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In Ca doped CePO 4 monazite (viz., Ce 0.8 Ca 0.2 PO 4 ) cerium exhibits mixed valence state (+3 and +4) and therefore can accommodate cations of any valence (by converting Ce 3+ to Ce 4+ or vice versa) subject to the size and other restrictions. A simulated waste form prepared based on the versatile monazite phase, Ce 0.8 Ca 0.2 PO 4 , showed higher leaching for Cs and Mo indicating that these elements do not enter the monazite lattice. Iron phosphate glass (IPG) is an alternate glass waste form considered for HLW immobilization. A glass–ceramic composite of crystalline monazite and IPG could have synergistic effects and can improve the leaching resistance. The preparation and characterization of a versatile monazite–IPG glass–ceramic waste form with 20 wt.% simulated HLW oxides and its leaching behavior are reported in this paper. The monazite–IPG glass–ceramic simulated waste form is found to have excellent chemical durability. [ABSTRACT FROM AUTHOR]