Holmium acetate is the acetate salt of holmium, with a chemical formula of Ho(CH<sub>3</sub>COO)<sub>3</sub> as well as at least one hydrate.
Holmium acetate can be obtained by dissolving holmium oxide in hot acetic acid
Dissolving holmium oxide in acetic acid at a pH of 4 will form the tetrahydrate of holmium acetate (Ho<sub>2</sub>(CH<sub>3</sub>COO)<sub>6</sub>÷4H<sub>2</sub>O): The anhydrous material can be obtained by heating the hydrated acetate in acetic acid.
Holmium acetate hemihepthydate decomposes at 105 ðC, forming into a hemihydrate, further decomposing at 135 ðC into an anhydride. Further adding heat will form Ho(OH)(CH<sub>3</sub>COO)<sub>2</sub>, HoO(CH<sub>3</sub>COO) then Ho<sub>2</sub>O<sub>2</sub>CO<sub>3</sub>, forming holmium oxide at 590 ðC.
According to X-ray crystallography, anhydrous holmium acetate is a coordination polymer. Each Ho(III) center is nine-coordinate, with two bidentate acetate ligands and the remaining sites occupied by oxygens provided by bridging acetate ligands. The lanthanum and praseodymium compounds are isostructural. In a second polymorph, holmium acetate has 8-coordination. A tetrahydrate has also been crystallized.
Holmium acetate is used in the manufacture of ceramics, glass, phosphors, metal halide lamps, and as a dopant in garnet lasers. It is also used in nuclear reactors to keep the chain reaction in check.