Okur Kutay Havva Esma
Department of Chemistry, Faculty of Engineering and Natural Sciences, Bursa Technical University, Bursa Turkey.
Turk J Chem. 2020 Dec 16;44(6):1463-1470. doi: 10.3906/kim-2005-78. eCollection 2020.
The existence of cation-vacancy sites in fullerides might lead to long-range ordering and generate a new vacancy-ordered superstructure. The purpose of this work is to search whether or not long-range ordering of vacant tetrahedral sites, namely superstructure emerges in nonstoichiometric K Ba CsC fulleride. Therefore, K Ba CsC with cation-vacancy sites is synthesized using a precursor method to avoid inadequate stoichiometry control and formation of impurity phases within the target composition. For this purpose, first, phase-pure K C , Ba C and Cs C precursors are synthesized. Stoichiometric quantities of these precursors are used for further reaction with C to afford K Ba CsC . Rietveld analysis of the high-resolution synchrotron X-ray powder diffraction data of the precursors and K Ba CsC confirms that K C , Ba C and Cs C are single-phase and they crystallize in a body-centered-cubic structure ( 3) as reported in the literature. The analysis also shows that K Ba CsC phase can be perfectly modeled using a face-centered cubic structure. No new peaks appear which could have implied the appearance of a superstructure. This suggests that there is no long-range ordered arrangement of vacant tetrahedral sites in K Ba CsC .
富勒化物中阳离子空位的存在可能导致长程有序，并产生一种新的空位有序超结构。本工作的目的是探究在非化学计量比的KₓBaₓCsₓC₆₀富勒化物中，空四面体位置的长程有序（即超结构）是否会出现。因此，采用前驱体法合成具有阳离子空位的KₓBaₓCsₓC₆₀，以避免化学计量控制不当以及在目标组成内形成杂质相。为此，首先合成了相纯的K₃C₆₀、Ba₃C₆₀和Cs₃C₆₀前驱体。使用这些前驱体的化学计量量与C₆₀进一步反应以得到KₓBaₓCsₓC₆₀。对前驱体和KₓBaₓCsₓC₆₀的高分辨率同步辐射X射线粉末衍射数据进行的Rietveld分析证实，K₃C₆₀、Ba₃C₆₀和Cs₃C₆₀为单相，并且如文献报道，它们结晶为体心立方结构（空间群Pm3̅m）。分析还表明，KₓBaₓCsₓC₆₀相可以用面心立方结构完美建模。没有出现可能暗示超结构出现的新峰。这表明在KₓBaₓCsₓC₆₀中不存在空四面体位置的长程有序排列。
