Please use this identifier to cite or link to this item: http://dx.doi.org/10.14279/depositonce-6299
|Main Title:||A study on the thermal conversion of scheelite-type ABO(4) into perovskite-type AB(O,N)(3)|
|Abstract:||Phase-pure scheelite AMoO(4) and AWO(4) (A = Ba, Sr, Ca) were thermally treated under an ammonia atmosphere at 400 to 900 degrees C. SrMoO4 and SrWO4 were shown to convert into cubic perovskite SrMoO2N and SrWO1.5N1.5, at 700 degrees C and 900 degrees C respectively, and to form metastable intermediate phases (scheelite SrMoO4-xNx and SrWO4-xNx), as revealed by X-ray diffraction (XRD), elemental analysis and FTIR spectroscopy. High-temperature oxide melt solution calorimetry reveals that the enthalpy of formation for SrM(O,N)(3) (M = Mo, W) perovskites is less negative than that of the corresponding scheelite oxides, though the conversion of the scheelite oxides into perovskite oxynitrides is thermodynamically favorable at moderate temperatures. The reaction of BaMO4 with ammonia leads to the formation of rhombohedral Ba3M2(O,N)(8) and the corresponding binary metal nitrides Mo3N2 and W4.6N4; similar behavior was observed for CaMO4, which converted upon ammonolysis into individual oxides and nitrides. Thus, BaMO4 and CaMO4 were shown to not provide access to perovskite oxynitrides. The influence of the starting scheelite oxide precursor, the structure distortion and the degree of covalency of the B-site-N bond are discussed within the context of the formability of perovskite oxynitrides.|
|DDC Class:||540 Chemie und zugeordnete Wissenschaften|
|Sponsor/Funder:||EC/FP7/264873/EU/FUnctional Nitrides for Energy Applications/FUNEA|
|Journal Title:||Dalton transactions|
|Publisher:||Royal Society of Chemistry|
|Notes:||Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.|
This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.
|Appears in Collections:||FG Keramische Werkstoffe » Publications|
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