Results 181 to 190 of about 1,762 (207)
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The Yellow Polymorphs of Mercuric Iodide (HgI2)
Helvetica Chimica Acta, 2003AbstractHgI2 crystallizes under ambient conditions from various solvents and by sublimation into three concomitant polymorphs whose colors are red, orange, and yellow. The orange and yellow phases are metastable and transform into the red phase when touched. A phase transition from red to yellow occurs at 400 K.
Marc Hostettler +2 more
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Journal of Applied Crystallography, 1982
Lattice-constant thermal expansions, Δa/a and Δc/c, have been measured on α-HgI2 single crystals from 293 K up to the red-to-yellow transition temperature. The curves Δa/a(T) and Δc/c(T) are linear. The thermal expansion coefficients are determined: α[100] = (1.0 ± 0.1) × 10−5 K−1 and α[001] = (4.6 ± 0.1) × 10−5 K−1.
S. Gauthier, I. F. Nicolau
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Lattice-constant thermal expansions, Δa/a and Δc/c, have been measured on α-HgI2 single crystals from 293 K up to the red-to-yellow transition temperature. The curves Δa/a(T) and Δc/c(T) are linear. The thermal expansion coefficients are determined: α[100] = (1.0 ± 0.1) × 10−5 K−1 and α[001] = (4.6 ± 0.1) × 10−5 K−1.
S. Gauthier, I. F. Nicolau
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Journal of Physics D: Applied Physics, 1990
Electron impact dissociative excitation of HgI2 molecules producing the B2 Sigma +1/2 state of HgI has been studied in the case of low energy electrons. Using the most intense band of the (B2 Sigma +1/2-X2 Sigma +1/2) system of the HgI radical at 444 nm, emission cross sections have been measured in the electron energy range 1-100 eV.
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Electron impact dissociative excitation of HgI2 molecules producing the B2 Sigma +1/2 state of HgI has been studied in the case of low energy electrons. Using the most intense band of the (B2 Sigma +1/2-X2 Sigma +1/2) system of the HgI radical at 444 nm, emission cross sections have been measured in the electron energy range 1-100 eV.
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physica status solidi (b), 1978
AbstractPhonon dispersion curves of red HgI2 are measured by inelastic neutron scattering up to a frequency of 1.5 THz for waves propagating in the [100] and [001] symmetry directions. Indications of a two‐dimensional character are found through a slight anisotropy in the sound velocities and through the comparison between inter‐ and intralayer ...
B. Prevot, C. Schwab, B. Dorner
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AbstractPhonon dispersion curves of red HgI2 are measured by inelastic neutron scattering up to a frequency of 1.5 THz for waves propagating in the [100] and [001] symmetry directions. Indications of a two‐dimensional character are found through a slight anisotropy in the sound velocities and through the comparison between inter‐ and intralayer ...
B. Prevot, C. Schwab, B. Dorner
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Solid State Ionics, 1981
Abstract The cation order-disorder phase transition of Ag2HgI4 and Cu2HgI4 involves a major change only in the cation sublattice and is accompanied by a jump in the dc conductivity. Critical dynamics of this phase transition have been studied by microwave conductivity measurement.
T. Wong, M. Brodwin, R. Dupon
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Abstract The cation order-disorder phase transition of Ag2HgI4 and Cu2HgI4 involves a major change only in the cation sublattice and is accompanied by a jump in the dc conductivity. Critical dynamics of this phase transition have been studied by microwave conductivity measurement.
T. Wong, M. Brodwin, R. Dupon
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Berichte der Bunsengesellschaft für physikalische Chemie, 1989
AbstractCalorimetric measurements have been performed on mixed crystals of couprous and mercury iodide at a wide range of compositions. From these investigations specific heats, transition enthalpies and finally the phase diagram CuI — HgI2were derived. The separating lines of different phase regions were calculated from enthalpies of transition versus
J. Nölting, F. Wiegert, E. Puschmann
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AbstractCalorimetric measurements have been performed on mixed crystals of couprous and mercury iodide at a wide range of compositions. From these investigations specific heats, transition enthalpies and finally the phase diagram CuI — HgI2were derived. The separating lines of different phase regions were calculated from enthalpies of transition versus
J. Nölting, F. Wiegert, E. Puschmann
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Exciton Polaritons in HgI2 Crystals
physica status solidi (b), 1975AbstractAt low temperatures a detailed study of the emission and reflection spectra of HgI2 crystals in the region of the ground state n = 1(Γ−Γ) exciton resonance has been carried out. It is found that the shape of the resonant exciton emission spectra in allowed and forbidden polarizations E ⊥ cand E ‖, and the relative positions of the emission and ...
I. Akopyan +4 more
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HgI/sub 2/ low energy beta particle detector
IEEE Transactions on Nuclear Science, 1990A HgI/sub 2/ device structure was designed and tested which allows HgI/sub 2/ to be used to make low energy beta particle detectors. The devices detected tritium beta particles with an efficiency of about 25%. A protective encapsulant has been developed which should protect the devices for up to 20 years and will attenuate only a small fraction of the ...
K.S. Shah, M.R. Squillante, G. Entine
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New concepts for scintillator/HgI/sub 2/ gamma ray spectroscopy
IEEE Transactions on Nuclear Science, 1994The construction of a high energy resolution gamma ray detector consisting of a scintillator/mercuric iodide photodetector combination has been investigated. Several HgI/sub 2/ photodetectors have been fabricated and tested with standard NIM electronics.
Y.J. Wang, J.S. Iwanczyk, B.E. Patt
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Stoichiometry and electrical charge transport in HgI 2 crystals
Journal of Crystal Growth, 1991Abstract Stoichiometry of vapor-grown HgI 2 (mercuric iodide) crystals has been studied quantitatively using Raman spectroscopy and liquid solution spectrophotometry. Evaluation of mercury excess is based on differentiation between the Raman spectra of HgI 2 and Hg 2 I 2 (mercurous iodide). Iodine excess is determined by dynamic dissolution of HgI
H. Hermon +4 more
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