Detailed knowledge of the phase diagram and the nature of the competing magnetic and superconducting phases is imperative for a deeper understanding of the physics of iron-based superconductivity. Magnetism in the iron-based superconductors is usually a stripe-type spin-density-wave, which breaks the tetragonal symmetry of the lattice, and is known to compete strongly with superconductivity. Re...

Oxide compositions of equimolar YO1.5 and TaO2.5 in the Y–Ta–Zr–O system have attractive properties for high-temperature applications, including as thermal barrier coatings. The effect of zirconia concentration, from 0 to 20 mol.% cation, on the tetragonal-to-monoclinic phase transition has been studied using high-temperature X-ray diffraction, Raman spectroscopy and electron microscopy. The tr...

The low-temperature orthorhombic (LTO) phase transition in La 2−x Sr x CuO 4 can be interpreted as a dynamic Jahn-Teller effect, in which the degenerate electronic states are associated with the large densities of states at the two van Hove singularities. The equations describing this phase are strongly nonlinear. This paper illustrates some consequences of the nonlinearity, by presenting a ric...

The effect of pressure on the crystalline structure and superconducting transition temperature (T(c)) of the 111-type Na(1-x)FeAs system using in situ high-pressure synchrotron X-ray powder diffraction and diamond anvil cell techniques is studied. A pressure-induced tetragonal to tetragonal isostructural phase transition was found. The systematic evolution of the FeAs(4) tetrahedron as a functi...

Alumina/zirconia (Al2O3/ZrO2) multilayer thin films were deposited on Si (100) substrates at an optimized oxygen partial pressure of 3 Pa at room temperature by pulsed laser deposition. The Al2O3/ZrO2 multilayers of 10:10, 5:10, 5:5, and 4:4 nm with 40 bilayers were deposited alternately in order to stabilize a high-temperature phase of zirconia at room temperature. All these films were charact...

A pathway for achieving intense green light emitting LiGdF4:Yb,Er upconversion nanophosphors (UCNPs) via Y(3+) doping is demonstrated. It was revealed that Y(3+) doping initiated the formation of a tetragonal phase and affected the particle size. Single tetragonal-phase LiGd0.4Y0.4F4:Yb(18%),Er(2%) (LGY0.4F:Yb,Er) UCNPs exhibited strong upconversion (UC) green luminescence and tetragonal bipyra...

objectives: masking ability of a restorative material plays a role in hiding colored substructures; however, the masking ability of zirconia ceramic (zrc) has not yet been clearly understood in zirconia-based restorations. this study evaluated the effect of three different core materials on masking ability of a zrc. materials and methods: ten zirconia disc samples, 0.5mm in thickness and 10mm i...

objectives : studies on the effect of coloring procedures on the bond strength of zirconia to resin cement are lacking in the literature. this study evaluated the effect of dipping of zirconia ceramic in different liquid color shades on the microtensile bond strength (mtbs) of zirconia ceramic to resin cement. materials and methods: this in vitro study was conducted on 100 microbar specimens di...

We report the dynamics of the structure of CaSiO3 perovskite from ab initio molecular dynamics (AIMD) calculations at high pressure (P up to 130 GPa) and high temperature (T up to 5000 K). Our calculations indicate three separate stability fields: orthorhombic, tetragonal and cubic, with the tetragonal phase dominating the pressure and temperature region between room temperature and 4000 K. The...