The introduction of lead-free metal halide powder into a scintillation screen took some tinkering. KAUST researchers have worked out the right technique. They were able to produce an exceptionally efficient, robust and flexible scintillation film. This will bring significant improvements in medical, industrial and security X-ray imaging.
Scintillation materials release “scintillate” in response to absorbing invisible X-ray high-energy photons. They are used to construct digital images which reveal the relative passage and obstruction of X-rays as they encounter any solid object. This includes a region of the body, an industrial component or an object being screened for security purposes.
X-ray scintillation is already routine technology. Scientists are continually exploring ways to make it more sensitive, efficient and readily adaptable.
Materials named lead halide perovskites have attracted considerable attention and shown significant promise. Novel perovskites are a category of materials that share the same crystal structure as the natural perovskite mineral calcium titanium oxide. But they include a variety of different atoms that replace all or some of those found in natural perovskite. Lead halide perovskites incorporate both lead and one or more elements of the halogen group. This includes fluorine, chlorine, bromine and iodine.
Despite the abilities of lead halide perovskites as X-ray scintillators, their commercial applications are limited by technical problems. These include poor stability when exposed to light and air, reabsorption of some of the scintillated light and the toxicity of lead.
Scientists have overcome these problems. They developed lead-free metal halides based on cesium, copper and iodide ions in the ratio Cs3Cu2I5, with crystals of that material incorporated into thin and flexible films of the polymer polydimethylsiloxane.
They said it was challenging to get the copper halide powders uniformly distributed in the film. But they achieved this by dispersing the powder in solvent before adding polydimethylsiloxane.
Their flexible scintillation screens can detect X-rays at ultralow levels. It is approximately 113 times lower than a typical standard dose for X-ray medical imaging.
Scientists already has plans to commercialize their advance. They are also hoping to refine their fabrication techniques. They want to explore the potential of similar screens made from similar material compositions.