Latest News Archive

Please select Category, Year, and then Month to display items
Previous Archive
27 July 2021 | Story Leonie Bolleurs | Photo UFS Photo Archive
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

Research into veld fires in grassland can now help with scientifically-grounded evidence
2015-04-10

While cattle and game farmers are rejoicing in the recent rains which large areas of the country received in the past growing season, an expert from the University of the Free State’s Department of Animal, Wildlife, and Grassland Sciences, says that much of the highly inflammable material now available could lead to large-scale veld fires this coming winter.

Prof Hennie Snyman, professor and  researcher in the Department of Animal, Wildlife, and Grassland Sciences, warns that cattle and game farmers should be aware, in good time, of this problem which is about to rear its head. He proposes that farmers must burn firebreaks as a precaution.

At present, Prof Snyman focuses his research on the impact of fire and burning on the functioning of the grassland ecosystem, especially in the drier grassland regions.

He says the impact of fire on the functioning of ecosystems in the ‘sour’ grassland areas of Southern Africa (which includes Kwazulu-Natal, Limpopo, Mpumalanga, the Eastern Cape, and the Harrismith environs) is already well established, but less information  is available for ‘sweet’ semi-arid grassland areas. According to Prof Snyman, there is no reason to burn grassland in this semi-arid area. Grazing by animals can be effectively used because of the high quality material without having to burn it off. In the sourer pasturage, fire may well form part of the functioning of the grassland ecosystem in view of the fact that a quality problem might develop after which the grass must rejuvenate by letting it burn.

Prof Snyman, who has already been busy with the research for ten years, says quantified data on the impact of fire on the soil and plants were not available previously for the semi-arid grassland areas. Fires start frequently because of lightning, carelessness, freak accidents, or damaged power lines, and farmers must be recompensed for this damage.

The shortage of proper research on the impact of fires on soil and plants has led to burnt areas not being withdrawn from grazing for long enough. The lack of information has also led to farmers, who have lost grazing to fires, not being compensated fairly or even being over-compensated.

“When above-and below-ground plant production, together with efficient water usage, is taken into account, burnt grassland requires at least two full growing seasons to recover completely.”       

Prof Snyman says farmers frequently make the mistake of allowing animals to graze on burnt grassland as soon as it begins to sprout, causing considerable damage to the plants.

“Plant roots are more sensitive to fire than the above-ground plant material. This is the reason why seasonal above-ground production losses from fire in the first growing season after the fire can amount to half of the unburnt veld. The ecosystem must first recover completely in order to be productive and sustainable again for the long term. The faster burnt veld is grazed again, the longer the ecosystem takes to recover completely, lengthening the problem with fodder shortages further.  

Prof Snyman feels that fire as a management tool in semi-arid grassland is questionable if there is no specific purpose for it, as it can increase ecological and financial risk management in the short term.

Prof Snyman says more research is needed to quantify the impact of runaway fires on both grassland plant productivity and soil properties in terms of different seasonal climatic variations.

“The current information may already serve as valuable guidelines regarding claims arising from unforeseen fires, which often amount to thousands of rand, and are sometimes based on unscientific evidence.”

Prof Snyman’s research findings have been used successfully as guidelines for compensation aspects in several court cases.

 

We use cookies to make interactions with our websites and services easy and meaningful. To better understand how they are used, read more about the UFS cookie policy. By continuing to use this site you are giving us your consent to do this.

Accept