arXiv subjects

P. Maneesha

Publications and source records attributed to P. Maneesha.

7 recordsLinked to original sources

arXiv2025

Hexagonal polymorphism induced structural disorder and dielectric anomalies of Ca/Mn modified BaTiO3

This work involves the local structural investigation of the samples using Extended X-ray Absorption Spectra (EXAFS) analysis to investigate structural changes due to the Ca and Mn-modified BaTiO3. TEM investigation of the crystal structure reveals the coexistence of the tetragonal and hexagonal phases of BaTiO3. Band gap modification and Urbach tail variation in UV-DRS measurements reveal a reduction of band gap from UV to Visible range (3.2 eV to 2 eV). This band gap change is correlated with the valence band modification observed in PES measurements due to localised defects in the material, and supported by theoretical Density of States calculations. The electron localisation function calculation is used to analyse the changes in the localised electron density near the dopant atoms. It reveals the local expansion and contraction of the lattice surrounding the dopant atom. All these structural modifications lead to variations in the dielectric properties and diffusive nature of the phase transition. The defect-induced structural modifications, multiple phase coexistence, band gap variations and dielectric properties are explored and correlated.

cond-mat.mtrl-sci↗

arXiv2025

Correlation of the role of Li-doping in control of O-vacancies and Li interstitial formations in NiO with electrochemical properties

Aliovalent doping in an oxide material introduces modifications in the valence state of the host cation and often leads to tailoring the oxygen content in the lattice. Moreover, if the dopant cation is larger than the host cation, the lattice strain and disorder may be affected. Such changes are expected to modify the electronic clouds and lead to different ligand fields, which in turn should modify the bond lengths, and therefore phonons, electronic properties, transport properties, and charge storage properties. To understand such correlations an example is being investigated in this study by doping a larger Li+ ion in a NiO lattice. The effect on structure, phonons, electronic properties, and charge storage properties are investigated and correlated in a first-of-its-kind report. The charge storage properties are observed to improve with Li+ doping until 3% substitution and thereafter decrease due to the generation of Li+ interstitial in a 6% incorporated sample. The connection of oxygen vacancies and Ni3+ formation with Li+ incorporation is the backbone of this report.

cond-mat.mtrl-sci↗

arXiv2024

Effect of pH on photocatalytic degradation of Methylene Blue in water by facile hydrothermally grown TiO2 Nanoparticles under Natural Sunlight

Each year, the production of synthetic dye wastewater reaches a trillion tons, posing a significant challenge to addressing water scarcity on a global level. Hence, the treatment of wastewater to prevent water scarcity is of prime importance, and failing to do so will increase ecotoxicological risks and human health. Textile wastewater contains harmful dye. Photocatalytic degradation of such dye-contaminated wastewater is crucial to purifying the dye-contaminated water. However, this process takes time, uses high-power lamps, and is expensive. Here, we report the effect of the concentration of precursor on the size and surface morphology of TiO2 nanostructures prepared by facile hydrothermal synthesis and its ability to perform as a photocatalyst to degrade the most common industrial textile dye, methylene blue (MB), under natural sunlight. The impact of particle size on the photocatalytic activity and photocarrier migration rate was thoroughly examined. Also, the effect of pH on adsorption and photocatalytic degradation has been evaluated in detail. With several optimized conditions, almost complete dye degradation was achieved within 40 minutes under the direct illumination of natural sunlight. The enhanced photocatalytic performance can be correlated to the synergetic effect of a higher charge transfer mechanism, good catalytic active surface area availability (386 m2/g), and several optimized parameters that affect the reaction efficacy. Additionally, repeated use of NPs without sacrificing performance five times confirmed its stability and Sustainability as a promising candidate for large-scale industrial textile wastewater remedies.

cond-mat.mtrl-sci↗

arXiv2024

Room temperature Multiferroicity and Magnetoelectric coupling in Ca/Mn modified BaTiO3

Materials with magnetoelectric coupling (MEC) between ferroic orders at room temperature are emerging field in modern technology and physics. BaTiO3 is a robust ferroelectric in which several doping has led to MEC. In Ca and Mn modified BaTiO3 has been study with a series of Ba(1-x)Ca(x)Ti(1-y)Mn(y)O3 (x=y= 0, 0.03, 0.06, 0.09), in this MEC was only observed in x=0.03. The structural modifications with changing substitution reveal a reduced Ti-O-Ti bond angle for this sample which is the most ferromagnetic in nature. A mixed phase of tetragonal P4mm and hexagonal P63/mmc space groups of BaTiO3 is observed in the substituted samples, with nominal contribution of the hexagonal phase for x=0.03. A valence state study using XPS and XANES reveals the presence of enhanced proportion of Mn3+ ions in the sample which support a pseudo Jahn-Teller distortion, thereby supporting the ferroelectricity for x=0.03. Direct evidences of MEC was obtained from magnetoelectric measurements. A magnetoelectric coupling coefficient, {\alpha}ME ~44 mVcm-1Oe-1 was obtained for dc magnetic field of 600 Oe and a 10Hz ac field of 40 Oe. Such MEC was not observed for higher substitution which emphasizes the sensitivity of the structural properties on substitution.

cond-mat.mtrl-sci↗

arXiv2024

Investigation of BaTiO$_3$-NiO composite as compact Dielectric Resonator Antenna

A compact dielectric resonator antenna has been fabricated on a microstrip transmission line for the purpose of C-band wireless communication using a ceramic material made out of a sintered mixture of BTO and NiO. The antenna parameters are optimized using Ansys HFSS software and verified experimentally. Ni replaces both Ba at A site and Ti at B site. Such a solid solution has a limit depending on the amount of NiO provided during sintering. A complete study of the structural changes and the dielectric constant enables the correlation with the resonating property. All the samples retain the ferroelectric tetragonal P4mm phase with a nominal decrease in the c/a ratio. NiO incorporation in BTO decreases the sintering temperature and shows two types of morphology associated with BTO-like and NiO-like phases. It induces prominent reduction in the permittivity and loss tangent (<0.01) in the range 100Hz to 1MHz. These properties make these samples suitable for DRA application in the C-Band range [4-8 GHz]. Experimental and theoretical assessment using HFSS software yields a C-band signal at ~7.27 GHz.

physics.app-ph↗

arXiv2023

Recent advances in La2NiMnO6 Double Perovskites for various applications; Challenges and opportunities

Double perovskites R2NiMnO6 (R= Rare earth element) (RNMO) are a significant class of materials owing to their Multifunctional properties with structural modifications. In particular, multifunctional double perovskite oxides La2NiMnO6 (LNMO) which possess both electric and magnetic orderings, chemical flexibility, versatility, and indispensable properties like high ferromagnetic curie temperature, high absorption rates, dielectrics, etc. have drawn a lot of attention due their rich physics and diverse applications in various technology. This justifies the intense research in this class of materials, and the keen interest they are subject to both the fundamental and practical side. In view of the demands of this material in lead-free perovskite solar cells, photocatalytic degradation of organic dyes, clean hydrogen production, electric tuneable devices, Fuel cells, gas sensing, and Biomedical applications, there is a need for an overview of all the literature so far, the ongoing research and the future prospective. This review summarised all the Physical and Structural Properties of LNMO such as electric, magnetic, catalytic, and dielectric properties with their underlying mechanisms. This review article provides insight into the scope of studies in LNMO material for exploring unexposed properties in new material research and to identify areas of future investigation of the materials in the double perovskite family.

cond-mat.mtrl-sci↗

arXiv2021

An overview of the structural correlation of magnetic and electrical properties of Pr2NiMnO6 Double perovskite

Double perovskites R2NiMnO6 (R= Rare earth element) (RNMO) are a significant class of materials owing to their varied tunability of the magnetic and electrical properties with the structural modifications. Pr2NiMnO6 (PNMO) is one of the least explored members of this series, which shows spin-phonon coupling, magnetocaloric effect, and electrochemical performance for various applications such as spintronics, magnetocaloric refrigerant, and solid oxide fuel cells. Most of the studies in PNMO are limited to the application domain and focus on the comparative study with different rare earth elements. Detailed structural studies like neutron diffraction are sparse in PNMO samples which will give a perception to the ordering in the compound that strongly depends on the physical and chemical properties. This review article goes through the various aspects of PNMO materials that have been reported till now and showcase the octahedral distortions and corresponding structural changes and the exchange interactions, which in turn correlates with the magnetic and electrical properties. The comparison study of PNMO with other members of the RNMO family and the relevance of PNMO over other members is also tried to showcase through this article. Hope this article provides an insight into the scope of studies in PNMO material for exploring unexposed properties of the materials in the double perovskite family.

cond-mat.mtrl-sci↗