Fe-bearing vanadium dioxide–paramontroseite: structural details and high-temperature transformation

IF 1.8 3区地球科学 Q2 MINERALOGY

European Journal of Mineralogy Pub Date : 2023-06-01 DOI:10.5194/ejm-35-373-2023

N. Curetti, A. Pavese

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引用次数: 0

Abstract

Abstract. A natural sample of Fe-bearing paramontroseite (V0.84Fe0.19Al0.03O2; a = 4.8960(14), b = 9.395(3), c = 2.9163(5) Å, V = 134.14(6) Å3; space group Pbnm) from Prachovice mine (Czech Republic) was investigated to shed light on cation partitioning and behavior upon heating. XRD experiments showed that V and Fe are not vicariant of one another, as V occupies the octahedral site at (0.09, 0.14, 0.25), whereas Fe enters a tetrahedral site at (0.41, 0.06, 0.25), the latter expected to be empty in the ideal structure. Thermal expansion is anisotropic, leading to the following β coefficients: -2.0×10-5, 3.0×10-5, 0.8×10-5 and 1.8×10-5 ∘C−1 for a, b, c and V, respectively. At T higher than 350 ∘C, V undergoes oxidation, from [4+] to [5+], and paramontroseite decomposes into Fe-tetrapolyvanadate (Fe2V4O13) and V-pentoxide (V2O5). µ-Raman spectroscopy analyses confirmed that paramontroseite is sensitive to heating: the crystal surface invested by the laser beam degrades very quickly, leading to the phases revealed by diffraction measurements. There is no evidence for the formation at high T of a rutile-type phase, as we observed for iso-structural ramsdellite MnO2.

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含铁二氧化钒-顺滑石:结构细节和高温转变

摘要含铁副斜长辉石(v0.84 fe0.19 al0.030 o2;= 4.8960 (14), b = 9.395 (3), c = 2.9163 (5), V = 134.14 (6) A3;研究了来自捷克共和国prachovice矿的空间群Pbnm)，以揭示其在加热时的阳离子分配和行为。XRD实验表明，在理想结构中，V和Fe不是相互替换的，V在(0.09,0.14,0.25)处占据八面体位置，而Fe在(0.41,0.06,0.25)处进入四面体位置，四面体位置为空。热膨胀是各向异性的，导致β系数如下:-2.0×10-5, 3.0×10-5, 0.8×10-5 and1.8×10-5对a, b, C和V分别是C−1。在T大于350°C时，V发生从[4+]到[5+]的氧化，副斜锰矿分解成四多钒酸铁(Fe2V4O13)和五氧化钒(V2O5)。微拉曼光谱分析证实，顺滑石对加热很敏感:激光束注入的晶体表面降解得非常快，导致衍射测量显示的相。没有证据表明在高温度下形成金红石型相，而我们在等结构的ramsdellite MnO2中观察到这一点。

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来源期刊

European Journal of Mineralogy 地学-矿物学

CiteScore

2.80

自引率

9.50%

发文量

审稿时长

6-12 weeks

期刊介绍： EJM was founded to reach a large audience on an international scale and also for achieving closer cooperation of European countries in the publication of scientific results. The founding societies have set themselves the task of publishing a journal of the highest standard open to all scientists performing mineralogical research in the widest sense of the term, all over the world. Contributions will therefore be published primarily in English. EJM publishes original papers, review articles and letters dealing with the mineralogical sciences s.l., primarily mineralogy, petrology, geochemistry, crystallography and ore deposits, but also biomineralogy, environmental, applied and technical mineralogy. Nevertheless, papers in any related field, including cultural heritage, will be considered.