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Heli Maarit Jantunen is a Finnish Professor of Technology at the University of Oulu and a member of the Scientific Advisory Board for the National Defense. She works on microelectronics and is a member of the 6G Flagship.
Liquid phase sintering is a sintering technique that uses a liquid phase to accelerate the interparticle bonding of the solid phase. In addition to rapid initial particle rearrangement due to capillary forces, mass transport through liquid is generally orders of magnitude faster than through solid, enhancing the diffusional mechanisms that drive densification. The liquid phase can be obtained either through mixing different powders—melting one component or forming a eutectic—or by sintering at a temperature between the liquidus and solidus. Additionally, since the softer phase is generally the first to melt, the resulting microstructure typically consists of hard particles in a ductile matrix, increasing the toughness of an otherwise brittle component. However, liquid phase sintering is inherently less predictable than solid phase sintering due to the complexity added by the presence of additional phases and rapid solidification rates. Activated sintering is the solid-state analog to the process of liquid phase sintering.
Lithium aluminium germanium phosphate, typically known with the acronyms LAGP or LAGPO, is an inorganic ceramic solid material whose general formula is Li
1+xAl
xGe
2-x(PO
4)
3. LAGP belongs to the NASICON (Sodium Super Ionic Conductors) family of solid conductors and has been applied as a solid electrolyte in all-solid-state lithium-ion batteries. Typical values of ionic conductivity in LAGP at room temperature are in the range of 10-5 - 10-4 S/cm, even if the actual value of conductivity is strongly affected by stoichiometry, microstructure, and synthesis conditions. Compared to lithium aluminium titanium phosphate (LATP), which is another phosphate-based lithium solid conductor, the absence of titanium in LAGP improves its stability towards lithium metal. In addition, phosphate-based solid electrolytes have superior stability against moisture and oxygen compared to sulfide-based electrolytes like Li
10GeP
2S
12 (LGPS) and can be handled safely in air, thus simplifying the manufacture process. Since the best performances are encountered when the stoichiometric value of x is 0.5, the acronym LAGP usually indicates the particular composition of Li
1.5Al
0.5Ge
1.5(PO
4)
3, which is also the typically used material in battery applications.
References
- ↑ "A room-temperature fabrication method for microwave dielectric Li2MoO4 ceramics and their applicability for antennas".
- ↑ Kähäri, Hanna; Teirikangas, Merja; Juuti, Jari; Jantunen, Heli (November 2014). "Dielectric Properties of Lithium Molybdate Ceramic Fabricated at Room Temperature". Journal of the American Ceramic Society. 97 (11): 3378–3379. doi:10.1111/jace.13277.
- ↑ Kähäri, Hanna; Teirikangas, Merja; Juuti, Jari; Jantunen, Heli (March 2015). "Improvements and Modifications to Room-Temperature Fabrication Method for Dielectric Li 2 MoO 4 Ceramics". Journal of the American Ceramic Society. 98 (3): 687–689. doi:10.1111/jace.13471.