Attach3-SamplePEDfigure15368.pdf

Bi2O3–PbO

Fig. 15368—System PbO–Bi2O3. T-X phase diagrams. (A) Calculated in this study;

(B)-(C ) experimentally determined in Refs. 1 and 2, respectively. α and δ = α- and δ-Bi2O3 solid solutions; Lit = litharge (PbO); Mas = massicot (PbO); γ = PbO solid solution; β = high temperature bcc phase. Dashed lines = estimated phase relations.

I. Diop, N. David, J. M. Fiorani, R. Podor, and M. Vilasi, J. Chem. Thermodyn., 41 [3]

420-432 (2009).

Both thermodynamic calculations and experimental studies were performed for this system. For the computational assessment, the thermodynamic functions of pure elements for the stable and metastable phases were from the SGTE database.3 The phases Bi12PbO19, Bi6Pb2O11, Φ-Bi8Pb5O17, and Bi2Pb3O6 were considered as stoichiometric compounds. δ-Bi2O3 was modeled using the formula (Bi+3,Pb+2)2(O–2,Va)4. Due to a lack of information, α-Bi2O3 was modeled using the same formula as δ-Bi2O3, which is obviously a simplification. The solid solution β has a body-centered cubic structure and was modeled as (Bi+3,Pb+2)2(O–2,Va)3. In order to describe the solubility of Bi2O3 in PbO, it was assumed that Bi+3 substitutes randomly for Pb+2 and extra oxygen is taken up to compensate for the valence of the cations. The liquid phase was described using Hillert’s partially ionic liquid model. Thermodynamic calculations were performed using the optimization module PARROT in the Thermo-Calc software.4 Experimental data from Refs. 1 and 5 were also taken into account.

For the experimental study, samples were prepared at ambient conditions in an agate mortar by mixing oxide powders PbO (99.999%) and Bi2O3 (99.9%). Several samples of each studied composition were prepared in order to carry out DTA and annealing at different temperatures. DTA was carried out at a heating and cooling rate of 5◦C/min.

Samples were analyzed using EPMA. Phases were identified using XRD.

To verify the existence of the β solid solution reported in Ref. 1 but not in Ref. 2, additional detailed experimental studies were carried out. The authors point out that all of their experimental results are in good agreement with those reported in Refs. 1 and 6.

The calculated phase diagram shows considerable differences in the central region when compared to the results in Ref. 2 (as shown in Fig. (C )). However, the calculated diagram shows excellent agreement with the authors’ experimental results and those from other literature sources (Ref. 1 as shown in Fig. (B), and Refs. 7 and 8 as shown below).

Temp. (◦C) Temp. (◦C) Temp. (◦C) Temp. (◦C) Invariant Equilibrium Calculated Experiment Ref. 7 Ref. 8 δ-Bi2O3 + L → β 721 not measured 725 720 δ-Bi2O3 → Bi12PbO19 711 not measured δ-Bi2O3 → α-Bi2O3 + Bi12PbO19 706 not measured 695 702 δ-Bi2O3 → Bi12PbO19 + β 695 not measured L → Mas + β 636 625 635 β → Φ-Bi8Pb5O17 604 600 605 Bi12PbO19 + β → Bi6Pb2O11 609 605 610 β → Bi6Pb2O11 + Φ-Bi8Pb5O17 589 588 590 Bi6Pb2O11→ Bi12PbO19 + Φ-Bi8Pb5O17 574 574 575 β + Mas → Bi2Pb3O6 604 600 605 β → Φ-Bi8Pb5O17 + Bi2Pb3O6 585 584 580 Bi2Pb3O6 → Φ-Bi8Pb5O17 + Mas 581 579 583

Editor’s Note: The calculated temperature for the invariant equilibrium Mas → Φ-Bi8Pb5O17 + Lit was listed as 762◦C, which seems to be a misprint.

1. R. M. Biefeld and S. S. White, J. Am. Ceram. Soc., 64 [3] 182-184 (1981).

2. Z. B. Shao, K. R. Liu, B. Meng, Y. Li, and Y. Q. Yang, Wuji Cailiao Xuebao, 11 [3]

570-572 (1996).

3. A. T. Dinsdale, CALPHAD: Comput. Coupling Phase Diagrams Thermochem., 15 [4]

317-425 (1991).

4. B. Sundman, B. Jansson, and J. O. Andersson, CALPHAD: Comput. Coupling Phase

Diagrams Thermochem., 9 [2] 153-190 (1985).

5. A. Braileanu, M. Zaharescu, D. Crisan, and E. Segal, J. Therm. Anal. Calorim., 49 [3]

1197-1205 (1997).

6. R. Ganesan, T. Gnanasekaran, and R. S. Srinivasa, J. Nucl. Mater., 375 [2] 229-242

(2008).

7. J. C. Boivin and G. Tridot, C. R. Seances Acad. Sci., Ser. C, 278 [12] 865-867 (1974).

8. S. A. Shaaban, M. F. Abadir, and A. N. Mahdy, Br. Ceram. Trans. J., 83 [4] 102-105

(1984).

Contributing Editor G.L. Gan

General Editors

M.D. Hill T.A. Vanderah

Fig. 15368-A

Fig. 15368-B

Fig. 15368-C