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Electronic structure of hydrothermally synthesized single crystal U 0.22 Th 0.78 O 2
Author(s) -
Turner D. B.,
Kelly T. D.,
Peterson G. R.,
Reding J. D.,
Hengehold R. L.,
Mann J. M.,
Kolis J. W.,
Zhang X.,
Dowben P. A.,
Petrosky J. C.
Publication year - 2016
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201600277
Subject(s) - cathodoluminescence , luminescence , materials science , band gap , single crystal , crystal (programming language) , analytical chemistry (journal) , impurity , spectroscopy , solid solution , crystallography , ultraviolet , chemistry , optoelectronics , physics , organic chemistry , chromatography , quantum mechanics , computer science , programming language , metallurgy
Single crystals of ThO 2 , UO 2 , and their solid solutions, U x Th 1– x O 2 , have been obtained through various hydrothermal growth conditions. This technique offers the better of two other growth processes: (i) single crystal purity as by photochemical growth of nanocrystals; and (ii) large/bulk sizes as obtained by the arc melt method. The band gap of the U x Th 1– x O 2 single crystal solid solution, along with the luminescence transition, have been characterized. The occupied and unoccupied structures are determined using ultraviolet and inverse photoemission spectroscopy and the electronic band gap was measured to be 3–4 eV. The strain of incorporating U into the ThO 2 is analyzed through Vegard's law. In this crystal there are defect and impurity sites, likely arising from the kinetic growth process, giving rise to a similar yet slightly different optical gap evident with cathodoluminescence spectroscopy. There is a major luminescence feature spanning the range from 3.18 to 4.96 eV (250–390 nm) with a maximum at 4.09 eV (303 nm), corresponding with the measured electronic band gap. In this paper, the electronic properties of a solid solution U 0.22 Th 0.78 O 2 are measured and interpreted compared to the pure actinide oxides, ThO 2 and UO 2 .