Prof. Reinhard Neder

Lehrstuhl für Kristallografie und Strukturphysik
Staudtstr. 3
D-91058 Erlangen

Raum 1.029

Tel.: +49 9131 85-25191
Fax: +49 9131 85-25182

 

Forschung
Offene Stellen und Abschlussarbeiten
Publikationen
Interactive Teaching
DISCUS_Workshop 2016

Research topics

The central research topic of our group are disordered crystal structures. We synthesized these and characterize them predominantly with scattering techniques. The diffraction pattern of disordered crystals exhibit strong diffuse scattering in addition to the Bragg reflections. Thus one of our main techniques is the analysis of disordered crystals via the Pair Distribution Function (PDF) techniques.

Currently our work covers:

Development of algorithms and computer code to analyze disordered crystals

The DISCUS program is a unique tool to simulate disordered crystals and to calculate the single crystal and powder diffraction data as well as the PDF. A particular strength of the DISCUS program is its ability to simulate nanoparticles including their organic shell. Further tools are under development to improves particularly this last aspect. The program is open source current releases are found at: DISCUS Releases. The development page is located at DISCUS Source Code. Further information is also found at the DISCUS Wiki.

DISCUS workshops in Erlangen are a regular event.

Discus Workshop

In September 2016 there will be a DISCUS Workshop During this workshop you will have the opportunity to learn to simulate crystal structures, modify these to generate disordered crystals, create nanoparticles, and to calculate the corresponding diffraction pattern. Don' t miss this opportunity!

 

Design and construction of a dedicated PDF beam line at PETRA III, DESY, Hamburg

Kaustuv Datta

As the need for PDF measurements is rapidly increasing the BMBF has funded a project to build a dedicated beam line at section 21. This project works in cooperation with the Swedish beam line at PETRA. We indent to build a beam line that will deliver a high intensity beam at 100 keV in order to offer fast measurements by use of an area detector and simultaneously reach a Qmax of 300 nm-1. This will allow fast in-situ experiments and will offer the ability to measure PDF's that are very well resolved in direct space.

 

ZnO as a very popular semiconductor material with a wide band gap

Mirijam Zobel, Haimantee Chatterjee

Nanoparticles are readily synthesized via a sol-gel techniques in ethanol solutions. We study this synthesis process in order to work out parameters that control the finite size of the nanoparticles. As the nanoparticles are stabilized by a shell of organic molecules, we employ both X-ray and neutron diffraction to determine the size, shape, structure, defect structure of the ZnO core, and the placement of the stabilizing molecules. Recently in-situ studies have been performed to study the nucleation and growth of ZnO nanoparticles.

Metaloxide nanoparticles such as titanium dioxide or zinc oxide (ZnO) are quite frequently produced in sol-gel processes. Although, also by adding organic stabilizers, the final nanoparticle size can be tuned very precisely, little is known about the evolution of the crystalline arrangement during the nucleation in solution. Hence, we conduct wide angle x-ray diffraction experiments on a model system of ZnO in different alcohols to learn more about the structure of precursors, nuclei as well as larger nanoparticles. We measure the currently lowest detectable concentrations of about 30 mM and can observe precursor structures of only 40 atoms. Without the addition of additional precipitation agents, those precursors nucleate and gradually grow on very long timescales of hours to diameters of 3 nm. Such in-situ PDF studies can currently be technically implemented at the ESRF in Grenoble, at Spring-8 in Japan, at DESY in Hamburg or APS in Chicago.

in-situ setup in-situ setup

Collaborations:

  • Prof. Dr. Dirk Zahn, chair for theoretical chemistry, Computer Chemistry Center (CCC), FAU Erlangen
  • Prof. Dr. Jean Geurts, chair for experimental physics III, University Würzburg

 

 

 

 

 

 

Offene Stellen und Abschlussarbeiten

Nanopartikel, z.B. das in Sonnencrèmes befindliche TiO2, wechselwirken mit der Umwelt: mit Wasser, mit dem menschlichen Körper, mit dem Blut, uvm. Die Grenzflächen zwischen verschiedenen TiO2 Nanopartikeln und wässrigen Umgebungen sind daher interessant um die Wechselwirkung der Nanopartikel mit dem menschlichen Körper besser zu verstehen. Im Rahmen einer Bachelor- oder Masterarbeit können Sie in unserer Arbeitsgruppe zum grundlegenden Verständnis von Nanopartikelgrenzflächen beitragen. Sie haben die Gelegenheit mit nach Frankreich oder USA auf eine Messreise an eine Synchrotronstrahlungsquelle zu fahren.

Nanoparticles, such as TiO2 in lotion, interact with their environment: with water, the human body, the blood. The interfaces between different TiO2 nanoparticles and aqueous surroundings are thus an interesting starting point to better understand the interaction of nanoparticles with the humand body. Within the scope of a Bachelor or Master thesis you can contribute in our workgroup to the fundamental understanding of nanoparticle solvent interfaces. You will get the chance to join a research team to a trip to a synchrotron radiation source and a beamtime there in either France or the USA.


Bachelor Arbeit


Nanopartikel-Wasser Wechselwirkungen in unserer Umwelt
Nanoparticle-water interactions in our environment

Master Arbeit


  TiO2 Nanopartikel-Wasser Grenzflächen in unserer Umwelt
Understanding TiO2 nanoparticle-water interfaces in our environment/





Master /Bachelor Arbeiten: Mustererkennung in diffuser Streuung

 

Ordnung im Chaos

 

I biete an, aktuelle

Bachelor / Master Arbeiten

um diffuse Streuung an imperfekten Kristallen zu untersuchen.

Viele Kristallstrukturen zeigen vielfältige Defekte, die die physikalischen Eigenschaften entscheidend prägen. Die Bestimmung einer Kristallstruktur aus Röntgen- oder Neutronenbeugungsexperimente ist heutzutage eine gut beherrschte Angelegenheit. Dagegen gibt es keine einheitliche Theorie der diffusen Streuung und eine automatische Bestimmung der Baufehler aus dem diffusen Beugungsbild zeigt sich bisher nur indirekt. Mit neuartigen Experimentellen Möglichkeiten kann man nun endlich diffuse Streuung quantitativ und schnell messen, und entdeckt dieses Phänomen bei vielen Kristallstrukturen.

In diesen Computer gestützten Arbeiten werden Sie 2-bzw. 3-dimensionale Kristalle mit Baufehlern generieren und deren diffuse Streuung analysieren. In Kooperation mit der Informatik ist es geplant Mustererkennungsmethoden zu entwickeln, die Zusammenhänge zwischen der Form bzw. Intensitätsverteilung der diffusen Streuung und den zugrunde legenden Baufehlern aufzeigen.

 

Beispiele diffuser Scattering (rot/gelb) zwischen den intensiven, scharfen Bragg Reflexen (weiße Maxima)

Welche charakteristischen Formen, Intensitäten zeigen derartige Muster und wie können dies verteilt sein?

 

Weitere Informationen bei

 

Professor Dr. Reinhard Neder

Lehrstuhl für Kristallographie und Strukturphysik

Friedrich-Alexander-Universität Erlangen-Nürnberg

Staudtstr. 3

91058 Erlangen

phone +49 9131 85 25 191

reinhard.neder@fau.de

 Und bei http://www.lks.physik.uni-erlangen.de/neder.shtml

http://www.lks.physik.uni-erlangen.de/diffraction/idif_b.html

http://discus.sourceforge.net

Juli 2015

 

Interactive Teaching

The Interactive Teaching pages at the department of cystallography allow you to explore the connection between a structure and its diffraction pattern. You will find simple simulations like a one dimensional row of atoms as well as simulations of shortr range order.

Publikationen