Control of the ferroelectricity in metastable state for orthorhombic RMnO 3 crystals Abstract. We have investigated orthorhombic RMnO 3 (R=(Gd 1−y Tb y)) crystals near the phase boundary between the paraelectric A-type-antiferromagnetic (AF) phase (PA) and the ferroelectric transverse-spiral-AF one (FS). The spiral AF structure breaks inversion symmetry and induces the ferroelectric polarizatio...

Pb0.4Bi1.6Sr2CaCu2O8+x (Bi(Pb)−2212) single crystal samples were studied using transmission electron microscopy (TEM), ab−plane (ρab) and c−axis (ρc) resistivity, and high resolution angle-resolved ultraviolet photoemission spectroscopy (ARUPS). TEM reveals that the modulation in the b−axis for Pb(0.4)−doped Bi(Pb)−2212 is dominantly of Pb−type that is not sensitive to the oxygen content of the...

Anion substitution is at present one of the pathways to destabilize metal borohydrides for solid state hydrogen storage. In this work, a solid solution of LiBH4 and LiCl is studied by density functional theory (DFT) calculations, thermodynamic modeling, X-ray diffraction, and infrared spectroscopy. It is shown that Cl substitution has minor effects on thermodynamic stability of either the ortho...

Hexagonal BaTiO3 undergoes a structural phase transition to an orthorhombic C2221 phase at T0 = 222 K. The transition is driven by a soft optical mode with E2u symmetry whose couplings force the appearance of a spontaneous E2g strain (improper ferroelastic character). Staying within the same E2u subspace, the system could in principle settle into a second (not observed) orthorhombic phase (Cmc2...

PbS quantum dots and nanoplatelets (NPLs) are of enormous interest in the development optoelectronic devices. However, some important aspects their nature remain unclear. Recent studies have revealed that colloidal NPLs may depart from rock-salt crystal structure bulk form an orthorhombic (Pnma) modification instead. To gain insight into implications such a change over properties, we synthesize...

Ab initio perturbed ion calculations were performed for the cubic, orthorhombic, hexagonal, and monoclinic phases of PbF2. A complete characterization of these phases was achieved in terms of the potential energy surfaces, the equations of state, and the phase-transition pressures. Thermal effects were included via a quasiharmonic nonempirical Debye model. The internal parameters of the unit ce...

Thermodynamically stable phases of sodium amide (NaNH2) at pressures up to 20 GPa have been determined using the ab initio evolutionary structure prediction. We find that the ground-state phase α-NaNH2 (orthorhombic, Fddd) first transforms into β-NaNH2 (orthorhombic, P21212) at 2.2 GPa; then, γ-NaNH2 (monoclinic, C2/c) becomes stable at 9.4 GPa. In addition to strong ionic bonding between Na an...

In light of directives around the world to eliminate toxic materials in various technologies, finding lead-free materials with high piezoelectric responses constitutes an important current scientific goal. As such, the recent discovery of a large electromechanical conversion near room temperature in (1-x)Ba(Zr0.2Ti0.8)O3-x(Ba0.7Ca0.3)TiO3 compounds has directed attention to understanding its or...

For temperatures above T∗ = 130K C60⋅C8H8 forms a cubic crystal consisting of two interpenetrating fcc sublattices, one of freely rotating Buckys C60 and the other of orientationally ordered cubane C8H8. The crystal structure below a discontinuous transition is found to be orthorhombic, but the nature of the ordering of the Buckys has not yet been determined. Here possible orderings of the Buck...