摘要
采用Ｘ射线衍射和分子动力学（ＭＤ）计算模拟等手段研究了６７ＣｄＦ２／３３ＢａＣｌ２玻璃（Ⅰ）和４０ＣｄＦ２／４０ＢａＦ２／２０ＣｄＣｌ２玻璃（Ⅱ）的结构。研究表明，在Ⅰ中Ｃｄ原子主要为６配位，Ⅱ中Ｃｄ原子主要为６或７配位。Ｃｄ—Ｆ的平均键长分别为２３１．６ｐｍ和２３０．４ｐｍ。在ＭＤ计算的玻璃中同时存在非桥Ｆ，桥Ｆ，３配位Ｆ和４配位Ｆ，几乎不存在不和Ｃｄ原子成键的游离Ｆ。弱的形成体阳离子和阴离子的连接较弱，Ｃｄ在大的阴离子空隙中的位置较松弛，体系随Ｃｄ含量增加稳定性下降。对混合卤化物玻璃的结构与形成的特点进行了讨论。
The structures of 67CdF 2 33BaCl 2(XCB0) glass and 40CdF 2 40BaF 2 20CdCl 2 (FCB3) glass were studied by X ray diffraction and molecular dynamics simulation methods. The Cd atoms are mainly sixfold coordinated by fluorine in XCB0 glass and six or sevenfold coordinated in FCB3 glass. The average Cd—F bond length is 230.4pm (FCB3) and 231.6pm (XCB0), increasing with the Cl content. Non bridging fluorine, bridging fluorine, threefold coordinated fluorine and fourfold coordinated fluoine are all present in the MD drived glass. Free fluorine, which is only bonded with Ba atoms, is hardly found in the MD glass. However, free chlorine is present in the MD glass. The Ba atoms are more bonded with Cl atoms. It is indicated that the glass structures studied can be described by the disordered anion packing model. The Cd 2+ and Ba 2+ ions insert in the empty sites of the disorder packed F - and Cl - anions. The Cd atoms are mobile in the lax joined sites, make the stability of these glass systems decrease with the increasing of Cd content. It can be concluded that, in the glass formation process, comparing with the effect that the introduction of Cl - decreases the bonds strength, the mix anion effect is the key factor, which makes this mixed anion glass system easier to form than the single fluoride or chloride glasses.
出处
《清华大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
1998年第6期74-78,共5页
Journal of Tsinghua University(Science and Technology)
基金
国家自然科学基金
