Study of magnetic behavior in co-precipitated Ni–Zn ferrite nanoparticles and their potential use for gas sensor applications

Abstract

A series of NixZn1−xFe2O4 (x = 0.5, 0.6, 0.7) were obtained by co-precipitation technique and followed by sintering at 800 °C. The random variation of bond angles resembles possible cation redistribution in the present series of ferrite samples. The cation distributions estimated from Mössbauer analysis are used to find out the net magnetic moment. The magnetic moment n′B estimated from Neel’s sub-lattice model is not consistent with experimental magnetic momet nB. But the magnetic moment (nB′′) estimated from the Yafet–Kittel (Y–K) model is in good agreement with the experimental magnetic moment nB, supporting the possibility of non-collinear arrangement of spins at B–site. The non-collinear spin arrangement at octahedral (B) site is influencing the magnetization of present series ferrite samples. The increase in saturation magnetization with increase in Ni2+ ion concentration is expected due to the decrease in non-collinear spin arrangement at octahedral (B) site. Higher saturation magnetization of 61.32 emu/g was reported for the composition x = 0.7. The single domain structure of samples is evident from the hysteresis loops, but interestingly nature of hyperfine interactions can be found from the Mössbauer spectra under spectral line intensities. The increase in the blocking temperature (magnetic ordering) is due to the increase in magnetocrystalline anisotropy rather than an increase in particle sizes. The composition x = 0.7 is showing good sensor response for both LPG and acetone. Moreover, its response and recovery times are less comparing to the other two compositions and therefore it is useful for the sensor fabrication.