Beyond Cu: The many colors of X-rays - selecting the best X-ray tube for your analysis
Modern laboratory diffractometers are designed to operate with X-ray tubes that may have many different types of anodes: Cr, Mn, Fe, Co, Cu, Mo, Ag, and more. The X-ray tube anode determines the wavelength of radiation that is produced for measurements. Despite the wide selection of anodes available, contemporary literature is dominated by research that uses Cu wavelength X-rays for powder diffraction and scattering studies—so much so that some researchers mistakenly believe it is the only choice because "everybody else uses it". While Cu anode X-ray tubes have always been widely used in laboratory diffractometers, literature provides many examples of measurements that benefited from the use of other wavelengths of radiation, including synchrotrons and neutron beamlines.
Selection of the X-ray anode can determine if the X-ray beam penetrates 4 microns or 100 microns into the sample, greatly influencing the irradiated volume and grain statistics that are important for quantitative phase analysis and texture analysis. Selection of the X-ray anode can optimize peak intensity and background noise. Selection of the X-ray anode can enhance sensitivity to certain dopants in an alloy or impurities in a mixture. Selection of the X-ray anode can determine the precision of large d-spac