase-Matching, derived from a periodically poled Lithium Tantalate sample with a randomly patterned mark-to-space-ratio.

First-Order Quasi-Phase-Matched Blue Light Generation in Surface-Poled Ti:Indiffused waveguide

2004

The application of surface periodic poling method for first order quasi-phase-matched (QPM) second harmonic generation (SHG) in Ti:indiffused lithium niobate channel waveguides, was investigated. On a 2.5 μm wide channel waveguide which was periodically poled with a period of 2.47 μm for TM waveguide mode interaction, efficient SHG was observed. The CCD camera was used for monitoring the near-field waveguide mode profiles of both the fundamental and second harmonic waves. The potential of surface domain inversion for efficient nonlinear waveguide interactions was shown after the production of 6 mW of continous-wave blue radiation.

The domain structure in PLZT (6-8)/65/35 and spontaneous ferroelectric-relaxor phase transition

1995

Abstract In order to test the hypothesis proposed in Reference 10 about a spontaneous relaxor-ferroelectric phase transition in PLZT (6-7)/65/35 the hysteresis loops and domain structure measurements were carried out. The results confirm this hypothesis. The appearance of the ferroelectric long range order in PLZT with decreasing concentration of La ions is explained by a larger coupling between the feroelectrically active BO6 octahedrons due to smaller concentration of defects and higher dielectric constant.

Электрооптические свойства и особенности фазовых переходов в сегнетокерамиках цирконата-титана свинца, модифицированного лантаном и скандата-ниобата …

1978

Фоторефракция, аномальный фотовольтаический эффект и механизм электропроводности в сегнетокерамике цирконата-титаната свинца, модифицированного ланта…

1979

Advisor: Круминь, Андрис

The electronic properties of SrTiO3-δ with oxygen vacancies or substitutions

2021

The authors would like to thank R. Dittmann for useful discussions, T. Kocourek, O. Pacherova, S. Cichon, V. Vetokhina, and P. Babor for their contributions to sample preparation and characterization. The authors (M.T., A.D.) acknowledge support from the Czech Science Foundation (Grant No. 19-09671S), the European Structural and Investment Funds and the Ministry of Education, Youth and Sports of the Czech Republic through Programme “Research, Development and Education” (Project No. SOLID21 CZ.02.1.01/0.0/0.0/16-019/0000760). This study was partly supported by FLAG-ERA JTC project To2Dox (L.R. and E.K.). Calculations have been performed on the LASC Cluster in the Institute of Solid State Phy…