Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “LuFeO3”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

5 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on LuFeO3 by Materials Project

LuFeO3 crystallizes in the hexagonal P6_3cm space group. The structure is three-dimensional. there are two inequivalent Lu3+ sites. In the first Lu3+ site, Lu3+ is bonded to seven O2- atoms to form distorted LuO7 pentagonal bipyramids that share corners with three equivalent FeO5 trigonal bipyramids and edges with three equivalent FeO5 trigonal bipyramids. There are a spread of Lu–O bond distances ranging from 2.24–2.33 Å. In the second Lu3+ site, Lu3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Lu–O bond distances ranging from 2.24–2.46 Å. Fe3+ is bonded to five O2- atoms to form FeO5 trigonal bipyramids that share a cornercorner with one LuO7 pentagonal bipyramid, corners with six equivalent FeO5 trigonal bipyramids, and an edgeedge with one LuO7 pentagonal bipyramid. There are a spread of Fe–O bond distances ranging from 1.95–2.04 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to three Lu3+ and one Fe3+ atom to form OLu3Fe tetrahedra that share corners with ten OLu3Fe tetrahedra, corners with two equivalent OLuFe3 trigonal pyramids, edges with three equivalent OLu3Fe tetrahedra, and edges with two equivalent OLuFe3 trigonal pyramids. In the second O2- site, O2- is bonded to three Lu3+ and one Fe3+ atom to form distorted OLu3Fe tetrahedra that share corners with ten OLu3Fe tetrahedra, corners with four equivalent OLuFe3 trigonal pyramids, edges with three equivalent OLu3Fe tetrahedra, and an edgeedge with one OLuFe3 trigonal pyramid. In the third O2- site, O2- is bonded to one Lu3+ and three equivalent Fe3+ atoms to form OLuFe3 trigonal pyramids that share corners with six equivalent OLu3Fe tetrahedra, corners with six equivalent OLuFe3 trigonal pyramids, and edges with three equivalent OLu3Fe tetrahedra. In the fourth O2- site, O2- is bonded to one Lu3+ and three equivalent Fe3+ atoms to form distorted OLuFe3 trigonal pyramids that share corners with six equivalent OLu3Fe tetrahedra, corners with six OLuFe3 trigonal pyramids, and edges with three equivalent OLu3Fe tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LuFeO3 by Materials Project

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

36 MATERIALS SCIENCE↗
DOE OSTI2020

Site-specific spectroscopic measurement of spin and charge in (LuFeO3)m/(LuFe2O4)1 multiferroic superlattices

Abstract Interface materials offer a means to achieve electrical control of ferrimagnetism at room temperature as was recently demonstrated in (LuFeO 3 ) m /(LuFe 2 O 4 ) 1 superlattices. A challenge to understanding the inner workings of these complex magnetoelectric multiferroics is the multitude of distinct Fe centres and their associated environments. This is because macroscopic techniques characterize average responses rather than the role of individual iron centres. Here, we combine optical absorption, magnetic circular dichroism and first-principles calculations to uncover the origin of high-temperature magnetism in these superlattices and the charge-ordering pattern in the m = 3 member. In a significant conceptual advance, interface spectra establish how Lu-layer distortion selectively enhances the Fe 2+ → Fe 3+ charge-transfer contribution in the spin-up channel, strengthens the exchange interactions and increases the Curie temperature. Comparison of predicted and measured spectra also identifies a non-polar charge ordering arrangement in the LuFe 2 O 4 layer. This site-specific spectroscopic approach opens the door to understanding engineered materials with multiple metal centres and strong entanglement.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Temperature-induced hexagonal–orthorhombic phase transition in lutetium ferrite nanoparticles

The x-ray diffraction, Raman, and infrared spectroscopies and magnetic measurements were used to explore the correlated changes of the structure, lattice dynamics, and magnetic properties of the LuFeO3 nanoparticles, which appear in dependence on their sintering temperature. We revealed a gradual substitution of the hexagonal phase by the orthorhombic phase in the nanoparticles, with sintering temperature increasing from 700 to 1100 °C. The origin and stability of the hexagonal phase in the LuFeO3 nanoparticles are of the special interest, because the nanoparticles in the phase can be a room-temperature multiferroic with a weak ferromagnetic and pronounced structural and ferroelectric long-range ordering. The antiferromagnetic and nonpolar orthorhombic phase is more stable in the bulk LuFeO3. To define the ranges of the hexagonal phase stability, we determine the bulk and interface energy densities of different phases from the comparison of the Gibbs model with experimental results. Using effective parameters of the Gibbs model, we predict the influence of size effects and temperature on the structural and polar properties of the LuFeO3 nanoparticles. Analysis of the obtained results shows that the combination of the x-ray diffraction, Raman and infrared spectroscopies, magnetic measurements, and theoretical modeling of structural and polar properties allows us to establish the interplay between the phase composition, lattice dynamics, and multiferroic properties of the LuFeO3 nanoparticles prepared under different conditions.

Materials Science↗
DOE OSTI2020

Defect-Enhanced Polarization Switching in the Improper Ferroelectric LuFeO 3

Results of switching behavior of the improper ferroelectric LuFeO 3 are presented. Here, using a model set of films prepared under controlled chemical and growth-rate conditions, it is shown that defects can reduce the quasi-static switching voltage by up to 40% in qualitative agreement with first-principles calculations. Switching studies show that the coercive field has a stronger frequency dispersion for the improper ferroelectrics compared to a proper ferroelectric such as PbTiO 3 . It is concluded that the primary structural order parameter controls the switching dynamics of such improper ferroelectrics.

36 MATERIALS SCIENCE↗