- Sm-Sm2Se3 phase diagram and properties of phases
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A Sm-Sm2Se3 phase diagram has been studied from 1000 K until melting. This system forms three congruently melting compounds: SmSe (ST NaCl, a = 0.6200 nm, T m = (2400 ± 50) K, and H = 2750 MPa), Sm3Se4 (ST Th3P4, a = 0.8925 nm, T m = (2250 ± 30) K, and H = 3350 MPa), and Sm2Se3 (ST Th3P4, a = 0.8815 nm, T m = (2150 ± 40) K, and H = 5300 MPa). There are eutectics between Sm and SmSe phases and between SmSe and Sm3Se4 phases at 2.5 at % Se, 1300 K and at 54.5 at % Se, 2100 K, respectively. Within the extent of Sm2+ Sm2 3+ Se4-Sm2 3+Se3 solid solution (ST Th3P4), the experimentally determined percentages of Sm2+ ions correspond with the values calculated from the formula compositions of samples. The bandgap width for SmSe1.45 and SmSe1.48 phases is ΔE = (1.90 ± 0.05) eV.
- Fainberg,Andreev,Kharitontsev,Polkovnikov
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- BAND EDGE EXCITION SPECTRA IN Sm MONOCHALCOGENIDES.
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Reflection spectra have been measured on semiconducting SmS, SmSe and SmTe single crystals at 2 K in the photon energy region from 3 to 6 ev. From a comparison of the spectra in these Sm monochalcogenides with those in BaS and BaSe, the reflection peaks observed in this photon energy region are identified as the Wannier excitons associated with the band-edges at the X-point and the GAMMA -point. Temperature dependence of the reflection peaks and the electroreflectance spectra of SmSe support this identification. The energy band structure of semiconducting Sm monochalcogenides is discussed on the basis of the observed exciton spectra.
- Kurita,Kaneko,Koda
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p. 463 - 466
(2008/10/08)
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