Atomic-Scale Understanding of Structure and Properties of Complex Pyrophosphate Crystals by First-Principles Calculations

Applied Sciences

Puja Adhikari¹  Wai-Yim Ching¹  Khalid Brouzi²  Hamid Ez-Zahraouy³  Mohamed Harcharras⁴  Redouane Khaoulaf⁵ 

[1] Department of Physics and Astronomy, University of Missouri, Kansas City, MO 64110, USA;Génie Urbain et Environnement Department, Université Mohammed V, Agdal BP 554, Morocco;Laboratory of Condensed Matter and Interdisciplinary Sciences (LAMCSCI), Faculty of Sciences, University Mohammed V, Rabat B.P 1014, Morocco;Laboratory of Materials Engineering and Environment, Université Ibn Tofail, Kenitra B.P 242, Morocco;Laboratory of Spectroscopy, Molecular Modeling, Materials, Nanomaterials, Water and Environment, (LS3MN2E-CERNE2), Faculty of Sciences, Mohammed V University, Av Ibn Battouta, B.P 1014, Rabat 10000, Morocco;

关键词: Pyrophosphate;    electronic structure;    mechanical properties;    optical properties;    first-principles calculations;   

DOI  :  10.3390/app9050840

来源: DOAJ

【 摘 要 】

The electronic structure and mechanical and optical properties of five pyrophosphate crystals with very complex structures are studied by first principles density functional theory calculations. The results show the complex interplay of the minor differences in specific local structures and compositions can result in large differences in reactivity and interaction that are rare in other classes of inorganic crystals. These are discussed by dividing the pyrophosphate crystals into three structural units. H₂P₂O₇ is the most important and dominating unit in pyrophosphates. The other two are the influential cationic group with metals and water molecules. The strongest P-O bond in P₂O₅ is the strongest bond for crystal cohesion, but O-H and N-H bonds also play an important part. Different type of bonding between O and H atoms such as O-H, hydrogen bonding, and bridging bonds are present. Metallic cations such as Mg, Zn, and Cu form octahedral bonding with O. The water molecule provides the unique H∙∙∙O bonds, and metallic elements can influence the structure and bonding to a certain extent. The two Cu-containing phosphates show the presence of narrow metallic bands near the valence band edge. All this complex bonding affects their physical properties, indicating that fundamental understanding remains an open question.

【 授权许可】

Unknown