Three doubly ordered double perovskites NaREMgWO (RE = La, Gd, Y) have been synthesized via traditional solid-state methods, doped with Eu, and characterized to evaluate their promise as Eu phosphor hosts. NaYMgWO, a new member of the family, was found to crystallize in the P2 space group and is isostructural with NaGdMgWO. Emissions characteristic of Eu ions (D → F) were observed, with the most intense transition being the D → F transition near 615 nm. Substitution of Eu onto a more compressed RE site in the NaYEuMgWO and NaGdEuMgWO hosts results in a blue shift of the charge-transfer excitation band and an increase in the intensity of the D → F transition compared to NaLaEuMgWO. All of the hosts can incorporate high concentrations of Eu before concentration quenching is observed. When the rare-earth ion is either Gd or Y, good energetic overlap between the Eu charge-transfer band and the absorption of the host lattice results in sensitization and energy transfer from the perovskite host lattice to the Eu activator sites. These hosts display comparable if not better luminescence than YO:Eu, a commonly used commercial standard, demonstrating their promise as red phosphors.

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Polyimides are widely utilized engineering polymers due to their excellent balance of mechanical, dielectric, and thermal properties. However, the manufacturing of polyimides into complex multifunctional designs can be hindered by dimensional shrinkage of the polymer upon imidization and post processing methods and inability to tailor electronic or mechanical properties. In this work, we developed methods to three-dimensional (3D) direct ink write polyimide closed-cell stochastic foams with tunable densities. These polyimide structures preserve the geometrical fidelity of 3D design with a linear shrinkage value of <10% and displayed microscale porosity ranging from 25 to 35%. This unique balance of morphology and direct-write compatibility was enabled by polymer phase inversion behavior without the need of conventional post-print cross-linking, imidization, or poreinducing freeze processing. The manufacturability, thermal stability, and dielectric properties of the 3D polyimide stochastic foams reported here serve as enablers for the exploration of hierarchical, lightweight, high-temperature, high-power electronics.