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Zero thermal expansion in a flexible, stable framework: tetramethylammonium copper(I) zinc(II) cyanide
Anthony E Phillips1, Gregory J Halder, Karena W Chapman
1School of Chemistry, The University of Sydney, NSW 2006, Australia.
Abstract:
Tetramethylammonium copper(I) zinc(II) cyanide, which consists of N(CH(3))(4)(+) ions trapped within a cristobalite-like metal cyanide framework, has been studied by variable-temperature powder and single-crystal X-ray diffraction. Its coefficient of thermal expansion is approximately zero over the temperature range 200-400 K and comparable with the best commercial zero thermal expansion materials. The atomic displacement parameters, apparent bond lengths, and structure of a low-temperature, low-symmetry phase reveal that the low-energy vibrational modes responsible for this behavior maintain approximately rigid Zn coordination tetrahedra but involve significant distortion of their Cu counterparts.
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