Publication detail

Structural study of BaO-MoO3-P2O5 glasses by Raman and NMR spectroscopy

Year: 2017

Type of publication: článek v odborném periodiku

Name of source: Journal of Non-Crystalline Solids

Publisher name: Elsevier Science BV

Place: Amsterdam

Page from-to: 114-121

Titles:

Language	Name	Abstract	Keywords
cze	Strukturní studie skel systému BaO-MoO3-P2O5 pomocí Ramanovy and NMR spectroskopie	Skla z ternárního systému BaO-MoO3–P2O5 byla připravena a byly stanoveny jejich základní fyzikální parametry a jejich struktura byla studována Ramanovou a 31P NMR spektroskopií. Pro stadium změn struktury i vlastností byly připraveny čtyři kompoziční řady skel (50-x/2)BaO-xMoO3-(50-x/2)P2O5 (řada A), 50BaO-yMoO3-(50-y)P2O5 (řada B), 20BaO-zMoO3-(80-z)P2O5 (řada C) a (70-u)BaO-uMoO3-30P2O5 (řada D). Byla určena oblast sklotvornosti při chlazení skel volně na vzduchu, která zahrnuje jak sklo s 10 mol% P2O5 tak i sklo se 70 mol% MoO3. 31P MAS NMR spektra ukázala na depolymerizaci fosfátové strukturní sítě při vestavování molybdátových strukturních celků. Fitování NMR spekter poskytlo kompoziční závislosti fosfátových strukturních celků Qn. Molybden tvoří ve sklech strukturní celky MoO6 tak jako v krystalickém MoO3 a ve sloučenině Ba(MoO2)2(PO4)2.	fosfátová skla; vlastnosti; struktura skel; NMR spektra; Ramanova spektra
eng	Structural study of BaO-MoO3-P2O5 glasses by Raman and NMR spectroscopy	Glasses in the BaO-MoO3P2O5 ternary system were prepared, their basic physical properties measured and their structure studied by Raman and P-31 NMR spectroscopies. A modified glass-forming region in this system under slow cooling of the melt was determined. Four compositional series, namely (50-x/2)BaO-xMoO(3)-(50-x/2)P2O5 (A), 50BaO-yMoO(3)-(50-y)P2O5 (B), 20BaO-zMoO(3)-(80-z)P2O5 (C) and (70-u)BaO-uMoO(3)-30P(2)O(5) (D) were chosen for a discussion on changes of the structure and properties of the studied glasses. The glass transition temperature revealed a maximum in series A at x = 40 mol% MoO3 and in series C at z = 50 mol% MoO3, whereas monotonous increase of T-g in the series B and monotonous decrease in the series D was observed. P-31 MAS NMR spectra of the glasses revealed depolymerization of the phosphate network, due to the incorporation of molybdate units, and isolated PO4 groups were identified in glasses with high MoO3 content. Fitting the NMR spectra provided compositional dependences of phosphate units Q(n). On the Raman spectra of glasses with low MoO3 content, a strong vibrational band at 940944 cm (-1), with a shoulder at similar to 910 cm (-1), dominated the spectra, which was assigned to the vibration of terminal oxygen atoms in molybdate structural units (M-O- and M=O). In glasses with high MoO3 content, a broad band at similar to 854 cm(-1), ascribed to Mo-O-Mo bonds, showed on the formation of octahedral clusters composed of MoO6 units in the structure of these glasses.	Phosphate glasses; Properties; Glass structure; NMR spectra; Raman spectra

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