Growth of high-perfect mixed K2NixCo1-x(SO4)2·6H2O crystals for fabrication of high-efficiency UV optical filters

Leaching Mechanisms of Industrial Powders of Spent Nickel Metal Hydride Batteries in a Pilot‐Scale Reactor

“…These local chemical analyses confirm the conclusions drawn from XRD analysis that REEs and K have coprecipitated. They also provide evidence of the coprecipitation of nickel and cobalt, probably in the form of double Tutton's salts, such as K 2 Ni(SO 4 ) 2 ⋅ 6 H 2 O, K 2 Co(SO 4 ) 2 ⋅ 6 H 2 O, or K 2 Ni x Co 1− x (SO 4 ) 2 ⋅ 6 H 2 O . The precipitation of nickel could at least partially explain the slow increase in aqueous nickel concentration measured in H 2 SO 4 at pH 3 at 40 °C.…”

“…They also provide evidenceo ft he coprecipitation of nickel and cobalt, probablyi nt he form of double Tutton's salts, such as K 2 Ni(SO 4 ) 2 ·6H 2 O, K 2 Co(SO 4 ) 2 ·6H 2 O, or K 2 Ni x Co 1Àx (SO 4 ) 2 ·6H 2 O. [45][46][47] The precipitation of nickel could at least partially explain the slow increase in aqueous nickel concentration measured in H 2 SO 4 at pH 3at408C. Although it is not possible to determine accurately the precipitate composition due to its complexity,i t is assumed that the precipitates consist of amixture of potassium-lanthanide double sulfates and K 2 Ni x Co 1Àx (SO 4 ) 2 ·6H 2 O.…”

Growth of mixed K2NixCo(1−x)(SO4)2 · 6H2O crystals for large supercooling without spontaneous crystallization in solution

“…In real growth systems, solution stability with respect to spontaneous nucleation depends on many factors, such as the purity of the initial components, temperature stability and the presence of temperature gradients in the growth zone, mechanical effects on the solution, pretreatment of the solution, hydrodynamic conditions, crystallizer device, etc. Growth conditions analysis in our previous works [4,[14][15][16] and some literature data [8,9] showed that temperature and mechanical perturbations have a significant effect on the stability of a solution with respect to spontaneous nucleation. To reduce the influence of these disturbances, we have implemented a growing scheme in which the crystallizer with pretreated solution was installed in a thermostat with a temperature difference across the internal volume of no more than 1°C without forcing the solution to be mixed.…”

The Problem of Formation of Mixed Crystals and High-Efficiency K2(Co, Ni)(SO4)2 • 6H2O Optical Filters

“…Figure 18 shows the experimental data [41] on the distribution of K2Co(SO4)·6H2O over the length of two crystals grown from solutions with component ratios of KCSH:KNSH = 1:2 and 1:1 on (110)-seeds at a rate of 0.8 However, another very strong source of stresses in mixed crystals is the nonstationarity of their composition, which arises in the initial transient regime, when a diffusion boundary layer is formed near the crystal-solution interface [39,40]. The zone of intensive composition variation in KCNSH crystals extends over a distance of 1 to 4 mm from the seed [38,41], depending on the crystal growth rate and the intensity of the solution stirring. The region of the initial transient is increased with decreasing the crystal growth rate and solution stirring intensity [40].…”

“…The region of the initial transient is increased with decreasing the crystal growth rate and solution stirring intensity [40]. Figure 18 shows the experimental data [41] on the distribution of K 2 Co(SO 4 )·6H 2 O over the length of two crystals grown from solutions with component ratios of KCSH:KNSH = 1:2 and 1:1 on (110)-seeds at a rate of 0.8 mm/day. It is possible to compensate for the shift of the crystal composition in the initial transient by adjusting the solution composition.…”