scholarly journals Synthesis and characterization of a nano-scaled barium cerate perovskite powder using starch as polymerization agent

2018 ◽  
Author(s):  
Roberto Köferstein
Keyword(s):  
Mixed Oxide ◽  
Size Range ◽  
Phase Evolution ◽  
Coarse Grained ◽  
Synthesis And Characterization ◽  
Barium Cerate ◽  
Phase Pure ◽  
Sintering Behaviour ◽  
Powder Compacts

The preparation of nano-sized BaCeO3 powder using starch as a polymerizationagent is described herein. Phase evolution during the decomposition process of a (BaCe)-gelwas monitored by XRD. A phase-pure nano-sized BaCeO3 powder was obtained aftercalcining of the (BaCe)-gel at 920 °C. The resulting powder has a specific surface area of 15.4m2/g. TEM investigations reveal particles mainly in the size range of 30 to 65 nm. Theshrinkage and sintering behaviour of resulting powder compacts were studied in comparisonto a coarse-grained mixed-oxide BaCeO3 powder (SBET = 2.1 m2/g). Dilatometricmeasurements show that the beginning of shrinkage of compacts from the nano-sized powder is downshifted by 300 °C compared to mixed-oxide powder. Compacts from the nano-sizedpowder reach a relative density of 91 % after sintering at 1450 °C for 10 h.

scholarly journals Sintering of a fine-grained BaCeO3 powder obtained from a co-precipitation method

2018 ◽  
Author(s):  
Roberto Köferstein
Keyword(s):  
Precursor Powder ◽  
Coarse Grained ◽  
Precipitation Method ◽  
Fine Grained ◽  
Grain Sizes ◽  
Three Phase ◽  
Sintering Behaviour ◽  
Co Precipitation ◽  
Precursor Powders ◽  
Powder Compacts

The formation of BaCeO3 by a co-precipitation method is described herein. The coprecipitationroute leads to an orange (BaCe)-precursor powder (1). To improve the sinteringbehaviour, a small amount of Ge4+ was incorporated, leading to a (BaCe0.95/Ge0.05)-precursor(2). Both precursor powders results in fine-grained preceramic powders (1A, 2A) aftercalcination. The shrinkage and sintering behaviour of resulting powder compacts were studiedin comparison to a coarse-grained mixed-oxide BaCeO3 powder (3). Compacts of 2A reach arelative density of 90 % after sintering at 1350 °C with grain-sizes between 0.9−3.2 μm. Onthe other hand ceramics of 1A and 3 have, after sintering at 1500 °C (10 h), relative densitiesof 85 % and 76 %, respectively. Ceramic bodies of 1A consisted of phase-pure orthorhombicBaCeO3, whereas bodies of 2A show reflections of BaCeO3 and a Ba2GeO4 phase. DTAinvestigations of samples 1A and 2A reveal three phase transitions at 255 °C (1A) and 256 °C (2A) as well as 383 °C (1A) and 380 °C (2A). A very weak one can be obtained in the range880−910 °C

Synthesis and characterization of two-dimensional Nb4C3 (MXene)

2014 ◽  
Vol 50 (67) ◽  
pp. 9517-9520 ◽  
Author(s):  
M. Ghidiu ◽  
M. Naguib ◽  
C. Shi ◽  
O. Mashtalir ◽  
L. M. Pan ◽  
...  
Keyword(s):  
Distribution Function ◽  
Hydrofluoric Acid ◽  
Pair Distribution Function ◽  
Function Analysis ◽  
Synthesis And Characterization ◽  
Two Dimensional ◽  
Phase Pure

By etching Nb4AlC3 powders in hydrofluoric acid, a phase-pure, highly conductive, Nb4C3 MXene – the second with formula M4X3 – was produced. The latter's structure was investigated using pair distribution function analysis.

Synthesis and Characterization of a New Family of Mixed Oxide−Proton Conductors Based on Tristrontium Oxysilicate

2008 ◽  
Vol 20 (5) ◽  
pp. 2026-2034 ◽  
Author(s):  
José M. Porras-Vázquez ◽  
Enrique R. Losilla ◽  
Laura León-Reina ◽  
María Martínez-Lara ◽  
Miguel A. G. Aranda
Keyword(s):  
Mixed Oxide ◽  
Proton Conductors ◽  
Synthesis And Characterization ◽  
New Family

Synthesis and characterization of nano-structured Th1−x Ce x O2 mixed oxide

2011 ◽  
Vol 107 (1) ◽  
pp. 105-110 ◽  
Author(s):  
Y. P. Naik ◽  
G. A. Ramarao ◽  
Ajita Banthiya ◽  
Deepika Chaudhary ◽  
Charu Arora
Keyword(s):  
Mixed Oxide ◽  
Synthesis And Characterization

scholarly journals Nano-sized BaSnO3 powder via a precursor route. Comparative study of sintering behaviour and mechanism of fine and coarse-grained powders.

2018 ◽  
Author(s):  
Roberto Köferstein
Keyword(s):  
Comparative Study ◽  
Single Crystal ◽  
Relative Density ◽  
Reference Value ◽  
Coarse Grained ◽  
Calcination Process ◽  
Precursor Route ◽  
Complex Precursor ◽  
Sintering Behaviour ◽  
Powder Compacts

Preparation of a very fine BaSnO3 powder by calcination of a barium tin 1,2-ethanediolato complex precursor and its sintering behaviour are described herein. A ratecontrolled calcination process to 820 °C leads to a nm-sized BaSnO3 powder with aspecific surface area of S = 15.1 m2/g (dav. = 55 nm). The powder has a slightly largercell parameter of a = 412.22(7) pm compared to the single crystal value, whichdecreases with increasing calcination temperature and reaches the reference value above1000 °C. The sintering behaviour is compared between fine- and coarse-grainedBaSnO3 powders. Corresponding powder compacts of the nano-sized BaSnO3 achieve arelative density of 90 % after sintering at 1600 °C for 1 h and at 1500 °C and a soakingtime of 30 h, whereas coarse-grained powder compacts reach only 80 % of the relative density at 1650 °C (10 h). Furthermore, the shrinkage mechanisms of fine and coarsegrainedpowder compacts have been investigated and are discussed.

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