Tin(II) Aminothiolate and Tin(IV) Aminothiolate Selenide Compounds as Single-Source Precursors for Tin Chalcogenide Materials.

Tin aminothiolate compounds SnII(dmampS)2 (1) and SnIV(dmampS)2Se (2), where dmampS = 1-(dimethylamino)-2-methylpropane-2-thiolate, were synthesized. The molecular structures of 1 and 2 reveal a seesaw and distorted trigonal-bipyramidal geometry, respectively. The 1H NMR spectrum of 1 shows two types of resonances for the methyl groups of the α-carbon, methyl groups of the amino groups, and methylene groups at room temperature. On the other hand, the 1H NMR spectrum of 2 exhibits a single resonance for each of these groups. According to variable-temperature 1H NMR analysis, each of these two types of resonances occurring at relatively low temperatures (under 223 K for 1 and under 333 K for 2) are merged as a single resonance with increasing temperature. By using thermogravimetric and thermal decomposition analyses, the residual materials of compounds 1 and 2 are confirmed to be SnS and SnSSe, respectively. Compound 1 was subjected to a metal-organic chemical vapor deposition process, which allowed for the deposition of a dense and well-faceted orthorhombic phase SnS thin film on a SiO2/Si substrate with ∼200 nm thickness.

Temperature and Vibration Dependence of the Faraday Effect of Gd2O3 NPs-Doped Alumino-Silicate Glass Optical Fiber.

All-optical fiber magnetic field sensor based on the Gd2O3 nano-particles (NPs)-doped alumino-silicate glass optical fiber was developed, and its temperature and vibration dependence on the Faraday Effect were investigated. Uniformly embedded Gd2O3 NPs were identified to form in the core of the fiber, and the measured absorption peaks of the fiber appearing at 377 nm, 443 nm, and 551 nm were attributed to the Gd2O3 NPs incorporated in the fiber core. The Faraday rotation angle (FRA) of the linearly polarized light was measured at 650 nm with the induced magnetic field by the solenoid. The Faraday rotation angle was found to increase linearly with the magnetic field, and it was about 18.16° ± 0.048° at 0.142 Tesla (T) at temperatures of 25 °C-120 °C, by which the estimated Verdet constant was 3.19 rad/(T∙m) ± 0.01 rad/(T∙m). The variation of the FRA with time at 0.142 T and 120 °C was negligibly small (-9.78 × 10-4 °/min). The variation of the FRA under the mechanical vibration with the acceleration below 10 g and the frequency above 50 Hz was within 0.5°.

Blue-emitting Eu2+-activated LaOX (X = Cl, Br, and I) materials: crystal field effect.

Novel blue-emitting LaOBr:Eu(2+) and LaOI:Eu(2+) phosphors have been successfully synthesized and compared to LaOCl:Eu(2+). The emission spectra of LaOX:Eu(2+) (X = Cl, Br, and I) show that the peak maxima change somewhat to the red-shift region; 425 nm for LaOCl:Eu(2+), 427 nm for LaOBr:Eu(2+), and 431 nm for LaOI:Eu(2+), which is quite opposite to one based on spectrochemical series (I(-) < Br(-) < Cl(-)). From diffuse reflectance spectra, the band gap energies for LaOCl, LaOBr, and LaOI host lattice are estimated as 5.53 eV (44,594 cm(-1)), 5.35 eV (43,142 cm(-1)), and 4.82 eV (38,868 cm(-1)), respectively, using the Kubelka-Munk function. For LaOX host lattices, the band gap energies are gradually decreased going from Cl to I as the order of energy levels of np orbitals is Cl 3p < Br 4p < I 5p. A quantum wave function calculation from crystal field theory (CFT) indicates the same tendency with experimental data in the LaOX:Eu(2+) (X = Cl, Br, and I) phosphor materials. With considerations of the radial wave function shape, crystral structure differences and electronegativities among phosphor materials, the splitting energies of 5d orbitals are calculaed; ΔECl = 14,597 cm(-1), ΔEBr = 14,864 cm(-1), ΔEI = 15,001 cm(-1) for LaOX:Eu(2+) (X = Cl, Br, and I). It is noteworthy that the crystal field strength decreases when the interatomic distance decreases, which is probably dependent on the ionic radius of halide ions in the series of LaOX:Eu(2+) phosphor materials.