Viscous flow spark plasma sintering of glass microspheres with YAG composition and high tendency to crystallization

Glass‐ceramic Ce3+‐doped YAG‐Al2O3 composites prepared by sintering of glass microspheres

“…In the case of yttrium aluminate glasses, this window is very narrow (only 20–40℃ wide) 27–32 . Due to the rapid crystallization of YAG from those glasses the preparation of transparent or translucent bulk glass or ceramic without sintering additives is very difficult and requires careful optimization of sintering conditions 37,38 . On the other hand, controlled crystallization of YAG phase from doped aluminate glasses during the sintering at relatively mild conditions (temperature up to 1100℃) enables preparation of glass‐ceramic compacts (e.g., Phosphor in Glass (PiG) composites) with the desired luminescence.…”

“…The consolidation of glass beads with eutectic composition into bulk was performed at a temperature of 840℃ without dwell time and applied pressure of 40MPa. These sintering conditions were selected based on our previous work 37,38 and dilatation curve for Ce 3+ ‐doped eutectic system; at a heating rate of 20℃/min, the viscous flow sintering took place in the temperature range from almost 800℃ up to 860℃. When a temperature of lower than 840℃ was applied, the bulk glass preparation was not successful.…”

Highly Nonstoichiometric YAG Ceramics with Modified Luminescence Properties

“…Glassy YAG materials can be synthesized by containerless melt‐quenching approaches including aerodynamic levitation [ 20 ] and spray pyrolysis methods, [ 21,22 ] and these crystallize into the cubic garnet structure at ≈900 °C, far below the range 1600–1700 °C typically required for ceramic synthesis of YAG. [ 23 ] Laser melting of aerodynamically levitated samples is useful in this context as it offers access to temperatures that are high enough to melt YAG, while the absence of a container‐melt interface inhibits heterogeneous crystallization on cooling, allowing access to non‐equilibrium states (i.e., glass or deeply undercooled melts) [ 24 ] from which crystallization occurs.…”

“…[15] Similarly, melt-quenching techniques offer non-equilibrium routes to a range of metastable aluminates and gallates with similar chemistries to YAG, by crystallization at temperatures below those typically required for solid-state reactions. [16][17][18][19] Glassy YAG materials can be synthesized by containerless melt-quenching approaches including aerodynamic levitation [20] and spray pyrolysis methods, [21,22] and these crystallize into the cubic garnet structure at ≈900 °C, far below the range 1600-1700 °C typically required for ceramic synthesis of YAG. [23] Laser melting of aerodynamically levitated samples is useful in this context as it offers access to temperatures that are high enough to melt YAG, while the absence of a containermelt interface inhibits heterogeneous crystallization on cooling, allowing access to non-equilibrium states (i.e., glass or deeply undercooled melts) [24] from which crystallization occurs.…”

Highly non-stoichiometric YAG ceramics with modified luminescence properties

“…14 Similarly, glass-crystallisation and direct crystallisation of undercooled melts can be used to isolate a range of metastable aluminates and gallates with similar chemistries to YAG. [15][16][17] Glassy YAG materials can be synthesised by containerless melt-quenching approaches including aerodynamic levitation 18 and spray pyrolysis methods, 19,20 and these crystallise into the cubic garnet structure at approximately 900°C, far below the range 1600-1700°C typically required for ceramic synthesis of YAG. 21 Laser melting of aerodynamically-levitated samples is useful in this context as it offers access to extremely high temperatures, whilst the absence of a container-melt interface inhibits heterogeneous crystallisation on cooling, allowing access to non-equilibrium states (i.e.…”