High temperature science 

Abstract: The dissociation energies D 0 0 (FeO) = 95.9 ± 1.8 and D 0 0 (MnO) = 88.1 ± 1.8 kcal mol-1 were determined by studying the metathesis reactions FeO(g) + Se(g) = Fe(g) + SeO(g) and MnO(g) + Fe(g) = Mn(g) + FeO(g) by the mass spectrometric Knudsen cell method in the respective temperature intervals, 1640–1810 K and 1660–2060 K. These results are critically compared with the literature data, which implied the need for their reevaluation and a review of the thermodynamic data for FeOH(g) and FeO2(g). For the latter molecule, thermodynamic functions are presented.

Abstract: The temperature-composition phase diagram for the GeSe-GeTe system was determined between 25 and 675°C using high temperature X-ray powder diffraction techniques (1). The orthorhombic phase extends from 100 to 92 ± 3 mol% GeSe and is stable below 651 ± 5°C. For compositions between 86 ± 3 and 58 ± 3 mol% GeSe a hexagonal phase exists. Above 415 ± 5°C the hexagonal phase decomposes via a peritectoid reaction to form an orthorhombic and cubic phase. A rhombohedral phase was observed for compositions between GeTe and 52 ± 3 mol% GeSe. Above 375 ± 10°C the rhombohedral phase transforms into a cubic phase. A complete series of cubic GeSe-GeTe solid solutions exists above 651 ± 5°C.

Abstract: The development of a unique, noncontact, temperature measurement device utilizing rotating analyzer ellipsometry is described. The technique circumvents the necessity of spectral emissivity estimation by direct measurement concomittant with radiance brightness. Using this approach, the optical properties of electromagnetically levitated liquid metals Cu, Ag, Au, Ni, Pd, Pt, Zr were measured in situ at 4 wavelengths and up to 600 K superheat in the liquid. The data suggest an increase in the emissivity of the liquid compared with the incandescent solid. The data also show moderate temperature dependence of the spectral emissivity, particularly when the wavelength of light is close to an absorption edge of the material. The data for both solids and liquids show excellent agreement with available values in the literature for the spectral emissivities as well as the optical constants.