The stability of aqueous nickel(II) chloride complexes in hydrothermal solutions: Results of UV–Visible spectroscopic experiments

Design Criteria, Operating Conditions, and Nickel–Iron Hydroxide Catalyst Materials for Selective Seawater Electrolysis

“…Indeed, under seawater conditions, some of the water ligands can be replaced by chloride ligands. It has been shown that in acidic conditions and room temperature the hexa‐aqua nickel is the dominant species and the octahedral [Ni(H 2 O) 5 Cl] + is the only significant chloro‐complex formed . Other complexations, like the octahedral NiCl 2(aq) or the tetrahedral NiCl 3 − and NiCl 4 2− , become relevant only at higher temperatures (i.e., 100–200 °C and higher) or in chloride concentrations higher than 0.5 m .…”

Trace Element Geochemistry of Magnetite and Its Relationship to Cu-Bi-Co-Au-Ag-U-W Mineralization in the Great Bear Magmatic Zone, NWT, Canada

“…Experimental studies indicate that full stability of the chlorinated Co tetrahedral complexes in aqueous solutions is reached at lower temperatures (250°C) than those of Ni (Liu et al, 2011;Tian et al, 2012). Liu et al (2012) obtained similar results by comparing the dissolution of pentlandite and Co pentlandite in saline aqueous solutions, where the solubility of the latter is at least 100× greater than that of pentlandite. This behavior of Co and Ni may explain why Ni-rich hydrothermal deposits are scarce compared to hydrothermal Co-rich deposits .…”

“…Despite this, and in the absence of suitable evidence suggesting otherwise, these deviations between the host rocks and magnetite ratio values could reflect the chemistry of the magnetite-depositing fluids. However, the coprecipitation of sulfides and magnetite is an important factor that limits our ability to characterize the geochemistry of the Fe-bearing fluids based only on the trace element contents in magnetite (see section below), although recent studies on the solubility of Co and Ni provide insights into the relative abundance of these metals in hydrothermal fluids (e.g., Liu et al, 2011Liu et al, , 2012Migdisov et al, 2011;Tian et al, 2012). In this section, we discuss the partitioning of Co and Ni in magnetite from Sue-Dianne and Damp as a function of fluid geochemistry using the Co/Ni ratio as a proxy.…”

Synthesis, characterization, in vitro bioactivity and antimicrobial activity of magnesium and nickel doped silicate hydroxyapatite

“…The intensity of the absorption band of the 3 A 2g -3 T 1g (P) transition increased slightly with the increase in the Ni 2 þ concentration, which also resulted in the shifting of peaks towards higher wavelength (red-shift) from 425 nm to 500 nm for 1Ni-Mg-SiHA and Ni-SiHA respectively (Fig. 5) [53]. The observed red-shift in the absorption band edge with Ni 2 þ doping in Mg-SiHA was assigned to the possible accelerated sp-d orbital exchange interaction between the band and localized d-electrons of Ni 2 þ ions [54,55].…”

“…5) [50,51]. The peak at 1197 nm was attributed to the 3 A 2g (F)-3 T 2g (F) in the infra-red region, whereas the peak at 743 nm and shoulder at around 666 nm were due to the 3 A 2g (F)-3 T 1g (F) transition, this transition could be attributed to Spin-orbit coupling that mixes the 3 T 1g (F) and 1 E g states [52,53]. The peak observed at around 400 nm was assigned to the most energetic transition, 3 A 2g (F)-3 T 1g (P).…”