STUDY OF THERMAL AND MECHANICAL PROPERTIES OF SELECTED SOLIDS FROM 4 DEGREES TO THE MELTING POINT.
Final rept. Nov 65-Oct 69,
MARTIN MARIETTA CORP ORLANDO FLA ORLANDO DIV
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The theory of thermal expansion is briefly reviewed with special emphasis on the negative low temperature expansion frequently found in the diamond and sphalerite crystal structures. Lattice parameters of the rock salt compounds AgCl, AgBr and MgO, and the sphalerite compounds CuCl, CuBr, CuI, AgI, BN, BP, SiC, and CdTe measured from 4.2K to 300K are presented. The rock salt compounds are found to behave normally, i.e., positive throughout the temperature range. CuCl, CuBr, AgI, CdTe, and probably BN and BP possess a region of low temperature negative expansion. Within the limits of experimental error, CuI and SiC do not. The thermal expansion of AgI is found to be dependent on its preparation this has been attributed to the presence of stacking faults. Author