The A.D. Wadsley Laboratory - April 1994
The X-Ray diffraction laboratory at the Division of Mineral Products was named the A.D. Wadsley Laboratory in April 1991, in a special dedication ceremony to honour the memory of one of Australia's most outstanding crystallographers, Dr. David Wadsley. The laboratory is divided into two sections, covering service and research activities, which are run by Mr. Lachlan Cranswick and Mr. Ian Madsen respectively.
(a) Scientific Services Powder X-ray Diffraction Laboratory.
The Service part of the laboratory deals with the analysis of powder samples and is built around two networked, PC controlled, automated Philips diffractometers (PW1710 and X'PERT systems) with diffracted beam curved graphite monochromators and 42-sample automatic sample changers. The diffractometers have both semi and full radiation enclosures to provide a safe working environment. There is a separate preparation area with sink, fume hood, preparation benches, microniser and centrifuge. A separate data analysis area has two networked 486 PCs using up-to-date software with the emphasis on user-friendliness. This includes the latest DOS JCPDS-ICDD powder diffraction data base on hard-disk for fast searches, latest DOS and MS-Windows XPLOT search-match software for easy data manipulation, Philips APD software for DOS, RIET7 Rietveld for DOS, ATOMS for DOS and also MS-Windows, Shelx93 for DOS, Word for Windows, 123 for Windows, SigmaPlot for DOS (and MS-Windows). Site XRD users and visitors have easy access to the internet via TCP-IP software, including the user-friendly PINE e-mail program. Applications include routine phase identification, quantitative analysis (using both Rietveld and non-Rietveld methods) and structure refinement using the Rietveld method.
The main internal research area of the laboratory is the application and optimisation of the Rietveld method for quantitative analysis and structure refinement. Another is involvement in developing the internet for the benefit of crystallographic communication via such facilities as the Usenet news groups, gopher and World Wide Web. Visitors from academia and other research organisations, who do not have access to powder XRD facilities, are welcome to use the equipment for fundamental research. Collaborative projects are possible and Lachlan is on hand to give assistance to users when requested. Industry users are also welcome but must pay commercial rates to use the equipment or have samples analysed.
(b) The Research Laboratory
The 'research' side of the laboratory houses a wide range of single crystal and powder diffraction equipment, including 3 Weissenberg cameras, 2 precession cameras and 2 Guinier powder cameras. Single crystal data sets can be collected using the recently revitalised Siemens AED diffractometer. A new, microprocessor based diffraction controller has been added to facilitate data collection using PC based software. The need to achieve the highest possible resolution in powder diffraction patterns prompted the Division of Mineral Products to include an incident beam focussing monochromator (IBFM) as a part of existing diffraction equipment. A Huber 611 monochromator with a curved Ge(111) crystal for Cu K(alpha1)has been adapted to work with a conventional Philips PW1050 goniometer. All of the adaptors required for the IBFM were designed and manufactured within the Division.
The Division has recently purchased a new powder diffractometer based on the Inel CPS120 curved position sensitive detector. The instrument will allow the collection of 120 degrees of diffraction data simultaneously, and will be ideally suited to the study of dynamic effects, e.g. high temperature studies. A range of sample holders have also been purchased, thus allowing the study of capillary specimens as well as conventional powder samples in both reflection and transmission mode. Staff in the Division have extensive experience in the application of the Rietveld method in both its structural and non-structural applications. Dr. Rod Hill has worked with Dr. Chris Howard from Ansto on major developments of the original Wiles and Young Rietveld code. Rod and Ian Madsen have carried out systematic studies to determine the optimum data collection conditions for Rietveld analysis, including the development of a novel variable counting time strategy which ensures that all peaks are collected with approximately equal counting statistics.
The Division also has considerable experience in the application of the Rietveld method for quantitative phase analysis and crystallite size/strain determination on a wide range of mineral and inorganic phase systems. The development of user-friendly software to remove the need for specialist crystallographic knowledge has been a feature of this work.
For further details, contact:
I.C. Madsen, tel (03) 6470366, Fax (03) 6463223
L. Cranswick, tel (03) 6470367, Fax as above