Lanthanide gallium/aluminum-based garnets have a great potential as host structures for scintillation materials for
medical imaging. Particularly attractive features are their high density, chemical radiation stability and more importantly,
their cubic structure and isotropic optical properties, which allow them to be fabricated into fully transparent, highperformance
polycrystalline optical ceramics. Lutetium/gadolinium aluminum/gallium garnets (described by formulas
((Gd,Lu)3(Al,Ga)5O12:Ce, Gd3(Al,Ga)5O12:Ce and Lu3Al5O12:Pr)) feature high effective atomic number and good
scintillation properties, which make them particularly attractive for Positron Emission Tomography (PET) and other γ-
ray detection applications. The ceramic processing route offers an attractive alternative to single crystal growth for
obtaining scintillator materials at relatively low temperatures and at a reasonable cost, with flexibility in dimension
control as well as activator concentration adjustment.
In this study, optically transparent polycrystalline ceramics mentioned above were prepared by the sintering-HIP
approach, employing nano-sized starting powders. The properties and microstructures of the ceramics were controlled by
varying the processing parameters during consolidation. Single-phase, high-density, transparent specimens were
obtained after sintering followed by a pressure-assisted densification process, i.e. hot-isostatic-pressing. The transparent
ceramics displayed high contact and distance transparency as well as high light yield as high as 60,000-65,000 ph/MeV
under gamma-ray excitation, which is about 2 times that of a LSO:Ce single crystal. The excellent scintillation and
optical properties make these materials promising candidates for medical imaging and γ-ray detection applications.