The detailed crystal and electronic structures of the cotunnite-type ZrO₂

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• 作者：Yan Zhang^a ; ^{yan.zhang@chd.edu.cn" class="auth_mail" title="E-mail the corresponding author} ; Li Duan^a ; Vincent Ji^b
• 关键词：A ; Oxides ; C ; Crystal structures ; C ; Electronic structures ; D ; Crystal-field splitting ; E ; First-principles
• 刊名：Solid State Communications
• 出版年：2016
• 出版时间：July 2016
• 年：2016
• 卷：239
• 期：Complete
• 页码：27-31
• 全文大小：1190 K

文摘

The detailed crystal and orbital-decomposed electronic structures of cotunnite-type ZrO₂ have been investigated by using the first-principles projector augmented wave (PAW) potential within the generalized gradient approximation as well as taking into account on-site Coulomb repulsive interaction (GGA+U). The optimized structure shows that the O_I${\mathrm{O}}_{\mathrm{I}}$ and O_II${\mathrm{O}}_{\mathrm{II}}$ anions are surrounded by an arbitrary tetrahedron of four Zr cations and an arbitrary pentahedron of five Zr cations, respectively, in turn, the Zr cation is surrounded by an arbitrary tetrakaidecahedron formed by nine oxygen ligands. Although one more Zr cation is coordinated to O_II${\mathrm{O}}_{\mathrm{II}}$, the larger bond lengths between O_II${\mathrm{O}}_{\mathrm{II}}$ and its adjacent five Zr cations (d_OII−Zr${\mathrm{d}}_{{\mathrm{O}}_{\mathrm{II}}-\mathrm{Zr}}$) than those between O_I${\mathrm{O}}_{\mathrm{I}}$ and its adjacent four Zr cations (d_OI−Zr${\mathrm{d}}_{{\mathrm{O}}_{\mathrm{I}}-\mathrm{Zr}}$) makes density of states (DOS) of s$\mathrm{s}$ and three p$\mathrm{p}$ (p_x${\mathit{p}}_{\mathit{x}}$, p_y${\mathit{p}}_{\mathit{y}}$ and d059f1fd364fedb48dbe0ec8994" title="Click to view the MathML source">p_z${\mathit{p}}_{\mathit{z}}$) states of the O_II${\mathrm{O}}_{\mathrm{II}}$ anion driving down in lower energy region and driving up in higher energy region. No crystal-field splitting is observed between three p$\mathrm{p}$ (p_x${\mathit{p}}_{\mathit{x}}$, p_y${\mathit{p}}_{\mathit{y}}$ and d059f1fd364fedb48dbe0ec8994" title="Click to view the MathML source">p_z${\mathit{p}}_{\mathit{z}}$) states of anions O_I${\mathrm{O}}_{\mathrm{I}}$ and O_II${\mathrm{O}}_{\mathrm{II}}$ (between three p$\mathrm{p}$ (p_x${\mathit{p}}_{\mathit{x}}$, p_y${\mathit{p}}_{\mathit{y}}$ and d059f1fd364fedb48dbe0ec8994" title="Click to view the MathML source">p_z${\mathit{p}}_{\mathit{z}}$) states and five d$\mathrm{d}$ (d_xy${\mathit{d}}_{\mathit{xy}}$, 82d655cdfdc253b19fda2" title="Click to view the MathML source">d_yz${\mathit{d}}_{\mathit{yz}}$, d_xz${\mathit{d}}_{\mathit{xz}}$, d_z²${\mathit{d}}_{{\mathit{z}}^2}$ and d_x²-y²${\mathit{d}}_{{\mathit{x}}^2{-\mathit{y}}^2}$) states of cation Zr) is resulted from the arrangements of the surrounding cations (anions) do not have any symmetry. The additional covalent character upon Zr–O ionic bonds is attributed to the hybridization of itinerant Zr(5s) and less filled Zr(4d) states to the separated O(2s) and O(2p) states.