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Cyclo[18]carbon has received considerable attention thanks to its novel geometric configuration and special electronic structure. Superalkalis have low ionization energy. Doping a superalkali in cyclo[18]carbon is an effective method to improve the optical properties of the system because considerable electron transfer occurs. In this paper, the geometry, bonding properties, electronic structure, absorption spectrum, and nonlinear optical (NLO) properties of superalkaline M 3O (M = Li, Na)-doped cyclo[18]carbon were studied by using density functional theory. M 3O and the C18 rings are not coplanar. The C18 ring still exhibits alternating long and short bonds. The charge transfer between M 3O and C18 forms stable [ M 3O]+[C18]− ionic complexes. C18 M 3O (M = Li, Na) shows striking optical nonlinearity, i.e., their first- and second-order hyperpolarizability (β vec and γ ||) increase considerably at λ = 1907 nm and 1460 nm. [ABSTRACT FROM AUTHOR]

An n-GaO x thin film is deposited on a single-crystal boron-doped diamond by RF magnetron sputtering to form the pn heterojunction. The n-GaO x thin film presents a small surface roughness and a large optical band gap of 4.85 eV. In addition, the band alignment is measured using x-ray photoelectron spectroscopy to evaluate the heterojunction properties. The GaO x /diamond heterojunction shows a type-II staggered band configuration, where the valence and conduction band offsets are 1.28 eV and 1.93 eV, respectively. These results confirm the feasibility of the use of n-GaO x as a termination structure for diamond power devices. [ABSTRACT FROM AUTHOR]

Taking the advantage of "parity kicks" pulses, we investigate the non-classical correlation dynamics and quantum state transfer in an atom–cavity–fiber system, which consists of two identical subsystems, each subsystem comprising of multiple two-level atoms trapped in two remote single-model optical cavities that are linked by an optical fiber. It is found that the non-classical correlations and the fidelity of quantum state transfer (between the atoms) can be greatly improved by the parity kicks pulses. In particular, with decrease of the time intervals between two consecutive pulses, perfect non-classical correlation transfer and entangled state transfer can be achieved. [ABSTRACT FROM AUTHOR]

Lanthanum silicates La10Si6−xMgxO27−x (x = 0–0.4) were prepared by solid state synthesis to investigate the effect of Mg doping on crystal structure and ionic conductivity. Rietveld analysis of the powder XRD patterns reveals that Mg substitution on Si site results in significant enlargement of channel triangles, favoring oxide-ion conduction. Furthermore, an increase of Mg concentration significantly influences the linear density of interstitial oxygen, which plays an important role in ionic conductivity. The Arrhenius plots of La10Si6−xMgxO27−x (x = 0–0.4) suggest that Mg-doped samples present higher conductivity and lower activation energy than non-doped La10Si6O27, and La10Si5.8Mg0.2O26.8 exhibits the highest conductivity with a value of 3.0×10−2 S ·cm−1 at 700 °C. Such conductive behavior agrees well with the refined results. The corresponding mechanism has been discussed in this paper. [ABSTRACT FROM AUTHOR]

Structural and spectroscopic properties of Sr2ZnTeO6 (SZTO) were investigated by angle-dispersive synchrotron X-ray powder diffraction and Raman spectroscopy in a diamond anvil cell up to 31 GPa at room temperature. Although SZTO remained stable up to the highest pressure, the different pressure coefficients of the normalized axial compressibility were obtained as βab=8.16x10-3 GPa-1 and βc=7.61x10-3 GPa-1. The bulk modulus B0 was determined to be 190(1) GPa by fitting the pressure--volume data using the Birch--Murnaghan equation of state. All the observed Raman modes exhibited a broadening effect under high pressure. The vibrational band ν1 around 765 cm-1, which is associated with the Te-O stretching mode in the basal plane of the TeO6 octahedron had the largest pressure coefficient, and the Grüneisen parameters for all the observed phonon modes were also calculated and presented. These parameters could be used to measure the amount of uniaxial or biaxial strain, providing a fundamental tool for monitoring the magnitude of the shift of phonon frequencies with strains. [ABSTRACT FROM AUTHOR]

The effect of external quasi-hydrostatic pressure on the inverse spinel structure of LiCuVO4 was studied in this paper. High-pressure synchrotron X-ray diffraction and Raman spectroscopy measurements were carried out at room temperature up to 35.7 and 40.3 GPa, respectively. At a pressure of about 20 GPa, both Raman spectra and X-ray diffraction results indicate that LiCuVO4 was transformed into a monoclinic phase, which remained stable up to at least 35.7 GPa. Upon release of pressure, the high-pressure phase returned to the initial phase. The pressure dependence of the volume of low pressure orthorhombic phase and high-pressure monoclinic phase were described by a second-order Birch-Murnaghan equation of state, which yielded bulk modulus values of B0 = 197(5) and 232(8) GPa, respectively. The results support the empirical suggestion that the oxide spinels have similar bulk modulus around 200 GPa. [ABSTRACT FROM AUTHOR]

The structural compression mechanism and compressibility of gallium oxyhydroxide, α-GaOOH, are investigated by in situ synchrotron radiation x-ray diffraction at pressures up to 31.0 GPa by using the diamond anvil cell technique. The α-GaOOH sustains its orthorhombic structure when the pressure is lower than 23.8 GPa. The compression is anisotropic under hydrostatic conditions, with the a-axis being most compressible. The compression proceeds mainly by shrinkage of the void channels formed by the coordination GaO3(OH)3 octahedra of the crystal structure. Anomaly is found in the compression behavior to occur at 14.6 GPa, which is concomitant with the equatorial distortion of the GaO3(OH)3 octahedra. A kink occurs at 14.6 GPa in the plot of finite strain f versus normalized stress F, indicating the change in the bulk compression behavior. The fittings of a second order Birch–Murnaghan equation of state to the P–V data in different pressure ranges result in the bulk moduli B0 = 199(1) GPa for P < 14.6 GPa and B0 = 167(2) GPa for P > 14.6 GPa. As the pressure is increased to about 25.8 GPa, a first-order phase transformation takes place, which is evidenced by the abrupt decrease in the unit cell volume and b and c lattice parameters. [ABSTRACT FROM AUTHOR]

This study presents high pressure phase transitions and equation of states of cerium under pressures up to 51 GPa at room temperature. The angle-dispersive x-ray diffraction experiments are carried out using a high energy synchrotron x-ray source. The bulk moduli of high pressure phases of cerium are calculated using the Birch–Murnaghan equation. We discuss and correct several previous controversial conclusions, which are caused by the measurement accuracy or personal explanation. The c/a axial ratio of ε-Ce has a maximum value at about 29 GPa, i.e., c/a ≈ 1.690. [ABSTRACT FROM AUTHOR]

The high-pressure behaviors of SmFeO3 are investigated by angle-dispersive synchrotron X-ray powder diffraction under a pressure of up to 40.3 GPa at room temperature. The crystal structure of SmFeO3 remains stable at up to the highest pressure. The different pressure coefficients of the normalized axial compressibility are obtained to be βa = 0.60 × 10−3 GPa−1, βb = 0.79 × 10m3 GPa−1, βc = 1.28 × 10−3 GPa−1, and the bulk modulus (B0) is determined to be 293(3) GPa by fitting the pressure-volume data using the Birch—Murnaghan equation of state. Furthermore, the larger compressibility of the FeO6 octahedra suggests the evolution of the orthorhombic structure towards higher symmetry configuration at high pressures. [ABSTRACT FROM AUTHOR]

The photoluminescence (PL) properties of Y2O3:Eu3+ nanophosphors were systematically investigated with the goal of improving the color quality and quantum efficiency of Y2O3:Eu3+ nanophosphors for potential applications in nanoscale devices. The emission spectra, excitation spectra and fluorescence decay curves were employed to trace the energy transfer process from Eu3+ at C3i site to Eu3+ at C2 site. The experimental results show that the energy transfer process becomes more and more efficient with the increase in the Eu3+ concentration. The emission of Eu3+ at C2 site is favorable because it has high radiative efficiency and better color quality. The successful suppress of the emission Eu3+ at C3i is especially important for its applications in general illumination or display technology. The quantum efficiency and color quality of Y2O3:Eu3+ can be improved by controlling the energy transfer between the Eu3+ at S6 site and Eu3+ at C2 site. [ABSTRACT FROM AUTHOR]

Structural and spectroscopic properties of Sr2ZnTeO6 (SZTO) were investigated by angle-dispersive synchrotron X-ray powder diffraction and Raman spectroscopy in a diamond anvil cell up to 31 GPa at room temperature. Although SZTO remained stable up to the highest pressure, the different pressure coefficients of the normalized axial compressibility were obtained as βab=8.16x10-3 GPa-1 and βc=7.61x10-3 GPa-1. The bulk modulus B0 was determined to be 190(1) GPa by fitting the pressure--volume data using the Birch--Murnaghan equation of state. All the observed Raman modes exhibited a broadening effect under high pressure. The vibrational band ν1 around 765 cm-1, which is associated with the Te-O stretching mode in the basal plane of the TeO6 octahedron had the largest pressure coefficient, and the Grüneisen parameters for all the observed phonon modes were also calculated and presented. These parameters could be used to measure the amount of uniaxial or biaxial strain, providing a fundamental tool for monitoring the magnitude of the shift of phonon frequencies with strains. [ABSTRACT FROM AUTHOR]