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The RT reflectivity of high quality NiO and 0.8% lithium-doped NiO single crystals has been measured in the range 4 to 30 eV. Reflectivity data have been analysed through KK transforms so as to obtain the values of dielectric constants. Vacuum cleaved fragments of the same crystals, examined through an XPS probe, are seen to be free from any contamination or segregated phases. Owing to the imperfect smoothness of crystal surfaces, it was not possible in the case of Li:NiO to obtain an absolute determination of reflectivity. Nevertheless a qualitative difference between the two spectra can be seen. This concerns especially the 4 eV peak, corresponding to the fundamental absorption onset, and the structure in the 5.5-7.5 eV range. These differences are attributed to a decrease in the O2p-Ni3d charge-transfer transition strength in Li-doped NiO with respect to undoped NiO, due to the creation of O2p holes following Ni(2+) substitution by Li(+). This interpretation is found to be in agreement with other spectroscopic studies.

Additional information

Authors: PARMIGIANI F, CISE SpA, Milano (IT);SCAGLIOTTI M, CISE SpA, Milano (IT);REVCOLEVSCHI A, Université de Paris XI (FR);SANGALETTI L, Dipartimento di Fisica A. Volta, Pavia (IT);ZEMA N, ISM-CNR, Roma (IT)
Bibliographic Reference: Paper presented: 12th Conference of the Condensed Matter Division, Prague (CS), April 1992
Availability: Available from (1) as Paper EN 36686 ORA
Record Number: 199210461 / Last updated on: 1994-12-02
Original language: en
Available languages: en
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