Applications of Cesium

Cesium Products

In elemental form, cesium is a soft, shiny, gold colored metal, which melts slightly above room temperature. Normally, cesium products come as salts, with properties similar to those of the corresponding potassium salts, although occasionally much more pronounced.

The high atomic number, extremely low charge density, and large radius of the monovalent cesium ion have important consequences which are directly related to current and future applications.

Purity Level

To guarantee high and consistent purity levels is one of our major ambitions, as we are serving our customer's needs to the best.

Our Team for your Service

We are pleased to support you with specifying the right purity level for your application and discuss with you the impurities which are critical in your application.

Due to our experience with various applications, we will be able to recommend a standard product or tailor a specification according to your particular needs.

Purity Levels

Our unique process yields various product grades depending on the distinct removal of particular impurities. In our Certificate of Analysis, we monitor the quality of our raw materials, intermediates, and supply products with a larger number of analyzed impurities than required by usual standards.

Our purity definition is based on metals, i.e. it is a calculated value based on the actual content of metallic impurities.

Purity = 100% - (content of specified metallic impurities in %)

Please find below an overview of our regular grades. The indicated metals constitute a minimum set. The calculation of purity is nevertheless based on all metals specified in the technical datasheet.

(Metal Base)
Number of Metals
Set of Metals


min. 99.0%6

Li, Na, K, Rb, Ca, Ba

99.9min 99.9 %11Li, Na, K , Rb, Ca, Mg, Sr, Ba, Al, Fe, Cr
99.99min 99.99 %12Li, Na, K, Rb, Ca, Mg, Sr, Ba, Al, Fe, Cr, Mn
99.999min 99.999 %14Li, Na, K, Rb, Ca, Mg, Sr, Ba, Al, Fe, Cr, Mn, Zn, Ni

We also monitor anionic impurities which are not included in the calculated purity by definition. Their lot-specific contents are listed on our Certificate of Analysis.

In order to determine the appropriate product for your application, please check our detailed specifications of the respective products, or better, discuss with us the impurities which are critical to your application.


All of our products are manufactured at least under DIN EN ISO 9001 guidelines and are accompanied by a Certificate of Analysis (CoA) and/or Certificate of Conformance (CoC). CoAs/CoCs show key impurities and/or performance-related physical parameters of our products.

Standard analytic procedures include ICP-OES, ICP-MS, AAS incl. FES and HGA, UV-VIS, IR, IC, GC, DSC, potentiometry, titrimetry, gravimetry, density measurements, RFA and others.

Rounding Rules for Cesium

The various analytical equipment used by Rockwood Lithium´s analytical laboratory supply raw data with various degrees of precision and occasionally with a larger number of decimal places than is required by the product specification.

Rockwood Lithium's SAP-based quality system requires the number of decimal places of the measured values to be identical to the one of the specification limits. Rounding will thus be obligatory if the precision of the raw data exceeds the specified precision.

In order to avoid misinterpretations due to rounding in the proximity of specification limits, a set of rules is in force to control the rounding.

General Procedure

Results are mathematically rounded, i.e. digits up to 4 are rounded down and those starting from 5 are rounded up.
Only one rounding operation following the last calculation is permitted. Any intermediary data must be used with the entire set of available decimal places.

Example: Rounding to 2 decimal places
0.0472 converts to 0.05
0.0449 converts to 0.04

Special Rules for Cesium Ultra-trace Analytics

In ultra-trace analytics the significance of the obtained raw data has to be critically evaluated. The high dilutions (0.5 g/L) and the determination limits in the corresponding concentration ranges render the following exceptions to the general rules suitable:

For a measurement range from 5 μg/kg to 100 μg/kg, and given 0 required decimal places, the rounding is performed in steps of 5 μg/kg.

12.4 μg/kg is rounded down to 10 μg/kg
13.7 μg/kg is rounded up to 15 μg/kg

For a measurement range from 100 mg/kg to 1000 mg/kg, and given 0 required decimal places, the rounding is performed in steps of 5 mg/Kg.

247.4 mg/kg is rounded down to 245 mg/kg
247.5 mg/kg is rounded up to 250 mg/kg

In all other measurement ranges rounding in increments of 5 is not applicable – it instead follows the general procedure.

Further Support

For more information on any of the above mentioned analytical methods, please specify your request and contact us.

Should you consider our standard methods not to be sufficient to describe your product, we may offer additional or modified analytical methods on request.


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