Copper Halides CuCl Research Articles

Comment on “Structural, electronic, elastic, optical and thermodynamic properties of copper halides CuCl, CuBr and their ternary alloys CuCl1−xBrx (0.0 ≤ x ≤ 1.0) using full-potential linear muffin-tin orbital (FP-LMTO) method”[Optik 127 (2016) 4559–4573

Kamel et al. (2016) [1] have recently published a paper in Optik 127 (2016) 4559–4573. They have studied several interesting properties, such as: structural, elastic, electronic, optical and thermodynamic properties of copper halides (CuCl, CuBr and their ternary alloys CuCl1−xBrx (0.0≤x≤1.0)) using full-potential linear muffin-tin orbital (FP-LMTO) method. After carefully reading the paper of Kamel et al. (2016), it is observed that the algebraic values of the longitudinal (vl), transverse (vt) and average (vm) wave velocities, and also that of the Debye temperature θD, of CuX (X=Cl, Br) binary compounds obtained in the paper Kamel et al. (2016) [1] are not correctly calculated. Although this mistake has no influence on the conclusion of the paper Kamel et al. (2016) [1], I think, that is better to correct the numerical values of the previous quantities, which can be reused in the future by other researchers, perhaps for comparison or for other object.In the present work, I recalculate the correct numerical values of the longitudinal (vl), transverse (vt) and average (vm) wave velocities, and the Debye temperature θD, of CuX (X=Cl, Br) compounds, using the lattice parameters and the elastic moduli obtained in the original work of Kamel et al. (2016) [1].

Structural, electronic, elastic, optical and thermodynamic properties of copper halides CuCl, CuBr and their ternary alloys CuCl1−xBrx (0.0 ≤ x ≤ 1.0) using full-potential linear muffin-tin orbital (FP-LMTO) method

The structural, electronic, elastic, and thermodynamic properties of alloy CuCl1−xBrx in B3 (zinc blend) phase are investigated to investigate the effect of substitution of Br in CuCl in the range 0≤x≤1. For this purpose, first-principal calculations are used via the full-potential linear muffin-tin orbital (FP-LMTO). The exchange and correlation energy is described in the generalized gradient approximation (GGA). The effect of composition on lattice constant, bulk modulus and band gap is investigated. The concentration dependence of the electronic band structure and the direct-indirect band gap structures are also investigated. Using the approach of Zunger and co-workers, the microscopic origins of band gap bowing parameter have been interpreted. The refractive index, electron (hole) and valence effective masses are also calculated. Furthermore, thermodynamic stability of CuCl1−xBrx ternary alloys is studied by calculating the excess enthalpy of mixing ΔHm as well as the phase diagram.

Electronic structure of copper halides CuI and CuCl: A comparative X-Ray photoelectron and absorption spectroscopy study

The energy distributions of the occupied and unoccupied electronic states for copper halides CuCl and CuI have been investigated using X-ray photoemission and absorption spectroscopy with a highenergy resolution on the equipment of the Russian-German beamline for outlet and monochromatization of synchrotron radiation from the electron storage ring BESSY II. A quasi-molecular analysis of the obtained experimental spectra has revealed that there is a fundamental similarity of the energy structures of the valence band and the conduction band of copper halides CuX (X = Cl, I) due to the identical atomic structure of the studied compounds. The differences in the positions of individual energy subbands in the valence band and the conduction band of CuX and in their intensities in the spectra are associated with different degrees of hybridization of the Cu 3d, 4s and X(n + 1)s, np valence states, as well as with different sizes of structural units (CuCl4 and CuI4 quasi-molecules) of the studied crystals.

Electronic structure of the copper halides CuCl, CuBr and Cul

The electronic bands structure and density of states of zinc-blende CuCl, CuBr and CuI have been computed using the tight-binding method. These band structures have been used to calculate the valence and conduction band effective masses. The results are compared with other calculated and experimental values.

Mechanism of CuCl and CuO chemiluminescence in microwave-induced plasma afterglows at 300 K

The sublimation of the copper halides CuCl or CuCl2 in microwave-induced plasma afterglows results in the chemiluminescence of CuCl at 300 K. In O2–He afterglows the A, B, C, D, E and F transitions up from v′= 3 are observed, while H2–He afterglows are much less effective, showing only A and B transitions. In addition, a weak chemiluminescence of CuO is detected in O2–He afterglows. Various chemiluminescence mechanisms are discussed, from which it appears that the termolecular recombination of hydrogen or oxygen atoms, with CuCl or CuO acting as a third body, is the most plausible chemiexcitation mechanism.

Interdependence of buffer gas pressure and optimum interpulse delay in a burst-mode copper halide laser

The variation of the laser output energy of a 100 pulse burst with interpulse delay has been studied for each of the copper halides CuCl, CuBr, and CuI as a function of the tube temperature and of the buffer gas pressure for helium and neon. The tube bore was 12 mm and the specific discharge energy was 3.8 mJ ċ cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> . For CuI, the optimum interpulse delay decreases with increase in tube temperature and with decrease in the buffer gas pressure. At each temperature and pressure the optimum interpulse delay is shorter for helium than for neon. Although the formation of the laser pulse is intimately connected with the mechanism of breakdown in the discharge tube, the effect of this mechanism on the optimum interpulse delay is small and the latter is determined mainly by the dissociation-recombination cycle of the copper halide. The increase in optimum interpulse delay with buffer gas pressure suggests that either collisions with halogen atoms or molecules or superelastic electron collisions are responsible for the decay of the population of the metastable copper atoms.

A copper vapour laser operating at room temperature

Laser action on the 5106 and 5782 Å lines of neutral copper has been achieved at temperatures from 20 to 140°C in the vapour of copper acetylacetonate, and at temperatures between 150 and 215°C in the vapour of copper nitrate. The peak output powers are compared with those obtained in the vapours of the copper halides CuCl, CuBr and CuI using the same longitudinal discharge operated in a double-pulse mode in low pressure argon. The highest peak power from copper acetylacetonate obtained to date is 5 kW at a temperature of 40°C. The optimum temperature for the nitrate is 180°C at which the peak output power is 20 kW. The halides can give pulses of 50 kW although the temperatures required are much higher. For the acetylacetonate and the nitrate it is necessary to purge the gas mixture of dissociation products by flowing the argon through the discharge tube. It is probable that the resulting reduction in copper density is partly responsible for the poorer performance observed to date with these vapours. Optimum argon pressures and delay times between the two pulses of discharge current were approximately the same for all the copper compounds tested.

Charged excitons in semiconductors

It is shown that there may exist stable three-particle bound states—the charged excitons—for all values of the effective-mass ratio. The full band structure and the electron-hole exchange interaction are taken into account. In a first step, we restrict ourselves to the case of the copper halides CuCl and CuBr, in which the most stable charged-exciton states are expected.

Far Infrared Study of the Copper Halides at Low Temperatures

The far infrared spectra of the copper halides CuCl, CuBr, and Cul have been measured in transmission and in reflection at various fixed temperatures from room temperature to liquid-helium temperature. Marked changes of such parameters as resonance frquency and damping as a function of temperature have been observed, also a line-splitting in the case of CuCl. In addition, a considerable increase in the asymmetry of the transmission curves with decreasing temperature has been observed.