Microcrystalline hydrogarnets in the following series were synthesized by the aging of precipitated gels at 85°-105°C and 1 atm in NaOH solutions of pH 13.5:
Ca3(Zr1Fe1)(FeO4)(SiO4)2-x (OH)4x with x = 2, 1.5, 1
Ca3(Ti1Fe1)(FeO4)(SiO4)2-x (OH)4x with x = 2, 1.75, 1.5, 1
Sr3Fe2(SiO4)3-x (OH)4x with x = 3, 2.75, 2.5
Ca3Fe2(SiO4)3-x (OH)4x with x∼2.75, ∼2.5, 2
We have similarly synthesized the hydrogarnets Sr3Sc2(OH)12, Sr3In2(OH)12, Sr3(Sc1Fe1)(OH)12, Sr3(Sc1In1)(OH)12, Sr3(In1Fe1)(OH)12 and Sr3Sc2(SiO4)(OH)11,. The unit-cell dimension and, in some instances, the index of refraction is given for the preparations. Efforts to synthesize Ca3Fe2(OH)12 and the Ba3Fe2, Pb3Fe2, Sr3TiFe and Sr3ZrFe analogues of the Sr3Fe2 hydrogarnets failed.