Solid‐State Reactive Sintering of Transparent Polycrystalline Nd:YAG Ceramics

Abstract

Transparent polycrystalline Nd:YAG ceramics were fabricated by solid-state reactive sintering a mixture of commercial Al 2 O 3 , Y 2 O 3 , and Nd 2 O 3 powders. The powders were mixed in methanol and doped with 0.5 wt% tetraethoxysilane (TEOS), dried, and pressed. Pressed samples were sintered from 17001 to 18501C in vacuum without calcination. Transparent fully dense samples with average grain sizes of B50 lm were obtained at 18001C for all Nd 2 O 3 levels studied (0, 1, 3, and 5 at.%). The sintering temperature was little affected by Nd concentration, but SiO 2 doping lowered the sintering temperature by B1001C. Abnormal grain growth was frequently observed in samples sintered at 18501C. The Nd concentration was determined by energy-dispersive spectroscopy to be uniform throughout the samples. The in-line transmittance was 480% in the 350-900 nm range regardless of the Nd concentration. The best 1 at.% Nd:YAG ceramics (2 mm thick) achieved 84% transmittance, which is equivalent to 0.9 at.% Nd:YAG single crystals grown by the Czochralski method. 1945J ournal

Ce:YAG ceramics: the influence of the synthesis technology features on the luminescent and the optical properties

“…So, for example, in the first method, the density of a compact was about 3 (47.9% о of YAG density). The powders in the second case (second method) were coarser after the calcination and the milling compared to the initial nanopowders in the first method.…”

“…The received powders were molded into compacts (disks Ø14×4 mm) at 200 MPa in a metal mold to a density of 40-50% from the theoretical density of YAG (4.55 g/cm 3 ) by means of the cold uniaxially press (CUP) method. The compacts were annealed in the atmosphere at 800 °C for 3 hours to remove the organic impurity.…”

“…The ceramic technology holds out the high-transparent and the large-size garnet materials production opportunity at the lower temperatures and the homogeneous distribution or the gradient-controlled activator ions distribution [2,3]. In this paper, we are mainly presenting the dependence between the research results on the optical and the luminescent properties of one of the known scintillation ceramic materials, namely, the aluminum-yttrium garnet Y 3 Al 5 O 12 activated by Се 3+ (Се 3+ :YAG) with the Се 3+ dopant concentration of 0.1 and 1 at.% on the synthesis technology features.…”

Synthesis of Nd‐YAG material by citrate‐nitrate sol‐gel combustion route

“…[1] Single crystals grown by the Czochralski method are commonly used for solid state lasers, but polycrystals are going to replace them. [2][3][4][5][6] Single crystals require long and expensive production routes, whereas the maximum Nd amount that can be used without affecting the final properties is about 1-1.5 at%. On the contrary, Nd:YAG ceramics are prepared through the relatively fast and cheap sintering of the ceramic powders and an amount of Nd up to 4.8 at % can be introduced in the system.…”

“…Calcination treatments performed under air atmosphere around 900°C lead to the formation of pure YAG phase at temperatures much lower than the temperature required for the solid-state reaction (1600°C). [3] On the other hand, the high specific surface area of the primary nanometric particles easily promotes the formation of strong aggregates during the gel drying and calcinations. These aggregates inhibit the densification of the powders.…”