In situ transmission electron microscopy analysis of electron beam induced crystallization of amorphous marks in phase-change materials

\u3cp\u3eThe crystallization of melt-quenched amorphous data marks in a crystalline (Ga\u3csub\u3e15\u3c/sub\u3eSb\u3csub\u3e85\u3c/sub\u3e) phase-change layer from rewritable disks by transmission electron microscopy was discussed. Electron irradiation induced crystallization was obtained at room temperature by using a 120 kV. A comparison with laser-crystallized amorphous marks was made. An electron beam (e \u3csup\u3e-\u3c/sup\u3e beam) induced crystallization started from the amorphous crystalline interface. A dependence of growth velocity on e\u3csup\u3e-\u3c/sup\u3e beam intensity and growth direction was observed.\u3c/p\u3

Luminescence and Energy Transfer of [Ru(bpy) 3 ] 2+ , [Cr(ox) 3 ] 3- , and [Os(bpy) 3 ] 2+ in Three-Dimensional Oxalato-Networks

Luminescence and energy transfer in [Zn1-xRux(bpy)3][NaAl1-yCry(ox)3] (x ≈ 0.01, y = 0.006 − 0.22; bpy = 2,2‘-bipyridine, ox = C2O42-) and [Zn1-x-yRuxOsy(bpy)3][NaAl(ox)3] (x ≈ 0.01, y = 0.012) are presented and discussed. Surprisingly, the luminescence of the isolated luminophores [Ru(bpy)3]2+ and [Os(bpy)3]2+ in [Zn(bpy)3][NaAl(ox)3] is hardly quenched at room temperature. Steady-state luminescence spectra and decay curves show that energy transfer occurs between [Ru(bpy)3]2+ and [Cr(ox)3]3- and between [Ru(bpy)3]2+ and [Os(bpy)3]2+ in [Zn1-xRux(bpy)3][NaAl1-yCry(ox)3] and [Zn1-x-yRuxOsy(bpy)3] [NaAl(ox)3], respectively. For a quantitative investigation of the energy transfer, a shell type model is developed, using a Monte Carlo procedure and the structural parameters of the systems. A good description of the experimental data is obtained assuming electric dipole−electric dipole interaction between donors and acceptors, with a critical distance Rc for [Ru(bpy)3]2+ to [Cr(ox)3]3- energy transfer of 15 Å and for [Ru(bpy)3]2+ to [Os(bpy)3]2+ energy transfer of 33 Å. These values are in good agreement with those derived using the Förster−Dexter theory

Archival-overwrite performance of GeSnSb-based phase-change discs

\u3cp\u3eHigh-speed rewritable digital versatile discs based on GeSnSb phase-change materials may show poor archival-overwrite performance. We have related this to a decrease in the crystalline reflectivity. Transmission electron microscopy images indicate that this is connected to morphology changes of the material. Materials optimization by addition of dopants such as Se or Te can stabilize the crystalline reflectivity and, as a result, improve the archival-overwrite performance to within the specifications for optical recording.\u3c/p\u3