Nanoscale potassium niobate (KNbO3) powders of orthorhombic structure were synthesized using the sol-gel method. The heat-treatment temperature of the gels had a pronounced effect on KNbO3 particle size and morphology. Field emission scanning electron microscopy and transmission electron microscopy were used to determine particle size and morphology. The average KNbO3 grain size was estimated t...

The photocatalytic production of H2 from water splitting was demonstrated on Ni/NiO/KNbO3/CdS nanocomposites using visible light irradiation at wavelengths >400 nm in the presence of isopropanol. The inherent photocatalytic activity of bulk-phase CdS was enhanced by combining Q-sized CdS with KNbO3 and Ni deposited on KNbO3. Enhanced activity is most likely due to effective charge separation of...

In demand for low-loss wide-band communication devices, Potassium niobate (KNbO3) is now receiving renewed interests because it has been found to exhibit high electromechanical coupling. This paper describes the optimum cuts of KNbO3 for bulk acoustic waves (BAW) and surface acoustic waves (SAW) devices, with expectation of their application in the future. In addition, our recent works on growt...

The origin of low thermal conductivity in niobium-containing perovskites was investigated. Therefore, dense NaNbO3 and KNbO3 ceramics were sintered by spark plasma sintering. grain size the 1–10 μm range. ceramic has shown a stable circa 2.6 W m−1 K−1 from 373 to 1000 K KNbO3, values 2.5 plateau at 1.2 since 673 K. This value is lowest reported for an oxide presenting perovskite structure. such...

We determine the anisotropy of the mobility of photoexcited charge carriers in single crystals of KNbO3 and BaTiO3 by means of a purely optical method. In orthorhombic KNbO3 the mobility anisotropy is measured for both electrons and holes giving ma mc 1.05 6 0.06, mb mc 2.9 6 0.3 for holes and ma mc 1.15 6 0.09, mb mc 1.9 6 0.2 for electrons. In BaTiO3 we find for holes ma mc 19.6 6 0.6. Our ex...

Owing to its high nonlinearity and low passive losses, KNbO3 has great potential as a medium for efficient frequency doubling and parametric oscillation." 2 For example, KNbO3 has been used successfully for the production of cw blue light by frequency doubling of a dye laser,3 doubling of a semiconductor diode laser,4 and nonlinear mixing of diode and Nd:YAG lasers.5 In recent work we observed ...

The lattice instabilities of perovskite structure oxides are responsible for many of their interesting properties, such as temperature-dependent ferroelectric phase transitions. First-principles calculations using linear response theory provide an accurate means to determine the lattice dynamics throughout the entire Brillouin zone (BZ). Using the LAPW linear response method [1], we have previo...

With the aim to get an insight in the origin of differences in the earlier reported calculation results for KNbO3 and to test the recently proposed “NFP” implementation of the full-potential linear muffin-tin orbital (FP-LMTO) method by M. Methfessel and M. van Schilfgaarde, we perform a comparative study of the ferroelectric instability in KNbO3 by FP-LMTO and full-potential linear augmented p...

We use molecular-dynamics simulation to examine the order-disorder behavior in pure ferroelectric KNbO3 and in KNbO3-KTaO3 ferroelectric-paraelectric solid solutions and superlattices. We find that the order-disorder behavior is remarkably robust and plays an important role in both the polarization rotation associated with switching of the perfect crystal and in the dynamical behavior of the so...