A second occurrence of lyndochite

1965 ◽  
Vol 34 (268) ◽  
pp. 237-248 ◽  
Author(s):  
J. E. T. Horne ◽  
J. R. Butler
Keyword(s):  
Heat Treatment ◽  
Rare Earth ◽  
Peak Concentration ◽  
Type Locality ◽  
X Ray Diffraction ◽  
X Ray ◽  
Suitable Heat Treatment ◽  
Diffraction Patterns ◽  
The Many ◽  
Almost All

SummaryLyndochite from Tura dukas, 35 miles north of Nanyuki, Kenya, agrees closely with the type material from Canada in its chemical analysis, in the distribution of the rare earths, and in X-ray diffraction data for powder after heat treatment. The mineral is compared and contrasted with aeschynite. Uranium-poor euxenite is intimately associated with lyndochite at the type locality.Since its discovery over thirty-five years ago, lyndochite has remained unrecorded outside its type locality of Lyndoch Township in Ontario, Canada. Its distinctive chemical composition sets it apart from almost all other Ti-rich metamiet niobates and, despite the many analyses that have been made on rare-earth niobate-tantalates, specimens that could have been regarded as similar to or approximating to lyndochite have rarely been mentioned. Its unusual characteristics include high ThO2 (about 10%) and appreciable rare-earth oxides (about 20%) with a lanthanon assemblage showing a peak concentration of Nd (and Ce), rather than any of the heavy lanthanons. The proportions of TiO2 (about 20%) and (Nb,Ta)2O5 (about 40%) are comparable to those in numerous niobate-tantalates, but are only associated with the percentages of ThO2 and Re2O3 mentioned above in some members of the aesehynite-priorite series. The lyndochite now described is chemically very close indeed to the Canadian lyndochite, and both specimens give closely similar X-ray diffraction patterns (after suitable heat treatment) which are distinct from those of any other metamict mineral.

A High-Temperature Study of Phase Precipitation in Superalloys

1959 ◽  
Vol 3 ◽  
pp. 365-375
Author(s):  
John F. Radavich
Keyword(s):  
Heat Treatment ◽  
Electron Diffraction ◽  
Grain Boundaries ◽  
Fluorescence Analysis ◽  
Phase Precipitation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Suitable Heat Treatment ◽  
Nickel Base ◽  
High Temperature Study

AbstractMany of the iron- and nickel-base superalloys exhibit brittle properties on heat treatment, welding, or other fabrication processes at temperatures of about 2000°F or higher. Studies have been carried out by means of electron microscopy, electron diffraction, and X-ray diffraction and fluorescence analysis of the precipitation in the metal and in an isolated form.Results of the electron microscope study of the surface of the metal show a grain boundary constituent to be present which increases in amount as the temperature is increased. Studies on the isolated residue of such samples show a very thin “featherlike” film to be located at the grain boundaries and enclosing the grains. Electron diffraction, X-ray diffraction, and X-ray fluorescence analysis studies of the thin films indicate that they are a TiC phase with very little alloying elements in solution.At temperatures above 2000°F the thin film becomes quite thick and tends to force the grains apart. It is believed that this form of the TiC phase promotes the severe embrittling nature of these alloys at high temperatures. Suitable heat treatment at lower temperatures causes the TiC film to agglomerate and the grain boundaries become “tight,” and a more ductile condition results.

Degradation of phenol by using magnetic photocatalysts of titania

2013 ◽  
Vol 67 (7) ◽  
pp. 1434-1441 ◽  
Author(s):  
Chiung-Fen Chang ◽  
I.-Peng Tseng
Keyword(s):  
Heat Treatment ◽  
Photocatalytic Activity ◽  
Single Phase ◽  
Health Impacts ◽  
X Ray Diffraction ◽  
Final Temperature ◽  
Soaking Time ◽  
X Ray ◽  
Green Materials ◽  
Diffraction Patterns

Magnetic TiO2 (MT) composites were prepared and applied to degrading phenol, which is one of the listed priority pollutants. The effects of heat treatment under preparation on the photocatalytic activity of MT composites have been investigated by varying the soaking time under a constant final temperature of 823 K. The total organic carbon and ring-remaining intermediates of o-DHB, p-DHB and 1,4-BQ in solution were detected during the photodegradation of phenol. All the resulting MT composites were the single-phase anatase and magnetite judged by X-ray diffraction patterns. The calcination of the as-prepared particles was proven to be extremely crucial to the photocatalytic activity. The best condition of heat treatment was found to be soaking time of 2 h at T = 823 K due to the good performance of photocatalytic activity, stable magnetic property, and reusability over three times. The results lead to the conclusion that recyclable MT composites prepared in this study, which belonged to the category of recyclable green materials, exhibit good photocatalytic activity to degrade phenol so as to possess applicable potential for the degradation of refractory organics in the aqueous solution. Furthermore, the environmental and health impacts were reduced as MT composites were applied in the treatment of water pollution.

(Rare Earth/Li) Titanates and Niobates as Ionic Conductors

2000 ◽  
Vol 658 ◽  
Author(s):  
A. Morata-Orrantia ◽  
S. García-Martín ◽  
E. Morán ◽  
U. Amador ◽  
M. A. Alario-Franco
Keyword(s):  
Rare Earth ◽  
Ionic Conductivity ◽  
Lithium Ion ◽  
Related Structure ◽  
Ionic Conductors ◽  
X Ray Diffraction ◽  
X Ray ◽  
Properties Of Materials ◽  
Ion Conducting ◽  
Diffraction Patterns

ABSTRACTThe lithium ion conducting properties of materials of composition La0.58Li0.26TiO3, Nd0.58Li0.26TiO3, La0.67Li0.25Ti0.75Al0.25O3 and La0.29Li0.12NbO3 have been compared in relation with their microstructure. All the oxides have powder X-ray diffraction patterns characteristic of a perovskite-related structure with lattice parameters a∼√2ap, b∼√2ap, c∼2ap (p refers to cubic perovskite). However, some important differences are observed in their microstructure by SAED and HRTEM. Ordering between vacancies, Li+ and La3+ or Nd3+ and twinning of the NbO6 or TiO6 octahedra tilting system are shown in La0.29Li0.12NbO3 and Nd0.58Li0.26TiO3, which are the materials having a lower ionic conductivity. The La0.58Li0.26TiO3 and La0.67Li0.25Ti0.75Al0.25O3 oxides do not show ordering between cations.

Rows of corner- and face-sharing Mg4 tetrahedra arranged as hexagonal rod packing in the hexagonal Laves phases REMg2 and the rare earth-rich phases RE9CoMg4 (RE=Y, Dy-Tm, Lu)

2018 ◽  
Vol 233 (9-10) ◽  
pp. 607-613 ◽  
Author(s):  
Sebastian Stein ◽  
Rainer Pöttgen
Keyword(s):  
Rare Earth ◽  
Rare Earth Metal ◽  
Diffraction Data ◽  
Earth Metal ◽  
Structural Motif ◽  
Induction Melting ◽  
X Ray Diffraction ◽  
Laves Phases ◽  
X Ray ◽  
The Many

Abstract Six new rare earth metal-rich intermetallic compounds RE9CoMg4 with RE=Y, Dy, Ho, Er, Tm and Lu were synthesized by induction-melting the elements in sealed niobium ampoules followed by annealing in muffle furnaces. The structures of Y9CoMg4 and Tm8.56CoMg4.44 were refined from single-crystal X-ray diffraction data: P63/mmc, a=965.65(6), c=971.07(5) pm, wR2=0.0599, 614 F2 values, 20 variables for Y9CoMg4 and a=945.20(4), c=953.11(5) pm, wR2=0.0358, 585 F2 values, 21 variables for Tm8.56CoMg4.44 (a small homogeneity range results from Tm/Mg mixing). The RE9CoMg4 phases crystallize with a coloring variant of the aristotype Co2Al5. The striking structural motif is a hexagonal rod packing of rows of corner- and face-sharing tetrahedral Mg4 clusters with Mg–Mg distances ranging from 304 to 317 pm in Y9CoMg4. These rows are similar to the hexagonal Laves phases REMg2. The space between the rows is filled with rows of face-sharing Co@Y6 trigonal prisms (TP) and empty Y6 octahedra (O) in the sequence –TP–O–O–. The many isopointal coloring variants of the aristotype Co2Al5 are briefly discussed.

scholarly journals Cryogenic coherent X-ray diffraction imaging of biological particles at SACLA

2014 ◽  
Vol 70 (a1) ◽  
pp. C292-C292
Author(s):  
Yuki Takayama ◽  
Masayoshi Nakasako ◽  
Tomotaka Oroguchi ◽  
Yuki Sekiguchi ◽  
Masaki Yamamoto ◽  
...  
Keyword(s):  
Thermal Contact ◽  
X Ray Diffraction ◽  
Promising Technique ◽  
Fresh Sample ◽  
X Ray ◽  
Internal Structures ◽  
Diffraction Imaging ◽  
Diffraction Patterns ◽  
Almost All ◽  
Better Than

Coherent X-ray diffraction imaging (CXDI) is a promising technique to visualize internal structures of whole biological cells without sectioning. Utilizing X-ray free-electron laser (XFEL) for CXDI has potential to collect huge number of projected electron densities of such samples at higher resolutions than that limited by radiation damage. For biological application of XFEL-CXDI, sample particles must be kept in a hydrated state to maintain their functional structures, but be placed in vacuum to obtain weak diffraction signals. In addition, we need to deliver fresh sample particles one after another for XFEL exposure because every particle explodes just after X-ray irradiation. To handle these problems, we have been developing a system to fulfill cryogenic XFEL-CXDI of frozen-hydrated specimens. For cryogenic XFEL-CXDI, we prepare frozen-hydrated specimens by plunge-freezing sample particles dispersed onto thin film with humidity-controlling [1]. The diffraction experiments are conducted by using the cryogenic X-ray diffractometer KOTOBUKI-1 [2]. In a vacuum chamber of KOTOBUKI-1, a cryogenic pot equipped on a goniometer is filled with liquid nitrogen, which cools the specimen via thermal contact. Thus, KOTOBUKI-1 allows data collection at a specimen temperature of ~66 K with a positional fluctuation of less than 0.4 μm. A small angle-resolution of better than 500 nm is attainable by using a pair of L-shaped Si-slits placed before the specimen, which eliminate almost all parasite scattering from upstream. Diffraction patterns recorded on two MPCCD detectors in tandem arrangement are automatically processed and phase-retrieved by program suite SITENNO [3]. In our recent experiments performed in Japanese XFEL facility SACLA, we were able to collect a large number of diffraction patterns from biological samples at a resolution of 50 - 30 nm at an XFEL hit-rate of 20 - 100%. We report details of the cryogenic XFEL-CXDI and introduce imaging of chloroplasts as an example.

Synthesis and Structures of Rare Earth 3-(4′-Methylbenzoyl)-propanoate Complexes – New Corrosion Inhibitors

2017 ◽  
Vol 70 (5) ◽  
pp. 478 ◽  
Author(s):  
Caspar N. de Bruin-Dickason ◽  
Glen. B. Deacon ◽  
Craig M. Forsyth ◽  
Schirin Hanf ◽  
Oliver B. Heilmann ◽  
...  
Keyword(s):  
Rare Earth ◽  
Corrosion Inhibitors ◽  
Free Acid ◽  
Rare Earth Ions ◽  
X Ray Diffraction ◽  
Bulk Materials ◽  
X Ray ◽  
Rare Earth Chloride ◽  
Diffraction Patterns ◽  
Paramagnetic Shifts

A series of rare earth 3-(4′-methylbenzoyl)propanoate (mbp–) complexes [RE(mbp)3(H2O)] (RE = rare earth = Y, La, Ce, Nd, Ho, Er) have been prepared by either metathesis reactions between the corresponding rare earth chloride and Na(mbp) or protolysis of rare earth acetates by the free acid. Single-crystal X-ray diffraction studies of [RE(mbp)3(H2O)] (RE = Ce, Nd) and [Ce(mbp)3(dmso)] reveal a 1D carboxylate-bridged polymeric structure in the solid state, featuring 9-coordinate rare earth ions. X-ray powder diffraction patterns of the bulk materials indicates that all of the [RE(mbp)3(H2O)] complexes except RE = La are isomorphous. Hence, there is no structural change from the complex with RE = Ce to that with RE = Er despite the lanthanoid contraction. The 1H NMR spectra of the RE = Ho or Er complexes in (CD3)2SO show large paramagnetic shifts and broadening of the CH2 resonances, indicating the retention of substantial carboxylate coordination in solution.

XRD Analysis of Ferrite Ceramics with Different Heat Treatment

2019 ◽  
Vol 970 ◽  
pp. 314-319
Author(s):  
Anatoly P. Surzhikov ◽  
Sergei A. Ghyngazov ◽  
Vitaly A. Vlasov ◽  
Oldrich Stary ◽  
Alexey N. Sokolovskiy
Keyword(s):  
Heat Treatment ◽  
Rietveld Method ◽  
Structural Characteristics ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Qualitative And Quantitative ◽  
Diffraction Patterns

A comparative analysis of the structural characteristics of LiZnTi ferrites sintered at the temperature of 1280 and 1360 K was performed. The qualitative and quantitative X-ray diffraction (XRD) analysis of the samples, main phase structural analysis, and unit cell parameters were carried out using the non-standard method (Rietveld method). Diffraction patterns were recorded on an ARL X'TRA diffractometer in the CuKα1+α2 and CuKβ scanning modes.

Production of Amorphous and Crystalline Silica from Philippine Waste Rice Hull

2015 ◽  
Vol 1098 ◽  
pp. 80-85
Author(s):  
Emie Salamangkit Mirasol ◽  
Rinlee Butch M. Cervera
Keyword(s):  
Heat Treatment ◽  
Glass Ceramics ◽  
Rice Hull ◽  
Rice Grain ◽  
X Ray Diffraction ◽  
Sem Images ◽  
Structural Result ◽  
X Ray ◽  
Structure Morphology ◽  
Diffraction Patterns

Rice husk is the covering of rice seeds and a by-product of milling rice grain. This study is conducted to investigate the production of silica (SiO2) formed from waste rice hull (RH) at different processing temperatures and study its structure, morphology, and thermal properties. Thermal analysis by thermogravimetric analysis (TGA) of the dried RH showed two mass-loss steps associated to the moisture desorption and thermal decomposition. Powder X-ray diffraction patterns of the rice hull calcined at 550oC showed a purely amorphous SiO2structure while those calcined for 900oC for 1 hour and for 3 hours showed a glass-ceramics and crystalline SiO2structure, respectively. This structural result is supported by the results obtained from the FTIR and Raman analyses of the samples. On the other hand, the Scanning electron microscopy (SEM) images showed the morphology of the samples revealing an increasing particle and grain size of the samples calcined at higher temperatures and longer heat treatment duration. In addition, Energy dispersive X-ray (EDX) spectra of both amorphous and crystalline SiO2samples confirm that the sample contains mostly silicon and oxygen. Thus, in this study, the desired form of either amorphous or crystalline SiO2from waste rice hull can be successfully obtained by controlled heat treatment.

Nanostructures of the Product Sequence in the Decomposition of Mixed Rare Earth Hydroxycarbonate Colloidal Particles

1992 ◽  
Vol 272 ◽  
Author(s):  
Z. C. kang ◽  
M. J. Mckelvy ◽  
L. Eyring
Keyword(s):  
Thermal Analysis ◽  
Electron Beam ◽  
Rare Earth ◽  
Colloidal Particles ◽  
X Ray Diffraction ◽  
Decomposition Products ◽  
X Ray ◽  
Colloidal Spheres ◽  
Diffraction Patterns ◽  
Product Sequence

ABSTRACTThe decomposition of colloidal spheres of mixed rare earth hydroxycarbonate to the oxide has been studied by three methods. a) The spheres are treated in a thermal analysis apparatus up to 1100°C and afterward successive reruns were made and specimens cooled rapidly at temperatures where intermediate or final products are formed. X-ray diffraction patterns and HREM studies were made of each sample thus produced. b) The spheres were heated to 450°C in the specimen chamber of a mass spectrometer and the gaseous decomposition products were monitored continuously. c) The colloidal spheres were introduced into the electron microscope and the decomposition followed at high resolution as evolution to the oxide was induced by the electron beam. The results are compared and contrasted.

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