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Role of molybdenum trioxide in enhancing the humidity sensing performance of magnesium ferrite/molybdenum trioxide composite

Babu Reddy, L.P.,Megha, R.,Chethan, B.,Raj Prakash, H.G.,Ravikiran, Y.T.,Ramana, C.H.V.V.,Kim, D. ELSEVIER 2018 Inorganic Chemistry Communications Vol.98 No.-
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Abstract In the present work, we prepared magnesium ferrite/molybdenum trioxide (MFMO) nanocomposite using mechano chemical mixing method for humidity sensor at room temperature. Enhancement in active sites for water adsorption in the composite due to the presence of MoO3 confirmed from X-ray diffraction (XRD) studies. Change in grain size distribution and increase in intergranular pores in the composite favouring water adsorption confirmed from its scanning electron microscopy (SEM) image. Increased agglomeration of nano sized particles and improved crystallinity of the composite confirmed from Transmission electron microscopy (TEM) studies and selected area electron diffraction (SAED) pattern. The composite showed maximum sensing response of 4902 as against 183 of MF in the range 11%–97% RH. The response and recovery times of the composite were found to be 45 s and 74 s respectively while those of MF 225 s and 364 s respectively. The nanocomposite sample showed stable humidity sensing ability and a low humidity hysteresis. Molybdenum trioxide plays a major role in enhancing the humidity sensing performance of MFMO composite at room temperature. The sensing mechanism discussed on the basis of chemisorptions, physisorption and capillary condensation processes. Highlights <UL> <LI> Humidity sensing response of magnisium ferrite (MF) and magnesium ferrite-molybdenum trioxide (MFMO) composite presented. </LI> <LI> The MFMO showed maximum sensing response of 4902 as against 183 of MF in the range 11%-97% RH. </LI> <LI> The response and recovery times of the composite were found to be 45 s and 74 s respectively. </LI> <LI> The sensing mechanism MFMO discussed on the basis of chemisorptions, physisorption and capillary condensation processes. </LI> </UL>
2
Asymmetric and symmetric modified bow‐tie slotted circular patch antennas for circular polarization

Naresh K. Darimireddy,R. Ramana Reddy,A. Mallikarjuna Prasad 한국전자통신연구원 2018 ETRI Journal Vol.40 No.5
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Modern communication systems employ wideband antennas with circular polarization (CP) radiation. In this work, asymmetric modified bow‐tie (ABT) and symmetric modified bow‐tie (SBT) slotted circularly polarized single‐point probe‐fed circular patch antennas with dimensions of 40 mm × 40 mm for wideband applications are proposed. A 10 dB RL bandwidth of 350 MHz with CP, 3 dB axial ratio (AR) bandwidth of 100 MHz, peak gain of 4.9 dBic, and 10 dB RL bandwidth of 530 MHz with CP, 3 dB AR bandwidth of 140 MHz, peak gain of 5 dBic are obtained for ABT and SBT slotted circular patch antennas, respectively. The proposed SBT slotted patch is scaled up and down to 50 mm × 50 mm and 30 mm × 30 mm, respectively. The proposed scaled‐up version offers 10 dB RL and 3 dB AR bandwidths of 340 MHz and 80 MHz, with a peak gain of 5 dBic. The scaled‐down version offers 10 dB RL and 3 dB AR bandwidths of 710 MHz and 180 MHz, with a peak gain of 5.25 dBic. These prototypes are suitable to work in IEEE 802.11a WLAN, ISM, and IEEE 802.11ac applications. The measured and simulated results are then discussed and compared.