Lanthanide-based luminescent hybrid materials.

Transparent ceramics have various potential applications such as infrared (IR) windows/domes, lamp envelopes, opto-electric components/devices, composite armors, and screens for smartphones and they can be used as host materials for solid-state lasers. Transparent ceramics were initially developed to replace single crystals because of their simple processing route, variability in composition, high yield productivity, and shape control, among other factors. Optical transparency is one of the most important properties of transparent ceramics. In order to achieve transparency, ceramics must have highly symmetric crystal structures; therefore, the majority of the transparent ceramics have cubic structures, while tetragonal and hexagonal structures have also been reported in the open literature. Moreover, the optical transparency of ceramics is determined by their purity and density; the production of high-purity ceramics requires high-purity starting materials, and the production of high-density ceramics requires sophisticated sintering techniques and optimized sintering aids. Furthermore, specific mechanical properties are required for some applications, such as window materials and composite armor. This review aims to summarize recent progress in the fabrication and application of various transparent ceramics.

Materials development and potential applications of transparent ceramics: A review

Fifty years have elapsed from the moment the first light transmitting ceramic-based commercial item—a sodium vapor-based street lamp component—reached the market. This paper intends to be a brief chronicle (albeit not a chronology) of this first half century of translucent and transparent ceramic history. The main ceramic materials now available in a transparent state are presented and their main applications are described. Applications range from aerospace and relativistic optics to medical care, supermarket shopping, and modern warfare. Light transmitting ceramics usable as laser gain-media, armor windows, IR domes, phosphors, scintillators, and electro-optical components have been developed. The principal achievements this research produced are discussed. Processing strategies for full densification have been devised and quantitative relationships were established between different microstructural features such as amount and size distribution of porosity or level of birefringence, and the level of electromagnetic radiation attenuation they cause. Future prospects list ends the paper.

Transparent Ceramics at 50: Progress Made and Further Prospects

The synthesis and functional characterization of dense bulk nanometric oxides are reviewed, with particular emphasis on the modifications that a grain size in the low nanometric range (10–50 nm) introduces in their physical properties. The preparation of ceramics with low porosity and extremely small grain size is particularly challenging and mostly relies on the sintering of extremely fine nanopowder. The most popular methods for the preparation of the starting nanopowders are introduced and briefly discussed as well as the most widely employed densification techniques. The role of nanostructure in controlling phase stability, electrical and thermal transport, optical and magnetic properties of nano-oxides is discussed in details. Several examples are given where bulk materials prepared with grain size equal or below 50 nm show characteristics that are either enhanced or, in some cases, completely different from those possessed by the same materials, but with larger grain sizes.

Densification and properties of bulk nanocrystalline functional ceramics with grain size below 50nm

KRE(WO4)2 (RE = Gd and Yb) nanocrystalline powder was obtained by the modified sol-gel Pechini method. The precursor powder was calcined between 923 and 1023 K for a maximum of 6 h at air atmosphere. DTA-TG of the precursor powder shows that the temperature for total calcination is around 800–850 K. Molar ratio between the complexing agent and the metal ions in the first step of the method and molar ratio between the complexing agent and the ethylene glycol in the second step of the method were studied to optimize the preparation process. X-ray diffraction and IR spectroscopy were used to study the transformation from precursor powder into a crystalline monoclinic phase. Raman spectroscopy was used to study the vibrational structure of the nanoparticles. The Scherrer formula was used to confirm the grain sizes visualized by SEM and TEM techniques. Small nanoparticles in the range of 20–50 nm of monoclinic KREW have been successfully obtained by this methodology.

/pdf/sol-gel-modified-pechini-method-for-obtaining-8l1cu46bl4.pdf

Sol-gel modified Pechini method for obtaining nanocrystalline KRE(WO 4 ) 2 (RE = Gd and Yb)

Method of preparation and structural properties of transparent YAG nanoceramics

Luminescence properties of Tb3+:Y3Al5O12 nanocrystallites prepared by the sol–gel method

Spectroscopic properties of LaAlO3 nanocrystals doped with Tb3+ ions

Fabrication and optical properties of transparent Nd3+:YAG nanoceramics

The luminescence properties of the Nd3+:LaAlO3 nanocrystalline powders characterized by different sizes of grains in the range of 25-50 nm were investigated. The effect of the nanocrystallites sizes on the luminescence behavior of Nd3+ was observed. In particular decreasing the grain sizes was found to increase emission from the thermally populated 4F5/2 state. It's intensity increased with the increase of excitation power density. The spectroscopic parameters of Nd3+ doped LaAlO3 nanocrystallites were determined from luminescence spectra by using the Judd-Ofelt method and compared to those obtained for a single crystal of Nd3+:LaAlO3.

P. Mazur

Papers

Method of preparation and structural properties of transparent YAG nanoceramics

Luminescence properties of Tb3+:Y3Al5O12 nanocrystallites prepared by the sol–gel method

Spectroscopic properties of LaAlO3 nanocrystals doped with Tb3+ ions

Fabrication and optical properties of transparent Nd3+:YAG nanoceramics

The crystal-size and power dependence of luminescence properties of Nd3+:LaAlO3 nanopowders