Effect of the Melt Temperature on the Solidification Process of Liquid Garnets Ln₃Al₅O₁₂ (Ln = Dy, Y, and Lu)

Abstract

The solidification process of liquid garnets Ln,A1,0,2 (Ln = Dy, Y, Lu) was probed by differential thermal analysis. A critical temperature r,g was evidenced in the liquid. Cooling from temperatures under rlg leads to the crystallization of the singIe garnet phase. Cooling from temperatures above rlg leads to the solidification of a mixture of perovskite LnAIO, and aluminum oxide a-Al2O3. For Ln = Y, the results are in agreement with stable and metastable phase diagrams previously proposed. The YAIO, melt was shown to display a critical temperature KIP also. Its metastable solidification from temperatures above ZIP leads to the formation of the perovskite at around 1550°C.

High temperature neutron diffraction study of the Al2O3–Y2O3 system

“…No changes can be seen in the patterns collected in the range of 1500-1850 • C. It can be seen from this figure that the sample lost crystallinity in the diffraction pattern collected at 1900 • C. This means that the sample had melted between 1850 • C and 1900 • C. For all spectra, Al 2 O 3 peaks and Y 2 O 3 peaks were identified using a rhomboheadral unit-cell (space group R3c, a = 4.759(0)Å and c = 12.992(0)Å) 15-17 and a cubic unit-cell (space group Ia3, a = 10.608(7)Å), [17][18][19] respectively, while YAG peaks were indexed as a cubic unit-cell (space group Ia3d, a = 12.016(3)Å). 3,12,20 Fig . 3 shows the cooling cycle of the E1 composition.…”

“…They could obtain synthesized high-purity YAG and YAM phases, but they concluded that YAP is a result of reaction between YAG and YAM, where residual amounts were left even after heat treatment. Gervais et al 12 studied the solidification process of liquid YAG and YAP by differential thermal analysis (DTA) and, unlike Maier and Saviniva, 8 was investigated using X-ray diffractometry, XRD, which provided the phases existing at room temperature but not the temperature ranges of the reactions. Hence, phase evolution in Al 2 O 3 -Y 2 O 3 system was studied in situ at elevated temperatures using neutron diffractometry which provided, in real time, information on the reactions and their temperature ranges.…”

Direct Synthesis of Yttrium Aluminum Garnet Particles in an Inductively Coupled Radio-Frequency Plasma System

“…A number of studies on the crystallization kinetics of YAG in other systems have been reported [34][35][36][37]. These studies indicate that direct synthesis of YAG is difficult due to the critical influence of the temperature-time history on crystallization pathways.…”

Thermal and optical properties of glass and crystalline phases formed in the binary R2O3-Al2O3 (R = La-Lu and Y) system

“…The R 2 O 3 -Al 2 O 3 (R ¼ La-Lu and Y) pseudo-binary system displays a variety of nonequilibrium phenomena, including glass formation, metastable crystallization and polyamorphism in the undercooled liquid. [1][2][3] In the R 2 O 3 -Al 2 O 3 binary system, cubic R 3 Al 5 O 12 garnet (R ¼ Eu-Lu and Y), 4,5 monoclinic R 4 Al 2 O 9 (R ¼ Nd-Lu and Y) and orthorhombic RAlO 3 (R ¼ La-Lu and Y) exist as stable phases. [6][7][8][9][10][11] RAlO 3 belongs to the perovskite family of prospective laser materials with common formula ABO 3 .…”