Substitutes

Substitutes and Alternatives for Cesium

The availability of viable substitutes is a key factor in assessing Cesium's criticality. Across its 2 primary applications, substitution options range from commercially viable alternatives with performance trade-offs to applications where Cesium currently has no effective substitute.

Substitution Analysis by Application

The following table details available substitutes for Cesium across its primary applications, including the trade-offs involved:

Performance Trade-offs

In most applications, substituting Cesium involves measurable performance penalties. Cesium-133 defines the SI second; rubidium clocks are less accurate but cheaper; optical clocks may eventually supersede cesium but are not yet standardized. In high-performance applications such as atomic clocks and gps systems, these trade-offs can be particularly significant.

Research and Development

Active research programs are underway to develop improved substitutes and to reduce the amount of Cesium required per unit of product (thrifting). However, timelines for commercializing new alternatives typically span years to decades. The limited substitutability of Cesium is a primary driver of its high criticality rating, prompting government-funded substitution research programs.