Davit Dhruv

Size-controlled electrical properties of sol–gel-grown nanostructured Gd0.95Ca0.05MnO3

In this communication, we report the results of the studies on electrical properties of cost-effective modified sol–gel-grown nanostructured Gd0.95Ca0.05MnO3 (GCMO) manganites sintered at different temperatures. Structural investigations, carried out using X-ray diffraction measurements, reveal the single-phasic nature of GCMO samples having orthorhombic unit cell structure. Frequency-dependent variation in AC conductivity (σAC) has been discussed on the basis of correlated barrier hopping (CBH) mechanism for the GCMO samples sintered at lower temperatures. Sintering temperature-induced transition from CBH mechanism to Maxwell–Wagner relaxation processes has been discussed in detail. Size-induced modifications in the impedance response of the samples have been understood, in detail, using size effects and Cole–Cole plots.Graphical Abstract

Temperature-dependent I–V and C–V characteristics of chemically-grown Y0.95Ca0.05MnO3/Si thin films

In this communication, we report the results of the studies on temperature-dependent current—voltage (I–V) and capacitance—voltage (C–V) characteristics of chemical solution deposition-grown Y0.95Ca0.05MnO3/Si films and annealing temperature-induced modified interface dependence on device characteristics. X-ray diffraction results reveal the single phasic nature of films having polycrystalline growth on single crystalline (100) Si substrate. The magnetic nature of the films is confirmed from magnetic force microscopy studies. I–V and C–V characteristics show a strong dependence on the temperature and nature of the film—substrate interface, which has been understood on the basis of the annealing effect involved. Various models and theories have been used to understand the mechanism responsible for the transport across the film—substrate interface. A large rectifying ratio of ~1.2 × 104 has been obtained across the interface annealed at a lower temperature, which becomes almost double in the film annealed at a higher temperature. A large electroresistance of ~600% has been achieved for the interface annealed at a lower temperature. The temperature dependence of C–V behavior recorded across the interfaces of the films is discussed in detail on the basis of free and trapped charge carrier density and interface modifications.

Synthesis and Optical Characterization of CuO Nanoparticles on Solar Borosilicate Glass

In this communication we report on the optical property of CuO nanoparticles prepared by cost effective, simplistic and environment-friendly sol-gel technique on borosilicate glass by dip coating. The particle size was analyzed by Transmission Electron Microscope (TEM) which depicted particle size of CuO ~ 5 nm. To understand the optical behavior of nanosized CuO particles on borosilicate glass tube UV-visible spectrum has been taken. Effective mass model calculations determined the size of particles as 2.26 nm, which supports the TEM analysis. Samples were also analyzed by Fourier transform infrared spectrum (FT-IR) to understand the chemical bond in detail.

Dielectric behavior of nanostructured Y0.95Ca0.05MnO3: Role of sintering temperature

Nanostructured Y0.95Ca0.05MnO3 (YCMO) samples have been synthesized using cost effective sol-gel method. The samples were sintered at various temperatures ranging between 700 – 1100°C (ST). XRD studies reveal the single phasic nature of the samples. Frequency dependent dielectric (e) and modulus (M) behaviors of YCMO samples imply the increase in e and activation energy (Ea) with ST which has been discussed in the light of oxygen vacancies and grain morphology.

Structure-property correlations in monovalent mixed oxide La1−xKxMnO3(0.0≤x≤0.3)manganites

Substitution of monovalent K+ at La3+ in solid state reaction synthesized La1−xKxMnO3(0.0≤x≤0.3) manganites results in metallic behavior. Increase in K+ content (x ≤ 0.15) enhances the FM interactions through ZDE mechanism while for higher x > 0.15, structural disorder and AFM interactions between Mn4+ ions become prominent.

Temperature dependent dielectric behavior of sol–gel grown Y0.95Ca0.05MnO3/Si junction

We have successfully fabricated divalent doped Y0.95Ca0.05MnO3 film on (100) single crystalline n-type Si substrate by spin coating assisted chemical solution deposition technique. The X–ray diffraction (XRD) pattern of thin film depicts that the film has (h00) directional growth on substrate. Thin film possesses –1.4% compressive strain at the interface level and thin film thickness is found to be ∼ 78nm. Dielectric property of film has been studied by Agilent LCR meter from 100Hz to 2MHz applied field frequency at temperatures 150 to 300K. Real dielectric permittivity decreases and imaginary dielectric permittivity increases with increasing applied frequency. Furthermore, at low temperatures, higher dielectric is observed in all the frequency range studied and it decreases with increasing temperature due to thermal excitation induced increased charge carrier movements across the film lattice. The relaxation mechanism of Y0.95Ca0.05MnO3 film has been understood through cole–cole plots.

Analysis and design optimization of organic dye sensitized solar cell based on simulation

In the present communication, simulation of multilayers organic dye-sensitized based solar cells (DSSC) was performed because of its tremendous application in different solar energy harvesting devices and their relatively high efficiency as well as cost effectiveness.J-V and I-V curves ofmultilayer organic dye sensitized solar cell with combination of different dyes were simulated to study the performance in the vicinity of efficiency. On the basis of above parameters, optimum design and operating parameters were derived from the simulation based analysis. It had been jointly shown that a systematic variation of different dye material and its thicknessare highly useful in achieving optimum efficiency of energy harvesting devices.

Effect of sintering temperature on the structural and electrical properties of Zn0.95Cr0.05O

In this communication, we report the results of the studies on the sintering temperature dependent structural properties and dielectric behavior of 5% Cr doped Zn0.95Cr0.05O samples synthesized by cost effective sol-gel technique. Crystallographic orientations, crystallinity and crystallite size (CS) have been understood by performing X-ray diffraction (XRD) measurement at room temperature. Values of CS have been further verified by carrying out Williamson – Hall (W-H) plot analysis and the difference between the CS from XRD and W-H analyses has been discussed. Dielectric behavior has been studied and its dependence on the sintering temperature has been understood in the light of crystallite size, crystal boundary density and oxygen vacancies induced possible conductivity in the samples.

Investigations on structural disorder-induced modifications in the transport behaviour of rare-earth manganites

The results of the studies on structural disorder-induced modifications in the transport behaviour of La0.5Pr0.2Ca0.3−xBaxMnO3 (LPCBMO) (0.05 ≤ x ≤ 0.30) manganites were reported. Structural studies using X-ray diffraction (XRD) measurements confirmed the single phasic nature of all the samples without any detectable impurities. The A-site size disorder (σA2

I-V and C-V characteristics of Y0.95Ca0.05MnO3/Si film

{ {\sigma }}_{\mathrm{A}}^{\mathrm{2}}