ELASTIC PROPERTIES OF SULFAMIC ACID AND SULFAMATES OF LI, NA, K, RB, CS, TL, NN4, C(NH2)(3) AND (CH3)(3)NCH2COOH

Single crystals having optical quality and dimensions up to 50 mm of s ulfamic acid (H[NH2SO3]), of the monosulfamates of Li, Na, K, Rb, Cs, Tl, NH4, C(NH2)(3), (CH3)(3)NCH2COOH, of CsH[NH2SO3](2) and NH4[NH2SO3 ]NH4[HSO4] have been grown from aqueous solutions by standard methods (controlled lowering of temperature and evaporation between 330 K and 285 K). All species possess orthorhombic symmetry, except those havin g larger cations (Cs,C(NH2)(3), (CH3)(2)NCH2COOH) which show monoclini c symmetry. No hydrates are formed above 300 K. The elastic constants c(ij) and the thermoelastic constants T-ij = d log c(ij)/dT, T tempera ture, were determined from ultrasonic resonance frequencies of thick p lates and their temperature dependence, respectively. The tenser of th ermal expansion has also been measured. The elastic and thermoelastic behavior of the sulfamates resembles those of alkali perchlorates and other chemically related families, despite their different structures. The elastic anisotropy is weak. The general rules concerning the rela tion between the mean elastic stiffness and molecular volume, the devi ation from Cauchy relations and the Gruneisen relation are confirmed. Cs[NH2SO3] and (CH3)(3)NCH2COOH[NH2SO3] undergo a first- order phase t ransition on heating above 350 K. An anomalous thermal expansion was f ound in NH4[NH2SO3] at temperatures below 260 K.