Date: Wednesday, April 27th, 2016

Time: 11:00 AM

Location: Building 4, Room 125

Research and Development Center, Saudi Aramco

 

Microstructure is a very important part in research, especially in the development of new materials. The microstructural parameters play a major role in physical and chemical properties of the material. The Commission on Powder Diffraction (CPD) of the International Union of Crystallography  (IUCr)  conducted a round robin study on size and strain effects in ceria materials and described that both Lorentzian and Gaussian contributions to the size broadening term should be refined in the Rietveld refinement to obtain accurate size and strain values. Rietveld refinement is becoming progressively more popular for nonstructural applications, such as texture.  In the present study, the Rietveld refinement with the March model for the crystallographic preferred orientation has been extended to describe crystal 

structure, texture and crystallite size in the XRD data of 31 bimetallic and trimetallic oxide catalysts. The results revealed that the structural refinement parameters obtained from the Rietveld refinement with the March model agreed well with the corresponding single crystal structure. Additionally, the crystallite size of the anatase phase is between 126Å and 351Å. In this paper, the structure, texture, crystallite size and microstrain of the anatase phase obtained from Rietveld

 refinement will be discussed.

 

 

Dr. Husin Sitepu joined Saudi Aramco in late December 2008. Since then, he has contributed to several research projects by providing crystallographic information files (CIFs) on synthesized nano-materials and zeolite catalysts. Before joining Saudi Aramco, Dr Sitepu worked at the NIST Center for Neutron Research in Gaithersburg, MD, USA; at the Institut Laue-Langevin Neutrons for Science in Grenoble, France; at the Virginia Tech's Crystallography Laboratory in Blacksburg, VA, USA; at Ruhr-Universität Bochum in Bochum, Germany; at the University of British Columbia in Vancouver, Canada; and at the Curtin University in Perth, Australia. Since 1989, Dr Sitepu has published 38 papers in several peer-reviewed journals. Also, he published six lightly reviewed papers in the Saudi Aramco Journal of Technology and presented ​76 papers at various conferences. Dr Sitepu has a very strong background in physics at a research level, and he is an expert in

 crystallography preferred orientation and diffraction science through his extensive experience in Rietveld refinement of polycrystalline structures using X-ray, synchrotron and neutron powder diffraction data. Dr Sitepu received his Postgraduate Diploma, Master of Science by research and Ph.D. degrees in Physics from the Curtin University, Perth, Western Australia,in 1989, 1991 and 1998, respectively. Dr Sitepu is an active member of the International Center for Diffraction Data (ICDD), 

the International Union of Crystallography (IUCr) and the Neutron Scattering Society of America (NSSA).

 

Courtesy: SAICSC- ACS

 

There will be a get-together with refreshments at 10:45-11:00 a.m.

 

All faculty, researchers and graduate students are invited to attend.