Modeling of Optical Band-Gap Values of Mixed Oxides Having Spinel Structure AB₂O₄ (A = Mg, Zn and B = Al, Ga) by a Semiempirical Approach.

Content Provider	Europe PMC
Author	Di Quarto, Francesco Zaffora, Andrea Di Franco, Francesco Santamaria, Monica
Copyright Year	2023
Description	Spinel oxides with the general formula AB2O4 comprise a large family of compounds covering a very wide range of band-gap values (1 eV < Eg < 8 eV) as a function of the nature of the metallic cations A and B. Owing to this, the physical properties of these materials have been largely exploited both from a fundamental point of view, for their variable electronic properties, and for their possible use in numerous engineering applications. Herein, the modeling of ZnAl2O4, ZnGa2O4, MgAl2O4, and MgGa2O4 cubic spinel oxides has been carried out by using the semiempirical approach based on the difference of electronegativity between oxygen and the average electronegativity of cations present in the oxides. The results of recent theoretical extensions of our semiempirical approach to ternary and quaternary oxides have been tested for spinel oxides with metallic ions occupying both octahedrally and tetrahedrally coordinated sites in different ratios. A detailed analysis of the experimental band-gap values and comparison with the theoretically estimated values has been carried out for ternary ZnAl2O4, ZnGa2O4, MgAl2O4, and MgGa2O4 spinels as well as for double spinels Mg(Al2xGa2–x)O4 and Zn(Al2xGa2–x)O4, and quaternary mixed oxides (ZnxMg(1–x))Al2O4 and (ZnxMg(1–x))Ga2O4. The wide range of band-gap values reported in the literature for simple or double spinels has been related to the different preparation methods affecting the grain dimension of crystalline spinel samples as well as to the presence of crystallographic defects and/or impurities in the spinel matrix. The good agreement between experimental band-gap values and the theoretical ones strongly supports the use of our semiempirical approach in the area of band-gap engineering of new materials.
Abstract	Spinel oxides withthe general formula AB2O4 comprise a large familyof compounds covering a very wide rangeof band-gap values (1 eV < Eg <8 eV) as a function of the nature of the metallic cations A and B.Owing to this, the physical properties of these materials have beenlargely exploited both from a fundamental point of view, for theirvariable electronic properties, and for their possible use in numerousengineering applications. Herein, the modeling of ZnAl2O4, ZnGa2O4, MgAl2O4, and MgGa2O4 cubic spinel oxides hasbeen carried out by using the semiempirical approach based on thedifference of electronegativity between oxygen and the average electronegativityof cations present in the oxides. The results of recent theoreticalextensions of our semiempirical approach to ternary and quaternaryoxides have been tested for spinel oxides with metallic ions occupyingboth octahedrally and tetrahedrally coordinated sites in differentratios. A detailed analysis of the experimental band-gap values andcomparison with the theoretically estimated values has been carriedout for ternary ZnAl2O4, ZnGa2O4, MgAl2O4, and MgGa2O4 spinels as well as for double spinels Mg(Al2xGa2–x)O4 and Zn(Al2xGa2–x)O4, and quaternary mixed oxides (ZnxMg(1–x))Al2O4 and (ZnxMg(1–x))Ga2O4. The wide range ofband-gap values reported in the literature for simple or double spinelshas been related to the different preparation methods affecting thegrain dimension of crystalline spinel samples as well as to the presenceof crystallographic defects and/or impurities in the spinel matrix.The good agreement between experimental band-gap values and the theoreticalones strongly supports the use of our semiempirical approach in thearea of band-gap engineering of new materials.
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Volume Number	4
DOI	10.1021/acsorginorgau.3c00030
PubMed Central reference number	PMC10853993
Issue Number	1
PubMed reference number	38344014
Journal	ACS Organic & Inorganic Au [ACS Org Inorg Au]
e-ISSN	2694247X
Language	English
Publisher	American Chemical Society
Publisher Date	2023-11-21
Access Restriction	Open
Rights License	Permits non-commercial access and re-use, provided that author attribution and integrity are maintained; but does not permit creation of adaptations or other derivative works (https://creativecommons.org/licenses/by-nc-nd/4.0/). © 2023 The Authors. Published by American Chemical Society
Subject Keyword	spinel oxides quaternary oxides double spinels band gap band gap engineering
Content Type	Text
Resource Type	Article
Subject	Physical and Theoretical Chemistry Inorganic Chemistry Organic Chemistry