Optical hole burning (OHB) on lanthanides in inorganic host-lattices provides a promising method for optical storage application. To gain a high memory capacity, materials of low nuclear spin moments are of interest because of line broadening due to spin flip-flop processes in spin rich host-lattices. In this work, it is shown that only a small number of elements may be used in building up low spin density OHB host-lattices doped with Pr3+ or Eu3+. Possible materials were explored with respect to crystal growth, doping, and optical absorption properties. Single crystals of Pr3+-doped CaWO4, SrWO4, BaWO4, (Ca,Sr)WO4, CaTiSiO5 (titanite), and Ca2ZnSi2O7 (hardystonite) were obtained by the Czochralski technique.