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Unique X-ray system gives Department of Physics a competitive advantage

27 July 2021 | Story Leonie Bolleurs | Photo UFS Photo Archive

Hendrik_web read more — Prof Hendrik Swart played a key role in the Department of Physics acquiring the PHI Quantes XPS system, the first in Africa and one of only 20 in the world.

The state-of-the-art equipment in the Department of Physics at the University of the Free State (UFS) differentiates this department from its competitors. Availability of the equipment makes it possible for researchers as well as students to deliver work that receives national and international recognition.

Recently, the department acquired a PHI Quantes XPS system, the first in Africa and one of only 20 in the world.

Creating better phosphor

“The Quantes XPS system uses X-rays to determine the chemical composition of molecules on the surface of a sample. The system is unique in the sense that it also has an extra X-ray source that can determine the chemical state below the surface, which was not possible in the past. This will help us to dictate the position of defects in our phosphor materials that will consequently enable us to create better phosphor for solid state lighting as well as solar cell applications,” explains Prof Hendrik Swart, Senior Professor in the Department of Physics, who also holds the SARChI Chair in Solid State Luminescent and Advanced Materials.

After he had the opportunity to observe the system in the factory in Chigasaki, Kanagawa, Japan, where he attended a conference, Prof Swart was very impressed by its performance. He discussed it with Prof Koos Terblans, Head of the department, and other colleagues, and started making plans to buy the system.

When the department first bought the X-ray photoelectron spectroscopy (XPS) system in 2007/2008, it became the national facility on XPS measurements. Not only is this an upgrade of the XPS system bought 14 years ago, but the new system will enable the department to do more measurements. “The number of samples that we have to handle has just become too much for one system. The new system’s increased capacity for making measurements addresses this challenge and it also gives UFS scientists and postgraduate students more time to spend on fundamental measurements to develop research of a higher level,” says Prof Swart.

(The Quantes XPS system. Photo:Supplied)

Explaining about the measurements, Prof Swart says: “This advanced X-ray photoelectron spectroscopy (XPS) instrument has the capability to analyse the very small area that the user is interested in and a large area of the uniform sample surface. The two different types of X-ray sources – the hard X-ray source and the more conventional soft X-ray source – can be switched automatically, allowing users to analyse the same area and/or points of a sample. The PHI Quantes XPS system ensures the availability of superior features such as automatic analysis, automatic sample transfer, turnkey charge neutralisation, and advanced data processing.”

“This XPS instrument is designed to pioneer new methods and applications transcending conventional ideas of what is possible.”

Optimising efficiency of materials

Prof Swart says the Department of Physics, especially the Research Chair in Advanced and Luminescent Materials, is developing new high-technology materials on a daily basis. “It is very important to know the chemical composition and defect distribution of the materials in order to add value to the fabrication of these materials,” he adds.

“The distribution of these defects is vital for the efficiency of the phosphor materials. If we know where these defects are located, we can determine the mechanisms of the light output coming from these phosphors,” describes Prof Swart.

Research conducted as part of the Research Chair in Solid State Luminescent and Advanced Materials will benefit significantly from this new system.

(Prof Koos Terblans, Head of the Department of Physics next to the Quantes XPS system. Photo:Supplied)

“We are currently concentrating on phosphors as sensors (temperature), light-emitting diodes (LEDs), and solar cells, where we optimise the efficiency and durability of these materials. Any new knowledge, which I believe the PHI Quantes XPS system will provide us, will help us to reach our goal much quicker,” he says.

Apart from the positive impact on research, the PHI Quantes XPS system will also be a benefit to society in the long term. Improved LEDs can be used to save electricity, and better solar cells can help to generate electricity, to mention but two examples.

News Archive

UFS involved in project to light up the townships

2006-06-06

The parties involved with the project are from the left: Prof Hendrik Swart (Departmental Chairperson of the UFS Department of Physics), Dr Thembela Hillie (CSIR), Prof Neerich Revaprasadu (Department of Chemistry at the University of Zululand) and Dr Wynand Steyn (CSIR).

UFS involved in project that could light up the townships

The University of the Free State’s (UFS) Department of Physics is involved with a project that could make life easier in the townships through the use of artificial light.

“The project is based on the use of sunlight to activate nano material in for example cement and paint during the day. At night the cement or paint can then radiate light,” said Prof Hendrik Swart, Departmental Chairperson of the UFS Department of Physics.

According to Prof Swart an amount of R3,9 million has been made available by the Council for Scientific and Industrial Research (CSIR) for the further development of the project.

Prof Swart visited the University of Florida in America in 1995 for a year where he researched luminescent phosphor material that is suitable for flat panel television screens. The red, green and blue spots on the television screens originate from these kinds of phosphor materials. “At that stage plasma television screens were only a dream. Today it is sold everywhere,” said Prof Swart.

“Upon my return I started a research group at the UFS which investigated the degrading of phosphor material. We also started to concentrate on the effectiveness of nano phosphors. In the mean time our cooperation with the Americans was strengthened with follow-up visits to America of my colleagues, Prof Koos Terblans and Mr Martin Ntwaeaborwa,” said Prof Swart.

“Nano phosphors are basically luminescent powders that consist of particles that are 1 millionth of a millimetre. These particles can provide light as soon as they are illuminated with, for instance, sunlight. The amount of time these particles can provide light, is determined by the impurities in the material,” said Prof Swart.

According to Prof Swart nano particles are developed and linked to infrastructure materials in order for these materials to be excited during the day by sunlight and then it emits light during night time.

“The nano material is of such a nature that it can be mixed with materials, such as paint or cement. The yellow lines of roads can for example emit light in a natural way during night time,” said Prof Swart.

About a year ago Prof Swart and Dr Thembela Hillie, a former Ph D-student of the UFS Department of Physics, had discussions with Prof Neerich Revaprasadu from the University of Zululand and the CSIR about the possibility of mixing these nano phosphor particles with other materials that can be used as light sources in the building of roads and houses.

“Prof Revaprasadu is also actively involved in the research of nano materials. Our efforts resulted in the CSIR approving the further extension of the project,” said Prof Swart.

“The UFS and the University of Zululand are currently busy investigating ways to extend the light emitting time,” said Prof Swart.

“There are eight M Sc and Ph D-students from the UFS and about five students from the University of Zululand working on this research project. The Department of Physics at the Qwaqwa Campus of the UFS, with Francis Dejene as subject head, is also involved with the project,” said Prof Swart.

According to Prof Swart the further applications of nano materials are unlimited. “Children whose parents cannot afford electricity can for instance leave any object such as a lamp, that is covered with these phosphor particles, in the sun during the day and use it at night as a light for study purposes,” said Prof Swart.

According to Prof Swart the further extension of the project will take about two years. “During this time we want to determine how the effectiveness of the phosphors can be increased. Discussions with the government and other role players for the possible implementation of the project are also part of our planning,” said Prof Swart.

Media release
Issued by: Lacea Loader
Media Representative
Tel: (051) 401-2584
Cell: 083 645 2454
E-mail: loaderl.stg@mail.uovs.ac.za
6 June 2006

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