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DOE OSTI2020

Materials Data on K2CrO4 by Materials Project

K2CrO4 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 1-coordinate geometry to ten O2- atoms. There are a spread of K–O bond distances ranging from 2.69–3.31 Å. In the second K1+ site, K1+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of K–O bond distances ranging from 2.78–3.31 Å. Cr6+ is bonded in a tetrahedral geometry to four O2- atoms. There is one shorter (1.66 Å) and three longer (1.67 Å) Cr–O bond length. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to five K1+ and one Cr6+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to five K1+ and one Cr6+ atom. In the third O2- site, O2- is bonded in a distorted single-bond geometry to four K1+ and one Cr6+ atom.

36 MATERIALS SCIENCE↗

NASA NTRS1983

Interatomic Auger transitions in maximal valent V and Cr compounds

The sensitivity of the intensities of the L(3)M(23)M(45) and L(3)M(45)M(45) Auger transitions toward the 3d character in the valence band has been demonstrated by using argon ion bombardment as a means of in situ reduction for the valence state of V and Cr in their maximal valent compounds. The selected V(5+) and Cr(6+) compounds were V2O5, NH4VO3, K2Cr2O7, K2CrO4, and CrO3. Auger and X-ray photoelectron spectra of fresh samples were obtained, and the samples were then subjected to ion bombardment of various durations. The subsequent spectra were recorded to monitor possible alterations due to the reduction of the cation valence state. The interatomic to intraatomic transitions of the Auger spectra transitions of the Auger spectra were observed dynamically and in situ. In particular, the intensity of the cation L(3)M(23)N(45) transitions was observed to increase dramatically with ion bombardment. The correlation between the interatomic Auger transition and covalency as well as the movements of the 3d electrons are discussed.

Yin, L. I.↗