کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1333671 | 979091 | 2005 | 6 صفحه PDF | دانلود رایگان |
(VO)2P2O7(VO)2P2O7 has been studied at high temperatures by in situ X-ray powder diffraction in an inert atmosphere. Lattice parameters indicate an anisotropic thermal expansion up to Tc=214∘C, followed by an approximately isotropic expansion up to 490∘C. It is proposed that TcTc is the temperature of a second-order phase transition between the known room temperature form with space group Pca21Pca21 and a high-temperature form with space group Pcab . Above 490∘C a minority phase develops in the sample that was identified as the V3+V3+ containing compound V4(P2O7)3V4(P2O7)3, while the anisotropic expansion along aa suggests that stoichiometric (VO)2P2O7(VO)2P2O7 transforms into (VO)2P2O7+x(VO)2P2O7+x with interstitial oxygen located between the layers. With an onset at 706∘C all of the (VO)2P2O7(VO)2P2O7 transforms into VPO4VPO4.
Temperature-dependent X-ray diffraction of (VO)2P2O7(VO)2P2O7, showing the anisotropic thermal expansion of the lattice parameter aa through the temperature dependence of the (400) reflection.Figure optionsDownload as PowerPoint slide
Journal: Journal of Solid State Chemistry - Volume 178, Issue 7, July 2005, Pages 2225–2230