ELASTIC PROPERTIES AND PIEZOELECTRIC COUPLING-COEFFICIENTS OF NITRILOTRIACETIC ACID, (N(CH2COOH)(3)=NTA=H(3)NTA'), LI(3)NTA'CENTER-DOT-2H(2)O, NA(2)HNTA', K2ZR(NTA')(2)CENTER-DOT-2H(2)O, RB2ZR(NTA')(2)CENTER-DOT-2H(2)O, CS2ZR(NTA')(2)CENTER-DOT-H2O AND (NH4)(2)ZR(NTA')(2)

Elastic and thermoelastic constants of nitrilotriacetic acid, N(CH2COO H)(3), Li3N(CH2COO)(3) . 2 H2O, Na2HN(CH2COO)(3), X(2)Zr(N(CH2COO)(3)) (2) . y H2O (X = K, Rb, Cs; y = 1, 2) and (NH4)(2)Zr(N(CH2COO)(3))(2) were determined from ultrasonic resonance frequencies of thick plates and their shift upon variation of temperature, respectively. In additi on, the piezoelectric-elastic coupling was studied by different method s. The packing density of these species and the chemical bonding are q uite similar due to the dominance of the large anions. Elastic and the rmoelastic properties behave as expected for chemically related compou nds. Large piezoelectric coupling coefficients > 0.25 are observed on crystals of N(CH2COO)(3) and X(2)Zr(N(CH2COO)(3))(2) . y H2O, whereas the other species exhibit considerably smaller coupling effects.