P B Joshi
Articles written in Bulletin of Materials Science
Volume 24 Issue 2 April 2001 pp 243-248 Ferroelectric Materials
The paper reports investigations of relative permittivity, 𝜀𝑟, electrical conductivity, 𝜎, saturation polarization, 𝑃𝑠, infrared absorption and structural properties of compensating valency substituted BaTiO3. The compositions investigated are BaTi(1-𝑥)Mn𝑥/2Nb𝑥/2O3 for 𝑥 = 0.00; 0.025; 0.05; 0.1; 0.2; 0.4. The compositions for 𝑥 < 0.1 are observed to be ferroelectric and the transition temperature and value of 𝜀𝑟 are observed to decrease as concentration of substitution is increased. The dielectric investigations are carried out on two sets of samples
as sintered and
Annealing is observed to improve quality factor `𝑄' of the materials with a consequent reduction in the 𝜀𝑟. The observations on 𝜀𝑟 and saturation polarization suggest that additional material engineering efforts are required to improve the material properties.
Volume 25 Issue 4 August 2002 pp 347-350 Ferroelectrics
Polycrystalline Pb(Mn0.5W0.5)O3, a ferroelectric oxide having perovskite structure, was prepared by high temperature solid state reaction technique. Preliminary X-ray diffraction analysis confirms single phase formation with the lattice parameters 𝑎 = 7.2501 Å, 𝑏 = 8.1276 Å and 𝑐 = 12.0232 Å. Room temperature dielectric constant (𝜀' ) and loss tangent (tan 𝛿) were scanned with respect to frequency in the range 100 Hz–1 MHz. Detailed study of dielectric constant and electrical conductivity reveals a phase change around 400 K, which is quite different from those in the other materials of the same type. Further, the seebeck coefficient (𝛼) is temperature independent. The conduction is interpreted as due to small polaron hopping.
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