Magnetic Ordering in Polycrystalline NixZn1xO Solid Solutions

Abstract

In order to examine the influence of the dilution of magnetic ions on the crystal and magnetic structure of Ni x Zn 1Àx O (x 1, 0.90, 0.80, 0.70) solid solutions we have performed neutron diffraction experiments on each sample at seven temperatures between 10 and 295 K. To determine the Ne  el temperatures, the magnetic susceptibility measurements were done in the temperature region between room temperature and 600 K. Starting from the known rhombohedral distortion the crystal structure has been refined in the trigonal space group R " 3m. In this space group the cations occupy octahedral 3a position (with the local symmetry " 3m), while the oxygen anion is placed in the 3b position (with the local symmetry " 3m). The magnetic structure for all concentrations x is found to be antiferromagnetic and the magnetic cell is the doubled nuclear cell along the c-axis. The magnetic atoms are arranged in the planes (003) in respect to the nuclear cell. The magnetic moments of two Ni 2 ions in adjacent sheets are oriented antiparallely and the magnetic vector makes an angle of 66 with the c-axis. The magnetic structure is preserved upon random site dilution of the magnetic ions. This is additionally confirmed from the Brillouin-type dependence of the magnetization on temperature as well as from the t T N xaT N 1 versus x variation obtained from the magnetic susceptibility measurements. Concentration dependence of the Ne  el temperature also shows that Ni x Zn 1Àx O behaves like a Heisenberg antiferromagnet with the dominant nearest-neighbor interaction, in agreement with the similar (Ni, Co) x Mg 1Àx O solid solution.

Interpretation of the Ni K-edge EXAFS in nanocrystalline nickel oxide using molecular dynamics simulations

“…The MSD values can be experimentally determined from diffraction measurements: MSD(O)=0.0032 Å 2 and MSD(Ni)=0.0028 Å 2 for c-NiO at 300 K [22]. This means that the values of the MSRDs equal to 0.0060 Å 2 and 0.0056 Å 2 are expected for Ni-O and Ni-Ni atom pairs, respectively, for uncorrelated motion (DCF=0) at large distances.…”

“…Crystalline c-NiO was modeled by the supercell 6a 0 ×6a 0 ×6a 0 , where the lattice parameter a 0 =4.1773 Å [16], with 3D periodic boundary conditions. The simulations for c-NiO were also performed for rhombohedrally distorted (R3m space group) lattice to check the effect of weak magnetostriction effect present in the antiferromagnetic phase below 523 K [21,22].…”

Formation of ZnO/Ni_0.6Zn_0.4O Mixture Using Mechanical Milling of Zn-NiO

“…The coordination environment of the Zn 2+ sites in ZnO is suitable for nickel ions (Ni 2+ ) and this is the reason why NiO and ZnO form a solid solution. [1][2][3] The resulting complex structure depends on the x value. To the best of our knowledge, work on the solid state synthesis of such structures is quite limited.…”

“…4) Physical, magnetic and optical properties of Ni-doped ZnO and Ni x Zn 1-x O solid solutions synthesized by addition of NiO (0-2.0 mol%) to ZnO is reported by different research teams. 1,[4][5][6][7][8] High energy mechanical milling and mechanochemical processes are, on the other hand, considered as simple and cost-effective techniques employed for preparation of nano-sized and nonocrystalline materials which can induce chemical reactions that do not normally happen at room temperature. [9][10][11][12] Mechanochamical reactions have been the subject of investigations on displacement reactions between metal compounds and a reducing metal.…”

Polarisation dependent Raman study of single-crystal nickel oxide

“…The transition to the antiferromagnetic state below T N is accompanied by a weak rhombohedral distortion (space group R − 3 ) with a contraction of the cubic unit cell along the 111 axes. The rhombohedral cell parameters are 0 = 2 9481 Å, α = 60 080°at 10 K and 0 = 2 9533 Å, α = 60 037°a t 295 K [2]. In the antiferromagnetic state, the pres- * E-mail: ulman@latnet.lv ence in NiO of crystallographic twins leads to the formation of antiferromagnetic twin-domains (T-type), having the walls at twin interfaces [3][4][5].…”