Preparation of Painting Material from Li-Ni Ferrite with Isovalent Substitution

   Nano Li-Ni ferrite samples having the structure Li were prepared by hydrothermal method in two sets from metal chlorides,ferrous sulfate and NaOH. Each set implicated varying x through 0, 0.1,0.3 to 1.0. The samples were without and with adding Fe0.5-0.5x2+. The ratio ofFe3+/ Fe2+ was kept at 1.7. The preparation temperature was 155 °C and pH was equal to 11. All composition was prepared except that for x=0 withoutFe2+ which cannot be prepared under used experimental conditions.Samples showed dominant spinel ferrite phase beyond x=0.3 for set one and pure phase at x=0.3 with Fe 2+addition. Lattice constant of set two is slightly lower than set one and both are slightly lower than theoretical values. The crystallite size gets minimum at x=0.5 for set one and roughly maximum at x=0 for set two.  Fourier ransformation Infrared (FTIR) spectrums tetrahedral showed peak shift to higher frequency with increasing Ni 2+ concentration. Particles shapes were: rods (often hematite) average diameter 40 nm, spherical (nanocube ferrite in origin) sizing around 20nm.Hysteresis Loops have S-shape like to superparamagnetic one. Generally the prepared samples have lower coercivety H , higher saturation magnetization Msc compared to these in literatures. Both sets give maximum susceptibility at x=0.5. These results are explained based on composition, cations distribution, cation interactions and particle size.NixFe2.-0.5xO4Resonance microwave absorption by using Ferromagnetic Resonance (FMR) test showed that the maximum imaginary susceptibility χ″ is at x=0.5 for set one besides high values of 0.7 and 0.9, with largest linewidth of about 950 G at x=0.7. Set two showed max absorption (χ″) and linewidth at x=0.9. Powders were then mixed with Novalac epoxy by 7.97 %wt.Shortcut-FMR test with no field showed that high absorption to microwave field for frequencies larger than 19 GHz. The explanation of that set two samples have larger absorption than set one is based on hopping conductivity and magnetic parameters (Ms and H) variation.Transmission line method by using vector network analyzer in X-band and Ku-band showed that return (reflection) loss RL got minimum at x=0.3 in for set one in X-band whereas that happen at x=0.3 and x=0.5 for set two. dding Fe2+c lowered the minimum by a factor of more than 1.5. The insertion losses IL in X-band ranging from -4.5 to -7 dB. RL and IL in Kuband have same behavior but their values are lower.RLgot minimum at  NixFe2.-0.5xO4x=0.5 with value of about near to -18dB whereas it was around -12dB by adding Fe 2+ . Average IL in Ku-band -6dB. Thickness effect is abstracted by enhancing RL and IL but shifting the nimum of peaks to lower frequency. 2mm thick has RL<-27dB and IL<-19dB.