High-quality Cu2O crystals with various morphologies grown by thermal oxidation

We present an improved preparation method for, and experimental results on, high-quality crystals of cuprous oxide (${\mathrm{Cu}}_2\mathrm{O}$) grown by thermal oxidation. X-ray diffraction and low-temperature optical measurements at 2 K confirm excellent characteristics that are on par with natural-growth cuprite crystals. Synthetic ${\mathrm{Cu}}_2\mathrm{O}$ crystals were prepared in different geometries including platelets, cylindrical wires, and spheroids. Interestingly, we observed that the oxidation of Cu wires at high temperatures leads to the formation of hollow tubules of ${\mathrm{Cu}}_2\mathrm{O}$. Such unconventional structures of ${\mathrm{Cu}}_2\mathrm{O}$ could be utilized to confine excitonic matter, or serve as high-density exciton–polariton cavities.     

Correlations between apparent activation energy and thermostability and glass forming ability for Fe based metallic glasses

Apparent activation energies (E_g) of glass transition, glass transition temperature (T_g) and crystallization temperature (T_x) of amorphous alloys of composition Fe_91?xB_xZr₅Nb₄ (FBZN, 5 ? x ? 30 at.%) and Fe_61?xCo_xZr₅B₃₀Nb₄ (FCZBN, 0 ? x ? 15 at.%) were obtained by using differential scanning calorimeter (DSC) measurement and Kissinger equation, and correlations between E_g and T_g, T_x and glass-forming ability (GFA) were studied in the present work. It was found that the T_g and T_x are not independent each other for each glass composition in the two alloy systems, but related by a formula, T_x = αT_g+β, where α and β are constants, and were measured by nonisothermally scanning in the DSC together with the Lasocka’s equation. The E_g was found to be directly proportional to α and β, respectively, and had a correlation with T_x and T_g, $T_{\text{x}}=\frac{E_{\text{g}}-1.09}{3.527}{T}_{\text{g}}-\frac{E_{\text{g}}-4.86}{0.0041}$, indicating that E_g determines linear relationship between T_x and T_g. Supercooled liquid region ΔT_x is used as characterization of GFA of the Fe based metallic glasses and related to E_g and T_g by a formula: $\mathrm{\Delta }{T}_{\text{x}}=E_{\text{g}}(\frac{T_{\text{g}}}{3.527}-234.9)+1185.37-1.309T_{\text{g}}$, indicating that E_g and T_g can characterize GFA of the Fe based metallic glass well.     

Optical properties of amorphous (As0.33S0.67)100−xTex (x = 0, 1, 5 and 10) chalcogenide thin films,photodoped step-by-step with silver

We have analysed in detail the effect of silver-content on the optical properties of Ag-photodoped amorphous (As_0.33S_0.67)_100?xTe_x (with x = 0, 1, 5 and 10 at.%) chalcogenide thin films; the chalcogenide host layers were prepared by vacuum thermal evaporation. Films of composition Ag_y[(As_0.33S_0.67)_100?xTe_x]_100?y, with y ? 18 at.%, were successfully obtained by successively photodissolving about 20- or 40-nm-thick layers of silver. The optical constants (n, k) have been accurately determined by an improved envelope method [J.M. González-Leal, R. Prieto-Alcón, J.A. Angel, D.A. Minkov, E. Márquez, Appl. Opt. 41 (2002) 7300], based on the two envelope curves of the optical-transmission spectrum, obtained at normal incidence. The dispersion of the refractive index of the Ag-photodoped chalcogenide films is analysed in terms of the Wemple–DiDomenico single-effective-oscillator model: $n^2(?\omega )=1-E_{\text{o}}{E}_{\text{d}}/(E_{\text{o}}^2-(?\omega {)}^2)$, where E_o is the single-oscillator energy, and E_d the dispersion energy. We found that the refractive index of the Ag-doped samples strongly increases with the Ag-content, whereas the optical band gap, $E_{\text{g}}^{\text{opt}}$, decreases also notably. For instance, in the particular case of x = 10 at.%, the largest Te-content, $E_{\text{g}}^{\text{opt}}$ decreases from 2.17 down to 1.67 eV. It should also be mentioned that, in the case of the undoped samples, when the Te-concentration increases from zero up to 10 at.%, the value of $E_{\text{g}}^{\text{opt}}$ decreases from 2.49 down to 2.17 eV.     

Ternary chalcogenides LiBC2 (B = In, Ga; C = S, Se, Te) for mid-IR nonlinear optics

We review on the growth improvement and optical characterization of a new family of ternary lithium-based chalcogenide crystals of generic formula ${\text{LiB}}^{\text{III}}{\text{C}}_2^{\text{VI}}$ (B = In, Ga; C = S, Se, Te) which displays improved thermo-mechanical properties for mid-IR nonlinear optical applications. Some of these compounds are now produced in sufficiently large size, single-domain quality to allow their implementation in optical parametric oscillators.