Фазовая диаграмма системы Pd-Te

К оглавлению: Другие диаграммы (Others phase diargams)

Pd-Te (Palladium-Tellurium) H. Okamoto The assessed Pd-Te phase diagram is based primarily on the work of [86Cha] and [86Ips]. The van't Hoff relationship and the (Pd) liquidus trend suggest that the limiting slope of the (Pd) solidus must be nearly vertical. The limiting slope of the (Pd) liquidus has been drawn assuming no Te solubility in (Pd). Considering the limiting slope of the (Pd) solidus and the observed thermal arrest points for the L = (Pd) + Pd3Te eutectic existing down to ~11 at.% Te, the assessed (Pd) solidus has been drawn closer to the 0 at.% Te line than proposed by [86Cha] or by [86Kim]. Pd17Te4 has a homogeneity range from 18.7 to 19.4 at.% Te, although [86Kim] could not determine its crystal structure. The peritectoid formation temperature of Pd17Te4 is 770 C [86Cha]. The temperature range of existence of Pd3Te is 785 to 727 C, and its composition is about 24.3 at.% Te [86Cha]. The "Pd3Te" in [61Med] should be Pd20Te7 [78Bha], and the "Pd3Te" found by [ 56Gro] was actually Pd20Te7, according to XRD data [86Kim]. PdTe melts congruently at 55.0 at.% Te and 746 C [86Ips]. The melting temperature of PdTe2 is 752 C, and the L = PdTe + PdTe2 eutectic point is 59. 5 at.% Te and 730 C [86Ips]. Earlier, [61Med] observed that PdTe and PdTe2 are completely miscible in the solid state above 640 C, and the existence of a continuous solid phase was supported by a high-temperature X-ray study at 670 C [65Kje]. This is an unusual situation, because the crystal structures of PdTe and PdTe2 are different. In addition, [61Med] showed a solidus with a minimum temperature at 690 C, violating the phase rule. To clarify these peculiar phase relationships, [82Ips] measured the Te vapor pressure between 1077 and 602 C from 35 to 75 at.% Te and established the existence of a PdTe + PdTe2 two-phase field at all temperatures. [86Kim] examined the microstructures of alloys homogenized in the single-phase field region in the diagram of [61Med] and found no evidence of a continuous solid phase. However, because PdTe and PdTe2 are both hexagonal and have similar lattice parameters, PdTe and PdTe2 may become coherent and form a continuous phase field in the metastable state. 29Tho: L. Thomassen, Z. Phys. Chem. B, 2(5-6), 349-379 (1929) in German. 55Gro: W.O.J. Groeneveld Meijer, Am. Mineral., 40, 646-657 (1955). 56Gro: F. Gronvold and E. Rost, Acta Chem. Scand., 10(10), 1620-1634 (1956). 61Med: Z.S. Medvedeva, M.A. Klochko, V.G. Kuznetsov, and S.N. Andreeva, Zh. Neorg. Khim., 6(7), 1737-1739 (1961) in Russian; TR: Russ. J. Inorg. Chem., 6( 7), 886-887 (1961). 65Fur: S. Furuseth, K. Selte, and A. Kjekshus, Acta Chem. Scand., 19(1), 257- 258 (1965). 65Kje: A. Kjekshus and W.P. Pearson, Can. J. Phys., 43(3), 438-449 (1965). 68Kha: V.S. Khar'kin, R.M. Imanov, and S.A. Semiletov, Izv. Akad. Nauk SSSR, Neorg. Mater., 4(10), 1801-1802 (1968) in Russian; TR: Inorg. Mater., 4(10), 1571-1572 (1968). 69Kha: V.S. Khar'kin, R.M. Imanov, and S.A. Semiletov, Kristallografiya, 14(5), 907-910 (1969) in Russian; TR: Sov. Phys. Crystallogr., 14(5), 779-781 (1970). 77Mat: P. Matkovic and K. Schubert, J. Less-Common Met., 52(2), 217-220 (1977) in German. 77Wop: W. Wopersnow and K. Schubert, J. Less-Common Met., 51(1), 35-44 (1977) in German. 78Bha: S. Bhan and H. Kudielka, Z. Metallkd., 69(5), 333-336 (1978). 78Mat: P. Matkovic and K. Schubert, J. Less-Common Met., 58, P39-P46 (1977) in German. 82Ips: H. Ipser, Z. Metallkd., 73(3), 151-158 (1982). 85Kim: W.S. Kim, Chungnam Kwahak Yonguchi, 12(2), 159-166 (1985). 86Cha: G. Chattopadhyay, Y.J. Bhatt, and S.K. Khera, J. Less-Common Met., 123, 251-266 (1986). 86Ips: H. Ipser and W. Schuster, J. Less-Common Met., 125, 183-195 (1986). 86Kim: W.S. Kim, J. Geol. Soc. Korea, 22(2), 146-160 (1986). Submitted to the APD Program. Complete evaluation contains 1 figure, 4 tables, and 20 references. Special Points of the Pd-Te System