Thermoanalytical study and crystallization of Ba(PO3)2–WO3 glasses
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Barium phosphate glasses of the composition (100 − x)Ba(PO3)2–xWO3 with 0–60 mol% WO3 were prepared and studied. Thermal studies of the glasses were carried out with DTA, dilatometry and hot-stage microscopy. Glass transition temperature in this glass series increases with increasing WO3 content from 461 °C (x = 0) to 623 °C (x = 60). Most glasses containing WO3 crystallize on heating within the range of 650–750 °C with the exception of glasses with 20–30 mol% WO3, which are thermally stable. Very high chemical durability of these glasses with dissolution rate of 1.4 × 10−8–6.2 × 10−9 g cm−2 min−1 was also revealed. Crystallization of glasses revealed the existence of a new compound Ba(WO2)2(PO4)2 in the studied compositional series. The compound Ba(WO2)2(PO4)2 possess hexagonal unit cell of dimensions a = 11.5191(1) Å and c = 6.3437(1) Å, and its melting point is 936 °C. Raman spectra of crystallized glasses confirmed the formation of crystalline compound in this glass series and revealed the presence of glass phase in some thermal-treated samples. 31P MAS NMR showed on only one coordination of phosphorus atoms in the Ba(WO2)2(PO4)2 compound.
KeywordsPhosphate glasses Thermal properties Physical properties Crystallization
The Czech authors are grateful for the financial support from the Project No. 18-01976S of the Grant Agency of the Czech Republic. EDS measurements were taken with the support of the Grants LM2015082 and ED4.100/11.0251 provided by the MSMT Czech Republic. The authors thank L. Montagne and B. Revel for the 31P MAS NMR spectra of the polycrystalline Ba(WO2)2(PO4)2 compound and the corresponding glass of the same composition.
- 12.Kuzmin A, Purans J. X-ray absorption study of the short range order of tungsten and molybdenum ions in BaO–P2O5–WO3 and CaO–P2O5–MoO3 glasses. Journal de Physique IV Colloque. 1997;7:971–3.Google Scholar
- 15.Joint Committee on powder diffraction standards, Swarthmore, PA, USA. International Centre of Diffraction Data.Google Scholar
- 18.Lide DR. Handbook of chemistry and physics. Boca Raton: CRC Press; 2001. p. 9–52.Google Scholar
- 22.Kierkegaard P, Holmen S. The crystal structure of AgMoO2PO4. Ark Kemi. 1965;23:213–21.Google Scholar
- 24.Kierkegaard P. The crystal structure of NaMoO2PO4 and NaWO2PO4. Ark Kemi. 1961;18:553–75.Google Scholar
- 31.Šubčík J, Koudelka L, Mošner P, Gregora I, Montagne L, Delevoye L. Glass-forming ability and structure of glasses in the ZnO–WO3–P2O5 system. Phys Chem Glasses Part B. 2012;53:79–85.Google Scholar