Using positive pressure to produce a sub-micron single-crystal column of cesium iodide (CsI) for scintillator formation

• A cost-effective and simple method for preparing an ionic compound in a CsI column is presented.
• High filling efficiency of CsI melt inside an AAO template under positive pressure.
• Elaboration of the sublimation points of CsI and I under various pressures.
• CsI solidifies as stable single nanowires in AAO without dendrite structures.
• Uniform CsI size can be controlled by the AAO template.

The scintillator can be directly coupled to a commercial CCD and has the fastest response time (several ns) for real-time radiography. Most scintillator material production uses an expensive vacuum deposition process or a single-crystal growth method. This work reports the development of a cost-effective way to prepare sub-micron scintillator cesium iodide (CsI) columns in a ceramic anodic aluminum oxide (AAO) template by a positive pressure penetration method. Positive pressure can decrease the iodine vapor pressure and increase the CsI sublimation point up to the CsI melting point. Because the CsI melt is confined to an AAO channel with a high aspect ratio, the melt easily solidifies into a stable single-crystal CsI column. The SEM images showed CsI in a single crystal with a column diameter of 440 nm, smooth surfaces, and no grain boundaries. This positive pressure penetration method enables fabrication of a single-crystal CsI column with controllable size.

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