Browsing by Author "Rajbala Nain"

Now showing 1 - 2 of 2

Synergistic doping effect of La2O3 on BaO-TiO2-SiO2 glass-ceramics: Evolution of physical, structural, morphological, and dielectric behaviour for electronics applications
(Elsevier Ltd, 2024) Rajat Kumar Mishra; Sarvesh Kumar Avinashi; Savita Kumari; Shweta; Rajbala Nain; Tarun Katheriya; Rakesh Kumar Dwivedi; Shail Upadhyay; Chandkiram Gautam
Herein, numerous investigations such as structural, physical, morphological, optical, and dielectric properties of BaO-TiO2-SiO2 glass-ceramics (GCs) doped with La2O3 were carried out. Various glasses were synthesized within a glass system [(30-x)BaO.30TiO2.40SiO2].x[La2O3], (x=0,2,4, and 6 mol% of La2O3) using a conventional melt-quench method. XRD confirmed the amorphous nature of the glass samples. Differential scanning calorimetry (DSC) was used to identify the glass transition (Tg) and crystallization temperatures (Tc) of the samples. Further, controlled heat treatment of the glasses led to the fabrication of glass-ceramics and their XRD analysis revealed polycrystalline structure, predominantly consisting of a major phase of tetragonal Fresnoite (Ba2TiO8Si2). Furthermore, with the addition of La2O3, the prepared GCs exhibited improved physical properties, including an increase in density (3.783–4.611 g/cm3) and oxygen packing density (81.177–92.303 g-atom/l). Additionally, to study the bonding and structural characteristics, FTIR and Raman spectroscopies were conducted. In order to study the optical properties, UV–visible spectroscopy was executed and showed a reduced indirect energy band gap from 4.290 to 4.220 eV with increasing La2O3. To study the morphological behaviour, SEM and TEM were performed. Eventually, to examine the dielectric characteristics, relative dielectric constant (εr) and dielectric loss (Tan δ) over the glass-ceramics was conducted using a ‘Novocontrol Impedance Analyzer’. The εr and Tan δ values exhibited temperature-dependent behaviour and found to be increased within the frequency range of 1 kHz to 1 MHz. The BTSLC6 glass-ceramic, (24BaO.30TiO2.40SiO2.6La2O3), exhibited a high dielectric constant of ⁓ 9335 and a low dielectric loss of 0.52 at 1 kHz, mainly due to space charge polarization. This makes it a promising candidate for applications in multilayer ceramic capacitors, energy storage, photonics, and electronics. © 2024 Elsevier B.V.
Unveiling of physical, structural, morphological, and electrical properties of Fe2O3doped (30-x)BaO•30TiO2•40SiO2•x[Fe2O3], (0≤x≤6) glass-ceramics potential for energy storage devices
(Elsevier Ltd, 2025) Rajat Kumar Mishra; Sarvesh Kumar Avinashi; Sachin Kumar Yadav; Zaireen Fatima; Rajbala Nain; Rakhi; Savita Kumari; Shweta; Neeraj Mehta; Rakesh Kumar Dwivedi; Chandkiram Gautam
Glass-ceramics with tuneable dielectric properties are increasingly sought after for next-generation multilayer ceramic capacitors (MLCCs) used in advanced electronic applications. However, developing compositions that simultaneously offer high dielectric constants, low dielectric losses, and excellent thermal stability remains a significant challenge. Herein, Fe2O3-doped (30-x)BaO•30TiO2•40SiO2•x[Fe2O3] (0≤x ≤ 6 mol%) glass and glass-ceramics are synthesized using a melt-quenching followed by controlled heat treatment technique. XRD is performed which indicates a transition from amorphous to crystalline structures after heat treatment, with a major phase of tetragonal fresnoite (Ba2TiSi2O8). To check the bonding mechanisms, Fourier transform infrared (FTIR) and Raman spectroscopies are performed. X-ray photoelectron spectroscopy was performed for analysing the elemental composition, and electronic state of a material. However, to study the microstructural behaviour, crystalline nature, and compositional variations, scanning electron microscopy (SEM) and transmission electron microscopy (TEM), followed by energy dispersive spectroscopy (EDS) were also performed. Dielectric properties of the GCs are studied over 10 Hz to 1 MHz. Notably, 24BaO•30TiO2•40SiO2•6Fe2O3(BTSFC6) (x = 6 mol%) sample demonstrates improved dielectric constant (εr = 31740.4) and low dielectric loss (Tanδ = 0.13) at 10 Hz (at 500 °C). The incorporation of Fe2O3not only enhances the AC conductivity but also modifies the electrical relaxation behaviour, as evident from modulus and Cole–Cole plots, which indicate non-Debye-type relaxation and a negative temperature coefficient of resistivity (NTCR) behaviour. Furthermore, hysteresis loop measurements were conducted, revealing that an increase in Fe2O3content in BTSFC glass-ceramics leads to a systematic enhancement in ferroelectric properties and energy storage capacity. This improvement enables material to be tailored for a wide range of applications, from low-loss dielectrics to high-energy storage devices. Therefore, this study demonstrates that strategic Fe2O3doping effectively tailors the structural and dielectric characteristics of barium-titanate silicate glass-ceramics, positioning the BTSFC6 composition as a promising candidate for the fabrication of energy storage devices in demanding thermal and electronic environments. © 2025 Elsevier Ltd and Techna Group S.r.l. All rights are reserved, including those for text and data mining, AI training, and similar technologies.