Study of Phase Transformation of Orthoboric Acid by X‐Ray Diffraction Method

1955 ◽  
Vol 23 (11) ◽  
pp. 2190-2191 ◽  
Author(s):  
D. R. Dasgupta ◽  
B. K. Banerjee
Keyword(s):  
Phase Transformation ◽  
Diffraction Method ◽  
X Ray Diffraction ◽  
X Ray

scholarly journals PHASE TRANSFORMATION IN THE FORMATION OF FAUJASITE FROM FLY ASH

2010 ◽  
Vol 5 (3) ◽  
pp. 278-282 ◽  
Author(s):  
Sutarno Sutarno ◽  
Yateman Arryanto
Keyword(s):  
Phase Transformation ◽  
Fly Ash ◽  
Specific Surface ◽  
Alkaline Solution ◽  
Weight Ratio ◽  
Diffraction Method ◽  
Hydrothermal Time ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ash Weight

Faujasite was hydrothermally synthesized from fly ash at 100oC in alkaline solution by reflux with 5M HCl and fusion with NaOH pretreatments. Phase transformation in the formation of faujasite was performed by variation of NaOH/fly ash weight ratios and hydrothermal times. The solid products were characterized by X-ray diffraction method. Results showed that faujasite was formed through dissolution of fly ash components such as quartz, mullite and amorphous aluminosilicates followed by crystallization to form faujasite. Arranging the NaOH/fly ash weight ratio as well as hydrothermal time can selectively form faujasite. Faujasite with crystallinity of 97.06%, Si/Al ratio of 2.68, and specific surface area of 452.93 m2/g was successfully formed using NaOH/fly ash weight ratio of 1.2 for hydrothermal time of 72 hours. In more concentrated alkaline solution as well as for longer hydrothermal time, faujasite was completely transformed into hydroxysodalite as the final product. Keywords: fly ash, faujasite, and phase transformation.

scholarly journals Zirconium Phase Transformation under Static High Pressure and ω-Zr Phase Stability at High Temperatures

Materials ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2244 ◽  
Author(s):  
Lucyna Jaworska ◽  
Jolanta Cyboron ◽  
Slawomir Cygan ◽  
Adam Zwolinski ◽  
Boguslaw Onderka ◽  
...  
Keyword(s):  
High Pressure ◽  
Phase Transformation ◽  
High Temperatures ◽  
High Purity ◽  
Stress Measurement ◽  
Diffraction Method ◽  
Quantitative Phase Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ω Phase

High-purity Zr has been observed to undergo a phase transformation from the α-phase to the hexagonal ω-phase under high pressure generated either statically or by shock loading. The transition pressure from α-Zr to ω-Zr at 300 K is 2.10 GPa. The main aim of this research was to determine the conditions of α-Zr in ω-Zr transformation and the state of stresses after the high-pressure pressing and sintering of zirconium powders. Commercially acquired zirconium powders of 99.9% and 98.8% purity were used in this study. Qualitative and quantitative phase analysis of the materials was carried out using X-ray diffraction. The materials were statically pressed and sintered using a Bridgman-type toroidal apparatus at under 4.0 and 7.8 GPa. After pressing, the transformation proceeded for the zirconium powder containing 98.8% purity (with hydrides admixture) but did not occur for the high-purity zirconium powders with 99.9% purity. The zirconium powders were sintered using the HPHT (High Pressure—High Temperature) method at temperatures of 1273 K and 1473 K. The transformation proceeded for both powders. The highest contribution of the ω-Zr phase was obtained in the zirconium (98.8% purity with the hydrides contents) sintered for 1 min at a temperature of 1473 K and a pressure of 7.8. The ω-phase content was 87 wt.%. The stress measurement was performed for the pressed and sintered materials using the sin2ψ X-ray diffraction method. The higher sintering temperature resulted in a decrease of the residual stresses in the ω-Zr phase for the sintered zirconium. The higher levels of stress limited the transformation of the α-Zr phase into the ω-Zr phase. Investigated materials characterized by higher compressive macrostresses were also typical of the greater stability of the ω-Zr phase at high temperatures.

scholarly journals Growth of sillenite Bi12FeO20 single crystals: structural, thermal, optical, photocatalytic features and first principle calculations

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Durga Sankar Vavilapalli ◽  
Ambrose A. Melvin ◽  
F. Bellarmine ◽  
Ramanjaneyulu Mannam ◽  
Srihari Velaga ◽  
...  
Keyword(s):  
Single Crystal ◽  
Single Crystals ◽  
Photoelectron Spectroscopy ◽  
Diffraction Method ◽  
Lattice Parameter ◽  
First Principle ◽  
X Ray Diffraction ◽  
X Ray ◽  
First Principle Calculations ◽  
Photodegradation Efficiency

AbstractIdeal sillenite type Bi12FeO20 (BFO) micron sized single crystals have been successfully grown via inexpensive hydrothermal method. The refined single crystal X-ray diffraction data reveals cubic Bi12FeO20 structure with single crystal parameters. Occurrence of rare Fe4+ state is identified via X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS). The lattice parameter (a) and corresponding molar volume (Vm) of Bi12FeO20 have been measured in the temperature range of 30–700 °C by the X-ray diffraction method. The thermal expansion coefficient (α) 3.93 × 10–5 K−1 was calculated from the measured values of the parameters. Electronic structure and density of states are investigated by first principle calculations. Photoelectrochemical measurements on single crystals with bandgap of 2 eV reveal significant photo response. The photoactivity of as grown crystals were further investigated by degrading organic effluents such as Methylene blue (MB) and Congo red (CR) under natural sunlight. BFO showed photodegradation efficiency about 74.23% and 32.10% for degrading MB and CR respectively. Interesting morphology and microstructure of pointed spearhead like BFO crystals provide a new insight in designing and synthesizing multifunctional single crystals.

scholarly journals Study of Corrosion Resistance and Degradation Mechanisms in LiTiO2-Li2TiO3 Ceramic

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 753
Author(s):  
Dmitriy Shlimas ◽  
Artem L. Kozlovskiy ◽  
Maxim Zdorovets
Keyword(s):  
Degradation Mechanism ◽  
Diffraction Method ◽  
Large Mass ◽  
Time Frame ◽  
X Ray Diffraction ◽  
Acidic Media ◽  
X Ray ◽  
Mass Losses ◽  
The Stability ◽  
Thermal Sintering

The interest in lithium-containing ceramics is due to their huge potential as blanket materials for thermonuclear reactors for the accumulation of tritium. However, an important factor in their use is the preservation of the stability of their strength and structural properties when under the influence of external factors that determine the time frame of their operation. This paper presents the results of a study that investigated the influence of the LiTiO2 phase on the increasing resistance to degradation and corrosion of Li2TiO3 ceramic when exposed to aggressive acidic media. Using the X-ray diffraction method, it was found that an increase in the concentration of LiClO4·3H2O during synthesis leads to the formation of a cubic LiTiO2 phase in the structure as a result of thermal sintering of the samples. During corrosion tests, it was found that the presence of the LiTiO2 phase leads to a decrease in the degradation rate in acidic media by 20–70%, depending on the concentration of the phase. At the same time, and in contrast to the samples of Li2TiO3 ceramics, for which the mechanisms of degradation during a long stay in aggressive media are accompanied by large mass losses, for the samples containing the LiTiO2 phase, the main degradation mechanism is pitting corrosion with the formation of pitting inclusions.

Study of the quality of GaAs thin film on Si substrate by X-ray diffraction method

1990 ◽  
Vol 7 (7) ◽  
pp. 308-311
Author(s):  
Li Chaorong ◽  
Mai Zhenhong ◽  
Cui Shufan ◽  
Zhou Junming ◽  
Yutian Wang
Keyword(s):  
Thin Film ◽  
Diffraction Method ◽  
X Ray Diffraction ◽  
Si Substrate ◽  
X Ray

A New X‐Ray Diffraction Method for Studying Imperfections of Crystal Structure in Polycrystalline Specimens

1951 ◽  
Vol 22 (5) ◽  
pp. 665-672 ◽  
Author(s):  
Alfred J. Reis ◽  
Jerome J. Slade ◽  
Sigmund Weissmann
Keyword(s):  
Crystal Structure ◽  
Diffraction Method ◽  
X Ray Diffraction ◽  
X Ray
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