Фазовая диаграмма системы Mn-Te

К оглавлению: Другие диаграммы (Others phase diargams)

Mn-Te (Manganese-Tellurium) M. Lasocka The assessed Mn-Te phase diagram is based on [77Man], as modified by the data of [68Abr] and [69Boo] regarding the homogeneity ranges of the gMnTe and eMnTe2 phases. The system is monotectic with two intermediate solid phases: polymorphic MnTe and MnTe2. The terminal solid solubility is negligible. A miscibility gap in the Mn-rich liquid is easy to confirm by visual observation of precipitated shiny droplets of Mn [70Van]. One metastable phase has been reported in the Mn-Te system. [78Gri] obtained metastable cubic MnTe by vapor deposition on cleaved NaCl at the substrate temperature between 150 and 400 C. [78Gri] measured the lattice spacings. The hexagonal NiAs-type MnTe was observed within this temperature range on the C substrate only. In a comparison of the structure of Mn chalcogenides, in the homologous series of compounds MnS, MnSe, and MnTe, the sulfide was observed to have several polymorphs including a hexagonal modification with a wurtzite structure. The selenide was reported to have an unstable hexagonal modification, while the telluride had a hexagonal NiAs-type structure as its stable form. The effect of pressure up to 130 kbar on the lattice parameters of MnTe at room temperature was measured by [69Nag]. According to [66Saw], MnTe2 undergoes a structural transformation at about 100 kbar. The pressure dependence of the N‚el temperature, TN, of the paramagnetic to antiferromagnetic phase transition in MnTe and MnTe2 was studied by [66Oza] and [66Saw]. TN shifts toward a higher temperature as pressure increases. Both MnTe and MnTe2 are antiferromagnetic semiconductors with a wide and narrow energy gap, respectively. The N‚el temperature of the phase transition from paramagnetic to antiferromagnetic structure is pressure sensitive. The curve of TN vs pressure for MnTe2 shows a kink near 100 kbar [ 66Saw]; this kink corresponds to some phase transition. A new and interesting class of materials is diluted magnetic semiconductors, which are compounds of the general formula A1-xMnx(Se or Te), where A is Cd, Hg, Mg, Pb, Zn, and Se or Te. Both their energy gap and magnetic susceptibility depend on the composition x. Because of the wide homogeneity range of these ternary compounds, a material of desired magneto-electrical properties may be obtained. 65Saw: A. Sawada and S. Miyahara, J. Phys. Soc. Jpn., 20, 2087 (1965). 66Oza: K. Ozawa, S. Anzai, and Y. Hamaguchi, Phys. Lett., 20, 132-133 (1966). 66Saw: A. Sawada, S. Miyahara, and S. Minomura, J. Phys. Soc. Jpn., 21, 1017- 1018 (1966). 68Abr: N.Kh. Abrikosov, K.A. Dyuldina, and V.V. Zhadanova, Izv. Akad. Nauk SSSR, Neorg. Mater., 4, 1878-1884 (1968) in Russian; TR: Inorg. Mater. (USSR), 4, 1638-1642 (1968). 68Car: F.M.A. Carpay, Philips Res. Rep., (Suppl. 10) (1968). 69Boo: J. van den Boomgaard, Philips Res. Rep., 24, 284-298 (1969). 69Nag: H. Nagasaki, I. Wakabayashi, and S. Minomura, J. Phys. Chem. Solids, 30, 329-337 (1969). 70Van: V.G. Vanyarkho, V.P. Zlomanov, and A.V. Novosalova, Izv. Akad. Nauk SSSR, Neorg. Mater., 6, 1257-1259 (1970) in Russian. 77Man: G.S. Mann and L.H. Van Vlack, Metall. Trans. B, 88, 53-56 (1977). 78Gri: C.H. Griffiths, J. Mater. Sci., 13, 513-518 (1978). Submitted to the APD Program. Complete evaluation contains 2 figures, 7 tables, and 57 references. Special Points of the Mn-Te System