Description
Cesium iodide is a soft material and extremely hygroscopic. Cesium iodide scintillators have been used extensively for indirect x-ray imaging detectors, such as for CT examinations. Cesium iodide is also used to construct electromagnetic shower detector for the CLEO II experiment, which investigates electron-positron annihilation at center-of-mass energies near 10 GeV. Cesium iodide is useful for beam splitters for Far IR spectrophotometers and IR transmission windows.
References
[1] W. Zhao, G. Ristic, J. A. Rowlands, X-ray imaging performance of structured cesium iodide scintillators, Medical Physics, 2004, vol. 31, 2594-605
[2] E. Blucher, B. Gittelmann, B. K. Heltsley, J. Kandaswamy, R. Kowalewski, Y.Kubota, N. Mistry and S. Stone, Tests of cesium iodide crystals for an electromagnetic calorimeter, Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1986, vol. 249, 201-227
[3] M. Völk, O. W. Hamer, S. Feuerbach, M. Strotzer, Dose reduction in skeletal and chest radiography using a large-area flat-panel detector based on amorphous silicon and thallium-doped cesium iodide: technical background, basic image quality parameters, and review of the literature, European Radiology, 2004, vol. 14, 827-834
[4] M. V. Mastryukov. “Preparation of Extrapure Cesium Iodide.” Inorganic Materials 56 10 (2020): 1050–1054.
Chemical Properties
white crystalline powder
Uses
Cesium iodide (CsI) is a kind of ionic compound that has been widely used as scintillators in many areas such as X-ray image intensifier tubes, photocathodes, and display devices.
Cesium iodide is used in scintillation counters(Geiger counters) to measure levels of external radiation. It is also useful as a "getter" to remove air molecules remaining in vacuum tubes.
Cesium Iodide is a material with high γ-ray stopping power due to its relative high density and atomic number. For scintillation counting, it is used either in its un-doped form or doped with sodium or thallium.
CsI is resistant to thermal and mechanical shock. The physical characteristics of CsI are independent of the activator used. Compared to NaI(Tl), it is relatively soft and plastic, and does not cleave. Because it has no cleavage plane, it is quite rugged-which makes it well-suited for well logging, space research or other applications where severe shock conditions are encountered.
Uses
Cesium iodide is used in FT-IR (Fourier Transform Infrared Spectrometers) as a beamsplitter. Cesium Iodide exhibits high gamma-ray stopping power. Useful as input phosphor in fluoroscopy equipment, and efficient photocathode for extreme ultraviolet wavelengths. Fast and dense scintillating material - useful in electromagnetic calorimetry in particle physics.
Uses
Prisms for infrared spectroscopy; in x-ray fluorescent screens, scintillation counters.
Production Methods
A single crystal can be grown from a melt solution by both the Kyropoulus method and the Stockbarger method.
General Description
Cesium iodide is a simple ionic salt. It has the capacity to undergo second order transformation from cubic B2 structure to body-centered tetragonal structure at low pressures. It is mostly used as input screens of X-ray image intensifiers.
Flammability and Explosibility
Non flammable
Safety Profile
Moderately toxic by
ingestion and intraperitoneal routes. See also
CESIUM and IODIDES. When heated to
decomposition, it emits toxic fumes of I-.
Synthesis
The main method for preparing cesium iodide-based single crystals is Kyropoulos growth, which allows one to obtain cylindrical ingots weighing up to several tens of kilograms.
Cs2CO3+ 2HI→2CsI+H2O+CO2↑
Technically, pure CsI was prepared by dissolving cesium carbonate in hydriodic acid at room temperature in a vessel from niobium, which was nonreactive with cesium iodide at elevated temperatures. The solution was heated to boiling at pH 3 to completely dissolve the caesium carbonate because the niobium vessel was unstable in an acid medium.The hot solution was filtered and boiled down at a temperature near 393 K. After crystallization, the material was vacuum-dried in a quartz ampule[4].
Solubility in water
Cesium iodide is soluble in water, with a solubility of 44/100 g H2O (0℃ and 160/100 g H2O (61℃). It is soluble in alcohol. One should handle it carefully, because it is deliquescent.
Purification Methods
Crystallise it from warm water (1mL/g) by cooling to -5o.
Structure and conformation
The space lattice of CsI belongs to the cubic system, and its cesium chloride structure has a lattice constant of a=0.8529 nm.
