Alloying effects on intermolecular magnetic interactions in verdazyl radical alloy crystal, (TOV)(1-x)(TOV-H)(x), x=0,0 similar to 0.09 (TOV : 1,3,5-triphenyl-6-oxoverdazyl)

To study the alloying induced drastic antiferro/ferro change of intermolecu lar magnetic interaction in 1,3,5-triphenyl-6-oxoverdazyl (TOV) radical all oy crystal, (TOV)(1-x)(TOV-H)(x), measurements of high-field magnetization, magnetic susceptibility, and powder X-ray diffraction pattern on this radi cal alloy have been carried out, where TOV-H is an amine precursor of TOV. The antiferromagnetic (AFM) exchange interaction in pure TOV crystal has ch anged drastically to ferromagnetic (FM) type by slight alloying (x = 0.03), due tb intermolecular distance expansion. The observed magnetization, M(x, H), for the TOV radical alloy at 1.7 K has shown deviation from a simple B rillouin function, and thus the M(x, H) was analyzed approximately by two t erms. The composition rate dependence of the lattice parameters of the TOV radical alloy crystals showed an abnormal elongation of the distance of abo ut 15% between-radicals along the c-axis at x = 0.03. Based-on the experime ntal facts, we will discuss the effects of elongation of inter-molecular di stance on the mechanism of magnetic interaction between the delocalized rad ical spins.