High temperature structural investigation of Na2O�0.5Fe2O3�3SiO2 and Na2O�FeO�3SiO2 melts and glasses

Structural Characterization of FeO–SiO₂–V₂O₃ Slags Using Molecular Dynamics Simulations and FT-IR Spectroscopy

“…4) Therefore, the variation in the coordination of Fe 2 + may imply that the network-modifying effect of Fe 2 + on the Si-O network is enhanced by the addition of V 2 O 3 . The existing structural positions of Fe 2 + in our simulations are in accordance with previous studies, 15,16,18,[21][22][23][24][25][26] in spite of the investigated silicate systems may vary from one to the other.…”

“…Fe 2 + adopts 4-, 5-or 6-fold coordination were found in silicate melts and glasses under different silicate composition, temperature, pressure and f O 2 . [14][15][16]18,[21][22][23][24][25] Notwithstanding, in most cases FeO acts as a network modifier which offers O 2 − and thus depolymerizes the silicate network. 4,15) Although there are numerous studies on the structural characterization and physicochemical properties of V-containing materials, rather limited information is available on the structural configurations of trivalent V in silicate melts and glasses.…”

Structure of (FexCa1−xO)y(SiODrewitt1, Sanloup2, Bytchkov3 et al. 2013Phys. Rev. B

“…23,30,46,47 Our results instead support predictions from optical and Raman spectra that suggest a significant fraction of sixfold coordinated Fe 2+ polyhedra. 6,17,18 Keppler 17 argued that the EXAFS evidence for Fe in tetrahedral coordination in silicate melts and glasses may be affected by positional disorder effects yielding significantly too short Fe-O distances and coordination numbers if the Fe cations occupy highly distorted octahedral sites. Indeed, Waychunas et al 65 found that even in crystalline fayalite, erroneously short Fe-O distances and small coordination numbers are found using EXAFS due to the distorted octahedral M1 and M2 sites.…”

“…22,23,25,30,34,36 This result is, however, in contrast to Raman and optical absorption spectra, which report Fe 2+ in sixfold coordination. 6,7,9,17,18,42 By comparison, very little direct information is available on the local coordination environment in iron silicate melts due to the difficulty of performing experiments at high temperatures. Information obtained from the glasses is of limited use as an analog to liquids, as studies have shown that the structure of glass forming liquids can change dramatically when quenched into the solid state.…”

The Effect of Iron Content on the Atomic Structure of Alkali Silicate Glasses using Solid-state NMR Spectroscopy

“…그러나 Fe 2 O 3 가 약 20 wt% 정도 포함된 알칼리 규산염 용융체의 경우 800 K에서 120 J/mol․K의 값을 갖는 것에 비해 온도에 따라 부적관계(negative correlation)의 열용량의 거동을 보이면서 1000 K 에서 94 J/mol․K으로 감소한다는 사실이 보고되 었으며 (Lange and Navrotsky, 1992;Tangemen and Lange, 1998), Na 2 SiO 3 -NaFeSi 2 O 6 시스템에서 철 의 함량이 증가함에 따라 엔탈피(H 1373 -H 298 )가 증 가한다는 사실을 실험적으로 확인하였다 (Sugawara and Akaogi, 2004 (Wang et al, 1993). 또한 X-선 흡수 분광분석(X-ray absorption spectroscopy, XAS)이나 뫼스바우어 분광분석(Mossbauer spectroscopy)을 이용한 기존 연구에서는 합성 환경에 따른 철의 산화상태를 조절하여 만들어진 시료의 평균적인 Fe-O 결합길이와 Fe 다면체의 비대칭성 등을 실험적으로 구하여 원자구조에 대한 정보, 특 히 철의 배위다면체에 대한 정보를 얻고자 하였다 (Brown et al, 1995;Calas and Petiau, 1983;Mysen et al, 1985a;1985b;Wilke et al, 2007;Wilke et al, 2001 (Mysen et al, 1984;Mysen and Virgo, 1985).…”