High-temperature Fe oxidation coupled with redistribution of framework cations in lobanovite, K2Na(Fe2+
                  4Mg2Na)Ti2(Si4O12)2O2(OH)4 – the first titanosilicate case

The high-temperature (HT) behaviour of lobanovite, K2Na(Fe2+ 4Mg2Na)Ti2(Si4O12)2O2(OH)4, was studied using in situ powder X-ray diffraction in the temperature range 25–1000°C and ex situ single-crystal X-ray diffraction of 17 crystals quenched from different temperatures. HT iron oxidation associated with dehydroxylation starts at 450°C, similar to other ferrous-hydroxy-rich heterophyllosilicates such as astrophyllite and bafertisite. A prominent feature of lobanovite HT crystal chemistry is the redistribution of Fe and Mg+Mn cations over the M(2), M(3), M(4) sites of the octahedral (O) layer that accompanies iron oxidation and dehydroxylation. This HT redistribution of cations has not been observed in titanosilicates until now, and seems to be triggered by the need to maintain bond strengths at the apical oxygen atom of the TiO5 pyramid in the heteropolyhedral (H) layer during oxidation–dehydroxylation. Comparison of the HT behaviour of lobanovite with five-coordinated Ti and astrophyllite with six-coordinated Ti shows that the geometry of the Ti polyhedron plays a key role in the HT behaviour of heterophyllosilicates. The thermal expansion, geometrical changes and redistribution of site occupancies which occur in lobanovite under increasing temperature are reported. A brief discussion is given of minerals in which the cation ordering (usually for Fe and Mg) occurs together with iron oxidation–dehydroxylation at elevated temperatures: micas, amphiboles and tourmalines. Now this list is expanded by the inclusion of titanosilicate minerals.

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In-Situ Isothermal Crystallization of Poly(l-lactide)

Polymers ◽

10.3390/polym13193377 ◽

2021 ◽

Vol 13 (19) ◽

pp. 3377

Author(s):

Zirui Huang ◽

Meiling Zhong ◽

Haibo Yang ◽

Enqin Xu ◽

Dehui Ji ◽

...

Keyword(s):

High Temperature ◽

Nucleation Rate ◽

Low Temperatures ◽

Isothermal Crystallization ◽

The Other ◽

Wide Angle ◽

X Ray Diffraction ◽

X Ray ◽

Different Temperatures

The isothermal crystallization of poly(l-lactide) (PLLA) has been investigated by in-situ wide angle X-ray diffraction (WAXD) and polarized optical microscopes (POM) equipped with a hot-stage accessory. Results showed that the spherulites of PLLA were formed at high temperature, whereas irregular morphology was observed under a low temperature. This can be attributed to the varying rates of crystallization of PLLA at different temperatures. At low temperatures, the nucleation rate is fast and hence the chains diffuse very slow, resulting in the formation of imperfect crystals. On the other hand, at high temperatures, the nucleation rate is slow and the chains diffuse fast, leading to the formation of perfect crystals. The change in the value of the Avrami exponent with temperature further verifies the varying trend in the morphological feature of the crystals.

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Observation of a Collapsing Layer Structure in Mg/Al Layered Double Hydroxides with Interlayer Hydrogen Phosphate by High Temperature In Situ X-Ray Diffraction with Synchrotoron Radiation

Materials Science Forum ◽

10.4028/www.scientific.net/msf.700.67 ◽

2011 ◽

Vol 700 ◽

pp. 67-70

Author(s):

Akihiro Shimamura ◽

Linus Perander ◽

Eiji Kanezaki ◽

Mark Ian Jones ◽

James B. Metson

Keyword(s):

High Temperature ◽

Thermal Behavior ◽

Layered Double Hydroxides ◽

Layer Structure ◽

Ex Situ ◽

X Ray Diffraction ◽

Hydrogen Phosphate ◽

X Ray ◽

Double Hydroxides

The collapsing layer structure of hydrogen phosphate intercalated Mg/Al-layered double hydroxides (LDH-HPO4) was investigated by high temperature in-situ X-ray diffraction with synchrotron radiation (in-situ XRD). The thermal behavior of the layer structure of LDH-HPO4 showed the same behavior in both in-situ and ex-situ XRD up until 109 °C as previously reported. The basal spacing of LDH-HPO4 continuously decreases above this temperature and finally the layer structure of LDH-HPO4 collapses. Another diffraction peak, d110, which gives a lattice constant a0, decreases at 62 °C, keeps constant to 120°C, increases up to 176°C and again keeps constant until the layer collapse. In this study, the different thermal behavior is observed between two reflections by in-situ XRD measurement, which explains the mechanism of the collapse of the layer structure in LDH-HPO4.

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A Low-High Temperature Camera for In-Situ X-Ray Diffraction Studies of Catalysts

Advances in X-ray Analysis ◽

10.1154/s0376030800017183 ◽

1983 ◽

Vol 27 ◽

pp. 285-291

Author(s):

J. Pielaszek ◽

J.B. Cohen

Keyword(s):

High Temperature ◽

Porous Silica ◽

X Ray Diffraction ◽

X Ray ◽

Controlled Atmospheres ◽

Research Areas ◽

High Temperature Xrd ◽

Different Temperatures ◽

Porous Silica Glass

X-Ray diffraction studies of substances under controlled atmospheres and at different temperatures are of great importance in many research areas. This is especially true in the area of catalysis, where the correlation of structural and catalytic properties is needed. The camera described here was made for this purpose although any sample in the powdered form can be studied as well. Many catalysts are in the form of highly dispersed metal deposited on a granulated support. The content of metal may vary from a few tenths to several percent. In a camera used by Janko and Borodzinski a small amount of catalyst was spread out on a porous silica glass sample holder which then was placed in a high temperature XRD camera with flowing gas of controlled composition.

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GAXRD and in situ X-ray diffraction characterizations of the yttrium implantation effect on pure iron oxidation at high temperature

Journal de Physique IV (Proceedings) ◽

10.1051/jp4:20020250 ◽

2002 ◽

Vol 12 (6) ◽

pp. 417-426

Author(s):

E. Caudron ◽

H. Buscail ◽

R. Cueff ◽

C. Issartel ◽

S. Perrier ◽

...

Keyword(s):

High Temperature ◽

Pure Iron ◽

Iron Oxidation ◽

X Ray Diffraction ◽

X Ray ◽

Yttrium Implantation

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The Application of X-Ray Diffraction at Elevated Temperatures to Study the Mechanism of Formation of Sodium Tripolyphosphate

Advances in X-ray Analysis ◽

10.1154/s0376030800001634 ◽

1961 ◽

Vol 5 ◽

pp. 276-284

Author(s):

E. L. Moore ◽

J. S. Metcalf

Keyword(s):

High Temperature ◽

Low Temperature ◽

Amorphous Phase ◽

Elevated Temperatures ◽

Sodium Tripolyphosphate ◽

X Ray Diffraction ◽

Mechanism Of Formation ◽

X Ray ◽

Temperature Form ◽

High Temperature Form

AbstractHigh-temperature X-ray diffraction techniques were employed to study the condensation reactions which occur when sodium orthophosphates are heated to 380°C. Crystalline Na4P2O7 and an amorphous phase were formed first from an equimolar mixture of Na2HPO4·NaH2PO4 and Na2HPO4 at temperatures above 150°C. Further heating resulted in the formation of Na5P3O10-I (high-temperature form) at the expense of the crystalline Na4P4O7 and amorphous phase. Crystalline Na5P3O10-II (low-temperature form) appears after Na5P3O10-I.Conditions which affect the yield of crystalline Na4P2O7 and amorphous phase as intermediates and their effect on the yield of Na5P3O10 are also presented.

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Thermal expansion of ellinaite (β-CaCr2O4): an in-situ high temperature X-ray diffraction study

Physics and Chemistry of Minerals ◽

10.1007/s00269-020-01126-2 ◽

2021 ◽

Vol 48 (1) ◽

Author(s):

Weihong Xue ◽

Kuan Zhai ◽

Shuangmeng Zhai

Keyword(s):

Thermal Expansion ◽

High Temperature ◽

Diffraction Study ◽

X Ray Diffraction ◽

X Ray

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A Superhydrophobic, Antibacterial, and Durable Surface of Poplar Wood

Nanomaterials ◽

10.3390/nano11081885 ◽

2021 ◽

Vol 11 (8) ◽

pp. 1885

Author(s):

Xinyu Wu ◽

Feng Yang ◽

Jian Gan ◽

Zhangqian Kong ◽

Yan Wu

Keyword(s):

Stearic Acid ◽

Antibacterial Properties ◽

Alkali Resistance ◽

Poplar Wood ◽

X Ray Diffraction ◽

X Ray ◽

Different Temperatures ◽

Acid And Alkali Resistance ◽

The Stability

The silver particles were grown in situ on the surface of wood by the silver mirror method and modified with stearic acid to acquire a surface with superhydrophobic and antibacterial properties. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and X-ray energy spectroscopy (XPS) were used to analyze the reaction mechanism of the modification process. Scanning electron microscopy (SEM) and contact angle tests were used to characterize the wettability and surface morphology. A coating with a micro rough structure was successfully constructed by the modification of stearic acid, which imparted superhydrophobicity and antibacterial activity to poplar wood. The stability tests were performed to discuss the stability of its hydrophobic performance. The results showed that it has good mechanical properties, acid and alkali resistance, and UV stability. The durability tests demonstrated that the coating has the function of water resistance and fouling resistance and can maintain the stability of its hydrophobic properties under different temperatures of heat treatment.

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In Situ X-Ray Diffraction Investigations during Diffusion Anneals of Ni-Cu Thin Film Diffusion Couples

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.89-91.503 ◽

2010 ◽

Vol 89-91 ◽

pp. 503-508 ◽

Cited By ~ 1

Author(s):

J. Sheng ◽

U. Welzel ◽

Eric J. Mittemeijer

Keyword(s):

Thermal Stresses ◽

Stress Generation ◽

Ex Situ ◽

Diffusion Annealing ◽

X Ray Diffraction ◽

Individual Layer ◽

X Ray ◽

Bilayer System ◽

Stress Changes

The stress evolution during diffusion annealing of Ni-Cu bilayers (individual layer thicknesses of 50 nm) was investigated employing ex-situ and in-situ X-ray diffraction measurements. Annealing at relatively low homologous temperatures (about 0.3 - 0.4 Tm) for durations up to about 100 hours results in considerable diffusional intermixing, as demonstrated by Auger-electron spectroscopy investigations (in combination with sputter-depth profiling). In addition to thermal stresses due to differences of the coefficients of thermal expansion of layers and substrate, tensile stress con-tributions in the sublayers arise during the diffusion anneals. The obtained stress data have been discussed in terms of possible mechanisms of stress generation. The influence of diffusion on stress development in the sublayers of the diffusion couple during heating and isothermal annealing was investigated by comparing stress changes in the bilayer system with corresponding results obtained under identical conditions for single layers of the components in the bilayer system. The specific residual stresses that emerge due to diffusion between the (sub)layers in the bilayer could thereby be identified.

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