Articles written in Bulletin of Materials Science

    • Synthesis and electrical studies of modified PbTiO3 ceramics: (Pb1−xCax) (Mn0·05W0·05Ti0·90) O3

      K Prasad R Sati R N P Choudhary T P Sinha

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      Modified ceramics (Pb1−xCax)[(Mn0·5W0·5)0·10Ti0·90]O3 have been fabricated forx=0, 0·05, 0·10 and 0·15 by high temperature solid state reaction technique. XRD, SEM, DTA and electrical studies of the sample withx=0·10 have been performed. These studies show that the sample is homogeneous single phase perovskite type with tetragonal structure. The phase transition occurs at 330°C. Electrical behaviour of other samples have also been investigated as a function of frequency (1 kHz to 1 MHz) and temperature (26°C to 300°C). The samples withx=0·05 and 0·10 have low loss, low dielectric constant, and show negligible pyroelectric effect. The sample withx=0·15 has minimum values ofɛ and loss which are temperature independent up to about 200°C. It also shows good pyroelectric behaviour. Hence it may be of use in pyroelectric infrared sensors.

    • Structural and dielectric properties of Pb(Li1/4Sm1/4Mo1/2)O3 ceramics

      S Bera R N P Choudhary

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      The ceramic samples of lithium-samarium modified lead molybdate, Pb(Li1/4 Sm1/4 Mo1/2)O3 (PLSM)—a member of ABO3 family were prepared by solid state reaction technique at ≈ 600–700°C. Preliminary X-ray analysis suggests the formation of single phase orthorhombic compound of PLSM. Studies of surface morphology, uniform particle/grain distribution, and presence of elements in the compound were completed using scanning electron microscope (SEM). Measurements of dielectric constant (ɛ), loss (tanδ) and conductivity (σ) at different frequencies and temperatures provided that the compound has a strong dielectric anomaly at 107°C.

    • Studies of structural and electrical properties of Pb(Li1/4Eu1/4Mo1/2)O3 ceramics

      S Bera R N P Choudhary

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      Polycrystalline sample of Pb(Li1/4Eu1/4Mo1/2)O3 was prepared by usual ceramic route. X-ray diffraction, SEM and EDAX were used to check the formation, homogeneity and elements present in the compound. The measurement of dielectric constant (ɛ), dielectric loss (tanδ), hysteresis loop parameters (e.g. spontaneous polarization) as function of frequency and temperature suggest that the compound is a ferroelectric one and has a ferro-paraelectric phase transition at 112 ± 2°C. The measurement of dc resistivity both as function of biasing electric field and temperature of the compound suggests that the compound has negative temperature coefficient (NTC) of resistance above 100°C.

    • Ferroelectric phase transition in Ba5RTi3Nb7O30 [R=Nd, Eu, Gd] ceramics

      R N P Choudhary S R Shannigrahi A K Singh

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      Polycrystalline samples of Ba5RTi3Nb7O30 [R=Nd, Eu, Gd], were prepared using high-temperature solid-state reaction technique. Preliminary X-ray structural analysis of the compounds shows the formation of single phase compounds (orthorhombic crystal system) at room temperature. Detailed studies of dielectric properties (ɛ, tanδ,σ) as a function of frequency (400 Hz to 10 kHz) and temperature (30° to 380°C) show that these compounds exhibit diffuse ferroelectric phase transition.

    • Structural, impedance and electrical evaluation of complex perovskite: Ca(Mn$_{1/3}$Ni$_{1/3}$W$_{1/3}$)O$_3$


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      A complex perovskite Ca(Mn$_{1/3}$Ni$_{1/3}$W$_{1/3}$)O$_3$, abbreviated as CMNWO, is synthesized by adopting the solid-stateceramic procedure. The X-ray diffraction analysis of CMNWO shows that the present perovskite is acquiring a cubic crystal structure having the cell dimension of $a = 3.8321$ Å. The obtained cell parameter is in good agreement with the theoretical cell parameter obtained from the SPuDS-V2.19.05.14 code. The micrograph describes the uniform grain distribution in the CMNWO sample. The average crystallite size of the sample was found to be 50.98 nm, which was calculated using the Scherrer relation. The dielectric and electrical properties like dielectric constant, dissipation factor, impedance, electrical modulus and conductivity of CMNWO were studied. The activation energies were determined from the AC-conductivity data in the temperature range of 200–350$^{\circ}$C and 360–500$^{\circ}$C. The dielectric spectra with temperature suggest that the present CMNWO is semiconducting in nature and follows the negative temperature coefficient of resistance kind of behaviour.

    • Structural, electrical and magnetic properties of lead-free double perovskite multiferroic: BiSrFeCeO$_6$


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      In this paper, detailed studies of structural, micro-structural, dielectric, electrical and magneto-electric characteristics of chemically synthesized a new double perovskite, BiSrFeCeO$_6$ (strontium cerate-modified bismuthferrite), are reported. The basic crystal data (unit cell dimension and orthorhombic crystal system) of the compound were obtained by analysing the room temperature X-ray powder diffraction data. Study of the surface microstructure of a sintered pellet sample, recorded by scanning electron microscope at room temperature, reveals the formation of highdensity sample with the homogeneously and uniformly distributed grains of different size and shape. Analysis of frequency- temperature dependence of dielectric parameters and nature of hysteresis loop has exhibited the ferroelectric characteristics of the material. Studies of complex impedance and modulus components at different temperatures and frequencies have provided electrical characteristics of grains and grain boundaries present in the material, which are closely related to its microstructure. Thus, the correlation between the crystal structure with electrical properties and relaxation mechanism of the prepared sample has been established. The type of dielectric relaxation process and mechanism occurred in the compound have also been studied not only by analysis of the dielectric properties (${\varepsilon}_r$, tan${\delta}$) and impedance parameters, but also from the study of frequency-temperature conductivity. The existence of negative temperature coefficient of resistance (NTCR) characteristics in the material has been confirmed from the temperature and dc conductivity analysis. Similarly, the frequency and ac conductivity analysis show that the studied compound follows Jonscher’s universal power law. Based on the structural, ferroelectric, magnetic and magneto-electric characteristics, multiferroism in the new composition of bismuth ferrite has been established.

  • Bulletin of Materials Science | News

    • Dr Shanti Swarup Bhatnagar for Science and Technology

      Posted on October 12, 2020

      Prof. Subi Jacob George — Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru
      Chemical Sciences 2020

      Prof. Surajit Dhara — School of Physics, University of Hyderabad, Hyderabad
      Physical Sciences 2020

    • Editorial Note on Continuous Article Publication

      Posted on July 25, 2019

      Click here for Editorial Note on CAP Mode

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