scholarly journals Direct Formation and Structural Characterization of Electride C12A7

Materials ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 84 ◽  
Author(s):  
J.R. Salasin ◽  
S.E.A. Schwerzler ◽  
R. Mukherjee ◽  
D.J. Keffer ◽  
K.E. Sickafus ◽  
...  
Keyword(s):  
High Temperature ◽  
Solid State ◽  
Structural Characterization ◽  
Sol Gel ◽  
Reducing Power ◽  
Reduction Process ◽  
Anionic Vacancy ◽  
Process Time ◽  
Vacuum Furnace ◽  
High Temperature Stability

Ca12Al14O33 (C12A7 or Mayenite) is a material whose caged clathrate structure and occluded anionic species leads to significant functionality. The creation of occluded anionic vacancies leads to the injection of localized electrons at the center of the cage, converting the wide band gap insulator to a semi- or metallic conducting material. The conversion to the electride historically requires the synthesis of oxy-C12A7, consolidation, and then reduction to introduce anionic vacancies. This report develops and characterizes an electride formation procedure from three starting points: unconsolidated oxy-C12A7, heterogenous solid-state reactants (CaCO3 and Al2O3), and homogenous non-carbonaceous polymer assisted sol-gel reactants. Electride-C12A7 formation is observed in a vacuum furnace where the reactants are in direct contact with a carbon source. Process time and temperature-dependent structural characterization provides insight into the source of high temperature C12A7 stability, the mechanism of anionic vacancy formation, and the magnitude of ultimate conductivity that cannot be explained by current reduction theories. A new theory is presented where mixed O- and C-occupied cages lead to high temperature stability, oxidation of C species creates anionic vacancies, and an equilibrium between the reducing power of the electride-C12A7 and of the C species leads to the ultimate conductivity achieved by the process. This represents a shift in understanding of the carbonaceous reduction process and the first report of high purity electride-C12A7 formation from heterogenous solid-state reactants and homogenous non-carbonaceous polymer assisted sol-gel reactants.

Sol-gel coated enamel for steel: 250 days of continuous high-temperature stability

2017 ◽  
Vol 43 (3) ◽  
pp. 2974-2980 ◽  
Author(s):  
Gundars Mezinskis ◽  
Ilona Pavlovska ◽  
Kaspars Malnieks ◽  
Laimons Bidermanis ◽  
Andris Cimmers ◽  
...  
Keyword(s):  
High Temperature ◽  
Sol Gel ◽  
Temperature Stability ◽  
High Temperature Stability

scholarly journals Size-dependent optical and thermochromic properties of Sm3Fe5O12

RSC Advances ◽  
2017 ◽  
Vol 7 (60) ◽  
pp. 37765-37770 ◽  
Author(s):  
Huanhuan Liu ◽  
Long Yuan ◽  
Hui Qi ◽  
Yanyan Du ◽  
Shan Wang ◽  
...  
Keyword(s):  
High Temperature ◽  
Solid State ◽  
Solid State Reaction ◽  
Sol Gel ◽  
Solid State Reaction Method ◽  
Inorganic Materials ◽  
Particle Sizes ◽  
Reaction Method ◽  
Size Dependent ◽  
Thermochromic Properties

Reversible thermochromic inorganic materials of Sm3Fe5O12with different particle sizes have been synthesized by a conventional high temperature solid state reaction method (2.51 μm) and sol–gel method (0.16 μm).

The Influence of Degree of Polymerization on Precursor-Derived Si-B-C-N Ceramics

2010 ◽  
Vol 650 ◽  
pp. 355-360
Author(s):  
Xiang Geng ◽  
X. Huang ◽  
Ya Jing Li ◽  
Song Li ◽  
Xiao Bin Shi
Keyword(s):  
High Temperature ◽  
Solid State ◽  
Amorphous Materials ◽  
Chemical Properties ◽  
Temperature Stability ◽  
High Hardness ◽  
Nitrogen Atmosphere ◽  
Degree Of Polymerization ◽  
Pyrolysis Process ◽  
High Temperature Stability

Precursor derived Si-B-C-N ceramic is a kind of amorphous materials with high hardness, low density, durability at extremely high temperature. The materials show a great potential to be used in the field of the Thermal Protective System (TPS). The physical states and chemical properties of the amorphous materials greatly depend on the starting materials. The effect of degree of polymerization (DP) of the precursor on the pyrolysis process and the characteristics of the amorphous Si-B-C-N materials are studied. The SiBCN-based preceramic polymer synthesized by dichloromethylvinylsilane, ammonia and BH3•SMe2. Dichloromethylvinylsilane reacted with ammonia and BH3•SMe2 in toluene or tetrahydrofuran (THF) as solvent in the presence of catalytic amounts of pyridine. The polymeric precursors were cured at low temperature to obtain solid-state precursors. Pyrolysis process of the solid-state precursors under various temperatures and carried out in nitrogen atmosphere. The results showed that DP of the precursor influences the pyrolysis process and the high temperature stability of the Si-B-C-N amorphous ceramics.

Synthesis and structural characterization of Li3Y(BO3)2

2017 ◽  
Vol 72 (2) ◽  
pp. 153-158 ◽  
Author(s):  
Sebastian Bräuchle ◽  
Hubert Huppertz
Keyword(s):  
Crystal Structure ◽  
High Temperature ◽  
Solid State ◽  
Boric Acid ◽  
Structural Characterization ◽  
Diffraction Data ◽  
Lithium Carbonate ◽  
X Ray Diffraction ◽  
X Ray

AbstractLi3Y(BO3)2 was prepared by high-temperature solid state synthesis at 900°C in a platinum crucible from lithium carbonate, boric acid, and yttrium(III) oxide. The compound crystallizes monoclinically in the space group P21/c (no. 14) (Z=4) isotypically to Li3Gd(BO3)2. The structure was refined from single-crystal X-ray diffraction data: a=8.616(3), b=6.416(3), c=10.014(2) Å, β=116.6(2)°, V=494.9(3) Å3, R1=0.0211, and wR2=0.0378 for all data. The crystal structure of Li3Y(BO3)2 consists of [Y2O14] dinuclear units, which are interconnected to each other by planar B(1)O3 groups and LiO4 tetrahedra via common edges and corners along the a axis.

Sol-gel synthesis of sodium-modified AlPO4–SiO2 glasses and structural characterization by solid state NMR

2009 ◽  
Vol 19 (8) ◽  
pp. 1151 ◽  
Author(s):  
Rashmi R. Deshpande ◽  
Long Zhang ◽  
Hellmut Eckert
Keyword(s):  
Solid State ◽  
Structural Characterization ◽  
Solid State Nmr ◽  
Sol Gel ◽  
Sol Gel Synthesis

Structure and Luminescence of Ba3MgSi2O8: Eu2+, Mn2+ Phosphors

2011 ◽  
Vol 399-401 ◽  
pp. 1016-1019
Author(s):  
Yue Li ◽  
Da Wei He ◽  
Yong Sheng Wang ◽  
Fu Ming ◽  
Yang Wu ◽  
...  
Keyword(s):  
High Temperature ◽  
Solid State ◽  
Phase Change ◽  
Emission Spectrum ◽  
Solid State Reaction ◽  
Crystallization Temperature ◽  
Sol Gel ◽  
Solid State Reaction Method ◽  
Reaction Method ◽  
Violet Light

In this paper, Ba3MgSi2O8: Eu2+, Mn2+ phosphor was synthesized by the sol-gel method and high temperature solid-state reaction method. The structure and emission spectrum excited by near violet light were investigated. we studied the process of phase change in roasting and determined the approximate crystallization temperature of Ba3MgSi2O8: Eu2+, Mn2+ phosphors. Our results demonstrate that 514 nm emission bands were from Eu2+ ions replacing of the sites of Ba2+ in Ba2SiO4. 440 nm emission bands originated from Eu2+ ions substituting the sites of Ba2+ in Ba3MgSi2O8, corresponded to 4f65d1→4f7 transition of Eu2+ ions. 615 nm emission bands ascribed to Mn2+ ions taking place of the sites of Mg2+ ions, corresponded to 4T→6A red launch of Mn2+ ions.

Structural Characterization and High-Temperature Behavior of Silicon Oxycarbide Glasses Prepared from Sol-Gel Precursors Containing Si-H Bonds

1995 ◽  
Vol 78 (2) ◽  
pp. 379-387 ◽  
Author(s):  
Gian Domenico Sorarù ◽  
Gennaro D'Andrea ◽  
Renzo Campostrini ◽  
Florence Babonneau ◽  
Gino Mariotto
Keyword(s):  
High Temperature ◽  
Structural Characterization ◽  
Sol Gel ◽  
Silicon Oxycarbide ◽  
Temperature Behavior ◽  
High Temperature Behavior ◽  
Silicon Oxycarbide Glasses

Synthesis and structural characterization of BaSr2Ge3O9

2016 ◽  
Vol 71 (12) ◽  
pp. 1225-1232
Author(s):  
Sebastian Bräuchle ◽  
Clivia Hejny ◽  
Hubert Huppertz
Keyword(s):  
High Temperature ◽  
Solid State ◽  
Structural Characterization ◽  
Diffraction Data ◽  
Barium Carbonate ◽  
Strontium Carbonate ◽  
X Ray Diffraction ◽  
Triclinic Space Group ◽  
X Ray

AbstractBaSr2Ge3O9 was prepared by high-temperature solid-state synthesis at 1100°C in a platinum crucible from barium carbonate, strontium carbonate, and germanium(IV) oxide. The compound crystallizes in the triclinic space group P1̅ (no. 2) isotypically to walstromite BaCa2Si3O9. The structure was refined from single-crystal X-ray diffraction data: a=7.104(5), b=10.060(7), c=7.099(5) Å, α=83.0(2), β=77.0(2), γ=70.2(2)°, V=464.3(6) Å3, R1=0.0230, and wR2=0.0602 for all data. BaSr2Ge3O9 is characterized by three-membered rings of germanate tetrahedra. There are three crystallographically different Ge sites (Ge1, Ge2, and Ge3) in each [Ge3O9]6− ring. The rings occur in layers with the apices of alternating rings pointing in opposite directions. The Sr2+ and Ba2+ ions are located in between. The Sr1 cation is eight-fold coordinated, while Sr2 is octahedrally surrounded by oxide anions, and the Ba cation again eight-fold coordinated.

Solid-state NMR investigations of the polymer route to SiBCN ceramics

2003 ◽  
Vol 81 (11) ◽  
pp. 1359-1369 ◽  
Author(s):  
Christel Gervais ◽  
Florence Babonneau ◽  
Lutz Ruwisch ◽  
Ralf Hauser ◽  
Ralf Riedel
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
Sol Gel ◽  
Temperature Stability ◽  
Silicon Carbonitride ◽  
High Temperature Stability ◽  
Carbonitride Phase ◽  
Polymer Pyrolysis ◽  
Silicon Based ◽  
Organosilicon Polymers

Silicon based polymers obtained by ammonolysis of organochlorosilylboranes and their pyrolytic transformation into Si-B-C-N ceramics were studied by a detailed solid-state NMR investigation. Sol–gel polymerisation/pyrolysis routes were applied to form Si-B-C-N materials with exceptional high-temperature stability. The polymer to ceramic conversion was analyzed by 11B, 13C, 15N, and 29Si MAS NMR spectroscopy as well as by thermal analysis measurements coupled with mass spectroscopy (TGA–MS). The results showed that a significant change in the carbon-, silicon-, and boron-coordination environments occurs during pyrolysis. An evolution of cleavage of silcon–carbon–boron bridges and the formation of new BN3 sites was observed. The NMR data obtained suggest the presence of a rather homogeneous dispersion of the boron atoms in the as synthesized silicon carbonitride phase, supporting the high thermal stability with respect to decomposition found in these compounds.Key words: organosilicon polymers, polymer pyrolysis, SiBCN ceramics, solid-state NMR.

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