Institute of Material Physics

Bad Münster am Stein-Ebernburg, Germany

Institute of Material Physics

Bad Münster am Stein-Ebernburg, Germany
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Huang Q.-S.,Institute of Material Physics | Huang Q.-S.,Key Laboratory of Display Materials and Photoelectric Devices of Ministry of Education | Huang Q.-S.,Tianjin University of Technology | Li L.,Institute of Material Physics | And 14 more authors.
Optoelectronics Letters | Year: 2010

Undoped ZnS nanocrystals (NCs) with different precursor molar ratios of [S2-]/[Zn2+] are prepared by the chemical precipitation method. The structural and optical properties of the samples are characterized by the X-ray diffraction (XRD) spectra, photoluminescence (PL) spectra and PL decay spectra. The XRD analysis shows that the crystal quality of ZnS NCs becomes better and the grain size is larger at higher [S2-]/[Zn2+] ratios. The PL peaked at 430 nm decreases with the [S2-]/[Zn2+] ratio increasing, which is ascribed to the structure defects of NCs. A multi-exponential decay time curve with hundreds of picoseconds, several nanoseconds and tens of nanoseconds is obtained, which also shows a distinct and regular change with [S2-]/[Zn2+] ratio. It is indicated that the PL and emission decay properties of ZnS NCs mainly depend on the change of the defects number from different particle sizes. © 2010 Tianjin University of Technology and Springer-Verlag Berlin Heidelberg.

Huang Q.-S.,Institute of Material Physics | Huang Q.-S.,Tianjin University of Technology | Dong D.-Q.,Institute of Material Physics | Dong D.-Q.,Tianjin University of Technology | And 8 more authors.
Chinese Physics Letters | Year: 2010

Spherical organic-bonded ZnS nanocrystals with 4.0±0.2 nm in diameter are synthesized by a liquid-solid-solution method. The photoluminescence spectrum of sample ([S2-]/[Zn2+] 1.0) shows a strong white emission with a peak at 490 nm and ∼ 170 nm full widths at half maximum. By Gauss fitting, the white emission is attributed to the overlap of a blue emission and a green-yellow emission, originating from electronic transitions from internal S2- vacancies level to valence band and to the internal Zn2+ vacancy level, respectively. After sealingZnS nanocrystals onto InGaN chips, the device shows CIE coordinates of (0.29,0.30), which indicates their potential applications for white light emitting diodes. © 2010 Chinese Physical Society and IOP Publishing Ltd.

Stoffers A.,Institute of Material Physics | Oberdorfer C.,Institute of Material Physics | Schmitz G.,Institute of Material Physics
Langmuir | Year: 2012

Self-assembled monolayers of amino-undecanethiol and perfluoro-decanethiol are studied by atom probe tomography based on laser-assisted controlled field desorption. In the case of hydrogenated chains the identification of detected molecular species is difficult because of residual hydrocarbons. By contrast, fractions of the fluorinated chains can be unequivocally identified. Although chemically similar, the evaporation of both chains appears in significantly different molecular fractions. For the fluorinated chains, a well-ordered evaporation sequence is determined that allows conclusions to be drawn about the strength of bonds under field conditions and may lay the basis for the future numerical reconstruction of the chemical structure of such films. © 2011 American Chemical Society.

Schmitz G.,Institute of Material Physics | Abouzari R.,Institute of Material Physics | Berkemeier F.,Institute of Material Physics | Gallasch T.,Institute of Material Physics | And 3 more authors.
Zeitschrift fur Physikalische Chemie | Year: 2010

Thin film ion-conductive materials may represent essential components of future all-solidstate batteries. Besides, they are also of interest from a fundamental point of view. In this article, the deposition of thin films of complex oxides and amorphous glasses is discussed. Methods of local chemical analysis by analytical electron microscopy and atom probe tomography are described and studies of atomic transport in sputtered network glasses are presented. As experimental examples, thin films of Li borate and silicate glasses, LiC0O2, V2O5, and Li 4 Ti5O12are addressed. © by Oldenbourg Wissenschaftsverlag, München.

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