Boron Carbide-Based Ceramics Via Polymer Route Synthesis

1991 ◽  
Vol 249 ◽  
Author(s):  
Haixing Zheng ◽  
Kevin Thorne ◽  
J.D. Mackenzie ◽  
Xiaoguang Yang ◽  
M.F. Hawthome
Keyword(s):  
Thermal Analysis ◽  
Infrared Spectroscopy ◽  
High Temperature ◽  
Nmr Spectroscopy ◽  
Physical Properties ◽  
Boron Carbide ◽  
X Ray Diffraction ◽  
Polymeric Precursors ◽  
X Ray ◽  
Crystalline Boron

ABSTRACTBoron carbide is a ceramic material with excellent high temperature physical properties. As compared to conventional techniques, the preparation of boron carbide from polymeric precursors is attractive as this technique offers a number of unique advantages. In this paper, the screening of polymeric precursors to boron carbide will be discussed. Two promising boron carbide, carborane containing polymeric precursors have resulted in 60-70 wt.% ceramic yields. The chemistry of polymer synthesis and the transformations from the polymer to amorphous and crystalline boron carbide were investigated with infrared spectroscopy, NMR spectroscopy, thermal analysis, and x ray diffraction.

scholarly journals Complex phase evolution of Brushite-based calcium phosphate CaHPO4·2H2O using in situ high temperature X-ray diffraction and thermal analysis

2020 ◽  
Author(s):  
Mouatamid El Hazzat ◽  
Adnane El Hamidi ◽  
Mohammed Halim ◽  
said ARSALANE
Keyword(s):  
Thermal Analysis ◽  
Infrared Spectroscopy ◽  
High Temperature ◽  
Calcium Phosphate ◽  
Amorphous Phase ◽  
Phase Evolution ◽  
High Temperature Treatment ◽  
X Ray Diffraction ◽  
X Ray

Abstract This study focused on a detailed examination of the thermal behavior of Brushite-based calcium phosphate (CaHPO 4 .2H 2 O, DCPD) to identify and characterize the intermediate phases which have been the subject of previous several controversies. For that, in situ high-temperature X-ray diffraction supported by infrared spectroscopy, thermal analysis, and scanning electron microscopy analysis were used and the results showed that the progressive thermal stress of DCPD in air resulted in a heterogeneous formulation consisting of dibasic calcium phosphate anhydrous (CaHPO 4 , DCPA) and an amorphous phase, which appears at low temperatures (~160 °C) and persists up to 375 °C. The deep examination of the amorphous phase by infrared spectroscopy revealed that its chemical composition is similar to that of disordered calcium pyrophosphate (Ca 2 P 2 O 7 , CPP) with the appearance of a characteristic band δ(P-O-P), located at 740 cm -1 . This IR band is shifted to low frequencies (725 cm -1 ) as the temperature is increased, indicating the crystallization of the amorphous phase into γ-CPP. The high temperature treatment (≥ 375 °C) leads to b-CPP polymorph. According to the present characterization results, obtaining pure DCPA from the thermal dehydration of DCPD is not effective and leads to biphasic materials including an amorphous phase.

Thermal analysis of rare earth gallates and aluminates

1990 ◽  
Vol 5 (1) ◽  
pp. 183-189 ◽  
Author(s):  
H. M. O'Bryan ◽  
P. K. Gallagher ◽  
G. W. Berkstresser ◽  
C. D. Brandle
Keyword(s):  
Thermal Analysis ◽  
Thermal Expansion ◽  
High Temperature ◽  
Superconducting Films ◽  
Czochralski Technique ◽  
X Ray Diffraction ◽  
X Ray ◽  
First Order ◽  
Expansion Matching ◽  
First Order Phase

Dilatometry, high-temperature x-ray diffraction, differential thermal analysis, and differential scanning calorirmetry have been performed on LaGaO3, NdGaO3, PrGaO3, SmAlO3, and LaAlO3 single crystals grown by the Czochralski technique. First order phase transitions have been located at 145°C for LaGaO3 and 785°C for SmAlO3, and ΔH has been measured for the LaGaO3 transition. Second order transitions have been identified for LaGaO3, PrGaO3, NdGaO3, and LaAlO3. The usefulness of these compounds as substrates for high temperature superconducting films is discussed in terms of thermal expansion matching.

Co-crystal formation between 2-amino-4,6-dimethylpyrimidine and new p-xylylene-bis(thioacetic) acid

CrystEngComm ◽  
2014 ◽  
Vol 16 (44) ◽  
pp. 10262-10272 ◽  
Author(s):  
A. Ostasz ◽  
R. Łyszczek ◽  
L. Mazur ◽  
B. Tarasiuk
Keyword(s):  
Thermal Analysis ◽  
Infrared Spectroscopy ◽  
Single Crystal ◽  
Crystal Formation ◽  
Thioacetic Acid ◽  
X Ray Diffraction ◽  
X Ray ◽  
Analysis Methods

Novelp-xylylene-bis(thioacetic) acid (p-XBTA) and its co-crystals with 2-amino-4,6-dimethylpyrimidine (DMP) have been synthesized and characterized by single-crystal X-ray diffraction, infrared spectroscopy and thermal analysis methods (TG/DSC).

Polypeptide Adsorption on a Synthetic Montmorillonite: A Combined Solid-State NMR Spectroscopy, X-ray Diffraction, Thermal Analysis and N2 Adsorption Study

2003 ◽  
Vol 2003 (7) ◽  
pp. 1366-1372 ◽  
Author(s):  
Régis D. Gougeon ◽  
Michel Soulard ◽  
Marc Reinholdt ◽  
Jocelyne Miehé-Brendlé ◽  
Jean-Michel Chézeau ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Solid State ◽  
Nmr Spectroscopy ◽  
Solid State Nmr ◽  
X Ray Diffraction ◽  
N2 Adsorption ◽  
Adsorption Study ◽  
X Ray ◽  
Solid State Nmr Spectroscopy

Characterization of Three 'Active' Rhodium(III) Hydroxides

1995 ◽  
Vol 48 (3) ◽  
pp. 557 ◽  
Author(s):  
SJ Crimp ◽  
L Spiccia
Keyword(s):  
Thermal Analysis ◽  
Thermal Decomposition ◽  
Infrared Spectroscopy ◽  
Ion Exchange ◽  
Ion Exchange Chromatography ◽  
Exchange Chromatography ◽  
X Ray Diffraction ◽  
X Ray

Pure solutions of [ Rh (H2O)6]3+, dimer [Rh2(μ-OH)2(H2O)8]4+ and trimer [Rh3(μ-OH)4(H2O)10]5+ have been converted into their respective 'active' hydroxides by dropwise addition to an imidazole solution. These 'active' hydroxides have been analysed by a variety of techniques including rhodium determination, infrared spectroscopy, thermal analysis and powder X-ray diffraction. Purity determinations using ion-exchange chromatography showed that the three hydroxides consist primarily of the neutral forms of the starting aqua ion (>96%) with small amounts of species with higher nuclearity. Rhodium analysis and thermogravimetric measurements confirmed the composition of these hydroxides to be Rh (OH)3(H2O)3.H2O, Rh2(μ-OH)2(OH)4(H2O)4 and Rh3(μ-OH)4(OH)5(H2O)5.5H2O. A scheme for the thermal decomposition of each of the hydroxides has been proposed on the basis of the t.g . and d.t.a . data and the knowledge that the final product in each case is α-Rh2O3. Heating of the hydroxides in air resulted in oxidation of RhIII to RhIV (temperature 250-300°C) forming RhO2 which on further heating decomposed to α-Rh2O3 and dioxygen.

Preparation of Boron Carbide Nanoparticles by Carbothermal Reduction Method

2004 ◽  
Vol 848 ◽  
Author(s):  
Baohe Chang ◽  
Bonnie Gersten ◽  
Jane W. Adams ◽  
Steve Szewczyk
Keyword(s):  
Boron Carbide ◽  
Reduction Method ◽  
X Ray Diffraction ◽  
Reaction Conditions ◽  
Boron Powder ◽  
X Ray ◽  
Transmission Electron ◽  
Crystalline Boron ◽  
Average Size ◽  
Carbide Particles

ABSTRACTA carbothermal reaction process was employed to synthesize nano-sized boron carbide particles. The reactions were carried out by heating a mixture of boric oxide powder and amorphous carbon reactant under a flow of argon atmosphere in a conventional high temperature tube furnace at 1350–1700 °C for 1–4 h. In order to obtain stoichiometric powder product, additional pure boron powder was added to the reaction mixture to compensate for the boron loss in the form of B2O2/B2O3vapor during the reaction. The effect of the structure and morphology of the precursor materials on that of the products was also investigated. X-ray diffraction (XRD) studies indicated that the powdered product prepared under optimized reaction conditions was crystalline boron carbide. Transmission electron microscopy (TEM) observations showed that the product nanoparticles ranged from 50 nm to 250 nm with the average size between 100 nm and 150 nm depending on the reaction conditions. Some boron carbide particles were as small as 50 nm. Energy dispersive spectroscopy (EDS) was also used to determine the stoichiometry of the boron carbide nanoparticle products.

Thermal analysis and high-temperature X-ray diffraction study of BiNbO4

2019 ◽  
Vol 137 (5) ◽  
pp. 1513-1518
Author(s):  
N. A. Zhuk ◽  
B. A. Makeev ◽  
V. A. Belyy ◽  
M. G. Krzhizhanovskaya
Keyword(s):  
Thermal Analysis ◽  
High Temperature ◽  
Diffraction Study ◽  
X Ray Diffraction ◽  
X Ray
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