A proposal for (B) VO2 ⇒ (A) VO2 phase transition:: A simple crystallographic slip
A proposal for (B) VO2 ⇒ (A) VO2 phase transition:: A simple crystallographic slip
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DOI：
10.1006/jssc.1999.8436
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发表时间：
1999-12-01
影响因子：
3.3
通讯作者：
Galy, J
中科院分区：
文献类型：
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作者：
Galy, J
(B)VO2为单斜晶系，晶胞参数为a=12.093(1)埃，b=3.7021(2)埃，c=6.4330(5)埃，β=6.4330(1°)，C2/m空间群。低温晶型A(L)采用P4/ncc空间群，a=8.4403(9)Angstrom，c=7.666(1)Angstrom，A(H)空间群I4/m，a=8.476(2)Angstrom，c=3.824(2)Angstrom。在这些结构中，VO6八面体在前一种结构中通过边共享而形成四重弦，而在后一种结构中它们形成了交联的双弦；两种无穷无尽的弦类型都沿着参数b或c发展(类似于3.8埃周期)。在第一种组合中，他们在(B)VO2中建立了所谓的双层D4，在(A)VO2中分别平行于(001)和(110)面建立了DZ，并在垂直方向上通过拐角共享来关联这些D4层，这些D4层表现出垂直于其中面(平行于(001))最弱的V-O键，使得晶体滑移Cs-1/3[100](001)在结构中发生，将(B)VO2转变为(A)VO2。通过晶体剪切机制设计(B)和(A)晶体结构与形成的化学实验条件有关：温度、压力和应力。(C)1999年学术出版社。
(B) VO2 crystallizes in the monoclinic system, C2/m space group with a = 12.093(1) Angstrom, b = 3.7021(2) Angstrom, c = 6.4330(5) Angstrom, and beta = 106.97(1 degrees) as cell parameters. (A) VO2 with two allotropic varieties crystallizes in the tetragonal system, the low temperature form A(L) adopts P4/ncc space group with a = 8.4403(9) Angstrom and c = 7.666(1) Angstrom and A(H) the space group I4/m with a = 8.476(2) Angstrom and c 3.824(2) Angstrom. In these structures, VO6 octahedra are associated in quadruple strings by edge sharing in the former structure whereas they form cross-linked double strings in the latter; both endless string types develop along parameters b or c (similar to 3.8 Angstrom periodicity). In the first association they build the so-called double layers D4 in (B) VO2 and Dz in (A) VO2, parallel to (001) and (110) planes, respectively, and associated, in their perpendicular direction, by corner sharing, These D4 layers exhibit the weakest V-O bonding perpendicular to their medium plane (parallel to (001)) allowing a crystallographic slip Cs-1/3 [100] (001) to occur in the structure, transforming (B) VO2 into (A) VO2. Design of (B) and (A) crystal structures via crystallographic shear mechanisms is related to chemical experimental conditions of formation: temperature, pressure, and stress. (C) 1999 Academic Press.