Salt-inclusion materials, SIMs, consist of a covalent metal oxide framework containing voids filled by an ionic salt-lattice. Recently, we reported on an enhanced flux growth method for the targeted synthesis of uranyl silicate SIMs. These materials are of interest as nuclear waste storage materials due to their potential to simultaneously immobilize multiple radionuclides. For SIMs to become a viable waste form material, their crystal chemistry must be expanded to allow for the tailoring of the salt channels for specific radioisotopes. For instance, accommodating CsI will require a SIM with larger channels than one designed to accommodate NaF. This can be achieved by expanding the framework to incorporate other building blocks including germanates, molybdates, and lanthanides. The enhanced flux growth method will have to be tuned to these specific building blocks. Initially, this will necessitate gaining an understanding of the conditions which are suitable for the flux growth of oxide compounds with these building blocks. The enhanced flux growth technique can then be modified based on these conditions in order to achieve the synthesis of expanded SIM frameworks.