摘要
为了解释界面上大的分散阈值与组分氧化物小的比表面之间的共存关系,在纳米尺度上提出了非单层分散模型,即各组分氧化物以球形八面体MeO6为单位,在二元氧化物界面上进行分散,八面体之间通过共用氧原子密置成为二维单层,再由有限个数这样的单层相互叠加而成为界面过渡层。该过渡层虽然是非单层的,但仍然属于非晶相,并具有非化学计量组成。具体计算了非单层模型的七个主要参数:每种组分氧化物的平均单层数分别为1.6～8.5,单层厚度为0.678～0.718nn3,叠加厚度为1.10～5.81 nm,过渡层总厚度分别为5.34～8.78 nm,以及各组分氧化物八面体的球形半径,密置单层容量和每百平米分散阈值。通过讨论非单层分散与非晶相之间的关联,概述了二元氧化物界面上非单层分散的晶相损失杌理以及界面的非晶相结构和对热的亚稳性。
The monolayer dispersion model is clarified to be unsuitable for interfacial structure of five transition metal binary oxides, namely, MoO3 -Fe2O3, MoO3-V2O5, MoO3-TiO2, (antaase), MoO3-WO3 and MoO3-ZrO2, even though the monolayer model is suitable for supported systems, such as MoO3/γ - Al2O3, MoO3/TiO2 (gel). In order to explain satisfactorily the relation of great dispersed threshold values to small specific area, the non-monolayer dispersion model is suggested. According to this non-monolayer model, each component oxide should be dispersed on another's surface with the unit of spherical octahedron MoO6 close-packed with each other by sharing O atoms to form a two - dimensional monolayer, and a limited number of such monolayers are stacked up to form the non - monolayer dispersed interfacial transition layer of a binary oxide. Seven parameters of the non -monolayer model are calculated and listed, the average monolayer number is 1.6 - 8.5, the thickness per monolayer is 0.678 - 0.718 nm, the stacking-up thickness of component oxide is 1.10-5.81 nm, and the total thickness of interfacial transition layer is 5.34-8.78 nm. In discussion the relation of non-monolayer dispersion with non-crystalline phase. The mechanism of crystalline phase loss and the non - crystalline structure of interfacial transition layer of binary oxides is described.
出处
《黑龙江大学自然科学学报》
CAS
2003年第1期96-99,共4页
Journal of Natural Science of Heilongjiang University
基金
国家自然科学基金资助项目(2860018)
黑龙江省自然科学基金资助项目(E9203)
关键词
二元过渡金属氧化物界面
非单层分散模型
单层内密置的球形八面体
binary transition metal oxide interface
non - monolayer dispersion model
spherical octahedron close-packed within a monolayer
