A. Bhanumathi

Ferroelectric properties of tungsten bronze ceramics

Abstract Modified strontium barium niobate and lead potassium niobate ceramics with tungsten bronze structure were prepared by the conventional ceramic techniques. The effect of various dopants on the properties of strontium barium niobate ceramics have been investigated. Curie temperature decreases with the increase of the ionic radius of dopant. The properties of filled and unfilled structures are compared. The effect of La3+ on Lead Potassium Niobate is discussed.

Ferroelectric behaviour of lanthanum doped (NaK)NbO3 ceramics

Abstract Specimens of NaxKx−3yLayNbO3 where x = 0.5 and y = 0.05, 0.1 and 0.15 have been prepared by conventional ceramic technique. The dielectric properties and conductivity were studied as a function of temperature. Substitution of rare-earth ions in (NaK)NbO3 play an important role on the ferroelectric curie temperature as well as dielectric constant. Curie temperature decreases as the concentration of the rare-earth ions increases. Lattice parameters are determined from X-ray studies.

Modified (NaK)NbO3 ceramics for transducer applications

Abstract Solid solutions of Na x K x−3y Pr y NbO3 where x = 0.5 and y = 0.05 and 0.1 were prepared by conventional ceramic technique. Two phase transitions were observed in dielectric studies. Curie temperature decreases as the concentration of rare-earth ion increases. The monoclinic lattice parameters are calculated from X-ray studies. Mechanical quality factor and frequency constant increases with Pr3+ addition.

Structural properties of inorganic materials: tungsten bronze SBN ceramics

Rare-earth doped strontium barium niobates were synthesized using usual ceramic technique. The dopants are La, Ce, Gd, Sm and Nd. The materials were characterized by XRD and density measurements. The grain sizes were determined from SEM analysis. Lattice parameters changed uniformly with rare-earth dopants in unfilled structures. Density measurements and SEM analysis confirmed only minute changes in the densities of the ceramics.

Effect of Nb5+ substitution on the piezoelectric properties of PLZT ceramics

Abstract The effect of Nb5+ substitution on the dielectric and piezoelectric properties of PLZT (5/65/35) ceramics are investigated for different Nb concentrations. Optimum piezoelectric properties are obtained for 0.5 mole% Nb substitution. The room temperature dielectric constant increases with Nb concentration whereas Curie temperature Tc and peak dielectric constant ϵTc decreases with increase of Nb concentration. As the Nb concentration increases from 0.5 mole% to 1.5 mole% both Kp and Kt decrease.

Relaxor behaviour in certain tungsten bronze ceramics

Abstract Relaxor ferroelectrics with high Curie temperature are attractive candidates for electro-optic and pyroelectric devices. Solid solutions of (Srx Ba1–x)0.8 Na0.4 Nb2O6 where × = 0.3 to 0.6 have been prepared by the conventional ceramic technique. The properties of relaxor ferroelectrics are dependent on ceramic processing conditions. Relaxor characteristics have been studied. A broad transition is observed in all the compositions. The broadness decreases gradually with the increase of strontium concentration.

Piezoelectric properties, hysteresis behaviour and dielectric properties of PMN-PZT ceramics

Ferroelectric and piezoelectric properties ofxPb(Mg1/3Nb2/3)O3−(1−x)Pb (Zr0·55Ti0·45)O3 system have been investigated. X-ray diffraction patterns indicate rhombohedral and cubic structures. Maximum dielectric constant and piezoelectric properties are exhibited by 0·5–0·5 PMN-PZT composition.Pr is high in 0·6–0·4 PMN-PZT composition.

Domain orientation and piezoelectric properties of Ag doped PMN-PZT ceramics

The hysteresis, dielectric, and piezoelectric properties of ternary 0.5PMN-0.5-PZT (lead magnesium niobate-lead zirconate titanate) ceramics with Ag substitution are described. These ceramics show good square hysteresis loops and thus are promising for thin-film memory applications. At high Ag concentrations the dielectric loss decreased, indicating an increase in the ordering of the structure. A marked increase in the piezoelectric properties, particularly the thickness coupling factor and the piezoelectric charge coefficient, d/sub 33/, was observed.<<ETX>>

Ferroelectric investigation of tungsten bronze lead barium lanthanum niobate ceramics with high d33 values

Abstract This paper reports the Ferroelectric and Piezoelectric properties of lanthanum doped lead barium niobate ceramics with formula Pbx-3y/2 Ba1-x Lay Nb2 O6. Piezoelectric properties showed a strong enhancement at morphotrophic phase boundary between tetragonal and orthorhombic phases. d33 value of 350 pc/N obtained is highest so far reported for this ceramic. Kt value is also very high.

Ferroelectric properties of modified strontium barium niobate ceramics

Modified Strontium Barium Niobate ceramics with tungsten bronze filled structure were prepared by the conventional ceramic techniques. The dielectric constant is measured at 1 MHz as a function of temperature. The ferroelectric transition temperature is considerably lowered by the introduction of rare-earth Nd3+. The dielectric constant is found to be lower in Lithium composition.