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Journal of Thermal Analysis and Calorimetry
Authors: M. Daviti, K. Chrissafis, K. Paraskevopoulos, E. Polychroniadis, and T. Spassov

Abstract  

The kinetics of the α-β phase transition of HgI2 were investigated by isothermal and non-isothermal differential scanning calorimetry. The effective activation energy of the transition, 41540 kJ mol-1, was determined applying the methods of Kissinger and Ozawa. The transition kinetics were described by the Johnson-Mehl-Avrami model and the value of the Avrami exponent n was found to range from high values (n>3) at the early stages to lower values at later stages of the transformation, with an average value of 2.

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A differential scanning calorimetric study on phase transformations of HgI2

II. The dependence of stoichiometry on the α toβ transformation temperature

Journal of Thermal Analysis and Calorimetry
Authors: S. N. Toubektsis, E. K. Polychroniadis, and C. A. Alexiades

The influence of stoichiometry on the mercuric iodideα toβ transformation temperature was studied in a limited region around the exact stoichiometry. It is concluded that although this influence is small, the transformation temperature has its highest value at the exact stoichiometry composition.

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A differential scanning calorimetric study on phase transformations of HgI2

I The parameters that influence the α- to Β-phase transition

Journal of Thermal Analysis and Calorimetry
Authors: S. Toubektsis and E. Polychroniadis
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Abstract  

The comparison of an ambient temperature mercuric iodide spectrometer (HgI2) with a conventional cooled Si(Li) spectrometer is presented for the determination of niobium in Venezuelan laterites in the laboratory. The energy resolution of the HgI2 spectrometer was only about 590 eV (FWHM) at 5.9 keV compared to about 150 eV for the conventional Si(Li) spectrometer. The efficiency was about 5 times lower in the region of the NbK peak as compared to the Si(Li) detector. Even though its energy resolution and efficiency is much poorer than the conventional Si(Li), the results it produced for the determination of niobium were acceptable for use in the exploration and exploitation of a niobium-rich deposit such as Cerro Impacto, Estado Bolívar, Venezuela.

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Abstract  

A new extraction reagent-dibutylester of N-/4-antipyryl/-amidophosphoric acid/DBAAP/—has been developed and used for the extraction of divalent mercury into chloroform from mixture of sodium iodide and perchloric acid. It was found that the composition of the species extracted into the organic phase depends on the acidity of the aqueous phase. The solvate HgI2. DBAAP is extracted at low HClO4 concentrations, an ion-pair, /DBAAPH/+.HgI 3 , is formed and extracted at high concentrations of perchloric acid.

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Abstract  

We report on the design, construction, and testing of a gamma-ray imaging system with spectroscopic capabilities. The imaging system consists of an orthogonal strip detector made from either HgI2 or CdZnTe crystals. The detectors utilize an 8×8 orthogonal strip configuration with 64 effective pixels. Both HgI2 or CdZnTe detectors are 1 cm2 devices with a strip pitch of approximately 1.2 mm (producing pixels of 1.2 mm × 1.2 mm). The readout electronics consist of parallel channels of preamplifier, shaping amplifier, discriminators, and peak sensing ADC. The preamplifiers are configured in hybrid technology, and the rest of the electronics are implemented in NIM and CAMAC with control via a Power Macintosh computer. The software used to readout the instrument is capable of performing intensity measurements as well as spectroscopy on all 64 pixels of the device. We report on the performance of the system imaging gamma-rays in the 20–500 keV energy range and using a pin-hole collimator to form the image.

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Abstract  

The possibility to use the monoionic Ag+-form (eventually Hg+- and Hg2+- forms) of clinoptilolite of domestic origin for radioactive iodide elimination from waters has been studied. The capacity of the monoforms of clinoptilolite towards iodide exceeds many times that of the capacity of clinoptilolite in natural form. Due to the low solubility product of AgI, Hg2I2 and HgI2 iodides generate precipitates on the zeolite surface. Rtg analyses of the silver form of clinoptilolite after sorption of iodide demonstrate the formation of new crystals on the zeolite surface. The influence of interfering anions on the adsorption capacity of silver clinoptilolite towards iodide was investigated, too. Kinetic curves of iodide desorption from the surface of silver and mercury clinoptilolite were compared. Simultaneously, adsorption isotherms for the systems aqueous iodide solution/Ag, Hg-clinoptilolite were determined.

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Journal of Thermal Analysis and Calorimetry
Authors: Peer Schmidt, Michael Schöneich, Melanie Bawohl, Tom Nilges, and Richard Weihrich

. Phase formation: mercury(II) iodide—HgI 2 As a last part of our investigations, the measurement characteristics of the HTGB should be used for a more complex experiment. In contrast to standard thermogravimetric measurements in an open system

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