• T P SINHA

Articles written in Bulletin of Materials Science

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

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, vibrational and microwave properties of $x$La(Mg$_{1/2}$Ti$_{1/2}$)O$_3$–($1 - x$)Ba(Mg$_{1/3}$Nb$_{2/3}$)O$_3$

Vibrational and microwave dielectric properties of $x$La(Mg$_{1/2}$Ti$_{1/2}$)O$_3$–($1 - x$)Ba(Mg$_{1/3}$Nb$_{2/3}$)O$_3$ ($x = 0.0, 0.1,0.3, 0.5, 0.7, 0.9$ and 1.0) synthesized by the solid-state reaction technique are investigated. The Rietveld refinement of the X-ray diffraction (XRD) data confirms that Ba(Mg$_{1/3}$Nb$_{2/3}$)O$_3$ ($x = 0.0$) adopts the 1:2-ordered structure with trigonal P-3$m$1 space group, whereas La(Mg$_{1/2}$Ti$_{1/2}$)O$_3$ ($x = 1$) has monoclinic $P2_1/n$ crystal structure. Both the materials have single phase crystal structure. For $x = 0.1$, the sample is found to have double phase. Further, with the increase in the value of $x$, the crystal structure becomes monoclinic $P2_1/n$. The vibrational properties of the materials are studied by the Raman spectroscopy and are correlated with the structural parameters. All the materials show high dielectric constant ($\epsilon_r$ > 35) at microwave range. The factors affecting the microwave dielectric properties are discussed based on the vibrational andstructural data.

• # Bulletin of Materials Science

Volume 45, 2022
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Continuous Article Publishing mode

• # 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