A study of the aragonite-calcite transformation using Raman spectroscopy, synchrotron powder diffraction and scanning electron microscopy

CrystEngComm ◽  
2010 ◽  
Vol 12 (5) ◽  
pp. 1590 ◽  
Author(s):  
J. E. Parker ◽  
S. P. Thompson ◽  
A. R. Lennie ◽  
J. Potter ◽  
C. C. Tang
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Raman Spectroscopy ◽  
Powder Diffraction ◽  
Synchrotron Powder Diffraction ◽  
Scanning Electron

The ikaite-to-vaterite transformation: new evidence from diffraction and imaging

2009 ◽  
Vol 42 (2) ◽  
pp. 225-233 ◽  
Author(s):  
C. C. Tang ◽  
S. P. Thompson ◽  
J. E. Parker ◽  
A. R. Lennie ◽  
F. Azough ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Calcium Carbonate ◽  
Powder Diffraction ◽  
Kinetic Control ◽  
Structural Arrangement ◽  
Synchrotron Powder Diffraction ◽  
Crystallite Sizes ◽  
New Evidence ◽  
Scanning Electron

Vaterite is one of three polymorphs of calcium carbonate (CaCO3) found in nature, the others being calcite and aragonite. Here the formation of vaterite from decomposition of ikaite (CaCO3·6H2O) was investigated using synchrotron powder diffraction and scanning electron microscopy. The crystallite sizes of vaterite (∼40 nm) were found to be much smaller than those of the precursor ikaite (∼0.5–1.0 µm) as a result of vaterite nucleating as ikaite dehydrates. The rate of decomposition to vaterite increases with temperature, indicating kinetic control of this transformation. It is postulated that the structural arrangement of the hydration sphere around Ca2+in ikaite determines the orientation of Ca2+and CO32−ions such that vaterite nucleates upon dehydration. This implies that the dehydration of a precursor hydrated phase such as ikaite is required for vaterite nucleation.

Dickite and kaolinite in the Pb-Zn-Ag sulphide deposits of northern Kosovo (Trepča and Crnac)

Clay Minerals ◽  
2009 ◽  
Vol 44 (1) ◽  
pp. 67-79 ◽  
Author(s):  
S. S. Palinkaš ◽  
S. B. Šoštarić ◽  
V. Bermanec ◽  
L. Palinkaš ◽  
W. Prochaska ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Raman Spectroscopy ◽  
Fluid Inclusion ◽  
Powder Diffraction ◽  
X Ray ◽  
Mineralogical Characteristics ◽  
Alteration Minerals ◽  
Sulphide Deposits ◽  
Scanning Electron

AbstractAlteration minerals dickite and kaolinite were detected in two hydrothermal Pb-Zn-Ag sulphide deposits in the northern Kosovo region. Dickite is associated with skarn mineralization in the Trepča (Stari Trg) deposit and kaolinite occurs in vein sulphide parageneses in the Crnac deposit. The mineralogical characteristics of dickite and kaolinite were determined by X-ray powder diffraction, Raman spectroscopy and scanning electron microscopy with EDS detector. Fluid-inclusion microthermometry and ion chromatography of leachates provided information on theP-T-Xconditions of the genesis of dickite at Trepča. It was formed at temperatures between 290 and 330ºC and pressures between 12 and 60 MPa from a fluid with salinity in the range 6–8.5 wt.% NaCl eq. and pH <5.5. Kaolinite was deposited from a fluid with minimum temperatures between 210 and 250ºC, minimum pressure of 1.7 to 3.7 MPa, and salinity between 4.6 and 5.1 wt.% NaCl eq. Both dickite and kaolinite are related to the acidic pre-mineralization phase in the deposits.

scholarly journals Size reduction-induced properties modifications of antiferromagnetic dielectric nanocrystalline Ba2NiMO6 (M = W, Te) double perovskites

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Jelena Bijelić ◽  
Dalibor Tatar ◽  
Manisha Sahu ◽  
Zvonko Jagličić ◽  
Igor Djerdj
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Raman Spectroscopy ◽  
Powder Diffraction ◽  
Dielectric Constants ◽  
Size Reduction ◽  
Double Perovskites ◽  
X Ray ◽  
The Impact ◽  
Scanning Electron

Abstract The main objective of this work was to synthesize phase pure double perovskites Ba2NiTeO6 (BNTO) and Ba2NiWO6 (BNWO) in nanocrystalline form and to reveal the impact of nanocrystallinity on their magnetic and dielectric properties. The studied double perovskites were synthesized in nanocrystalline form by employing a citrate sol-gel route. A detailed investigation of their structure and properties using X-ray powder diffraction, scanning electron microscopy, Raman spectroscopy technique, energy-dispersive X-ray spectroscopy, SQUID magnetometry and electrical measurements is carefully described. Rietveld refinement of X-ray powder diffraction patterns revealed phase purity of both compounds: BNTO is trigonal (R-3m) while BNWO is cubic (Fm-3m). Raman spectroscopy studies reveal optical phonons that correspond to vibrations of Te6+/W6+O6 octahedra, while scanning electron microscopy images show irregular plate-like nanocrystals. Magnetic property measurements speak in favor of antiferromagnetic order but, in both compounds, size reduction affected their properties. BNTO has Néel temperature (TN) of 10.3 K which is higher than previously reported for its bulk form. Magnetic ground state of BNWO can be explained as canted antiferromagnetism with TN = 48.2 K. Room temperature measurements of dielectric constants at various frequencies suggest that these materials are high-κ dielectrics with low dielectric loss. The Nyquist plot reveals depressed a semicircle arc typical for non-Debye type of relaxation phenomena for BNWO ceramic, whereas for BNTO ceramic an almost straight line of Zʹʹ versus Z' has been observed, indicating its high insulating behavior. To conclude, size-dependent properties of studied double perovskites are discussed, introducing a possibility for implementation in electronic devices.

scholarly journals Improving the reactivity of phenylacetylene macrocycles toward topochemical polymerization by side chains modification

2014 ◽  
Vol 10 ◽  
pp. 1613-1619 ◽  
Author(s):  
Simon Rondeau-Gagné ◽  
Jules Roméo Néabo ◽  
Maxime Daigle ◽  
Katy Cantin ◽  
Jean-François Morin
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Raman Spectroscopy ◽  
Self Assembly ◽  
Significant Enhancement ◽  
Side Chains ◽  
X Ray Diffraction ◽  
X Ray ◽  
Topochemical Polymerization ◽  
Scanning Electron

The synthesis and self-assembly of two new phenylacetylene macrocycle (PAM) organogelators were performed. Polar 2-hydroxyethoxy side chains were incorporated in the inner part of the macrocycles to modify the assembly mode in the gel state. With this modification, it was possible to increase the reactivity of the macrocycles in the xerogel state to form polydiacetylenes (PDAs), leading to a significant enhancement of the polymerization yields. The organogels and the PDAs were characterized using Raman spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM).

SYNTHESIS, MORPHOLOGY AND STRUCTURAL PROPERTIES OF (GD,ND)SR2RUCU2O8 SAMPLES

2003 ◽  
Vol 17 (04n06) ◽  
pp. 899-904 ◽  
Author(s):  
A. VECCHIONE ◽  
M. GOMBOS ◽  
C. TEDESCO ◽  
A. IMMIRZI ◽  
L. MARCHESE ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Solid State ◽  
Powder Diffraction ◽  
Solid State Reaction ◽  
X Ray ◽  
Structure And Morphology ◽  
Polycrystalline Powder ◽  
Scanning Electron

NdSr 2 RuCu 2 O x material has been prepared as polycrystalline powder by solid state reaction. The compound has been investigated by synchrotron x-ray powder diffraction and scanning electron microscopy. The experimental results show that the average crystal structure is a disordered cubic perovskite with Nd and Sr cations occupying the same site and the same substitution is found for Cu and Ru atoms. A comparison between the crystal structure and morphology of this compound and the superconducting tetragonal GdSr 2 RuCu 2 O 8 is also discussed.

Synthesis of PZT Disks by a Hydrothermal Method

2012 ◽  
Vol 174-177 ◽  
pp. 592-595
Author(s):  
Lin Lin Yang ◽  
Yong Gang Wang ◽  
Yu Jiang Wang ◽  
Xiao Feng Wang
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Hydrothermal Method ◽  
Formation Mechanism ◽  
Powder Diffraction ◽  
Self Assembly ◽  
Hydrothermal Process ◽  
X Ray ◽  
Extended Length ◽  
Scanning Electron

The organization of nanostructures across extended length scales is a key challenge in the design of integrated materials with advanced functions. PbZr0.52Ti0.48O3multilayer disks which were constructed by oriented rectangle nanoparticles were easily prepared by a simple surfactant-free hydrothermal process. The as-prepared powders were characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The results indicated that the as-prepared PZT disks were constructed by self-assembly of rectangle nanoparticles by a perfect manner. The formation mechanism of the products was discussed.

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