Crystal growth and characterization of Haldane chain compound Ni(C 3H 10N 2) 2NO 2ClO 4

Abstract

The bulk single crystals of S=1 chain compound Ni(C 3H 10N 2) 2NO 2ClO 4 are grown by using a slow evaporation method at a constant temperature and a slow cooling method. It is found that the optimum condition of growing large crystals is via slow evaporation at 25 °C using 0.015 mol Ni ( ClO 4 ) 2 · 6 H 2 O , 0.015 mol NaNO 2, and 0.03 mol 1,3-propanediamine liquid dissolved into 30 ml aqueous solvent. High-quality crystals with size up to 18 × 7.5 × 5 mm 3 are obtained. The single crystals are characterized by measurements of X-ray diffraction, magnetic susceptibility, specific heat and thermal conductivity. The susceptibilities along three crystallographic axes are found to exhibit broad peaks at ∼ 55 K , and then decrease abruptly to zero at lower temperatures, which is a characteristic of a Haldane chain system. The specific heat and the thermal conductivity along the c-axis can be attributed to the simple phononic contribution and are analyzed using the Debye approximation.