Here, we develop and characterize high thermal conductivity/high thermal shock-resistant bulk Ce-doped Al 2 O 3 and propose it as a new phosphor converting capping layer for high-powered/high-brightness solid-state white lighting (SSWL). The bulk, dense Ce:Al 2 O 3 ceramics have a 0.5 at.% Ce:Al concentration (significantly higher than the equilibrium solubility limit) and were produced using a simultaneous solid-state reactive current activated pressureassisted densification (CAPAD) approach.

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... e:Al 2 O 3 exhibits a broadband emission from 400 to 600 nm, which encompasses the entire blue and green portions of the visible spectrum when pumped with ultraviolet (UV) light that is now commercially available in UV light-emitting devices and laser diodes (LD). These broadband phosphors can be used in the commonly used scheme of mixing with other UV-converting capping layers that emit red light to produce white light. Alternatively, they can be used in a novel composite down-converter approach that ensures improved thermal-mechanical properties of the converting phosphor capping layer. In this configuration, Ce:Al 2 O 3 is used with proven phosphor conversion materials such as Ce:YAG as an active encapsulant or as a capping layer to produce SSWL with an improved bandwidth in the blue portion of the visible spectrum. To study the effect of crystallinity on the Ce photoluminescent (PL) emission, we synthesize Ce:YAG ceramics using high-pressure CAPAD at moderate temperatures to obtain varying crystallinity (amorphous through fully crystalline). We investigate the PL characteristics of Ce:Al 2 O 3 and Ce:YAG from 295 to 4 K, revealing unique crystal field effects from the matrix on the Ce dopants. The unique PL properties in conjunction with the superior thermal-mechanical properties of Ce:Al 2 O 3 can be used in high-powered/high-brightness-integrated devices based on high-efficiency UV-LD that do not suffer efficiency droop at high drive currents to pump the solid-state capping phosphors. LLC., where he helps develop ceramic materials and manufacturing routes for high-temperature turbomachinery and heat exchangers. Dr. Penilla has also held visiting lecturer and professor positions at the Department of Physics and Astronomy at Pomona, College, his alma mater. His research interests focus on the synthesis of 3d-bulk transparent polycrystalline ceramics, for light emitting and guiding applications. e.g. broadband and monochromatic sources for high-power lighting, high-energy lasers and waveguide based photonic structures for unconventional/extreme environment applications. Dr. Penilla also enjoys investigating laser-matter interactions at different timescales and has developed techniques for ultrafast laser welding of transparent and opaque ceramics. In addition, he works on optical spectroscopy, non-linear optics, and opto-electronics materials and devices. He was also elected and served as a recent (2016-2018) chair for the Gordon Research Seminar (GRS) in Solid-State Studies in Ceramics and continues to advise the newly elected chairs of the GRS.