Journal of Alloys and Compounds, 190 (1993) 219-227 219 JALCOM 474 The lead-zirconium system: binary phases and a series of interstitial compounds of the host ZrsPb3 Young-Uk Kwon and John D. Corbett* Department of Chemistry and Ames Laboratory DOE, Iowa State University, Ames, 1A 50011 (USA) (Received July 16, 1992) Abstract The Pb-Zr system contains the phases Zr~s.8Pb (Cr3Si-type), ZrsPb3 (MnsSi3) and ZrsPb4 (TisGa4). ZrsPb4 has a substoichiometric region above approximately 800 °C, extending to about ZrsPb3.65 at 1000 °C. Reactive powder sintering in sealed Ta containers at 1000-1350 °C is the most effective route for the synthesis of pure phases of both the binaries and the interstitial derivatives ZrsPb3Z. Twenty examples of the latter were obtained with Z = AI, Si, P, S, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Ag, Cd, In, Sn, Sb, Te, (Pb), (second period Z were not investigated). Single crystals for Z=AI, Cd, Zn, Pbo.s7,Pbo.94were obtained by metal flux or vapor phase transport reactions, and the last three were quantified by X-ray crystallography. Volume trends as a function of group and period follow metal/covalent radii trends for Z fairly well. 1. Introduction Two-phases have been reported to form in the Pb-Zr system, namely, ZrsPb3 [1, 2] (hexagonal, MnsSi3-type ) and either ZrsPb [3] or Zr3Pb [4] (cubic, Cr3Si-type). The purities, lattice parameters and compositions have not been confirmed, especially for the second phase, and the possibility of analogues of ZrsSn4 or ZrSn2 [5] has not been established. Almost nothing is known regarding the phase relationships [6]. The phase ZrsPb3 has recently attracted interest as a potential neutron multiplier in nuclear fusion power generation [7, 8]. Donne et al. [9] subsequently investigated the synthesis of ZrsPb3 for this purpose. They assumed the overall phase behavior of the Zr-Pb system was like those of the partially known Zr-Sn and Zr-Ge systems. Their best ZrsPb3 products were obtained by hot isostatic pressing of the elemental powders in steel containers at 870 °C and 150 MPa, but they were not able to get a very pure product, and they did not know about the very similar ZrsPb4. The related phases ZrsSn3 and ZrsSb 3 with the same MnsSi3-type structure have recently been thoroughly studied with regard to their places in the binary systems [5, 10] as well as the numerous interstitial (Z) compounds each forms with the general compositions ZrsSn3Z [11] and Zr5Sb3Z [12]. The approximately 15 Z elements that can be so bound in each host range from late *Author to whom correspondence should be addressed. transition elements to chalcogens and span periods two to five. Both hosts are electron-rich and metallic, and the similar interstitial ranges with each imply that localized Zr-Z interactions may be a major factor in the stability of the ternary products. In this context, it was deemed worthwhile not only to determine the role of common impurities on the stability of the supposed Zr5Pb3 binary, including the self-interstitial that might exist as ZrsPb3 +x, 0 <x < 1, but also to examine the effect that the larger interstitial hole in ZrsPb3 might have on the range of Z possible. Rieger et al. [13] have reported the synthesis of such a ZrsPb3Cu derivative with a plausible hexagonal unit cell. 2. Experimental section 2.1. Materials Reactor-grade zirconium was utilized in all sample preparations. The details of its cleaning and the gen- eration of powder from zirconium strips have been described previously [5, 10]. Electrolytic lead bar (Ames Lab., 99.9999%) was scraped free of surface oxidation, cold-rolled to 2-3 mm sheet, and cut to the appropriate size. The other reagents were: A1 (United Mineral & Chemical, high purity), Si (Ames Lab., zone refined crystal bar), P (Aldrich, 99.999%), S (Alfa, 99.999%), Cr and Mn (A. D. Mackay), Fe (Plastic Metals, 99.9%), Co (Aesar, 99.9 + %), Ni (Matheson, Coleman & Bell, 0925-8388/93/$6.00 © 1993- Elsevier Sequoia. All rights reserved