THE CHEMICAL-BONDS IN MNSB2O4, NISB2O4, FESB2O4, ZNSB2O4 ISOMORPHOUS COMPOUNDS - THERMAL-EXPANSION, FORCE-CONSTANTS, ENERGIES

The various chemical bonds (Me-O, Sb-O) in the MeSb//2O//4 isomorphous compounds (Me equals Mn, Ni, Fe, Zn) are characterized by four quantities: the interatomic distance (r//i//j), the force constant (f//i//j), the thermal expansion ( alpha //i//j equals 1/r dr/dT), the bond energy. Using structural evolution data (neutron diffraction) and Raman infrared spectroscopic studies at low temperature (5-300 K), it has been possible to connect the various r//i//j, f//i//j, and alpha //i//j quantities with bond energies; such energies have been calculated using a simplified pair potential model U(r) equals Ar** minus **m - Br** minus **n; calculated force constants and thermal expansions have been derived from the derivatives d**2U/dr**2 and d**3U/dr**3.