Holmium(III) chloride
Holmium(III) chloride is the inorganic compound with the formula HoCl. It is a common salt but is mainly used in research. It exhibits the same color-changing behavior seen in holmium oxide, being a yellow in natural lighting and a bright pink color in fluorescent lighting. Preparation. It forms upon union of the elements, but a more commonly used method involves heating a mixture of holmium(III) oxide and ammonium chloride at 200-250 °C: Structure. In the solid state it has the YCl layer structure.