hexagonal system

2009 ◽  
pp. 426-426
Keyword(s):  
Hexagonal System

Diffraction study on bainite of Cu-Al alloy

1990 ◽  
Vol 48 (4) ◽  
pp. 1006-1007
Author(s):  
Delu Liu ◽  
T. Ko
Keyword(s):  
Diffraction Study ◽  
Parent Phase ◽  
Al Alloy ◽  
Alloy Sample ◽  
Bright Field Image ◽  
Hexagonal System ◽  
Iced Brine ◽  
Diffraction Patterns ◽  
Zone Pattern ◽  
Stacking Structure

Structure of bainite in Cu-Al and Cu-Zn-Al alloys has been reported as 3R, 9R or 18R long period stacking structure (LPS) by X-ray and electron diffraction studies. In the present work, a Cu-25.5 (at)% Al alloy sample was heated at 900°C for 2 h then isothermally held at 450°C for 60 s before quenching into iced brine. FIG.1 shows a TEM bright field image of bainite plates (marked B) grown from grain boundary. The parent phase ( with DO3 structure ) has transformed to martensite (marked M ) during cooling from 450° C to 0°C. Both bainite and martensite plates have dense striations inside.Careful diffraction study on a JEOL 2000FX TEM with accelerating voltage 200 KV revealed (FIG.2) that the diffraction patterns contai_ning the same zone axis [001] ( hexagonal index ) or [111]c ( cubic index ) are from a bainite plate with obtuse V-shape. They are indexed as [010], [140], [130], [120], [230], [340] and [110] zone pattern for hexagonal system respectively.

Study on Ferroelastic Phase Transition of Hexagonal System by Slowness-Curved-Surface and Polarization

2006 ◽  
Vol 345 (1) ◽  
pp. 103-108
Author(s):  
Wang Aikun ◽  
Zhou Guoxiang ◽  
He Wenchen ◽  
Li Guochang
Keyword(s):  
Phase Transition ◽  
Curved Surface ◽  
Hexagonal System ◽  
Ferroelastic Phase Transition

scholarly journals Structural, optical, electric and dielectric characterization of a NaCu0.2Fe0.3Mn0.5O2 compound

RSC Advances ◽  
2022 ◽  
Vol 12 (3) ◽  
pp. 1563-1570
Author(s):  
Ichrak Ben Slima ◽  
Karim Karoui ◽  
Abdelfattah Mahmoud ◽  
Frédéric Boschini ◽  
Abdallah Ben Rhaiem
Keyword(s):  
Solid State ◽  
Solid State Method ◽  
Hexagonal System ◽  
Space Group ◽  
Dielectric Characterization ◽  
Type Phase ◽  
State Method

The compound NaCu0.2Fe0.3Mn0.5O2 was synthesized using a solid-state method and it crystallized in a hexagonal system with a R3̄m space group in an O3-type phase.

Effects of Calcination Temperature on Crystal Structure of Pr-Nd Oxides

2011 ◽  
Vol 233-235 ◽  
pp. 2918-2921 ◽  
Author(s):  
Hui Qing Li ◽  
Rui Xiang Zhang ◽  
Hai Wang Liu ◽  
Shi Zhi Wang ◽  
Xian Ku Hao
Keyword(s):  
Crystal Structure ◽  
Calcination Temperature ◽  
Chloride Solution ◽  
Neodymium Oxide ◽  
Raw Material ◽  
Praseodymium Oxide ◽  
Hexagonal System ◽  
Binary Oxides ◽  
Hydrogen Carbonate ◽  
Ammonium Hydrogen

Ammonium hydrogen carbonate is taken as the precipitating agent to prepare Pr-Nd carbonates from the raw material of Pr-Nd chloride solution. Pr-Nd oxides have been prepared at different calcination temperature in the range of 800°C-1500°C. The oxides were characterized by XRD and XPS.Calcination temperature effects on the structure of Pr-Nd oxides and the valence state of Pr in Pr-Nd oxides have been studied; Results showed that praseodymium oxide full entered into the lattices of neodymium oxide. The crystal structure changed from cubic into hexagonal system with increasing calcination temperature.The valence of Pr in Pr-Nd binary oxides are Pr3+ and Pr4+.

Table 35. Hexagonal system

2005 ◽  
pp. 247-251
Author(s):  
A. G. Every ◽  
A. K. McCurdy
Keyword(s):  
Hexagonal System

X-ray and electron diffraction study of penfieldite: average structure and multiple cells

1995 ◽  
Vol 59 (395) ◽  
pp. 341-347 ◽  
Author(s):  
S. Merlino ◽  
M. Pasero ◽  
N. Perchiazzi ◽  
A. Gianfagna
Keyword(s):  
Electron Diffraction ◽  
Diffraction Study ◽  
Direct Methods ◽  
Electron Diffraction Study ◽  
Hexagonal System ◽  
Modulated Structure ◽  
Structural Relationships ◽  
Modulated Structures ◽  
The Common ◽  
Multiple Cells

AbstractPenfieldite is a lead hydroxychloride mineral with composition Pb2Cl3(OH). It belongs to the hexagonal system, space group P, a = 11.393(3), c = 4.024(1) Å. The 4 Å c parameter corresponds to the basic sub-cell, whereas modulated structures are known with a true c axis 12 times longer. The average crystal structure of penfieldite has been solved with direct methods and refined to Rw = 0.041 for 871 refections collected with Mo-Kα radiation. The chemical and structural relationships between penfeldite and laurelite, Pb2F3(F,Cl,OH), are briefly discussed. An electron diffraction study of penfieldite revealed the occurrence, besides the common modulated structure with C = 12c, of domains with a 15c periodicity. Moreover, a 9c periodicity has been observed in crystals heated at 180°C Penfieldite is quickly destroyed above 200°C.

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