Interface modification for increased fracture toughness in reaction-formed yttrium aluminum garnet/alumina eutectic composites

1999 ◽  
Vol 14 (10) ◽  
pp. 3907-3912 ◽  
Author(s):  
Luke N. Brewer ◽  
Derrick P. Endler ◽  
Shani Austin ◽  
Vinayak P. Dravid ◽  
Joseph M. Collins
Keyword(s):  
Rare Earth ◽  
Yttrium Aluminum Garnet ◽  
Rare Earth Ions ◽  
Alumina Powder ◽  
Interface Modification ◽  
Interfacial Toughness ◽  
Third Phase ◽  
Transmission Electron ◽  
Yttrium Aluminum ◽  
Scanning Transmission

The validity of controlling interfacial toughness in reaction-formed composites was explored using solid-state reaction processing and microanalysis techniques. A variety of rare-earth oxides was added to a yttrium aluminum garnet (YAG)/alumina powder mixture and then melted in air. Some melts retained the crystallography and microstructure of the pure, binary YAG–alumina eutectic. Using scanning transmission electron microscopy in conjunction with energy dispersive X-ray spectroscopy, rare-earth ions were observed both to segregate to the YAG/alumina interface and to form a third phase. Some evidence of increased crack deflection at these interfaces was observed via indentation fracture.

Facet-Related Site Selectivity for Rare-Earth Ions in Yttrium Aluminum Garnet

1971 ◽  
Vol 26 (25) ◽  
pp. 1570-1573 ◽  
Author(s):  
R. Wolfe ◽  
M. D. Sturge ◽  
F. R. Merritt ◽  
L. G. Van Uitert
Keyword(s):  
Rare Earth ◽  
Yttrium Aluminum Garnet ◽  
Rare Earth Ions ◽  
Site Selectivity ◽  
Yttrium Aluminum

scholarly journals Влияние J-J-взаимодействия возбужденных состояний редкоземельного иона Pr-=SUP=-3+-=/SUP=- на магнитополяризованную люминесценцию празеодим-иттриевого граната-алюминия

2019 ◽  
Vol 61 (5) ◽  
pp. 848
Author(s):  
У.В. Валиев ◽  
Gary W. Burdick ◽  
Р.Р. Вильданов ◽  
R.Yu. Rakhimov ◽  
Dejun Fu
Keyword(s):  
Rare Earth ◽  
Circular Polarization ◽  
Spectral Region ◽  
Yttrium Aluminum Garnet ◽  
Visible Spectral Region ◽  
Irreducible Representations ◽  
Green Luminescence ◽  
Rare Earth Ion ◽  
Yttrium Aluminum ◽  
Polarization Of Luminescence

AbstractThe spectra of luminescence and magnetic circular polarization of luminescence of praseodymium–yttrium aluminum garnet Pr^3+ : Y_3Al_5O_12 (PrYAG) are studied in the visible spectral region at temperature T = 300 K. An analysis of spectral dependences of magnetooptical and optical spectra makes it possible to identify optical 4  f –4  f -transitions between Stark sublevels of multiplets ^3 P _0, ^3 P _1, ^3 Н _5, and ^3 Н _6 in PrYAG. It was shown that an important role in the spectrum of the degree of magnetic circular polarization of luminescence of this paramagnetic garnet is played by the effect of quantum-mechanical J – J mixing of states of Stark singlets ^3 Н _5 and ^3 Н _6 of non-Kramer rare-earth ion Pr^3+ in the “green” luminescence band related to forbidden 4  f → 4  f transition ^3 P _0 → ^3 Н _5 in the visible spectral region. To interpret the spectra of magnetic circular polarization of luminescence, the energy of experimentally determined Stark sublevels of multiplets under study, their irreducible representations and wave functions determined by numerical simulation of the energy spectrum of the rare-earth ion Pr^3+ in the garnet structure are used.

scholarly journals Photoluminescence Enhancement of Titanate Nanotubes by Insertion of Rare Earth Ions in Their Interlayer Spaces

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Thalles M. F. Marques ◽  
Cleanio Luz-Lima ◽  
Marco Sacilloti ◽  
Kazunori Fujisawa ◽  
Nestor Perea-Lopez ◽  
...  
Keyword(s):  
Optical Properties ◽  
Rare Earth ◽  
Strong Dependence ◽  
Sodium Titanate ◽  
Rare Earth Ions ◽  
Titanate Nanotubes ◽  
Visible Range ◽  
Exchange Reactions ◽  
X Ray ◽  
Transmission Electron

The optical properties of titanate nanotubes (TiNts) intercalated with rare earths (RE) ions were intensively investigated in this study. To prepare the nanomaterials, sodium titanate nanotubes (Na-TiNts) were submitted to ion exchange reactions with different rare earth elements (RE: Pr3+, Er3+, Nd3+, and Yb3+). To the best of our knowledge, it is the first time that these RE-TiNts were synthesized. All samples were characterized by Raman spectroscopy, X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDS). Furthermore, the optical properties were examined using photoluminescence spectroscopy (PL) and UV-Vis-NIR absorption spectroscopy. The PL intensity (visible range) of the RE-TiNt samples showed a strong dependence when the temperature was decreased down to 20 K. This PL enhancement probably was promoted by electronic modifications in titanate layer band gap and/or interface charge transfers due to RE ions intercalation.

Crystallization kinetics of yttrium aluminum garnet (Y3Al5O12)

2001 ◽  
Vol 16 (6) ◽  
pp. 1795-1805 ◽  
Author(s):  
Bradley R. Johnson ◽  
Waltraud M. Kriven
Keyword(s):  
Yttrium Aluminum Garnet ◽  
Three Dimensional ◽  
Constant Number ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Yttrium Aluminum ◽  
Temperature Transformation ◽  
Kinetics Of ◽  
Dimensional Crystal

The kinetics and pathways for crystallization of solid, amorphous, yttrium aluminum garnet (YAG) were studied using isothermal differential thermal analysis, x-ray diffraction, and transmission electron microscopy. The activation energy for crystallization was 437 KJ/mol and the measured Avrami exponent was 2.74, which corresponded to three-dimensional crystal growth with a constant number of nuclei. Time–temperature–transformation (T–T–T) curves were developed from the data to predict crystallization rates as a function of temperature. The crystallization pathway for YAG in this system is compared to others reported in the literature.

Glycothermal synthesis of rare earth iron garnets

1998 ◽  
Vol 13 (4) ◽  
pp. 856-860 ◽  
Author(s):  
Masashi Inoue ◽  
Toshihiro Nishikawa ◽  
Tomoyuki Inui
Keyword(s):  
Rare Earth ◽  
Yttrium Aluminum Garnet ◽  
Hydrothermal Reaction ◽  
The Other ◽  
Spontaneous Nucleation ◽  
Iron Garnets ◽  
Yttrium Aluminum ◽  
Ionic Size ◽  
Two Phases ◽  
Iron Garnet

The reactions of rare earth (RE) acetates with iron acetylacetonate in 1,4-butanediol at 300 °C (glycothermal reaction) yielded two novel phases depending on the ionic size of the RE element: one was obtained for Er-Lu and the other for Tb and Dy. The former phase was hexagonal REFeO3, while the latter phase has not been identified. The reaction of Y or Ho acetate yielded the mixture of these two phases. When the reactions were carried out in the presence of seed crystals of yttrium aluminum garnet (Y3Al5O12), these phases were not formed but RE iron garnet (RE3Fe5O12) grew on the seed, which suggests that spontaneous nucleation of RE iron garnet does not occur, but crystal growth proceeds easily under the glycothermal conditions. Hydrothermal reaction of the same starting materials yielded a mixture of Fe2O3 and an amorphous RE phase.

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