Ionothermal Synthesis of Layered Zirconium Phosphates and Their Tribological Properties in Mineral Oil.

[C6H16N2] 0.5Zr (H0.5PO4)2·H2O (I) is synthesized by reaction of ZrOCl2, H3PO4, HF, and 1,4-dimethylpiperazine in a deep eutectic solvent composed of (Pr4N)Br and oxalic acid (autoclave, 180 °C, 3 d).