The crystal structure of zirconium oxide nanoparticles was refined by the Rietveld analysis of synchrotron X-ray powder diffraction data measured at 298 K. In the nanoparticles, two phases of tetragonal ZrO(2 - delta) (average particle size: 11 +/- 2 nm) and monoclinic ZrO2 (average particle size: 24 +/- 4 nm) existed, where the weight fractions were estimated to be 84.9 and 15.1 wt%, respectiv...

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...

We present our theoretical results on the mechanism of two transitions in vanadium spinel oxides AV2O4 (A=Zn, Mg, or Cd) in which magnetic V cations constitute a geometrically-frustrated pyrochlore structure. We have derived an effective spin-orbital-lattice coupled model in the strong correlation limit of the multiorbital Hubbard model, and applied Monte Carlo simulation to the model. The resu...

Barium titanate (BaTiO3) powders with particle sizes about 50 nm in diameter were synthesized using a hydrothermal route. The powders were characterized using various experimental techniques such as XRD, TEM and Raman spectroscopy, and they showed a good crystallinity and homogeneity without heat treatments. Also, Raman spectra showed the presence of the tetragonal phase. In addition, various c...

Full-perovskite Pb0.87Ba0.1La0.02(Zr0.6Sn0.33Ti0.07)O3 (PBLZST) thin films were fabricated by a sol-gel method. These revealed both rhombohedral and tetragonal phases, as opposed to the full-tetragonal phase previously reported in ceramics. The fractions of tetragonal and rhombohedral phases are found to be strongly dependent on film thickness. The fraction of tetragonal grains increases with i...

An efficient solid-state approach was established to synthesize (K0.5Na0.5) NbO3 ceramics using calcination kinetics and microwave assisted sintering. Milling of carbonate and oxide raw materials were carried out for 15h to obtain homogeneous nano particles. The crystallite size of 5.30 nm was obtained for the KNN system after calcination through optimized parameters and observed to be stoichio...

Crystals of a single-point mutant (T109S) of Escherichia coli dihydroorotase (DHOase) with diminished activity grown in the presence of L-dihydroorotate (L-DHO) are tetragonal, with a monomer in the asymmetric unit. These crystals are extremely unstable and disintegrate shortly after formation, which is followed by the growth of orthorhombic crystals from the remnants of the tetragonal crystals...

We discuss the strategy for development of novel functional materials with the tetragonal tungsten bronze structure. From the starting composition Ba6GaNb9O30, the effect of A- and B-site substitutions on the dielectric properties is used to develop an understanding of the origin and stability of the dipolar response in these compounds. Both tetragonal strain induced by large B-site cations and...