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Journal articles on the topic 'Ni valence'

Author: Grafiati

Published: 25 May 2024

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1

KUMARI, KAMLESH, R. K. SINGHAL, K. B. GARG, M. HEINONEN, J. LEIRO, PER NORBLAD, and L. C. GUPTA. "A COMPREHENSIVE STUDY OF THE ELECTRONIC STRUCTURE OF BOROCARBIDES BY XPS TECHNIQUE." International Journal of Modern Physics B 17, no. 03 (January 30, 2003): 361–71. http://dx.doi.org/10.1142/s0217979203015772.

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Polycrystalline samples of YNi 2 B 2 C and magnetic ErNi 2 B 2 C prepared by arc melting technique have been investigated. Resistivity and magnetization measurements yield superconducting transition temperatures for the two samples of ~ 15 K and ~ 11 K respectively. Core level spectroscopic studies on C (1s), B (1s), Ni (2p), Er (4d) and Y (3d) as well as valence band measurements were performed in order to investigate the electronic structure. The results are interpreted to deduce the valence of Y, Er and Ni. Ni is found to exist in 2+ and y in 3+ valence state. The Er spectra indicate that Er may either be in an intermediate valence state or some minor impurity phase.

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2

Hsu, Li-Shing, K. L. Tsang, and S. C. Chung. "Resonant Valence-Band Satellites at the Ni-3p Edge of Ni3Al, Ni3Ga and Ni3In." International Journal of Modern Physics B 12, no. 26 (October 20, 1998): 2757–67. http://dx.doi.org/10.1142/s0217979298001605.

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Valence-band photoemission sspectra of Ni 3 Al , Ni 3 Ga and Ni 3 In were measured with synchrotron radiation at photon energies around the Ni-3p core excitation threshold. The valence-band satellites are resonantly enhanced. The number of holes per Ni atom in the Ni-d band for Ni 3 Al , Ni 3 Ga and Ni 3 In is estimated to be 0.37, 0.30 and 0.34, respectively. The self-energy correction due to the configuration interaction is 0.72, 0.71 and 0.72 eV, respectively, for Ni 3 Al , Ni 3 Ga and Ni 3 In . The Fano parameters and the effective Coulomb interactions between two 3D holes for these intermetallic compounds are determined.

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3

Hacisalihoglu, M. Y., L. Tortora, G. Tomassucci, L. Simonelli, and N. L. Saini. "Anisotropic Local Structure of SrFe2−xNixAs2 (x = 0.00, 0.16, and 0.23) Superconductor Probed by Polarized X-ray Absorption Fine Structure Measurements." Materials 17, no. 6 (March 11, 2024): 1301. http://dx.doi.org/10.3390/ma17061301.

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We have investigated the effect of the Ni substitution on the local structure and the valence electronic states of the SrFe2−xNixAs2 (x = 0.00, 0.16, and 0.23) superconductor with a multi-edge extended X-ray absorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES) spectroscopy. The As K-edge and Fe K-edge EXAFS measurements in the two polarizations (E‖ab and E‖c) show a clear change in the local structure with Ni concentration. The near-neighbor bondlengths and the related mean-square relative displacements (MSRDs) decrease as the Ni content increases. The polarized XANES spectra at the As, Fe and Ni K edges reveal a systematic change in the anisotropy of the valence electronic structure. The results suggest that the quasi 2D electronic structure of this system tends to become more isotropic as the Ni content increases. The local structure and the valence electronic states are discussed in the frame of the evolving electronic transport of the SrFe2−xNixAs2 system.

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4

Liqing, Chen, Liu Zuqin, and Zhang Wei. "Valence state analysis of elements by EPMA and its application." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 2 (August 12, 1990): 230–31. http://dx.doi.org/10.1017/s0424820100134752.

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Valence state analyses of Fe and Mn in oxides by EPMA have been reported in literature. In this paper, the effects of valence state on intensity ratios ILα/IKα and ILα/ILβ of Cu, Ni, Co, Fe, Mn, Cr and their oxides, and on intensity ratios ILβ2/ILα1 and ILγ1/ILα1 of Mo, Nb, Zr and their oxides were studied. It was observed that intensity ratios change with valence states in accordance with some regularities, and these effects could be utilized for analyzing the valence states of catalysts.Valence state analysis of elements by EPMA is based on the fact that changes in the states of valence electrons in the outer shells of an atom cause corresponding changes in line intensities. The M electrons of Cu, Ni, Co, Fe, Mn, Cr and the N electrons of Mo, Nb, Zr are valence electrons. Line Kα1,2 and six lines of L are produced from the transitions of K-L2,3 and L-M or L-N respectively.

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5

Hatakeyama, Makoto, Yuki Sakamoto, Koji Ogata, Yuto Sumida, Tomoe Sumida, Takamitsu Hosoya, and Shinichiro Nakamura. "A study on an unusual SN2 mechanism in the methylation of benzyne through nickel-complexation." Phys. Chem. Chem. Phys. 19, no. 39 (2017): 26926–33. http://dx.doi.org/10.1039/c7cp04739h.

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6

D'Souza, S. W., R. S. Dhaka, Abhishek Rai, M. Maniraj, J. Nayak, Sanjay Singh, D. L. Schlagel, T. A. Lograsso, Aparna Chakrabarti, and S. R. Barman. "Surface Study of Ni₂MnGa(100)." Materials Science Forum 684 (May 2011): 215–30. http://dx.doi.org/10.4028/www.scientific.net/msf.684.215.

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The (100) surface of Ni2MnGa ferromagnetic shape memory alloy exhibits intrinsic surface property dissimilar to the bulk as well as influence of compositional variation at the surface. It is shown that by sputtering at room temperature and annealing at high temperature, it is possible to obtain a clean, ordered and stoichiometric surface. However, for even higher annealing temperatures, the surface becomes Mn rich. The (100) surface of Ni2MnGa is found to have Mn–Ga termination. A surface reconstruction to p4gm symmetry is observed in the austenite phase, while the expected bulk truncated symmetry at surface is p4mm. For the stoichiometric surface, the XPS valence band is compared with our calculations based on first principles density functional theory and good agreement is obtained. The ultraviolet photoelectron spectroscopy (UPS) valence band spectra depend sensitively on composition varying from Ni rich to Mn rich surfaces. A satellite feature observed in both Ni 2p core-level and valence band spectra is related to the narrow 3d valence band in Ni2MnGa.

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7

Vereshchagin, Oleg, Olga Frank-Kamenetskaya, and Ira Rozhdestvenskaya. "Bond valence constraints on the composition of 3d-elements bearing tourmalines." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C1118. http://dx.doi.org/10.1107/s2053273314088810.

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F.C. Hawthorne (2002) and F. Bosi (2011) showed that bond valence approach is to be applied to stability prediction of tourmaline structure with different chemical composition. Using this approach we considered bond valence constraints on occupation of Y, Z, V and W sites of Cu-, Ni-bearing tourmalines. From the standpoint of the bond valence approach, [3YW] unit is unstable if W site is fully occupied by O2-. The stability of [3YW] unit decreases along a row: 3 divalent cations → 2 divalent cations + 1 trivalent cation → 2 trivalent cation + 1 divalent cations → 3 trivalent cations if W site is fully occupied by OH- or F-. There is no limitation on 3d elements and aluminum content in [2ZYV] if V site is fully occupied by OH-. The [2ZYV] unit is unstable if V site is fully occupied by O2-. The data, obtained from calculation of bond valences are in a good agreement with results of single crystal structure refinements of synthetic Cu- (Ertl et al., 2013) and Ni-tourmalines: Cu-bearing olenite with a CuO content of 8.39 wt.% [a = 15.849(1), c =7.087(1) Å, R = 2.5%] and Ni-bearing olenite with a NiO content of 18.96 wt.% [a = 15.890(2), c = 7.1815(8), R = 3.1%]. In all cases W and V sites are predominantly occupied by OH- anions. The composition of [3YW] units are [(Cu1.80Al1.20)(OH)0.60F0.40] and [(Ni1.80Al1.20)(OH)1.00]. Breaking of charge balance with increasing of bivalent cations is maintained by increasing of portion of vacancies at X site and increasing of content of trivalent cations (Al, B) at T site.

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8

HAGIWARA, M., and K. KATSUMATA. "OBSERVATION OF FRACTIONAL SPIN DEGREES OF FREEDOM IN AN S=1 LINEAR CHAIN HEISENBERG ANTIFERROMAGNET." Modern Physics Letters B 05, no. 11 (May 10, 1991): 741–46. http://dx.doi.org/10.1142/s0217984991000915.

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We have studied the typical spin one linear chain Heisenberg antiferromagnet, Ni ( C 2 H 8 N 2)2 NO 2( ClO 4) containing a small amount of Cu2+ by electron spin resonance (ESR) technique. The ESR results are successfully explained by the model that the valence bonds in the valence bond solid state are broken at the Cu 2+ sites resulting in fractional spin degrees of freedom at the Ni 2+ sites neighboring the Cu 2+.

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9

MUN, B. S., M. WATANABE, M. ROSSI, V. STAMENKOVIC, N. M. MARKOVIC, and P. N. ROSS. "THE STUDY OF SURFACE SEGREGATION, STRUCTURE, AND VALENCE BAND DENSITY OF STATES OF Pt3Ni(100), (110), AND (111) CRYSTALS." Surface Review and Letters 13, no. 05 (October 2006): 697–702. http://dx.doi.org/10.1142/s0218625x06008682.

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The surface segregation, structure, and valence band density of states of Pt 3 Ni (100), (110), and (111) single crystals are characterized with low energy ion scattering (LEIS), low energy electron diffraction (LEED), and ultraviolet photoemission spectroscopy (UPS). The results of LEIS clearly reveal the complete surface segregation of Pt to the top layer on all crystal alloys. LEED indicates the (5 × 1) surface reconstruction on the Pt 3 Ni (100), while (110) and (111) surfaces show (2 × 1) and (1 × 1) patterns, respectively, identical to Pt single crystals. The valence bands density of states on Pt 3 Ni alloys are compared to those of Pt single crystals via UPS measurements.

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10

Wang, Shuli, Xudong Yang, Zong Liu, Dawen Yang, and Ligang Feng. "Efficient nanointerface hybridization in a nickel/cobalt oxide nanorod bundle structure for urea electrolysis." Nanoscale 12, no. 19 (2020): 10827–33. http://dx.doi.org/10.1039/d0nr01386b.

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Efficient Ni valence state synergism was found active in the electrocatalysis reaction, resulting from the crystal lattice hybridization in the interface of Ni/Co oxide nanoparticles assembled as a nanorod bundle structure.

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11

Kakizaki, Akito. "Spin-resolved photoemission of ferromagnetic Ni valence band." Journal of Electron Spectroscopy and Related Phenomena 88-91 (March 1998): 163–70. http://dx.doi.org/10.1016/s0368-2048(97)00108-4.

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12

Paolucci, G., R. Rosei, K. C. Prince, and A. M. Bradshaw. "Valence levels of the carbided Ni(110) surface." Applications of Surface Science 22-23 (May 1985): 582–89. http://dx.doi.org/10.1016/0378-5963(85)90189-8.

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13

Manohar, Arumugam, Kuppukannu Ramalingam, Kottamalai Karpagavel, and Gabriale Bocelli. "Crystallographic Distances Based Bond Valence Sum (BVS) Analysis on Nickel(II) Complexes Containing Ni-S and Ni-P Bonds." Advanced Materials Research 584 (October 2012): 84–87. http://dx.doi.org/10.4028/www.scientific.net/amr.584.84.

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Bond valence sum (BVS) analysis is used by many researchers to determine the oxidation state of metal ions in solids based on crystallographically determined metal-ligand bond distances. In this paper, bond valence sums (BVS) have been calculated for a series of mixed ligand complexes involving Nickel(II)dithiocarbamates and phosphorous donor ligands. The BVS values are calculated first time for the complexes whose crystal structures have been reported from our laboratory and a few others reported from other laboratories. The calculated values show that the BVS values are higher than the expected formal oxidation state of +2. The higher values observed in the complexes support the fact that the Ni-S, Ni-P bonds are more covalent and the back bonding effects are very highly pronounced.

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14

TAN, SHUYONG, XUHAI ZHANG, RUI ZHEN, LEI ZHANG, ZENG TIAN, ZHIXIN BA, and ZHANGZHONG WANG. "STUDY ON THE RELATIONSHIP BETWEEN VALENCE ELECTRON STRUCTURE AND COATING ORIENTED GROWTH." Surface Review and Letters 22, no. 03 (May 13, 2015): 1550039. http://dx.doi.org/10.1142/s0218625x15500390.

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The coating oriented growth has attracted great attention because of its effect on coating properties. In this paper, the valence electron structures of TiN and Ni were calculated with the empirical electron theory (EET) in solid and molecules for investigating preferred orientation of nitride coatings containing Ni . The calculation results show that Ni (111), CrN (100) and TiN (100) are the maximum crystal-face electron density, respectively. In CrN (or TiN ) coatings, if Ni does not form a single nickel phase, CrN (100) (or TiN (100)) preferred orientation appears easily due to its high crystal-face electron density. When Ni exists as a single phase, CrN (100)/ Ni (111) (or TiN (100)/ Ni (111)) with the minimum crystal-face electron density difference is the most likely to appear in the coatings. Furthermore, high crystal-face electron density difference usually implies fine grain microstructure. The calculation results are consistent with the experimental results.

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15

Su, Hang, Xiao-Tong Wang, Jing-Xiao Hu, Ting Ouyang, Kang Xiao, and Zhao-Qing Liu. "Co–Mn spinel supported self-catalysis induced N-doped carbon nanotubes with high efficiency electron transport channels for zinc–air batteries." Journal of Materials Chemistry A 7, no. 39 (2019): 22307–13. http://dx.doi.org/10.1039/c9ta08064c.

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The optimized CoMn₂O₄/NCNTs@Ni with high valence Mn^3.4+ as the catalytic site center, combined with the spinel-NCNTs-Ni electron transport channels jointly promote the electrocatalytic activity and successfully applied in zinc–air battery.

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16

Hamaguchi, Tomohiko, Ryo Kuraoka, Takumi Yamamoto, Naoya Takagi, Isao Ando, and Satoshi Kawata. "Synthesis and Characterization of Dithiooxamidate-Bridged Polynuclear Ni Complexes." Chemistry 5, no. 4 (October 18, 2023): 2246–56. http://dx.doi.org/10.3390/chemistry5040150.

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Mixed-valence complexes contain two metals with different formal oxidation numbers and, therefore, show mixed properties that are influenced by the electronic coupling between the two metals, which is, in turn, regulated by a bridging ligand. This is an attractive point for many researchers. Oxalate is widely used as a bridging ligand for preparing polynuclear complexes. More than 1000 complexes have been reported until now. However, dithiooxamidate, which is an oxalate analog, is less popular as a bridging ligand. Here, a new dithiooxamidate-bridged Ni-diphosphine dinuclear complex with the formula [(μ2-toxa){Ni(dppe)}2](BF4)2 (toxa = dithiooxamidate; dppe = 1,2-bis(diphenylphosphino)ethane) was prepared and characterized via single-crystal X-ray diffraction. When using 1,3-bis(diphenylphosphino)propane (dppp) instead of dppe, dinuclear, trinuclear, and tetranuclear complexes were obtained, i.e., [(μ2-toxa){Ni(dppp)}2](BF4)2, [{μ2-Ni(toxa)2}{Ni(dppp)}2](BF4)2, and [{μ3-Ni(toxa)3}{Ni(dppp)}3](BF4)2, respectively. Bidentate toxa ligands in dinuclear complexes coordinate each Ni atom as κ(S,N). However, the trinuclear and the tetranuclear complexes have the toxa ligands with κ(N,N) and κ(S,S) coordination. The [(μ2-toxa){Ni(dppe)}2](BF4)2 complex undergoes four reversible redox processes, whose analysis via a controlled-potential absorption spectrum reveals the presence of a Ni(II)-Ni(I) mixed-valence state at ∆E1/2 = 0.22 V with a comproportionation constant of 6.1 × 103.

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17

Zhao, Baohuai, Binhang Yan, Zhao Jiang, Siyu Yao, Zongyuan Liu, Qiyuan Wu, Rui Ran, Sanjaya D. Senanayake, Duan Weng, and Jingguang G. Chen. "High selectivity of CO2 hydrogenation to CO by controlling the valence state of nickel using perovskite." Chemical Communications 54, no. 53 (2018): 7354–57. http://dx.doi.org/10.1039/c8cc03829e.

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18

Vereshchagin, Oleg S., Olga V. Frank-Kamenetskaya, and Ira V. Rozhdestvenskaya. "Crystal structure and stability of Ni-rich synthetic tourmaline. Distribution of divalent transition-metal cations over octahedral positions." Mineralogical Magazine 79, no. 4 (August 2015): 997–1006. http://dx.doi.org/10.1180/minmag.2015.079.4.09.

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AbstractThe crystal structure of synthetic Ni-rich tourmaline with a nickel content of 18.96 wt.% NiO (a = 15.890(2), c = 7.1815(8) Å) has been refined to R = 3.1% using single-crystal X-ray diffraction data. It has been shown that Ni is distributed not only over the Y, but also over the Z sites according to the ideal formula Na(Ni22+Al)(Al5Ni2+)(Si6O18)(BO3)3(OH)4. Based on bond valences and charge balance analysis it has been shown that this composition corresponds to the stable disordered member of the solid solution series NaAl3Al6(Si6O18)(BO3)3(O)3(OH) NaNi32+Al6(Si6O18)(BO3)3(OH)4.Taking into consideration available structural data on Me2+ (Ni, Cu, Co, Fe, Mn)-rich tourmalines, cation-size mismatch and bond-valence calculations we assume that there are no structural constraints precluding occurrence of these cations in both octahedral sites. Divalent transitional metal-rich tourmalines have not been found in Nature probably due to the insufficient concentration of these elements in B-rich geological systems.

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19

Zou, Zheng Guang, Yi Wu, Fei Long, Wen Wu Xu, and Dong Ye Yao. "Effects of Mo(Ni) on Valence Electron Structures of TiC/Fe Cermets." Key Engineering Materials 368-372 (February 2008): 1119–22. http://dx.doi.org/10.4028/www.scientific.net/kem.368-372.1119.

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Based on the empirical electron theory (EET) of solids and molecules, the valence electron structures (VESs) of TiC-Mo(Ni)-Fe system were calculated by building proper structure model. The results indicate that additives of Mo and Ni improve the interface conjunction factors of the cermets in different ways. By adding Mo, the VESs of the ceramic phase are improved for the formation of the rim phase (Ti1-xMox)C, which leads to the enhancement of the interface conjunction, while the improvement of the VESs on metal phase by adding Ni is due to the formation of the Fe100-yNiy. Mo and Ni additives increase the interface electron density of cermets, that is, the adding of the Mo and Ni enhance the overlapping grade of the electron cloud on interface and increase the binding energy of the interface, which is propitious to the wettability. The best wettability was found at x=0.5 or y=30.

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20

Yang, Hao, Jian-Lan Liu, Lan-Cheng Zhou, and Xiao-Ming Ren. "Experimental and theoretical investigation of the magnetic and photoconductive nature of a novel two-dimensional, mixed-valence bis(2-thioxo-1,3-dithiole-4,5-dithiolato)nickelate molecular solid." Inorg. Chem. Front. 1, no. 5 (2014): 426–33. http://dx.doi.org/10.1039/c3qi00106g.

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21

Yang, Ting, Kunlin Liu, Tianli Wu, Jizong Zhang, Xuewen Zheng, Chengyang Wang, and Mingming Chen. "Rational valence modulation of bimetallic carbide assisted by defect engineering to enhance polysulfide conversion for lithium–sulfur batteries." Journal of Materials Chemistry A 8, no. 35 (2020): 18032–42. http://dx.doi.org/10.1039/d0ta05927g.

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22

Sun, Chuan, Yun Kai Li, and Lin Jiang. "Valence Electron Theoretical Analysis of Mechanical Properties in Low-Alloy Steel." Materials Science Forum 704-705 (December 2011): 389–94. http://dx.doi.org/10.4028/www.scientific.net/msf.704-705.389.

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The mechanical properties in low-alloy steel are studied systematically from the view of valence electrons using the Empirical Electron Theory in solid and molecules (EET). Two new valence electron structure parameters ρcvand ρlv, which have closely relation with the mechanical properties of alloy steel are summed up according to the basic idea of EET. The values of the two new valence electron structure parameters in carbon steel and alloy steel which contains Cr, Mn, Ni, Si, W and Mo are calculated. The result demonstrates that ρcvhas a very good corresponding relationship with intensity, and ρlvhas a very good corresponding relationship with plasticity. In this note, a quantitative empirical formula between the valence electrons structure and the intensity and plasticity of alloy steel is initially set up. Keywords: EET, valence electron structure, mechanical property, low-alloy steel

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23

Starnberg, H. I., and P. O. Nilsson. "Experimental self-energy corrections to the Ni valence band." Journal of Physics F: Metal Physics 18, no. 11 (November 1988): L247—L250. http://dx.doi.org/10.1088/0305-4608/18/11/001.

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24

Kakizaki, A., K. Ono, K. Tanaka, K. Shimada, and T. Sendohda. "Spin-resolved photoemission of valence-band satellites of Ni." Physical Review B 55, no. 11 (March 15, 1997): 6678–81. http://dx.doi.org/10.1103/physrevb.55.6678.

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25

Aires, F. J. Cadete Santos, A. Howie, and C. A. Walsh. "Valence Loss Electron Spectroscopy of Ni-Al Mixed Oxides." Journal of Solid State Chemistry 106, no. 1 (September 1993): 48–54. http://dx.doi.org/10.1006/jssc.1993.1263.

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26

Pham, M. T., M. F. Maitz, H. Reuther, E. Richter, W. Matz, A. Muecklich, N. Shevchenko, and F. Prokert. "Redox and Electrocatalytic Activity of Ni Ion-Implanted Ti." Journal of Materials Research 19, no. 4 (April 2004): 1249–56. http://dx.doi.org/10.1557/jmr.2004.0162.

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Ni-Ti surface alloy was prepared by ion-implanting Ni into Ti. The surface film was amorphous having a Ni surface content of 10–40 at.%. The material was compared with a Ni-Ti bulk alloy (44.08:55.9) regarding their redox and electrocatalytic behavior in NaOH by cyclic voltammetry. The surface was characterized by x-ray photoelectron spectroscopy, x-ray and electron diffraction, transmission electron microscopy, and atomic force microscopy. The ion-implanted material revealed an enhanced activity toward the redox conversion of Ni(OH)2 ↔ NiOOH and the anodic oxidation of glucose. The effect is discussed considering the enhanced generation of active Ni surface sites from amorphous Ni and the stabilization of higher valence Ni by Ti.

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27

Zheng, Yan-Zhen, Haiyang Ding, Evan Uchaker, Xia Tao, Jian-Feng Chen, Qifeng Zhang, and Guozhong Cao. "Nickel-mediated polyol synthesis of hierarchical V2O5 hollow microspheres with enhanced lithium storage properties." Journal of Materials Chemistry A 3, no. 5 (2015): 1979–85. http://dx.doi.org/10.1039/c4ta05500d.

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Hierarchical Ni–V₂O₅ hollow microspheres, prepared via a template-free Ni-mediated polyol process, have excellent Li storage properties as a Li-ion battery cathode (high capacity (294 mA h g⁻¹), superior cycling stability/rate performance) due to their unique structure and low V valence state.

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28

Abu-Eittah, R. H., M. El-Esawy, N. Ghoneim, and A. T. Aly. "A comparative theoretical study of the electronic structure of some nickel(II) azides, thiocyanates, and isothiocyanates." Canadian Journal of Chemistry 76, no. 7 (July 1, 1998): 1006–14. http://dx.doi.org/10.1139/v98-109.

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The electronic structure, conformation, and molecular orbitals of some nickel(II) azides, thiocyanates, and isothiocyanates have been studied. Three different basis sets: split valence (SV), split valence with six d-Gaussians (SV6D), and double zeta (DZ) sets, were used to find the best ground state for nickel. It has been found that the combination, DZ-3F, gives results closest to the experimental values. The electronic structures of the nickel azides studied were completely different from those of the nickel thiocyanates. On the other hand, the electronic structures of the nickel thiocyanates studied were highly comparable to those of the corresponding nickel isothiocyanates. Molecular orbitals were computed for the complexes studied and the types of electronic transitions expected were identified and discussed.Key words: Ni(II) azides, thiocyanates, and isothiocyanates: ab initio SCF calculations; MO calculations on some Ni(II) complexes; theoretical treatment of some Ni(II) ions and salts; geometry and energetics of some nickel(II) azides, thiocyanates, and isothiocyanates.

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29

Hashemi, T., and A. W. Brinkman. "X-ray photoelectron spectroscopy of nickel manganese oxide thermistors." Journal of Materials Research 7, no. 5 (May 1992): 1278–82. http://dx.doi.org/10.1557/jmr.1992.1278.

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The major problem in the NiMn2O4 system has been the determination of the valencies and the cation distribution between the two sublattices of the inverse spinel structure, in which both manganese and nickel can adopt more than one valence state. X-ray photoelectron spectroscopy (XPS) was used to elucidate the valence distribution of the manganese and nickel ions. The results showed that identification of the three Mn and two Ni species in the nickel manganite phase is possible, enabling the validity of crystal structure configurations, proposed in the literature, to be assessed. A small amount of copper, added as CuO to the system, was found to be present in both monovalent and divalent states, the Cu+ ions inducing the creation of the large amount of tetravalent Mn observed. This led to a larger number of sites for electron hopping, the mechanism of conduction, and consequently the electrical conductivity of the Cu doped material is much higher than the undoped NiMn2O4.

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30

Cader, M. S. R., and F. Aubke. "Hexafluoro antimonates(V) of divalent metals, synthesis and properties." Canadian Journal of Chemistry 67, no. 11 (November 1, 1989): 1700–1707. http://dx.doi.org/10.1139/v89-262.

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Solvolysis of metal(II) fluorosulfates in liquid antimony(V) fluoride according to:[Formula: see text]with M = Sn, Ni, Pd, Cu, or Ag, is found to be a clean, efficient route to the hexafluoro antimonates of the corresponding metals. Two of the compounds reported here display unusual features: Pd(SbF6)2 is, like its fluorosulfate precursor, paramagnetic with the Pd2+ ion in a 3A2g ground state, and an analysis of the ligand field spectrum is presented; Ag(SbF6)2 is, unlike a recently reported paramagnetic, blue, valence isomer, diamagnetic and nearly white in color. Formulation as a mixed valency compound Ag(I)Ag(III)(SbF6)4 is suggested. Low temperature magnetic susceptibility measurements (where appropriate), Raman, and IR data are reported. The hexafluoro antimonates of Ni, Pd, and Cu show antiferromagnetic exchange at very low temperatures. Pd(SbF6)2 shows very weak ferromagnetism below 10 K. Keywords: fluoroantimonates of divalent metals, synthesis and solvolysis in SbF5, vibrational spectra, magnetic susceptibility measurements.

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31

Ney, V., B. Henne, M. de Souza, W. Jantsch, K. M. Johansen, F. Wilhelm, A. Rogalev, and A. Ney. "Valence state, lattice incorporation, and resulting magnetic properties of Ni in Zn/Co-based magnetic oxides." Journal of Applied Physics 133, no. 3 (January 21, 2023): 033904. http://dx.doi.org/10.1063/5.0130731.

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Ni incorporation has been studied in a comprehensive range of Zn/Co-based magnetic oxides to elucidate its valence state and lattice incorporation. The resulting structural and magnetic properties of a range of related types of samples are studied in detail. On the one hand, Ni doping is studied in wurtzite ZnO which is either done by in-diffusion of the Ni into bulk ZnO or by reactive magnetron sputtering for Ni-doped thin films of ZnO. The latter is complemented by Ni and Co codoping of ZnO leading to altered magnetic properties which are then dominated by Co. On the other hand, the [Formula: see text] spinel is codoped with varying amounts of Ni. In the wurtzite oxides, Ni is exclusively found on tetrahedral lattice sites in its formal 2+ oxidation state as deep donor. It behaves as an anisotropic paramagnet, and a limited solubility of Ni below 10% is found. Furthermore, the partial compensation of the antiferromagnetically coupled Co magnetic moments is induced by the Ni due to its smaller magnetic moment. In the [Formula: see text] spinel, Ni is found to be incorporated in its formal 3+ oxidation state on octahedral sites and also couples antiferromagnetically to the Co moments. At low Ni concentrations, this leads to a lifting of the partial magnetic compensation of the antiferromagnetic [Formula: see text] spinel and to ferrimagnetism at higher Ni concentrations. Increasing the Ni concentration even further leads to phase separation of cubic NiO resulting in a structurally less defined, exchange-biased composite magnetic oxide.

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32

Morenzin, J., H. Kietzmann, P. S. Bechthold, G. Ganteför, and W. Eberhardt. "Localization and bandwidth of the 3d-orbitals in magnetic Ni and Co clusters." Pure and Applied Chemistry 72, no. 11 (January 1, 2000): 2149–57. http://dx.doi.org/10.1351/pac200072112149.

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Photoelectron spectra of negatively charged Nin- , Cun-, and Con- clusters are presented. The spectra of the Nin- clusters contain information about the degree of localization of the 3d valence orbitals, which is strongly related to the magnetic properties. In the clusters with less than 7 atoms, the 3d orbitals seem to be almost totally localized. For Co13- we find indications of a narrowing of the 3d-derived valence "bandwidth" corresponding to a presumed high symmetry and a high degree of degeneracy of the 3d electronic states.

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33

Ibupoto, Z. H., M. A. Abbasi, X. Liu, M. S. AlSalhi, and M. Willander. "The Synthesis of NiO/TiO2Heterostructures and Their Valence Band Offset Determination." Journal of Nanomaterials 2014 (2014): 1–6. http://dx.doi.org/10.1155/2014/928658.

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In this work, a heterojunction based on p-type NiO/n-type TiO2nanostructures has been prepared on the fluorine doped tin oxide (FTO) glass substrate by hydrothermal method. Scanning electron microscopy (SEM) and X-Ray diffraction techniques were used for the morphological and crystalline arrays characterization. The X-ray photoelectron spectroscopy was employed to determine the valence-band offset (VBO) of the NiO/TiO2heterojunction prepared on FTO glass substrate. The core levels of Ni 2p and Ti 2p were utilized to align the valence-band offset of p-type NiO/n-type TiO2heterojunction. The valence band offset was found to be∼0.41 eV and the conduction band was calculated about∼0.91 eV. The ratio of conduction band offset and the valence-band offset was found to be 2.21.

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34

Yamashita, Masahiro, and Ichiro Murase. "Moisture affected disproportionation reaction of a Ni(III) complex to a Ni(II)Ni(IV) mixed-valence complex." Inorganica Chimica Acta 97, no. 2 (February 1985): L43—L44. http://dx.doi.org/10.1016/s0020-1693(00)86569-x.

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35

Minamikawa, Kento, Shun Sarugaku, Masashi Arakawa, and Akira Terasaki. "Electron counting in cationic and anionic silver clusters doped with a 3d transition-metal atom: endo- vs. exohedral geometry." Physical Chemistry Chemical Physics 24, no. 3 (2022): 1447–55. http://dx.doi.org/10.1039/d1cp04197e.

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Cationic and anionic AgNM+/− (M = Sc–Ni) clusters are explored to examine the electron-counting rule. Among 18-valence-electron clusters, endohedrally doped ones are stable due to superatomic electron-shell closure involving delocalized 3d electrons.

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36

Song, Huijun, Jingjing Li, Guan Sheng, Ruilian Yin, Yanghang Fang, Shigui Zhong, Juan Luo, Zhi Wang, Ahmad Azmin Mohamad, and Wei Shao. "Chemical Transformation Induced Core–Shell Ni2P@Fe2P Heterostructures toward Efficient Electrocatalytic Oxygen Evolution." Nanomaterials 12, no. 18 (September 11, 2022): 3153. http://dx.doi.org/10.3390/nano12183153.

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The oxygen evolution reaction (OER) is a crucial reaction in water splitting, metal–air batteries, and other electrochemical conversion technologies. Rationally designed catalysts with rich active sites and high intrinsic activity have been considered as a hopeful strategy to address the sluggish kinetics for OER. However, constructing such active sites in non-noble catalysts still faces grand challenges. To this end, we fabricate a Ni2P@Fe2P core–shell structure with outperforming performance toward OER via chemical transformation of rationally designed Ni-MOF hybrid nanosheets. Specifically, the Ni-MOF nanosheets and their supported Fe-based nanomaterials were in situ transformed into porous Ni2P@Fe2P core–shell nanosheets composed of Ni2P and Fe2P nanodomains in homogenous dispersion via a phosphorization process. When employed as the OER electrocatalyst, the Ni2P@Fe2P core–shell nanosheets exhibits excellent OER performance, with a low overpotential of 238/247 mV to drive 50/100 mA cm−2, a small Tafel slope of 32.91 mV dec−1, as well as outstanding durability, which could be mainly ascribed to the strong electronic interaction between Ni2P and Fe2P nanodomains stabilizing more Ni and Fe atoms with higher valence. These high-valence metal sites promote the generation of high-active Ni/FeOOH to enhance OER activity.

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37

Korusenko, Petr M., Olga V. Petrova, Anatoliy A. Vereshchagin, Konstantin P. Katin, Oleg V. Levin, Sergey V. Nekipelov, Danil V. Sivkov, Victor N. Sivkov, and Alexander S. Vinogradov. "A Comparative XPS, UV PES, NEXAFS, and DFT Study of the Electronic Structure of the Salen Ligand in the H2(Salen) Molecule and the [Ni(Salen)] Complex." International Journal of Molecular Sciences 24, no. 12 (June 7, 2023): 9868. http://dx.doi.org/10.3390/ijms24129868.

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A comparative study of the electronic structure of the salen ligand in the H2(Salen) molecule and the [Ni(Salen)] complex was performed using the experimental methods of XPS, UV PES, and NEXAFS spectroscopy along with DFT calculations. Significant chemical shifts of +1.0 eV (carbon), +1.9 eV (nitrogen), and −0.4 eV (oxygen) were observed in the 1s PE spectra of the salen ligand atoms when passing from a molecule to a complex, unambiguously indicating a substantial redistribution of the valence electron density between these atoms. It is proposed that the electron density transfer to the O atoms in [Ni(Salen)] occurred not only from the Ni atom, but also from the N and C atoms. This process seemed to be realized through the delocalized conjugated π-system of the phenol C 2p electronic states of the ligand molecule. The DFT calculations (total and partial DOS) for the valence band H2(Salen) and [Ni(Salen)] described well the spectral shape of the UV PE spectra of both compounds and confirmed their experimental identification. An analysis of the N and O 1s NEXAFS spectra clearly indicated that the atomic structure of the ethylenediamine and phenol fragments was retained upon passing from the free salen ligand to the nickel complex.

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38

Kir, Esengul, Yunus Cengeloglu, and Mustafa Ersoz. "Sorption of Nickel and Iron on Polysulfone Cation Exchange Membranes." Collection of Czechoslovak Chemical Communications 66, no. 9 (2001): 1420–28. http://dx.doi.org/10.1135/cccc20011420.

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Sorption of NiCl2 and FeCl3 or di- and trivalent cation salt mixtures on polysulfone or polysulfone polyester-supported cation exchange membranes was investigated as a function of pH and concentration. The sorption of Fe(III) was higher than that of Ni(II) for both types of membranes. The maximum sorption for Fe(III) and Ni(II) ions was observed at pH 2.8 and 4.4, respectively. The selectivity coefficient of Fe(III) was also higher than that of Ni(II). The results were explained by considering the hydration effect and ionic valence.

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39

Xi, Wang, Zhiyu Ren, Lingjun Kong, Jun Wu, Shichao Du, Jiaqing Zhu, Yuzhu Xue, Huiyuan Meng, and Honggang Fu. "Dual-valence nickel nanosheets covered with thin carbon as bifunctional electrocatalysts for full water splitting." Journal of Materials Chemistry A 4, no. 19 (2016): 7297–304. http://dx.doi.org/10.1039/c6ta00894a.

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Dual-valence nickel nanosheets covered with thin carbon, synthesized by controlling the successive assembly and carbothermal reduction, achieve 10 mA cm⁻²of water-splitting current due to synergetic effects of adjacent Ni and NiO.

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40

Yang, Hao, De-Yue An, Jian-Lan Liu, Xiao-Ming Ren, Lan-Cheng Zhou, and Hua-Bing Wang. "Observation of a magnetic phase transition but absence of an electrical response in a new two-dimensional mixed-valence nickel-bis-dithiolene molecular crystal." RSC Advances 5, no. 18 (2015): 13857–66. http://dx.doi.org/10.1039/c4ra13354d.

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A two-dimensional mixed-valence molecular crystal of [Ni(dmit)₂]₃⁻ shows a magnetic phase transition at ca. 77 K but absence of an electrical response in the same temperature interval.

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41

Sakisaka, Y., T. Komeda, M. Onchi, H. Kato, S. Masuda, and K. Yagi. "New observation of the valence-band satellite in Ni(110)." Physical Review Letters 58, no. 7 (February 16, 1987): 733–36. http://dx.doi.org/10.1103/physrevlett.58.733.

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42

Sakisaka, Y., T. Komeda, M. Onchi, H. Kato, S. Masuda, and K. Yagi. "Photoemission study of the valence-band satellite of Ni(110)." Physical Review B 36, no. 12 (October 15, 1987): 6383–89. http://dx.doi.org/10.1103/physrevb.36.6383.

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43

Shibata, Takayuki, Fumiya Nakada, Hayato Kamioka, and Yutaka Moritomo. "Magnetic and Electronic Properties of Valence-Controlled Ni–Fe Cyanide." Journal of the Physical Society of Japan 77, no. 10 (October 15, 2008): 104714. http://dx.doi.org/10.1143/jpsj.77.104714.

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44

McConville, C. F., and D. P. Woodruff. "Valence band photoemission study of iodine adsorption on Ni{100}." Surface Science Letters 152-153 (April 1985): A129. http://dx.doi.org/10.1016/0167-2584(85)90119-7.

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45

McConville, C. F., and D. P. Woodruff. "Valence band photoemission study of iodine adsorption on Ni{100}." Surface Science 152-153 (April 1985): 434–42. http://dx.doi.org/10.1016/0039-6028(85)90174-8.

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46

Chen, Wei-Yu, Jiann-Shing Jeng, Kuo-Lun Huang, and Jen-Sue Chen. "Modulation of Ni valence in p-type NiO films via substitution of Ni by Cu." Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films 31, no. 2 (March 2013): 021501. http://dx.doi.org/10.1116/1.4774209.

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47

Sivakumar, Periyasamy, Milan Jana, Min Gyu Jung, Aharon Gedanken, and Ho Seok Park. "Hexagonal plate-like Ni–Co–Mn hydroxide nanostructures to achieve high energy density of hybrid supercapacitors." Journal of Materials Chemistry A 7, no. 18 (2019): 11362–69. http://dx.doi.org/10.1039/c9ta02583a.

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Nanostructured mixed multi-metal compounds (NCM) based on nickel (Ni), cobalt (Co), and manganese (Mn) are considered as promising electrode materials owing to their multiple valence states, facile accessibility to active sites, and low activation energy for electron transfer.

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48

Sun, Yang-Kook. "High-Performance Ni-Rich Cathodes through Precision Control for Electric Vehicle Batteries." ECS Meeting Abstracts MA2022-02, no. 3 (October 9, 2022): 288. http://dx.doi.org/10.1149/ma2022-023288mtgabs.

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Li-ion batteries (LIBs) become the main portable energy source for electric vehicles (EVs) owing to their high energy and power densities as compared to those of other forms of secondary batteries. As the overall performance and cost of LIBs are largely determined by the cathode material, recent research has heavily focused on developing high-capacity cathode materials. However, chasing high-energy-density without compromising service life is very challenging. Among the available cathode materials for LIBs, layered Li[Ni1-x-yCox(Mn or Al)y]O2 (NCM or NCA) is the material of choice owing to its high theoretical capacity of 275 mAh g−1. The demand for higher energy density at a lower cost has pushed the Ni content to approach 90% because Ni is in charge of energy density in NCM and NCA cathode. The inclusion of more Ni in the NCM and NCA cathodes has significant benefits in LIB energy density and cost, as it concomitantly reduces the content of expensive Co. However, the increase in Ni content sacrifices cycling and thermal stability due to the high reactivity of Ni. Such a trade-off between energy density and stability becomes increasingly severe with increasing Ni content. Capacity fading of Ni-rich NCM and NCA cathodes, especially above Ni 80%, largely originates from microcracking which exposes a large portion of the cathode interior to deleterious electrolyte attack. To suppress the development of microcracks on cathode materials, Ni-rich cathode materials should guarantee mechanical stability even in highly charged states. In this presentation, Ni-rich layered cathodes through precision control are presented. One approach is an optimization of both the crystal structure and primary particle morphology by introducing high valence ions. Another strategy is to develop concentration gradient (CG) cathodes with rod-shaped primary particles that are elongated along the radial direction. The CG cathodes are further optimized via high-valence ion doping thereby preserving the microstructure until the cathode attains optimal crystal structure via the reduction of cation mixing. These cathodes exhibit outstanding performance in long-term cycling tests.

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49

Zheltysheva, Olga R., Dmitry V. Surnin, Dmitry E. Guy, Faat Z. Gil'mutdinov, Yuri V. Ruts, and Vladimir I. Grebennikov. "The Change of the LMM Auger Spectra in 3d-Metals Due to Oxidation and Its Correlation with the Change of the Atomic Magnetic Moment." Microscopy and Microanalysis 11, no. 6 (November 15, 2005): 562–66. http://dx.doi.org/10.1017/s1431927605050622.

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The surfaces of crystalline samples of 3d-metals (Mn, Fe, Co, Ni, and Cu) and their stoichiometric oxides have been studied by Auger spectroscopy. A correlation between the change in the LVV (L-inner level-valence-valence electron transition) Auger intensities and the change of the squares of the corresponding atomic-magnetic moments has been observed. This is because of the complicated nature of the Auger process. That is, the Auger electron emission is a result of the inner atomic level excitation by electron impact and Auger annihilation of the inner-level hole. Therefore, the Auger process has been considered a second-order process, and spin polarization of the valence states has been taken into account for the LMM (L-inner level-M-inner level-M-inner level electron transition) Auger spectra of 3d-metals.

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50

Yuan, Ronghua, Weina Xu, Liquan Pan, Ruibin Li, Chuanying Xiao, and Xiaochang Qiao. "Ni-Doped La0.6Sr0.4CoO3 Perovskite as an Efficient Electrocatalyst for Oxygen Reduction and Evolution Reactions in Alkaline Media." Catalysts 13, no. 10 (October 13, 2023): 1366. http://dx.doi.org/10.3390/catal13101366.

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: The Co-based perovskite La0.6Sr0.4CoO3 has received significant attention as a potential electrocatalyst for its oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) due to its abundance, facile synthesis, and high oxygen kinetics. However, research on the catalytic performance of Ni-doped La0.6Sr0.4Co1−xNixO3 as a bifunctional cathode catalyst for Zn-air batteries (ZABs) is still scarce. In this work, lanthanum strontium cobalt-based perovskite catalysts with various Ni contents (La0.6Sr0.4Co1−xNixO3, x = 0, 0.2, 0.5, and 0.8) were synthesized using a simple combustion method. The effects of Ni doping on the morphology, structure, surface oxygen-related species, and valence states of the transition metals of the perovskite were characterized. The electrochemical behaviors of the perovskite catalysts in both ORR and OER were also assessed. The characterization results revealed that proper Ni doping can decrease particle size, increase surface oxygen vacancies, and create mixed valence states of the transition metal and, thus, lead to improvement of the electrocatalytic activity of perovskite catalysts. Among the different perovskite compositions, La0.6Sr0.4Co0.8Ni0.2O3 exhibited the best ORR/OER activity, with a higher limiting current density, smaller Tafel slope, higher half-wave potential, lower overpotential, and lower potential difference than the other compositions. When La0.6Sr0.4Co0.8Ni0.2O3 was applied as the cathodic catalyst in a primary ZAB, it delivered a peak power density of 81 mW cm−2. Additionally, in rechargeable ZABs, the La0.6Sr0.4Co0.8Ni0.2O3 catalyst exhibited a lower voltage gap (0.94 V) and higher stability during charge–discharge cycling than the commonly used catalyst Pt/C. These results indicate that Ni-doped La0.6Sr0.4Co0.8Ni0.2O3 is a promising bifunctional electrocatalyst for ZAB.

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