Ab initio calculations of yttrium chromite
06 Feb 2013-Vol. 1512, Iss: 1, pp 846-847
TL;DR: In this paper, first principles calculations of the electronic and magnetic properties of Yttrium Chromite (YCrO3) are performed within generalized gradient approximation by ultrasoft pseudopotential with plane wave basis.
Abstract: First principles calculations of the electronic and magnetic properties of Yttrium Chromite (YCrO3) are performed within generalized gradient approximation by ultrasoft pseudopotential with plane wave basis. Structural optimization revealed G-type antiferromagnet as the most stable structure for YCrO3. Electronic properties indicate that the material is an insulator and the introduction of Hubbard U parameter further increases the band gap from 1.43 eV to 1.64 eV. Using mean field approximation, the magnetic ordering temperature of YCrO3 is found to be 137 K which is close to the experimental value.
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TL;DR: In this paper, a high-resolution XRD and X-ray photoelectron spectroscopy (XPS) study was conducted on 100 compositions of polycrystalline ceramics and the results revealed that the average bond length decreases with increasing Ca content.
Abstract: Y $$_{{1-x}}$$
Ca
$$_{x}$$
CrO
$$_{3}$$
polycrystalline ceramics with 0.000 $$\le $$
x $$\le $$
0.100 compositions were studied by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results revealed that the $$\langle $$
Cr–O
$$\rangle $$
average bond length decreases with increasing Ca content. This fact infers that the charge compensation is through the change from Cr
$$^{+3}$$
to Cr
$$^{+4}$$
instead of oxygen vacancies. To confirm this supposition, the high-resolution XPS study revealed that as the Ca is introduced in the YCrO
$$_{3}$$
matrix, the Cr 2p
$$_{{3/2}}$$
core-level is well fitted at 576.22 and 577.57 eV belonging at Cr
$$^{+3}$$
and Cr
$$^{+4}$$
core-level, respectively. Furthermore, we found an increase of the valence band XPS spectra at the Fermi energy as the Ca replaces the Y site. This fact suggests an increase of the Cr 3d-state at the Fermi energy, which is confirmed by the XPS valence band spectra and the electrical conductivity measurements.
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