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P. Balaji Bhargav,V. Madhu Mohan,A.K. Sharma,V.V.R.N. Rao 한국물리학회 2009 Current Applied Physics Vol.9 No.1
Solid polymer electrolytes based on poly (vinyl alcohol) (PVA) complexed with sodium fluoride (NaF) at different weight percent ratios were prepared using solution cast technique. The structural properties of these electrolyte films were examined by XRD studies. The XRD data revealed that the amorphous domains of PVA polymer matrix increased with increase of NaF salt concentration. The complexation of the salt with the polymer was confirmed by FT-IR studies. Electrical conductivity was measured in the temperature range of 303–373 K and the conductivity was found to increase with the increase of dopant concentration as well as temperature. The dielectric constant (ε') increased with the increase in temperature and decreased with the increase in frequency. A loss peak was identified at 365 K in the dielectric loss spectra and is attributed to the orientation of polar groups. Measurement of transference number was carried out to investigate the nature of charge transport in these polymer electrolyte films using Wagner’s polarization technique and Watanabe technique. Transport number data showed that the charge transport in these polymer electrolyte systems was predominantly due to ions and in particular due to anions. Using these polymer electrolytes, solid state electrochemical cells were fabricated. Various cell parameters like open circuit voltage (OCV), short circuit current (SCC), power density and energy density were determined. Solid polymer electrolytes based on poly (vinyl alcohol) (PVA) complexed with sodium fluoride (NaF) at different weight percent ratios were prepared using solution cast technique. The structural properties of these electrolyte films were examined by XRD studies. The XRD data revealed that the amorphous domains of PVA polymer matrix increased with increase of NaF salt concentration. The complexation of the salt with the polymer was confirmed by FT-IR studies. Electrical conductivity was measured in the temperature range of 303–373 K and the conductivity was found to increase with the increase of dopant concentration as well as temperature. The dielectric constant (ε') increased with the increase in temperature and decreased with the increase in frequency. A loss peak was identified at 365 K in the dielectric loss spectra and is attributed to the orientation of polar groups. Measurement of transference number was carried out to investigate the nature of charge transport in these polymer electrolyte films using Wagner’s polarization technique and Watanabe technique. Transport number data showed that the charge transport in these polymer electrolyte systems was predominantly due to ions and in particular due to anions. Using these polymer electrolytes, solid state electrochemical cells were fabricated. Various cell parameters like open circuit voltage (OCV), short circuit current (SCC), power density and energy density were determined.
K. Ganesh Kumar,P. Balaji Bhargav,Nafis Ahmed,C. Balaji 한국전기전자재료학회 2021 Transactions on Electrical and Electronic Material Vol.22 No.6
In the present study, pure and Tin (Sn) doped ZnO (Sn–ZnO) nanostructures are grown using hydrothermal method. The effect of Sn doping on the physical properties of ZnO is extensively studied. Till 4 mol% of Sn doping, the dopant is completely dissolved in the host matrix and no secondary phases are formed as evident from XRD studies. The presence of the constituent elements of the host matrix (Zn,O) and dopant (Sn) is confi rmed using Energy Dispersive X-ray Spectroscopy (EDX). From FESEM images, it is evident that the morphology of the grown structures changes from rods to flowers and flakes with doping. The microstructural analysis is carried out using HRTEM analysis. Various polar and non-polar optical modes present in the samples are analysed using Raman spectra. Two dominant emission bands around ~391 nm, ~470 nm are noticed from photoluminescence (PL) spectra. The potential of the Sn doped ZnO nanostructures in photocatalytic degradation of Rhodamine B is investigated and found that 1 mol% Sn doped ZnO exhibits superior photo catalytic performance.
Charge transport studies on chemically grown manganite based heterostructures
Keval Gadani,Khushal Sagapariya,K.N. Rathod,Hetal Boricha,Bhargav Rajyaguru,V.G. Shrimali,A.D. Joshi,K. Asokan,N.A. Shah,P.S. Solanki 한국물리학회 2019 Current Applied Physics Vol.19 No.4
In this communication, we have successfully fabricated mixed valent La0.7Ca0.3MnO3 (LCMO) manganite based (i) ZnO/LCMO/LAO and (ii) LMO/LCMO/LAO (LMO: LaMnO3–d thin layer; LAO: LaAlO3 substrate) thin film heterostructures using chemical solution deposition (CSD) method. 100 nm LCMO layer was initially grown on single crystalline (100) LAO substrate followed by the growth of 50 nm ZnO and LMO layers separately on the two different heterostructures. In the present study, upper layers of ZnO and LMO were intentionally prepared at 700 °C for 12 h under air environment, thereby some naturally created oxygen vacancies are expected to be present in their lattices. Presence of oxygen vacancies makes ZnO and LMO layers as n–type oxides in the heterostructures. Temperature dependent current–voltage (I–V) characteristics and interface resistivity (under different applied electric fields across interface only) were carried out to understand their charge transport behavior. A strong effect of electric field on the resistivity behavior has been observed due to a reasonable electrically polarizable (active) nature of ZnO and LMO thin layers. Zener double exchange (ZDE) polynomial law has been employed to understand various scattering processes as source of resistivity across, both, ZnO/ LCMO and LMO/LCMO interfaces. Transport properties and charge conduction mechanisms have been discussed and compared for both the interfaces in the context of interface state and barrier between electrically active layer and LCMO film. Also, power consumption criteria have been discussed in detail for the presently studied heterostructures for their practical device applications such as field effect devices, memory devices, read–write head devices or any other spintronic devices.
Dadhich Himanshu,Rajyaguru Bhargav,Gadani Keval,Goswami Hardika,Rathod V.R.,Shrimali V.G.,Mukherjee S.,Asokan K.,Shah N.A.,Solanki P.S. 한국물리학회 2023 Current Applied Physics Vol.50 No.-
In the present communication, temperature dependence of resistive switching (RS) behavior across chemically grown LaMnO3/La0.7Ca0.3MnO3 (LMO/LCMO) interface have been discussed by employing various theoretical approaches and mechanisms. Temperature dependent RS behavior of LMO/LCMO interface highlights impactful switching between high resistance state (HRS) and low resistance state (LRS) under reverse bias mode through an active role of depletion region. Trapping–detrapping processes assisted charge conduction has been identified as a source of RS nature of LMO/LCMO interface. Thermionic emission model and space charge limited conduction (SCLC) mechanism have been employed to understand the charge conduction and charge transport across LMO/ LCMO interface. Present structure of Ag/LMO/LCMO/Ag has also been investigated for possible retention and endurance behaviors under different external parameters which verify the stability, reliability, reproducibility, non–volatile nature and applicability of LMO/LCMO interface.