Magnetic ordering in polycrystalline NixZn1-xO solid solutions

In order to examine the influence of the dilution of magnetic ions on the c rystal and magnetic structure of NixZn1-xO (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 Neel temperatu res, the magnetic susceptibility measurements were done in the temperature region between room temperature and 600 K. Starting from the known rhombohe dral distortion the crystal structure has been refined in the trigonal spac e group R (3) over bar m. fn this space group the cations occupy octahedral 3a position (with the local symmetry (3) over bar m), while the oxygen ani on is placed in the 3b position (with the local symmetry (3) over bar m). T he magnetic structure for all concentrations x is found to be antiferromagn etic and the magnetic cell is the doubled nuclear cell along the c-axis. Th e magnetic atoms art: arranged in the planes (003) in respect to the nuclea r cell. The magnetic moments of two Ni2+ ions in adjacent sheets are orient ed antiparallely and the magnetic vector makes an angle of 66 degrees with the c-axis. The magnetic structure is preserved upon random site dilution o f 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 (x)/T-N(1) versus x variation obtained from the magnetic susceptibility mea surements. Concentration dependence of the Neel temperature also shows that NixZn1-xO behaves like a Heisenberg antiferromagnet with the dominant near est-neighbor interaction, in agreement with the similar (Ni, Co)(x)Mg1-xO s olid solution.