Browsing by Author "Baniya R. Meena"

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Effect of Bi modification on structural and dielectric properties of selenium-rich Se-In chalcogenide glasses
(Elsevier Ltd, 2025) Himanshu Meena; Saurabh Mishra; Devanand Gupta; Baniya R. Meena; Horesh Kumar
This work focuses on the structural and electrical characteristics of Se90In10-xBix (x = 0, 2, 4, 6, and 8) chalcogenide alloys that were synthesized using the traditional melt quenching method. The X-ray diffraction patterns of the prepared samples show that they are polycrystalline in nature. Transmission electron microscopy (TEM) backs the XRD phase identification and shows the formation of nanorods and nanoparticle clusters, which increase with the increasing bismuth concentration. Raman spectroscopy is used to further support the structural aspects, which were established by XRD and TEM analysis. In Se90 in10-xBix glass, the band gap decreases on increasing the Bi content, and the lowest band-gap value is observed in Se90In2Bi8 chalcogenide, which is attributed to the larger crystallite size. Measured electrical properties, such as dielectric constant, dielectric loss, and electrical conductivity, were found to depend on temperature (309–348 K) and frequency (100 Hz - 1 MHz). The undoped binary Se-In sample has the lowest dielectric constant and loss values at a given frequency and temperature, but with increasing Bi incorporation, an increment in dielectric constant and loss values is observed. For sample x = 6 (Se90In4Bi6), the maximum values of dielectric constant and loss are noted. On inclusion of Bi in place of In in the studied system, the conductivity of the sample increased significantly, and the highest conductivity value was noted for sample x = 6. Also, a change in the conduction mechanism was observed from the CBH model with IVPA to the CBH model with NVAP © 2025 Elsevier Ltd and Techna Group S.r.l.
Insight into charge conduction and relaxation in La2-xCaxFeMnO6 solid solution double perovskites
(Elsevier Ltd, 2025) Baniya R. Meena; Sandip Chatterjee; Anup Kumar Ghosh
A series of La2-xCaxFeMnO6 (where x = 0, 0.1, 0.2, 0.3, and 0.5) solid solution has been prepared by the solid-state reaction method. Single-phase disordered cubic crystal structure of crystallite size ∼ 50 nm has been confirmed by the Rietveld refinement of X-ray diffraction (XRD) data. Raman spectroscopic study shows improper ordering of MnO6 and FeO6 octahedral. The average grain size (∼ 4 µm) and elemental analysis have been estimated by SEM and EDS measurements, respectively. The electronic structure of the prepared samples has been investigated by using the X-ray photoemission spectroscopy (XPS). The value of dielectric constant has been improved from colossal (∼1826) to giant (∼15238) with low dielectric loss at room temperature due to Ca2 + doping. All samples exhibit the negative temperature coefficient of resistance (NTCR) characteristic. The electrical characteristics of both the grain and grain boundary have been investigated by the analysis of imaginary part of impedance (Z''). The non-Debye type relaxation has been explained by the non-overlapping small polaron tunnelling (NSPT) transport mechanism. I-V characteristic shows the low value of leakage current density (∼ 10−4 Amp/cm2) for all measured samples. This study may open an intriguing path for the engineering of better-performing dielectric materials for various electronic devices. © 2025
Structural, dielectric, and electrical transport properties of La2FeMnO6 double perovskite for multifunctional applications
(Elsevier Ltd, 2025) Baniya R. Meena; Mohd Intaf Alam; Sandip Chatterjee; Anup Kumar Ghosh
The polycrystalline La2FeMnO6 has been prepared by the solid-state reaction method. The Rietveld refinement of X-ray diffraction (XRD) data confirms a single-phase double perovskite cubic structure. The vibrational modes have been investigated by the Raman and Fourier transform infrared (FTIR) spectroscopy. The X-ray photoemission spectroscopy (XPS) measurement reveals the presence of mixed valence states of Mn and Fe cations. The dielectric, impedance, modulus, and AC conductivity measurements of La2FeMnO6 have been done over temperature range (125–300 K) and frequencies (1 kHz - 1 MHz). This material exhibits a high ε′ (∼1826) with a low dissipation factor near room temperature. The NTCR (negative temperature coefficient of resistance) characteristics of both resistivity and impedance showed the semiconducting nature of the sample. Grains and grain- boundaries play important role in the process of electrical conduction. The Cole-Cole plots follow the RC equivalent circuit and verify non-Debye-type relaxation. The value of the exponent ‘s’ suggests the non-overlapping small polaron tunneling (NSPT) process in La2FeMnO6. The NTCR characteristic of this material, with good stability factor, thermistor constant, and sensitivity factor may be useful for NTC-type thermistor. © 2024