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.
Investigation of magnesium substituted nano particle zinc ferrites for relative humidity sensors
Abstract Nano particle Spinel ferrites, the magnetic semiconductor, are exhibiting remarkable surface phenomenon, wherein the process of adsorption is most significant. Humidity sensing is the realization of adsorption mechanism. Therefore, ferrites would be suitable for humidity sensing applications. Considering this fact into account, the compositions of polycrystalline Mg-Zn ferrites have been prepared by chemical route and characterized by standards tools like X-ray powder diffraction and FTIR spectroscopy. From the results of X-ray diffraction investigation, formation of single phase compositions is confirmed. The resulted structure is FCC with 311 as a prominent reflection. Average particle size obtained by using Scherrer method is within the range from 40 nm to 48 nm. The existence of the nanoparticles results into increase of the surface area required to favour adsorption mechanism. The significant absorption bands were observed for higher range of frequencies in FTIR, which are attributed to the modes of vibration of water molecules. Therefore, it can be used for development of the humidity sensor. The relative humidity sensor is designed by depositing thick film of the materials under investigation on ceramic substrate. Electrical resistance of the sensor (RH) reveals decreasing trend with increase in the relative humidity. Relative deviation in the resistance (RDR) with humidity depicts two significant regions attributed to the existence of protonic conduction mechanism. The sensor, developed from x = 0.40, reveals good linearity over wide range of humidity from 40%RH to 75%RH, which suggests its suitability for sensor development. Moreover, the features of the composition for x = 0.40 is suitable for design of electronic interfaces required for instrumentation. The sensitivities of the compositions less than 1 s for 10% variation in the relative humidity. This confirms that the humidity sensors developed by employing compositions of ferrite on ceramic substrate are very fast and reliable.
Recalculation of Mass Defects
THE well-known mass defect curve of the old nuclear scheme calculated with regard to α-particles and protons presented a difficulty with its minimum of binding energy for tin and an increasing portion between tin and lead. On the other hand, the mass defect values against protons give a rather smoothly decreasing curve.1 As has already been pointed out,2 the number of α-particles must be considerably reduced from the point of view of the new scheme, which does not admit any electrons in nuclei, but only neutrons and protons (presumably joined as α-particles). The curve of mass defect against protons and neutrons (perhaps with a single ‘central’ α-particle) is very similar to the old curve against protons, but decreases less rapidly. Clearly the new mass defect values relatively to α-particles, neutrons and protons must lie somewhere between the old values computed relative to protons and α-particles respectively (because the number of α-particles is decreased). We may emphasise that this new mass defect curve shows no increasing portion between tin and lead. For illustration we give two typical values: Old: 50Sn124 = 31α + 12&#38;epsiv;; mass defect = 0.158 (in mass units); 82Pb208 = 52α + 22&#38;epsiv;; mass defect = 0.035. New: 50Sn124= 25α + 24ω (ω = neutron); mass defect = 0.304; 82Pb208 = 41α + 44ω; mass defect = 0.366.