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Variation of Band Gap and Lattice Parameters of β−(Al x Ga 1− x ) 2 O 3 Powder Produced by Solution Combustion Synthesis
Author(s) -
Krueger Benjamin W.,
Dandeneau Christopher S.,
Nelson Evan M.,
Dunham Scott T.,
Ohuchi Fumio S.,
Olmstead Marjorie A.
Publication year - 2016
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.14222
Subject(s) - x ray photoelectron spectroscopy , monoclinic crystal system , lattice constant , band gap , gallium , materials science , analytical chemistry (journal) , lattice (music) , stoichiometry , crystallography , diffraction , crystal structure , chemistry , nuclear magnetic resonance , metallurgy , optics , physics , chromatography , acoustics , optoelectronics
Single‐phase monoclinic aluminum–gallium oxide powders, β−(Al x Ga 1− x ) 2 O 3 , have been produced by solution combustion synthesis for Al fraction 0 ≤ x < 0.8. α−(Al x Ga 1− x ) 2 O 3 is observed for x = 1, with mixed α + β for x = 0.8. The contraction in lattice parameters and increase in band gap with increasing Al concentration were characterized by X‐ray diffraction ( XRD ) and X‐ray photoelectron spectroscopy ( XPS ), respectively, and are compared with a first‐principles density‐functional theory calculation. A novel filtering procedure is described to reduce the uncertainty involved in measuring band gap using photoemission, and to remove asymmetry in XPS line shapes caused by differential charging of loose powder. The lattice parameters vary linearly with Al fraction, but exhibit a change in slope at x = 0.5 that is attributed to the difference between aluminum occupying tetrahedral and octahedral sites in the monoclinic lattice. The band gap changes linearly with local stoichiometry, including increasing when aluminum content at the surface is enriched relative to the interior, with a range of over 1.8 eV.