Single-crystal samples of Al-doped potassium niobate (KNbO3) [KN] were synthesized by a high-temperature flux technique. X-ray diffraction analysis of the crystal suggests that a single phase with an orthorhombic structure was formed. The dielectric studies of the KN single crystal as a function of temperature (from 30 to 500 °C) show that the compounds underwent a phase transition, which was confirmed by thermal analysis of the DTA curve. The measured loss tangent of the crystal, which is in good agreement with the dielectric studies. The ferroelectric property of the crystal was confirmed by studying the hysteresis loop. In this study, several parameters, like the coercive field and spontaneous polarization, were measured and calculated. The domain study was carried out using a trinocular microscope, which reported the formation of the 60° domain line and dislocation etch pits. The effects of the electric field on the domain of the Al-doped KN single crystal were discussed.

Synthesis, structural, dielectric and domain properties of Al-doped KNbO3 single crystal

Processing, micro structures and mechanical properties of AZ91E, Sic and fly ash composites: A review

The domain structure of the single crystal KNbO3 (KN) in the orthorhombic ferroelectrics phase at room temperature is investigated using optical and trinocular microscope. The cleavage face of ferr...

Effect of methyl alcohol and nitric acid as an etchant on the motions of ferroelectric domains in Al-doped KNbO3 single crystal

Photographic proof of domain wall nucleation was originated on the surface of Al-doped KNbO3 single crystal. For the photographic proof, experiment were performed using a trinocular microscopy technique. Nucleation and evaporation of 60° and 90° domain were conducted under the applied electric field at room temperature which is consistent to the elastic theory of dislocation. An attempt was made by the dislocation model to clarify that the nucleation and evaporation of the domain walls was dependent on impurity dipoles. The appearance of nucleation and evaporation of domains under the influence of electric fields was interestingly studied in domain engineering.

Nucleation and evaporation of new domains under the influence of successive electric field in Al-doped KNbO3 single crystal

K1-xCaxNbO3 (x = 0–0.2) ceramic samples were prepared by self-sacrifice method to study the effects of Ca2+ doping on the crystal structure, dielectric properties and magnetic phase transition of KNbO3. XRD analysis showed that all samples belong to a single-phase orthogonal crystal system with a spatial group of Amm2. The valence states of K, Nb and O elements, the atomic proportion in K1-xCaxNbO3 (x = 0–0.2) samples, and the relationship between the binding energies of K, Nb and O and x were studied through XPS. SEM showed that Ca2+ doping had a significant regulation effect on the micromorphology and grain size of KNO samples. Two transitions were observed in er -T of KNbO3, the first transition was at 213 °C and the second transition was at 424 °C, corresponding to the ferroelectric phase transition from the orthogonal phase to the tetragonal phase and from the tetragonal phase to the cubic phase, respectively. The TC decreased from 424 °C to 415 °C with the increase of x. The variation relationship of M-T of K1-xCaxNbO3 (x = 0–0.2) samples within the range of 5-350k was measured. It is found from M-T curve that the M of KNO sample is positive when T   Td. This conclusion was confirmed by testing the M-H variation relationship, providing experimental basis for the diamagnetism of KNO at room temperature.

Vivek B. Korde

Papers

Domain imaging in Fe-doped KNbO3 single crystal via trinocular microscopy and scanning electron microscopy

Synthesis, structural, dielectric and domain properties of Al-doped KNbO3 single crystal

Effect of methyl alcohol and nitric acid as an etchant on the motions of ferroelectric domains in Al-doped KNbO3 single crystal

Kinetics of ferroelectric domains investigated by etching technique in Al-doped KNbO3 single crystal

Nucleation and evaporation of new domains under the influence of successive electric field in Al-doped KNbO3 single crystal