Additionally, low temperature heat capacity measurements on Ni 4 V 3 O 10 show a broad peak below 30 K. As can be seen in Fig. , this does not correspond to a change in the magnetization curves. A similar heat capacity response has been noted in several spinel systems where mixed or frustrated magnetic behavior is present. For CoAl 2 O 4 spinels, Tristan et al. show that with low substitution of Co onto the primarily Al octahedral site, a hump in the heat capacity appears slightly above the characteristic temperature, but with a greater degree of substitution, the hump broadens and appears at a lower temperature than the bifurcation in the FC and ZFC susceptibility curves. They associate this behavior with a mixed magnetic phase. Ghara et al. likewise observe that increasing cation antisite disorder in CoAl 2 O 4 samples shifts the heat capacity magnetic peak to lower temperatures and broadens it. Another spinel system, FeSc 2 S 4 , also shows a broad peak below its ordering temperature that is associated with geometric magnetic frustration and disorder in the sample. Ba 15 V 12 S 34 O 3 , noted before for its structural similarities to Ni 4 V 3 O 10 and its inclusion of V 3+ , V 4+ , and V 5+ cations, similarly exhibits antiferromagnetic interactions and a broad hump in its C P /T curve below the bifurcation of the FC and ZFC curves. Therefore, frustrated magnetic behavior in Ni 4 V 3 O 10 appears to lead to weak, incommensurate ordering that emerges over a range of temperatures below T N . Single crystals may be needed to further explore the magnetic structure.