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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. [ABSTRACT FROM AUTHOR]

Differential scanning calorimetry (DSC), dilatometry and X-ray diffraction have been used to study thermal behavior and stability of glasses prepared simultaneously in Al2O3 or Pt crucibles in compositional series (40 − x)MgO-xFe2O3-60P2O5 within the concentration range of x = 0-40 mol% Fe2O3. Mössbauer spectra showed that all glasses with Fe2O3 contained both Fe(II) and Fe(III) ions. The contamination glasses from alumina crucibles ranged from 0.3 to 0.9 mol% Al2O3. The replacement of MgO by Fe2O3 resulted in a gradual decrease in glass transition temperature and dilatometric softening temperature, whereas thermal expansion coefficient did not change significantly. The DSC curves showed that all glasses crystallize on heating in the broad temperature range ≈ 560-900 °C. Crystallization temperature decreases with increasing Fe2O3 content. The highest tendency toward crystallization was found for the glass containing 40 mol% Fe2O3. X-ray diffraction measurements showed that the major compounds formed by glass crystallization were Mg(PO3)2, Fe(PO3)3, Fe3(P2O7)2 and FePO4. All thermoanalytical studies showed differences in thermal behavior of glasses prepared in Al2O3 or Pt crucibles. [ABSTRACT FROM AUTHOR]

The thermal behavior and crystallization of barium molybdate-phosphate glasses were studied in two compositional series, namely A: (100 − x)Ba(PO3)2–xMoO3 (with x = 0–70 mol%) and B: 50BaO–yMoO3–(50 − y)P2O5 (with y = 0–15 mol% MoO3). Thermal properties were studied with differential thermal analysis and dilatometry. Glass transition temperature increases in series A in the range of 0–40 mol% MoO3 and then decreases with a further increase in MoO3 content, whereas the thermal expansion coefficient in series A reveals a minimum at 50 mol% MoO3. These trends are not observed in series B, where the glass transition temperature increases in the range of 0–15 mol% MoO3 and the thermal expansion coefficient almost does not change. Crystallization of these glasses was studied by X-ray diffraction analysis, Raman and 31P MAS NMR spectroscopy. Large thermal stability of glass with a composition 35BaO–30MoO3–35P2O5 toward crystallization was demonstrated. Crystallization of glasses resulted in the formation of the compound Ba(MoO2)2(PO4)2 in this ternary system. Raman spectroscopy also provided information on the formation of glass-crystalline samples in some studied compositions. [ABSTRACT FROM AUTHOR]

Borophosphate glasses of the BaO-BO-PO ternary system were prepared and studied within the large glass-forming region of the system. Fourteen investigated glass samples of barium borophosphate glasses were discussed for a comparison of the compositional trends in their properties in four compositional series such as A: (100 − x)Ba(PO)- xBO, B: 40BaO- yBO-(60 − y)PO, C: (50 − z)BaO- zBO-50PO, and D: (60 − w)BaO- wBO-40PO. Changes in glass density and molar volume primarily depend on the BaO content in the glasses. The thermal properties were studied with a differential thermal analysis, hot-stage microscopy, and dilatometry. Glass transition temperature increases with a rising BO content most rapidly in the glass series A and B. It reaches its maximum in these series for the glasses containing 20-30 mol%, where the glass network represents a 3D structure interlinked with P-O-B, P-O-P, and B-O-B bridges. The thermal expansion coefficient decreases, in contrast, with the increasing BO content in these ternary glasses as well as their chemical durability. The crystallization of these glasses, in the samples with a low BO content, results in the formation of barium metaphosphate BaPO. Certain crystallized samples also contain a small amount of BPO, and diffraction lines of ternary compounds BaBPO and BaB(PO) were revealed in a number of samples. A new compound of the composition BaBPO was identified in the crystallized glass 50BaO-10BO-40PO. [ABSTRACT FROM AUTHOR]

The effect of indium oxide on the structure and properties of zinc phosphate and zinc borophosphate glasses has been investigated in the series (50− x)ZnO-xInO-50PO and 30ZnO-(20− x)BO-xInO-50PO with x = 0-20 mol% InO in both series. Their physical properties were measured, and their structure was studied by Raman and NMR spectroscopy. Glass transition temperature in the phosphate glass series increases with increasing InO content as well as their chemical durability. The observed changes in the P MAS NMR spectra with increasing InO content revealed the depolymerization of phosphate chains due to the replacement of ZnO by InO resulting in an increase in the O/ P ratio in the glass structure. B MAS NMR spectra revealed the presence of BO units in the glass structure in the borophosphate glass series; these spectra give no evidence for the formation of B-O-In bonds. Their glass transition temperature slightly decreases with increasing InO content. The values of the molar volume in these glasses do not change substantially when BO is replaced by InO. This can be ascribed not only to differences in boron (BO) and indium (InO) coordination, but also to a higher ionicity of In···O bonds in comparison with B-O bonds. The obtained data resulted in the conclusion that indium oxide behaves as a modifying oxide in both glasses. [ABSTRACT FROM AUTHOR]

The structural relaxation of three compositional series of PbO–WO 3–P 2O 5 glasses with composition (0.5 −  x/2)PbO· xWO 3·(0.5 −  x/2)P 2O 5, x = 0, 0.1, 0.2, 0.3, 0.4, and 0.5; 0.5PbO· xWO 3·(0.5 −  x)P 2O 5, x = 0, 0.1, 0.2, and 0.3; and (0.5 −  x)PbO· xWO 3·0.5P 2O 5, x = 0, 0.1, 0.2, 0.3, 0.4, and 0.5 was studied by thermomechanical analysis. The structural relaxation was studied in the transformation region using the Tool–Narayanaswamy–Moynihan’s and Tool–Narayanaswamy–Mazurin’s models. The relaxation function of Kohlrausch Williams and Watts was used. The parameters of both models were calculated by nonlinear regression analysis of thermodilatometric curves measured by thermomechanical analyzer under the constant load. Both models very well describe the experimental data. It was found that the modulus is increasing with increasing amount of WO 3 in all glasses. On the contrary, the width of the spectrum of relaxation times is decreasing with increasing amount of WO 3 in all studied glasses. Both models possess the values of metastable melt thermal expansion coefficient equal to their experimental value. [ABSTRACT FROM AUTHOR]

Thermal properties and crystallization of glasses from PbO-MoO-PO ternary system were studied in three compositional series (100 − x)[0.5PbO-0.5PO]- xMoO (A), 50PbO- yMoO-(50 − y)PO (B), and (50 − z)PbO- zMoO-50PO (C). Glass transition temperature, crystallization temperature, coefficient of thermal expansion, and dilatation softening temperature of the studied glasses were determined by differential thermal analysis and dilatometry. Crystallization products of annealed glass samples were investigated by X-ray diffraction and Raman spectroscopy. X-ray diffraction analysis of crystallized glasses revealed the formation of PbPO, PbPO, and PbMoO in the samples of the B series. In the series A and C in the samples with a high MoO content, crystalline compounds of Pb(MoO)(PO) and (MoO)(PO), respectively, were identified. Raman spectra of crystalline samples confirmed the results of X-ray diffraction measurements and provided also information on thermal stability of glasses and formation of glass-crystalline phases in the studied glass series. [ABSTRACT FROM AUTHOR]

Glasses of the ternary system ZnO–Bi2O3–P2O5 were prepared and studied in two compositional series 50ZnO– xBi2O3–(50 − x)P2O5 and (50 − y)ZnO– yBi2O3–50P2O5. Two distinct glass-forming regions were found in the 50ZnO– xBi2O3–(50 − x)P2O5 glass series with x = 0–10 and 20–35 mol.% Bi2O3. All prepared Bi2O3-containing glasses reveal a high chemical durability. Small additions of Bi2O3 (∼5 mol.%) improve thermal stability of glasses. All glasses crystallize on heating within the temperature range of 505–583 °C. Structural studies by Raman and 31P MAS NMR spectroscopies showed the rapid depolymerisation of phosphate chains within the first region with x = 0–15 and the presence of isolated Q0 phosphate units within the second region with x = 20–35. Raman studies showed that bismuth is incorporated in the glass structure in BiO6 units and their vibrational bands were observed within the spectral region of 350–700 cm−1. The evolution of properties and the spectroscopic data are both in accordance with a network former effect of Bi2O3. [ABSTRACT FROM AUTHOR]