Flame spray of metalloorganics provides a general route to common phase pure spinel nanopowders, (MO)(1-x)(-) (Al2O3)x M = Mg, Ni, Co, Zn, and (MgO)(0.6)(Fe2O3)(0.4), with compositions previously unknown, thereby greatly extending their phase fields. The access to entirely new compositions in spinel phase materials could expand the horizons of spinel materials' properties greatly.