Certain thallous and cesium halides, either used alone or in combination with other ceramic materials, are provided in cryogenic applications such as heat exchange material for the regenerator section of a closed-cycle cryogenic refrigeration section, as stabilizing coatings for superconducting wires,...http://www.google.com.au/patents/US4356235?utm_source=gb-gplus-sharePatent US4356235 - Thallous and cesium halide materials for use in cryogenic applications
