K7P2W17LnO61 (330 mg) and 40 mg of KAc were dissolved in 20 ml of deionized water, and the pH was adjusted to 4.0 by acetic acid. CTAB (330 mg) and 69 mg of TBAB were dissolved in 30 ml of chloroform. The organic phase was added dropwise into the POM solution under vigorous stirring. After 16 hours, the mixture was centrifuged at 10,000 rpm for 5 min, and the organic phase was collected. The clear solution was evaporated under ambient condition. The product was obtained as some powder (Ln = Ce, Pr, Nd, Sm, Eu, Gd).