Abstract:We performed the first-principles band-structure calculations for a pure and a Cd-doped AgInO 2 delafossite compound. The results are carefully analyzed and compared with the results obtained for a pure and a Cddoped CuAlO 2 compound, calculated previously by our group. The electronic structures of both systems are found to be similar in many details, being characterized by the same hybridization scheme that occurs at both Cu and Ag positions. Introduction of Cd impurity into the Cu site produces a shallow ban… Show more
“…The local density of unoccupied states for E 10 eV was published for AgInO 2 and CuAlO 2 [12] and for CuGaO 2 and CuInO 2 [13]. XANES at the L 2,3 -edge of the transition metal M was measured for AgFeO 2 , AgCoO 2 and AgNiO 2 [14].…”
Cu K-edge x-ray absorption near-edge structure (XANES) spectra of trigonal (3R) CuScO(2) and CuLaO(2) and of hexagonal (2H) CuScO(2) were investigated experimentally and theoretically, in order to study differences between spectra of isostructural and isoelectronic compounds. Significant differences were found in the Cu K-edge XANES of 3R CuScO(2) and 3R CuLaO(2); these differences can be understood by considering the calculated polarization dependence of the XANES spectra and the differences between the phaseshifts of Sc and La. Spectra of the 3R and 2H polytypes of CuScO(2) differ only weakly and the difference originates from the long-range order. The pre-edge peak around 8980 eV is generated by the same mechanism as the pre-edge peak in Cu(2)O, i.e. involving scattering by the Cu atoms in the plane which is perpendicular to the O-Cu-O axis.
“…The local density of unoccupied states for E 10 eV was published for AgInO 2 and CuAlO 2 [12] and for CuGaO 2 and CuInO 2 [13]. XANES at the L 2,3 -edge of the transition metal M was measured for AgFeO 2 , AgCoO 2 and AgNiO 2 [14].…”
Cu K-edge x-ray absorption near-edge structure (XANES) spectra of trigonal (3R) CuScO(2) and CuLaO(2) and of hexagonal (2H) CuScO(2) were investigated experimentally and theoretically, in order to study differences between spectra of isostructural and isoelectronic compounds. Significant differences were found in the Cu K-edge XANES of 3R CuScO(2) and 3R CuLaO(2); these differences can be understood by considering the calculated polarization dependence of the XANES spectra and the differences between the phaseshifts of Sc and La. Spectra of the 3R and 2H polytypes of CuScO(2) differ only weakly and the difference originates from the long-range order. The pre-edge peak around 8980 eV is generated by the same mechanism as the pre-edge peak in Cu(2)O, i.e. involving scattering by the Cu atoms in the plane which is perpendicular to the O-Cu-O axis.
“…There are, however, too few experimental data that can be analysed (just two Ag-based compounds were treated in [8]). We have already performed calculations of Cd-doped AgInO 2 [17] and plan to investigate this subject in more detail in the future.…”
In this paper we offer an interpretation of the previously observed trend of the electric
field gradient (EFG) values measured in a group of semiconducting delafossites
CuBO2
(B = Al,
Fe, Cr, Nd) at Cd impurities which substitute either Cu or B atoms. Our theoretical study
indicates that this EFG trend reveals one of the most subtle details in the electronic
spectrum of the compounds, namely whether the impurity states are formed within or out
of the band gap. When Cd substitutes the Cu, it exhibits a larger EFG value in
CuAlO2 and
CuFeO2 than
in CuCrO2
and CuNdO2. This occurs because the Cd states form in the first two compounds a shallow band within
the gap, but in the second two compounds they do not. When Cd substitutes the B atom it
exhibits almost the same EFG in all delafossites. In this case, Cd states are not formed within
the gap in any of the compounds. The same interpretation can be applied to the whole family of
CuBO2
delafossites, whatever the B atom is. To arrive at these conclusions we analysed and calculated various systems
(Cd-doped CuAlO2
and CuCrO2
compounds, and molecular clusters) using the full-potential linear augmented plane wave
method.
“…Presently, significant attention is given to Cu-delafossites because these structures combine strong electrical conductivity with excellent visible light transparency. The outstanding properties of the CuAlO2 based materials, such as their wide band gap, high electrical conductivity, optical transparency, and interesting thermal and chemical stabilities, have drawn considerable interest [2][3][4][5][6][7][8]. A wide range of technical options are also made possible by these materials' modifiable conductivity and transparency.…”
The solid-state technique was utilized to make a single phase of delafossite CuAlO2, along with 1%, 2%, 3% and 4% silver doped CuAlO2 samples in this study. The content of the samples was investigated using energy dispersive X-ray spectroscopy (EDS) equipped with a field emission scanning electron microscope (FE-SEM). The polycrystalline nature of all of the analyzed cases was confirmed by structural analyses utilizing an X-ray diffraction (XRD) pattern with a simple typical peak of CAO rhombohedral phase. Raman, FT-IR and UV–Vis spectroscopy were used to study the structural, and optical energy band gap (Eg) of Ag doped CuAlO2 nanoparticles. The Kubelka–Munk function was used to calculate the optical band gap of ACAO alloys using diffuse reflectance spectra, and it altered as the Ag ion concentration increased. A. c. impedance spectroscopy was used to investigate the dielectric characteristics of Ag doped CuAlO2 nanoparticles.
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