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Saturation of Free Carrier Concentration in Semiconductors
Published in Kazumi Wada, Stella W. Pang, Defects in Optoelectronic Materials, 2021
Although the limitations in the doping levels are most apparent in wide gap materials where, either the conduction or the valence band edge can easily fall outside the band of the allowed Fermi energies, it may also be important in lower or even zero gap semiconductors. Mercury Selenide is an example of a zero-gap semiconductor with a distinct asymmetry in the doping behavior. As is seen in Figure 7 in HgSe the energy of the degenerate conduction and valence band edge is located at the very low energy of EFS − 1.2 eV. This band alignment indicates that for any Fermi energy position incorporation of donors is energetically favored over incorporation of acceptor like defects. Indeed HgSe is always n-type with the lowest reported electron concentration of about 1016 cm-3 [101]. This electron concentration corresponds to a Fermi energy EFS − 1.2 eV, very close to the lower boundary of the allowed Fermi energies. It also explains why the attempts to dope HgSe with acceptors have never been successful.
Signature of precious metal mineralization in hydrocarbon fluids, Central Scotland
Published in Adam Piestrzyński, Mineral Deposits at the Beginning of the 21st Century, 2001
The bright masses of bitumen at Alva contain a variety of mineral inclusions. In addition to quartz (see below), there are also numerous micron-scale inclusions of metallic ore minerals. These include oxides, sulphides and selenides, particularly: Uraninite (Fig. 4);a uranium phase with a consistent content of calcium and silicon, probably uranophane (Fig. 5);cinnabar (HgS) (Fig. 4);tiemannite (HgSe);a copper-mercury selenide;a range of silver-bismuth selenides (Parnell 1988);native bismuth.
Kinetic mechanism of selenium leaching from selenium-rich acid sludge in NaOH solution
Published in Canadian Metallurgical Quarterly, 2023
Xijian Pan, Yan Hong, Tu Hu, Libo Zhang, Kun Yang
According to Table 1, the main elements in the acid sludge are Se and Hg, with 83.98% selenium and 12.99% mercury. It can be seen from Figure 1 that the physical phase of the acid sludge is mainly monolithic selenium and mercury selenide, and the mercury selenide is spherical particles attached to the monolithic selenium.
Leaching of Mercury from Contaminated Solid Waste: A Mini-Review
Published in Mineral Processing and Extractive Metallurgy Review, 2020
Feng Xie, Kaiwei Dong, Wei Wang, Edouard Asselin
Hintelmann and Nguyen (2005) developed an efficient HNO3 extraction method to measure methylmercury (MeHg) in benthic organisms and plant material. The digestion process used 5 mL of 4 M HNO3 at 55°C to leach MeHg from 20 mg of tissue and plant material. The acid digestion resulted in 96 ± 7% recovery of MeHg from oyster tissue and 93 ± 7% from pine needles. Jang et al. (2005) applied a rotary shaking process using different acid solutions to extract mercury from fluorescent lamps. For HCl and HNO3, the extracted mercury fraction seemed to increase with an increase in acid concentration. The mixture of HNO3 and HCl exhibited higher mercury extraction than HNO3 alone. The mercury extraction increased sharply to about 35% when 5% of the mixed acid solution was used. Above 5%, the maximum extraction was 36% for the mixed acid and 28% for the nitric acid only. Rey-Raap and Gallardo (2013) also examined the feasibility of using mixtures of HCl and HNO3 to remove mercury bound in residual glass from spent fluorescent lamps. Under optimized conditions, more than 69% mercury was removed from the waste glass. These authors believed that because HCl reacted easily with divalent mercury, the acidic solution not only removed the mercury in the phosphorous powder attached to the surface of the glass but also the mercury that had diffused through the glass matrix (Rey-Raap and Gallardo 2013). Al-Ghouti et al. (2016) investigated mercury removal from a phosphorous powder with HNO3 and HCl with and without microwave. Microwave almost doubled the amount of mercury leached (76%) compared to acid alone. Zhou and Dreisinger (2017) used hypochlorite to leach elemental mercury. The process consisted of extraction of elemental mercury into solution to form aqueous mercury (II), then mercury precipitation as mercury sulfide or mercury selenide. Elemental mercury could be effectively extracted with hypochlorite in acid to form aqueous mercury (II) chloride. Near complete extraction could be achieved within 8 h by using excess sodium hypochlorite at pH 4 and 1,000 rpm.