SYNTHESIS AND IMPLEMENTATION OF NiZnFe 2 O 4 FERRITES TO DESIGN EMBEDDED SYSTEM FOR HUMIDITY MEASUREMENT
2 ABSTRACT: Along with magnetic properties, the spinel ferrites exhibit promising electrical properties, deployment of which results into evolution of new area of applications as the electronic sensor materials. The electrical properties significantly depend upon the environmental compositions, for which it has been exposed. The electrical resistance of these sensor materials varies not only with gas concentration but also with change in water vapour concentration. With the view to develop an embedded technology based smart sensor module for humidity measurement a sensor material NixZn1-xFe2O4 are synthesized by chemical method and characterized by XRD and IR tools. The x-ray powder diffraction reveals the formation of single phase spinel ferrite, which is also supported by the IR absorption bands attributed to tetrahedral (A) site and octahedral (B) sites. Employing embedded philosophy, the sensor module is designed about AVR ATmega8L microcontroller for humidity measurement. The thick film of materials under investigation, prepared by screen painting technique, is used to sense the concentration of water molecules. Analog part of the system is wired about highly precise instrumentation amplifier AD620. Deployment of on-chip ADC of 10-bit resolution causes to increase in the preciseness of the results. The system is calibrated to the humidity in RH%. The data shown by the system under investigation reveals close match with the standard data.
Size dependent magnetic and magneto-optical properties of Ni0.2Zn0.8Fe2O4 nanoparticles
Abstract Ni 0.2 Zn 0.8 Fe 2 O 4 spinel nanoparticles have been synthesized by combustion method. Average particles size varies from 15.5 to 50.0 nm depending on annealing temperature. Correlations between particles size and magnetic and magneto-optical properties are investigated. Magnetization dependences on temperature and external magnetic field correspond to the sum of paramagnetic and superparamagnetic response. Critical size of single-domain transition is found to be 15.9 nm. Magnetic circular dichroism (MCD) studies of nickel zinc spinel are presented here for the first time. The features in magnetic circular dichroism spectrum are assigned to the one-ion d–d transitions in Fe 3+ and Ni 2+ ions, as well to the intersublattice and intervalence charge transfer transitions. The MCD spectrum rearrangement was revealed with the change of the nanoparticles size.
Electrical conductivity of some nickel‐zinc ferrites
The electrical conductivity of some nickel-zinc ferrites is studied as a function of temperature. The ferrites with iron in excess show n-type conduction and those with iron in deficiency show p-type conduction. Seebeck coefficient, X-ray analysis, and saturation magnetisation are also carried out to discuss the conductivity of these ferrites. 
 
 
 
Es wird die elektrische Leitfahigkeit einiger Nickel-Zinkferrite als Funktion der Temperatur gemessen. Ferrite mit Eisenuberschus zeigen n-Leitfahigkeit, solche mit Eisenmangel p-Leitfahigkeit. Untersuchungen des Seebeckkoeffizienten, der Sattigungsmagnetisierung sowie Rontgenanlysis werden durchgefuhrt, um die Leitfahigkeit dieser Ferrite zu diskutieren.