Syntheses and Characterisation of Gd3Al5O12 and La3Al5O12 Garnets

Abstract

A sol-gel method based on in situ generation of mixed-metal chelates by complexing metal ions with ethane-1,2-diol in aqueous media has been elaborated to prepare lanthanide-ion containing garnets, Gd 3 Al 5 O 12 (GAG) and La 3 Al 5 O 12 (LAG). XRD patterns of the powders sintered at 1 000°C revealed the formation of monophasic GAG. However, LAG does not form under the same experimental conditions. The phase composition of the samples was characterised by IR spectroscopy. Microstructural features of the polycrystalline garnets were studied by SEM.Garnets, both natural and synthetic, form a wide range of compounds which are closely related by their structure and chemical and physical properties. Garnets containing transition and rare-earth metals have many important technological applications such as magnetic and phosphorescent materials employed in solid-state lasers and TV screens, computer memories and in many devices such as microwave optical elements 1-4 .Yttrium aluminium garnet (Y 3 Al 5 O 12 , YAG) with excellent structural and optical properties is one of the most popular garnets. Since the discovery of ruby laser, which is Cr-doped Al 2 O 3 , the search for new solid-state laser materials with diverse properties such as laser ability at new wavelengths, broad tunability in to the near infrared (NIR) region and high efficiency, has been an important task for material scientists. Rare-earth-doped YAG oxides are also widely used in cathode-ray tubes (projection TV sets), field

Neodymium substitution effects in sol–gel derived Y3−xNdxAl5O12

“…Importantly, two broad bands observed at 664 cm À1 and 455 cm À1 are not resolved to several sharp absorptions. According to our earlier investigations these bands are typical metaleoxygen absorptions for the perovskite-type compounds [33]. Thus, the observed MeO vibration which in view of the earlier reports are characteristic of REeO and AleO stretching frequencies let us to conclude, that the IR results are consistent with crystallization process observed by XRD measurements.…”

Investigation of lanthanum substitution effects in yttrium aluminium garnet: importance of solid state NMR and EPR methods

“…The monophasic Sm 3 Al 5 O 12 garnet phase is not synthesized and characterized so far as well [16]. However, during the heat treatment of the La-Al-O precursor gel powders at the same temperatures the LaAlO 3 :Al 2 O 3 or LaAlO 3 :La 2 O 3 :2Al 2 O 3 mixtures instead of the single La 3 Al 5 O 12 garnet phase have formed [17,18]. The main aim of this study was for the first time to investigate lanthanum substitution effects in Y 3-x La x Al 5 O 12 garnet using mainly XRD, NMR and EPR characterization methods.…”

Comment on “A planar refractive x-ray lens made of nanocrystalline diamond” [J. Appl. Phys. 108, 123107 (2010)]

“…This is consistent with previous reports of unsuccessful attempts to synthesize LAG. 6,7 A recent description of the Diamond Light Source B16 beamline's high resolution x-ray microscope reveals that the scintillator referred to is actually europium doped lutetium aluminium garnet Lu 3 Al 5 O 12 (LuAG). 8 The error is understandable but should be corrected in order to prevent confusion regarding the existence of LAG.…”