Anomalous elastic and piezoelastic properties of monoclinic bis(hexylammonium) zirconium bis (nitrilotriacetate) dihydrate, (C6H13NH3)2Zr(N(CH2COO)3)2 · 2 H2O

Abstract

Abstract Large single crystals with optical quality of bis(hexylammonium) zirconium bis (nitrilotriacetate) dihydrate with dimensions up to about 15 cm3 were grown from aqueous solutions. The complete elastic stiffness tensor was determined at 293 K. The propagation velocities of ultrasonic modes which are strongly related to the elastic constants c 11, c 22, c 33, and c 66, displayed anomalous behaviour between 260 K and 300 K. We observed distinct anomalies in the temperature dependent evolution of the elastic coefficient c 22 as indicated by a drastic change of the thermoelastic constant T 22 between about 275 K and 295 K. No discontinuity of any ultrasonic wave velocity and no anomalous attenuation effects have been measured in the temperature range between 120 K and 330 K by plane wave techniques. Additionally, strong anomalies occur in the thermal expansion between 310 K and 270 K which is also recognized by differential scanning calorimetry. The complete piezoelastic tensor was measured between 1 and 1600 bar under hydrostatic conditions.