Microwave Synthesis and Consolidation of Gadolinium Aluminum Perovskite, a Ceramic Extraordinaire

Selvam, Maria; Rao, K. J.

doi:10.1002/1521-4095(200011)12:21<1621::aid-adma1621>3.0.co;2-x

Cited by 28 publications

(8 citation statements)

References 2 publications

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“…At the same time, the corresponding log[σ] is proportional to T ‐1/4 over a wide temperature range of 300‐5 K, plot (a) in Figure B. Such a behavior is observed in disordered conductors in which conduction electrons are in weak localization states, indicating that a thermally activated mechanism such as hopping or variable e − range hopping controls the transport of the encaged electrons . These observations agree with those of conductive C12A7 in previous reports .…”

Section: Resultssupporting

confidence: 88%

Insights into the direct formation of [Ca₂₄Al₂₈O₆₄]⁴⁺(4e⁻) and its electrical characterization

2019

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C12A7:e− electrides are potentially useful in various technological applications. However, it usually needs to be synthesized through a complicated multistep process under severe conditions. Therefore, the search is on for a more facile and direct process that occurs under milder conditions. Here, a facile and efficient synthesis strategy has been developed for the rapid production of highly conductive C12A7:e− directly from commercially available chemical ingredients of CaO, Al2O3, and Al powders at 1200°C in a 10−2 Pa vacuum for 20 minutes using SPS process. The electron concentration in the as‐prepared C12A7:e− was enhanced up to 2.13 × 1021 cm−3 by simply regulating the addition amounts of Al, covering IM transition. The electronic structure results indicated the formation of homogeneous trapped electrons in the lattice. Further thermal analyses illustrated that Al made a dual function of reducing agent and and reaction promoter, which remarkably reduced the formation temperature of mayenite structure. This study fills in the gaps of direct formation mechanisms of conductive mayenite phase, and provides a new perspective to regulate the resultant Ne.

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Section: Resultssupporting

confidence: 88%

Insights into the direct formation of [Ca₂₄Al₂₈O₆₄]⁴⁺(4e⁻) and its electrical characterization

2019

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“…In this communication, we report a novel microwave route that has well-known advantages. [11][12][13][14][15][16][17][18] It was established by Warshaw and Roy 19 that YAG is the most stable phase in the Y 2 O 3 -Al 2 O 3 phase diagram, which has since been repeatedly confirmed. 20 De With sintered YAG to almost theoretical density and obtained a translucent product at a temperature of 1750°C using SiO 2 and MgO as sintering aids.…”

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confidence: 99%

Translucent yttrium aluminum garnet: Microwave-assisted route to synthesis and processing

2001

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A novel and fast microwave route is described for the synthesis of yttrium aluminum garnet (YAG) and for its sintering to translucent bodies. Precursor was made by microwave decomposition (20 min) of aluminum tri-sec-butoxide and yttrium nitrate dissolved in ethyl acetate. The precursor, conventionally calcined at 1000 °C (1 h), was sintered in microwave using SiC as secondary heater for just 35 min. Resulting translucent YAG has a microhardness (HV) of 18.1 GPa and fracture toughness (KIC) of 4.3 MPa m1/2. A 0.86-mm-thick sintered pellet exhibits approximately 45% transmission for 520-nm radiation. The entire microwave process requires less than 3 h.

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“…This study investigates utilizing composites of GZO and gadolinia alumina perovskite (GdAlO 3 ‐ GAP) in varying weight fractions to impart improved erosion durability with respect to monolithic GZO. GAP is a member of the RE aluminate family, a group of materials which can exhibit high melting temperatures of up to 2500°C, and improved toughness with respect to the RE zirconates . Most importantly, the RE aluminates have thermochemical stability with the pyrochlore zirconates, as shown in the Gd 2 O 3 ‐ZrO 2 ‐Al 2 O 3 system (Figure ).…”

Section: Introductionmentioning

confidence: 99%

“…Most importantly, the RE aluminates have thermochemical stability with the pyrochlore zirconates, as shown in the Gd 2 O 3 ‐ZrO 2 ‐Al 2 O 3 system (Figure ). In addition to thermodynamic compatibility with GZO, GAP possesses phase stability up to its melting temperature of ~2045°C, as well as a reportedly high fracture toughness . This high fracture toughness has been attributed to plasticity near the crack tip, and therefore a form of ductility in the material .…”

Section: Introductionmentioning

confidence: 99%

Durable aluminate toughened zirconate composite thermal barrier coating (TBC) materials for high temperature operation

et al. 2019

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Research on advanced thermal barrier coating (TBC) materials capable of operating beyond 1200°C has primarily focused on the rare earth zirconate pyrochlores, particularly gadolinium zirconate (Gd 2 Zr 2 O 7 -GZO). The drawback of this material is a significant reduction in durability due to a low fracture toughness. This study investigates utilization of a thermodynamically compatible gadolinia alumina perovskite (GdAlO 3 -GAP) toughening phase to improve the durability of GZO. Dense pellets were fabricated to assess the material properties with minimal microstructural influence. Thermal stability, elastic modulus, hardness, indentation fracture resistance and erosion durability were evaluated for GZO, GAP, and composite pellets containing 10, 30, and 50 wt.% GAP. It was demonstrated that GAP and GZO are thermodynamically compatible through 1600°C and thus capable of operating well beyond the limits of traditional 7 wt.% yttria stabilized zirconia (YSZ). Grain sizes are maintained due to a lack of diffusion, and thus microstructural stability is enhanced. The GAP fracture toughness was shown to be over 2X that of GZO while exhibiting a lower elastic modulus and similar hardness. The 50:50 GZO-GAP composite exhibited a 63% reduction in the absolute erosion rate, demonstrating the immense toughening capabilities of this system. The implications for composite TBCs utilizing this system are discussed, along with future work. K E Y W O R D Saluminates, composites, durability, gadolinium zirconate, thermal barrier coatings

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Microwave Synthesis and Consolidation of Gadolinium Aluminum Perovskite, a Ceramic Extraordinaire

Cited by 28 publications

References 2 publications

Insights into the direct formation of [Ca₂₄Al₂₈O₆₄]⁴⁺(4e⁻) and its electrical characterization

Insights into the direct formation of [Ca₂₄Al₂₈O₆₄]⁴⁺(4e⁻) and its electrical characterization

Translucent yttrium aluminum garnet: Microwave-assisted route to synthesis and processing

Durable aluminate toughened zirconate composite thermal barrier coating (TBC) materials for high temperature operation

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Microwave Synthesis and Consolidation of Gadolinium Aluminum Perovskite, a Ceramic Extraordinaire

Cited by 28 publications

References 2 publications

Insights into the direct formation of [Ca24Al28O64]4+(4e−) and its electrical characterization

Insights into the direct formation of [Ca24Al28O64]4+(4e−) and its electrical characterization

Translucent yttrium aluminum garnet: Microwave-assisted route to synthesis and processing

Durable aluminate toughened zirconate composite thermal barrier coating (TBC) materials for high temperature operation

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Insights into the direct formation of [Ca₂₄Al₂₈O₆₄]⁴⁺(4e⁻) and its electrical characterization

Insights into the direct formation of [Ca₂₄Al₂₈O₆₄]⁴⁺(4e⁻) and its electrical characterization