Preparation, characterization, and magnetic properties of organic-intercalated two-dimensional ionic ferromagnets (CnH2n+ 1NH3)2CrCl4(n= 3, 5, or 12)

Abstract

The title compounds have been prepared and characterized by chemical analysis and powder X-ray diffraction. Spacing between the planes of chromium(II) ions increases from 12.35 to 17.81 to 31.05 Å as n increases from 3 to 5 to 12 but the spacing between Cr^II within the planes remains almost constant. Magnetic susceptibility data in the range 60–140 K have been fitted to a high-temperature series expansion for a square two-dimensional lattice to give J= 6.5 ± 0.2 cm^–1(ℋ=–JS_iS_j) and g= 1.95 for all three compounds. Low-temperature magnetization measurements show that all the salts order ferromagnetically in the region 50 ± 10 K although the transition is broadened by the applied magnetic field. The effective magnetic moments of 5.04–5.35 µ_B at 140 K remain higher than the spin-only value of 4.90 µ_B because of persisting short-range order.