Distribution Of Ni2 Research Articles

Microreactor facilitated preparation and Ni-doping of MnO2 nanoparticles for supercapacitors

Clustered countercurrent-flow micro-channel reactors (C-CFMCR) with varying magnification times were applied for the preparation of Ni-doped manganese dioxide (Ni-MnO2) via co-precipitation processes. Effects of the feeding flow rate of reactants and the concentration of the doping agent on the doping processes were investigated. The C-CFMCR, which is of intensified micromixing efficiency as compared with conventional stirred reactors (STR), played a crucial role in facilitating the uniform nucleation and growth of MnO2 crystals and then the doping of Ni. As a result, the prepared Ni-MnO2 had a decreased particle size and a more uniform microporous structure. EDS analysis showed an even distribution of Ni2+ within the nanocomposites and thus enhanced electrochemical performance of the MnO2 composite materials as supercapacitor electrodes was achieved. The 1.0 at% Ni-MnO2 nanocomposites prepared under optimal conditions exhibited the highest specific capacitance of ~ 389.6 F g−1 at a current density of 1 A g−1 and showed excellent cycling stability with 79.3% retention of the initial capacitance after 5000 charge/discharge cycles in 2 M KOH aqueous solution. The as-assembled Ni-MnO2//activated carbon (AC) asymmetric supercapacitor displayed a wide operating voltage (0–1.6 V), high energy and power densities (13.3 W h kg−1 and 187.52 W kg−1 at 0.25 A g−1, respectively), and a stable cycling behavior (83.8% capacitance retention after 1000 cycles at 1 A g−1). In addition, only a weak scaling-up effect of C-CFMCR on the co-precipitation process was observed, suggesting that C-CFMCR is a prospective technique for the continuous and large-scale production of nanoparticles.

Kinetics and mechanism of formation of nickel(II)porphyrin and its interaction with DNA in aqueous medium.

Graphic abstractKinetics between 5,10,15,20-tetrakis(N-methylpyridium-4-yl)porphyrin and Ni2+ species were investigated in aqueous solution at 25 ±1 °C in I = 0.10 M (NaNO3). Speciation of Ni2+ was done in I = 0.10 M (NaNO3) for knowing distribution of Ni2+ species with solution pH. Experimental data were compared with speciation diagram constructed from the values of hydrolysis constants of Ni2+ ion. Speciation data showed that hexaaquanickel(II) ions took place in hydrolysis reactions through formation of [Ni(OH2)6-n(OH)n]2-n species with solution pH. According to speciation of Ni2+ and pH dependent rate constants, rate expression can be written as: d[Ni(TMPyP)4+]/dt = (k1[Ni2+(aq)] + k2[Ni(OH)+(aq)] + k3[Ni(OH)2o(aq)] + k4[Ni(OH)3-(aq)])[H2TMPyP4+], where k1, k2, k3 and k4 were found to be k1 = (0.62 ± 0.22) × 10-2; k2 = (3.60 ± 0.40) × 10-2; k3 = (2.09 ± 0.52) × 10-2, k4 = (0.53 ± 0.04) × 10-2 M-1s-1 at 25 ±1 °C, respectively. Formation of hydrogen bonding between [Ni(H2O)5(OH)]+ and [H2TMPyP]4+ causes enhanced reactivity. Rate of formation of [Ni(II)TMPyP]4+ complex was to be 3.99 × 10-2 M-1s-1 in I = 0.10 M, NaNO3 (25 ± 1 °C). UV-Vis and fluorescence data suggested that [Ni(II)TMPyP]4+ and [H2(TMPyP)]4+ interact with DNA via outside binding with self-stacking and intercalation, respectively.SYNOPSIS Kinetics of tetrakis(1-methylpyridium-4-yl)porphyrin with Ni2+ were studied in aqueous medium at 25 ±1 °C in I = 0.10 M (NaNO3). Speciation data revealed the stepwise formation of [Ni(H2O)6-n(OH)n]2-n species with solution pH. Kinetic results showed that [Ni(H2O)5(OH)]+ is the most reactive species because of the formation of hydrogen bonding. UV-Vis/fluorescence data suggested that [Ni(II)TMPyP]4+ and [H2TMPyP]4+ interact with DNA via outside binding and intercalation, respectively.Supplementary InformationThe online version contains supplementary material available at 10.1007/s12039-021-01945-y.

Cation distribution of Ni2+ and Mg2+ ions improve structure and Magnetic Properties of Spinel Ferrites

Cation distribution of Ni2+ and Mg2+ ions improve structure and Magnetic Properties of Spinel Ferrites

Multi-phase induced ultra-broad 1100-2100 nm emission of Ni2+ in nano-glass composites containing hybrid ZnGa2O4 and ZnF2 nanocrystals

A new type of Ni2+-doped dual-phase glass ceramics (GCs) is developed by a simple one-step thermal-induced crystallization process. The GCs thus obtained are embedded simultaneously with hybrid ZnGa2O4 and ZnF2 nanocrystals (NCs). When pumped by a readily available 808 nm laser diode, an ultra-broad near-infrared (NIR) emission in a range of 1100−2100 nm is observed at room temperature. The NIR emission band with a full-width-at-half-maximum (FWHM) of more than 450 nm is comparable to the largest value ever reported in Ni2+-doped GCs, and much broader than those of single-phase GCs embedded with either pure ZnGa2O4 or ZnF2 NCs. The microscopic morphologies of the embedded hybrid NCs, and especially the distribution of Ni2+ in the dual-phase GCs are studied by analytical transmission electron microscopy (TEM). The intriguing photoluminescence properties of Ni2+ are thoroughly investigated by steady-state and time-resolved emission spectra. The GCs demonstrated herein hold promise as broadband solid-state NIR-light sources.

Short-range cation and spin ordering in the relaxor ferromagnet La3Ni2SbO9 studied by polarized-neutron scattering and Monte-Carlo methods

Spin-polarised neutron scattering experiments have facilitated the separation of the nuclear and magnetic diffuse scattering from the partially-ordered cation distribution in the perovskite La3Ni2SbO9. The nuclear component of the data collected at 110 and 175 K could be modelled using Monte-Carlo methods when it was assumed that the distribution of Ni2+ and Sb5+ cations over their shared six-coordinate site is that which minimises the repulsive interactions between Sb5+ cations ~5.5 Å apart. Analysis of the diffuse magnetic scattering showed that nearest-neighbour and next-nearest neighbour spins show short-range antiferromagnetic and ferromagnetic coupling, respectively, at 110 K. The former persists to 175 K but the latter weakens with increasing temperature.

Stabilisation of magnetic ordering in La3Ni2-xCuxB’O9 (B’ = Sb, Ta, Nb) by the introduction of Cu2+

La3Ni2-xCuxB’O9 (x = 0.25; B’ = Sb, Ta, Nb: x = 0.5; B’ = Nb) have been synthesized and characterised by transmission electron microscopy, neutron diffraction and magnetometry. Each adopts a perovskite-like structure (space group P21/n) with two crystallographically-distinct six-coordinate sites, one occupied by a disordered arrangement of Ni2+ and Cu2+ and the other by a disordered ∼1:2 distribution of Ni2+ and B′5+, although some Cu2+ is found on the latter site when x = 0.5. Each composition undergoes a magnetic transition in the range 90 ≤ T/K ≤ 130 and shows a spontaneous magnetisation at 5 K; the transition temperature always exceeds that of the x = 0 composition by ≥ 30 K. A long-range ordered G-type ferrimagnetic structure is present in each composition, but small relaxor domains are also present. This contrasts with the pure relaxor and spin-glass behaviour of x = 0, B’ = Ta, Nb, respectively.

The distribution of reactive Ni2+ in 2D Mg2-xNixAl-LDH nanohybrid materials determined by solid state 27Al MAS NMR spectroscopy.

Layered double hydroxides (LDHs), especially (doped) with transition metals, as well as nanohybrid and 2D materials derived from these structures, are interesting materials due to their catalytic and electrochemical properties. Their reactivity is determined by the atomic level distribution of the transition metal in the LDH cation layer, which is essential to control the design of LDHs with optimized properties. However, low crystallinity, absence of long range order, and/or isoelectronic ions often prevent atomic level structural characterization. A series of poorly crystalline Mg2-xNixAl-NO3 LDH materials were investigated by ultrafast 27Al MAS NMR spectroscopy to determine the distribution of Ni2+ in these as well as possible superstructures and their miscibility gaps. Four Ni2Al-LDH samples with interlayer distances ranging from 7.6 to 17.5 Å were prepared to assess the contribution of inter- and intralayer magnetic interactions. The effects of the Ni2+ content and the atomic level distribution of Ni2+ were probed by ultrafast 27Al MAS NMR spectroscopy: the Al distribution can be modeled using a binomial distribution and neither a superstructure was identified for the MgNiAl-LDH sample nor a miscibility gap. The 27Al isotropic shift, δiso(27Al), is a very sensitive probe for a number of neighboring Ni2+ in the first metal ion sphere, but to a smaller degree it is also affected by the intercalated anion (interlayer distance). These results were used for detailed characterization of an exfoliated (2D)-restacked Mg1.83Ni0.17Al-LDH nanohybrid material and a Mg1.83Ni0.17Al-LDH-alginate nanohybrid material, in which 27Al MAS NMR showed how the structure and partial dissolution of the LDHs were retained. In contrast, both powder X-ray diffraction and vibrational spectroscopies (IR and Raman) reflected only the overall change in sample composition.

Magnetic properties of iron oxide-based nanoparticles: Study using Mössbauer spectroscopy with a high velocity resolution and magnetization measurements

We review the results of the study of magnetite, maghemite and nickel ferrite nanoparticles (NPs), applying for magnetic fluids, using Mössbauer spectroscopy with a high velocity resolution and magnetization measurements. The Mössbauer spectra of these NPs were fitted using a large number of magnetic sextets reflecting NPs complicity. The presence of polar molecules at the magnetite surface in magnetic fluid increases the NPs magnetic moment and the median hyperfine magnetic field. However, surface coating of maghemite NPs with dimeracptosuccinic acid decreases the median hyperfine magnetic field. An example of nickel ferrite NPs demonstrated a new physical model based on distribution of Ni2+ in the local microenvironment of Fe3+ which can explain a large number of magnetic sextets in the Mössbauer spectra measured with a high velocity resolution.

A solid solution series of atacamite type Ni2xMg2−2xCl(OH)3

For the first time a complete solid solution series Ni2xMg2−2xCl(OH)3 of an atacamite type alkaline main group metal chloride, Mg2Cl(OH)3, and a transition group metal chloride, Ni2Cl(OH)3, was prepared and characterized by chemical and thermal analysis as well as by Raman and IR spectroscopy, and high resolution laboratory X-ray powder diffraction. All members of the solid solution series crystallize in space group Pnam (62). The main building units of these crystal structures are distorted, edge-linked Ni/MgO4Cl2 and Ni/MgO5Cl octahedra. The distribution of Ni2+- and Mg2+-ions among these two metal-sites within the solid solution series is discussed in detail. The crystallization of the solid solution phases occurs via an intermediate solid solution series, (Ni/Mg)Cl2x(OH)2−2x, with variable Cl: OH ratio up to the 1:3 ratio according to the formula Ni2xMg2−2x Cl(OH)3. For one isolated intermediate solid solution member, Ni0.70Mg0.30Cl0.58(OH)1.42, the formation and crystal structure is presented as well.

Characterization of Nickel Ions in Nickel‐Doped Yttria‐Stabilized Zirconia

The distribution of Ni2+ ions in NiO‐doped 10YSZ powder is examined with Superconducting Quantum Interference Device magnetometry, a technique that is able to distinguish between randomly distributed Ni2+ ions in solid solution and ordered Ni2+ ions within NiO with high precision. Very high purity powders containing 0.01, 0.1, 0.5, and 1.0 mol% NiO in 10YSZ (all levels below the solid solubility limit of NiO in 10YSZ) were made from acetate precursors and a modified EDTA (ethylenediaminetetraacetic acid)‐citrate synthesis method. The powders were calcined in air at either 873 or 1273 K. The 873 K calcination leads to single phase YSZ particles about 10 nm in diameter, and almost all of the NiO dopant exists in complete solid solution. The 1273 K calcination leads to a larger YSZ particle size (55–95 nm), and also to the formation and/or growth of NiO particles, the amount of which depends on the length of time of calcination. Upon sintering the powders in air (1773 K, 1 h), the NiO dissolves back into 10YSZ. The results demonstrate that particle growth during calcination leads to the exsolution of Ni2+ ions to form NiO. This has important implications for the synthesis of NiO‐doped 10YSZ from chemical precursors.

Structures of surface‐ and bulk‐dispersion phases of NiO/Al2O3

AbstractThe structural features of surface‐dispersion and bulk‐dispersion states of NiO on /in γ‐Al2O3 have been studied by x‐ray absorption fine structure (XAFS) in combination with x‐ray diffraction (XRD) and XPS. The results obtained from XRD and XAFS show that surface and bulk dispersions of Ni2+ ions need different conditions and have different diffraction features and different coordination structures. In both the surface‐dispersion phase and the solid solution, Ni2+ ions seem to prefer to keep the coordination mode in NiO, which is quite different from that in the stoichiometric spinel. The Ni/Al intensity ratios of XPS at different etching depths of samples have a maximum and the distribution of Ni2+ ions in the solid solution is not homogeneous. Both it and the coordination features provide evidence of the transition process of dispersing from surface to bulk. Copyright © 2001 John Wiley & Sons, Ltd.

NO adsorption study on the distribution of Ni2 + ions on the various micro-environments of carriers

The decrease of the electron density in the d orbits of Ni2 + ions, resulting from the disturbance of micro-environments in which Ni2+ ions are located, makes the frequency of adsorbed NO shlft higher. The shift degree is determined mainly by the property of the microenvironments. When Ni2+ ions are located onSII,SII(SI) sites of Y zeolite or on the surface of γ-alumina, their NO adsorption gives rise to IR bands at 1 905, 1 900 and 1 855–1 875 cm−1, respectively. The distribution of Ni2+ ions on the various micro-environments of USY zeolite, Al2O3 and MS mixed carrier has also been discussed according to the different frequencies of adsorbed NO, as well as the influence of NiO loading.

Time resolved spectroscopy of Ni2+doped fluoroclorozirconate glasses

Abstract Optical absorption, time resolved luminescence and fluorescence decay measurements of Ni2+-doped fluoroclorozirconate glasses are reported. Time resolved luminescence measurements were taken exciting the samples at different wavelengths. The position of the orange emission band (1T2g(D) → 3A2g(F)) moves to the blue when the excitation is changed to higher energies. For a fixed excitation wavelength, the emission moves also to the blue when the time of measurement after the laser pulse increases. The fluorescence decays are non-exponential and depend of the detection wavelength. They are slower for the shorter detection wavelengths. The results show a distribution of Ni2+ sites with different ‘crystal field’ environments.

ＳＤＳミセル表面に吸着したＮｉ｀２＋´の数分布

ＳＤＳミセル表面に吸着したＮｉ｀２＋´の数分布