SYNTHESIS AND ELECTRICAL CHARACTERIZATION OF BULK SYNTHESIS AND ELECTRICAL CHARACTERIZATION OF BULK FULLY DENSE NANOCRYSTALLINE ELECTROLYTES PREPARED BY FULLY DENSE NANOCRYSTALLINE ELECTROLYTES PREPARED BY HIGH-PRESSURE SPARK PLASMA SINTERING HIGH-PRESSURE SPARK PLASMA SINTERING U. Anselmi Tamburini 1 , F. Maglia 1 , G. Chiodelli 2 , G. Spinolo 1 , Z.A. Munir 3 1 Dept. of Chemical Engineering and Materials Science, UC Davis, USA 2 IENI - CNR, Dipartimento di Pavia, Italy 3 Dipartimento di Chimica fisica, Universita’ di Pavia, Italy
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SYNTHESIS AND ELECTRICAL CHARACTERIZATION OF BULK FULLY DENSE NANOCRYSTALLINE ELECTROLYTES PREPARED BY HIGH-PRESSURE SPARK PLASMA SINTERING U. Anselmi.
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SYNTHESIS AND ELECTRICAL CHARACTERIZATION OF SYNTHESIS AND ELECTRICAL CHARACTERIZATION OF BULK FULLY DENSE NANOCRYSTALLINE ELECTROLYTES BULK FULLY DENSE NANOCRYSTALLINE ELECTROLYTES
PREPARED BY HIGH-PRESSURE SPARK PLASMA PREPARED BY HIGH-PRESSURE SPARK PLASMA SINTERINGSINTERING
U. Anselmi Tamburini1, F. Maglia1, G. Chiodelli2, G. Spinolo1, Z.A. Munir3
1Dept. of Chemical Engineering and Materials Science, UC Davis, USA 2IENI - CNR, Dipartimento di Pavia, Italy
3Dipartimento di Chimica fisica, Universita’ di Pavia, Italy
•Small grain size produce modification of the defects concentrations, distribution and on transport properties
NANOIONICSNANOIONICS
•These effects become particularly evident when the grain size becomes comparable with the Debye lenght.
•In most ionic materials this requires grain size close to 10 nm.
Synthesis and electrical characterization of bulk fully dense nanocrystalline electrolytes prepared by high-pressure SPSSynthesis and electrical characterization of bulk fully dense nanocrystalline electrolytes prepared by high-pressure SPS
•Densification of nanopowders •General applicability•Grain growth difficult to control•Very sensitive to the characteristics of the nanopowders
•Controlled crystallization of amorphous precursors•Applicable only to few systems•Single phase samples are difficult to obtain
Synthesis of bulk nanocrystalline ionic oxides Synthesis of bulk nanocrystalline ionic oxides with grain size below 20 nmwith grain size below 20 nm
Synthesis and electrical characterization of bulk fully dense nanocrystalline electrolytes prepared by high-pressure SPSSynthesis and electrical characterization of bulk fully dense nanocrystalline electrolytes prepared by high-pressure SPS
Filippo Maglia
University of Pavia, Italy
200 m 20 nm
Powders obtained by solution chemistry are usually characterized by a high level of agglomeration
Synthesis of nanopowders (d<10 nm)Synthesis of nanopowders (d<10 nm)
This makes the densification much more difficult
Synthesis and electrical characterization of bulk fully dense nanocrystalline electrolytes prepared by high-pressure SPSSynthesis and electrical characterization of bulk fully dense nanocrystalline electrolytes prepared by high-pressure SPS
Densification of nanopowdersDensification of nanopowders
Dept. Chemical Engineering and Materials Science
University of California, Davis
Prof.Z.A.Munir
Synthesis and electrical characterization of bulk fully dense nanocrystalline electrolytes prepared by high-pressure SPSSynthesis and electrical characterization of bulk fully dense nanocrystalline electrolytes prepared by high-pressure SPS
Synthesis and electrical characterization of bulk fully dense nanocrystalline electrolytes prepared by high-pressure SPSSynthesis and electrical characterization of bulk fully dense nanocrystalline electrolytes prepared by high-pressure SPS
Filippo Maglia
University of Pavia, Italy
Characteristics of SPS/FAST
Synthesis and electrical characterization of bulk fully dense nanocrystalline electrolytes prepared by high-pressure SPSSynthesis and electrical characterization of bulk fully dense nanocrystalline electrolytes prepared by high-pressure SPS
•Very short sintering times (minutes instead of hours)
•Lower sintering temperatures
Particularly suited for the densification of nanopowders
University of Pavia, Italy
HIGH-PRESSURE FIELD ASSISTED SINTERING (HP-FAST)HIGH-PRESSURE FIELD ASSISTED SINTERING (HP-FAST)
Synthesis and electrical characterization of bulk fully dense nanocrystalline electrolytes prepared by high-pressure SPSSynthesis and electrical characterization of bulk fully dense nanocrystalline electrolytes prepared by high-pressure SPS
Filippo Maglia
University of Pavia, Italy
HIGH-PRESSURE FIELD ASSISTED SINTERING (HP-FAST)HIGH-PRESSURE FIELD ASSISTED SINTERING (HP-FAST)
Sintering time 5 min
Synthesis and electrical characterization of bulk fully dense nanocrystalline electrolytes prepared by high-pressure SPSSynthesis and electrical characterization of bulk fully dense nanocrystalline electrolytes prepared by high-pressure SPS
Filippo Maglia
>98% relative density
University of Pavia, Italy
Material Starting powder grain size (nm)
Heating rate(°C/min)
Hold temp.(°C)
Hold pressure(MPa)
Hold time(min)
Relative density(%)
Grains sizeDirect measurement(nm)
CeO2 7 200 625 600 5 > 98 11.6 ± 2.1
Ce0.7Sm0.3O2 8 200 750 610 5 > 98 16.9 ± 3.1
YFSZ (8%) 6.6 200 850 530 5 > 98 15.5 ± 3.2
Powder agglomeration has very little influence
Example of materials obtained by HP-FAST
Synthesis and electrical characterization of bulk fully dense nanocrystalline electrolytes prepared by high-pressure SPSSynthesis and electrical characterization of bulk fully dense nanocrystalline electrolytes prepared by high-pressure SPS
Filippo Maglia
100 nm
YSZ (8%)
100 nm
CeO2 (30%Sm)
100 nm
CeO2
University of Pavia, Italy
YSZ (8%)YSZ (8%)
Grain size 15.5 nm T=200°C
Very large apparent grain boundary resistance
dr = 98%
Synthesis and electrical characterization of bulk fully dense nanocrystalline electrolytes prepared by high-pressure SPSSynthesis and electrical characterization of bulk fully dense nanocrystalline electrolytes prepared by high-pressure SPS
Filippo Maglia
The difference between gb and bulk reduces with grain size
Guo X, Zhang Z. Acta Mater 2003;51:2539
University of Pavia, Italy
Interaction of nanocrystalline YSZ with waterInteraction of nanocrystalline YSZ with water
Dehydration at 200°C for (b) 10 min, (c) 20 min, (d) 30 min, (e) 40 min , (f) 80 min
Synthesis and electrical characterization of bulk fully dense nanocrystalline electrolytes prepared by high-pressure SPSSynthesis and electrical characterization of bulk fully dense nanocrystalline electrolytes prepared by high-pressure SPS
Filippo Maglia
•If exposed for 400h to air saturated with water the conductivity increases almost 2 orders of magnitude at 200°C
•The change involves both bulk and grain boundaries
•It is totaly reversible
•It is observed only in samples with grain size below 20 nm
University of Pavia, Italy
Nanocrystalline
Microcrystalline
Interaction of nanocrystalline YSZ with waterInteraction of nanocrystalline YSZ with water
Synthesis and electrical characterization of bulk fully dense nanocrystalline electrolytes prepared by high-pressure SPSSynthesis and electrical characterization of bulk fully dense nanocrystalline electrolytes prepared by high-pressure SPS
Filippo Maglia
•Results suggests protonic conductivity
•Protonic conductivity in YSZ has been proposed before but never observed
OXOO OHOVOH )(22
•Nanostructure can enhance the localization of protons at the grain boundary
University of Pavia, Italy
Conclusions
•HP-SPS represent the first reliable method for the synthesis of large amounts of bulk ceramic materials with grain size < 20 nm and relative density >98%
•This suggest the possibility of a new class of ionic materials whose properties are totally controlled by the nanostructure
•Approaching grain size of 10 nm traditional ionic compounds show unexpected new properties as interface and confinement effects become dominant
•Nanostructure represent a powerful new parameter (beside doping) to control the electrical properties of ionic materials
•This offers for the first time the possibility to investigate systematically the physical properties of these materials
Synthesis and electrical characterization of bulk fully dense nanocrystalline electrolytes prepared by high-pressure SPSSynthesis and electrical characterization of bulk fully dense nanocrystalline electrolytes prepared by high-pressure SPS