Thermal Expansion Behavior of Pure and Doped Cordierite by Time-of-Flight Neutron Diffraction

1986 ◽  
Vol 30 ◽  
pp. 395-405
Author(s):  
J. Haas ◽  
Paul Predecki ◽  
J. Faber ◽  
R. L. Hitterman
Keyword(s):  
Thermal Expansion ◽  
Neutron Diffraction ◽  
Volume Expansion ◽  
Time Of Flight ◽  
Interatomic Bond ◽  
Neutron Powder Diffraction Data ◽  
Hexagonal Form ◽  
Expansion Behavior ◽  
Bond Strengths ◽  
Cordierite Structure

AbstarctIn order to reveal the mechanism of the negative c-axis expansion in cordierite (4 MgO 4 Al2O3 10 SiO2), the thermal expansion of cordierite containing small amounts of Cs, Li, B, Ge, Sc and Ni-cations was investigated by time-of-flight neutron diffraction at temperatures between 22 and 750°C. The samples were prepared by melting the constituent oxides followed by quenching and devitrification to obtain the hexagonal form (Indialite). Using the neutron powder diffraction data, the atom positions in the space group P6/mcc were refined by Rietveld least squares analyses.The expansion behavior of the cordierite structure could be explained in terms of the various kinds of constraints and the interatomic bond strengths of the structure. It was found that cordierite doped with Cs-cations shows the largest volume expansion, followed by the Li-doped sample. So-doped cordierite has the lowest volume expansion. All cordierite samples show positive expansion along the a-axis and negative expansion along the c-axis, except the Cs-doped sample which has positive expansion in both directions.

scholarly journals Lattice Thermal Expansion Effects in Pure and Doped Cordierite by Time-of-Flight Neutron Diffraction*

1985 ◽  
Vol 29 ◽  
pp. 173-184 ◽  
Author(s):  
F. K. Predecki ◽  
J. Haas ◽  
J. Faber ◽  
R. L. Hitterman
Keyword(s):  
Thermal Expansion ◽  
Neutron Diffraction ◽  
Powder Diffraction ◽  
Rietveld Method ◽  
Time Of Flight ◽  
Neutron Powder Diffraction ◽  
Lattice Thermal Expansion ◽  
Space Group ◽  
Thermal Expansion Behavior ◽  
Expansion Behavior

AbstractThe thermal expansion behavior of pure, Ge-doped and Li-doped hexagonal cordierites with respective compositions: 2MgO 2Al2O3 5Si02 2Mg0 2Al2O3 4Si02 Ge02) and 2MgO (2+x)AL203 (5-2x)Si02 xLi20 with x = .174, was investigated using time-of-flight neutron powder diffraction at temperatures from 22 to 750°C in vacuum. The data were refined in space group P6/mcc using the Rietveld method. The lattice thermal expansion curves of all 3 samples were quite similar. The negative axis expansion is associated with (1)displacement of the T2 cations generally toward the axis channels and (2) changes in the distortion of the coupled T1/M tetrahedra/octahedra in the structure. Both contributions were present in all 3 samples but the first was more dominant in the Ge doped sample. The nature and origin of the distortions in T1 and M are discussed.

H/D isotope effect on the molar volume and thermal expansion of benzene

2018 ◽  
Vol 20 (24) ◽  
pp. 16736-16742 ◽  
Author(s):  
A. D. Fortes ◽  
S. C. Capelli
Keyword(s):  
Thermal Expansion ◽  
Molar Volume ◽  
Isotope Effect ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Time Of Flight ◽  
Neutron Powder Diffraction ◽  
Powder Diffraction Data ◽  
Neutron Powder Diffraction Data ◽  
Invariant Volume

Time-of-flight neutron powder diffraction data have been collected from C6H6 and C6D6 between 10 and 276 K, revealing no cross-over in their molar volumes and an almost temperature invariant volume-isotope-effect, in contrast with previously published work.

Negative Thermal Expansion Behaviour in The NZP Phase NbTi(PO4)3

1998 ◽  
Vol 547 ◽  
Author(s):  
D. A. Woodcock ◽  
P. Lightfoot ◽  
R. I. Smith
Keyword(s):  
Thermal Expansion ◽  
Neutron Diffraction ◽  
Volume Expansion ◽  
Negative Thermal Expansion ◽  
Structural Data ◽  
Thermal Expansion Behaviour ◽  
Powder Neutron Diffraction ◽  
Positive Volume ◽  
The Difference ◽  
Expansion Behaviour

AbstractWe present new detailed structural data versus temperature on the Nasicon structured material NbTi(PO4)3 obtained from powder neutron diffraction studies. This material shows a significant volume contraction over the range 20°C < T < 700°C. αa varies between –4.34 and -0.11 × 10-6°C-1 and αc between 0.08 and 3.07 × 10-6°C-1 over this range. This behaviour contrasts with the case of NaTi2(PO4)3 (NaTP) which shows a positive volume expansion. The difference in this behaviour can be explained by the presence of filled MI sites in NaTP which are vacant in the case of NbTP.

Thermal expansion behavior of Ce2Zr2O7 up to 898 K in conjunction with structural analyses by neutron diffraction

2010 ◽  
Vol 37 (8) ◽  
pp. 555-559 ◽  
Author(s):  
Philippe E. Raison ◽  
Claudiu C. Pavel ◽  
Regis Jardin ◽  
Emmanuelle Suard ◽  
Richard G. Haire ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Neutron Diffraction ◽  
Thermal Expansion Behavior ◽  
Expansion Behavior

scholarly journals Through-Thickness Microstructure Characterization in a Centrifugally Cast Austenitic Stainless Steel Nuclear Reactor Primary Loop Pipe Using Time-of-Flight Neutron Diffraction

2021 ◽  
Vol 5 (2) ◽  
pp. 12
Author(s):  
Matthew M. Schmitt ◽  
Daniel J. Savage ◽  
James J. Wall ◽  
John D. Yeager ◽  
Chanho Lee ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Neutron Diffraction ◽  
Time Of Flight ◽  
Radial Distance ◽  
Ultrasonic Waves ◽  
Science Center ◽  
Los Alamos ◽  
Inspection Method ◽  
Centrifugally Cast

The US code of Federal Regulations mandates regular inspection of centrifugally cast austenitic stainless steel pipe, commonly used in primary cooling loops in light-water nuclear power plants. These pipes typically have a wall thickness of ~8 cm. Unfortunately, inspection using conventional ultrasonic techniques is not reliable as the microstructure strongly attenuates ultrasonic waves. Work is ongoing to simulate the behavior of acoustic waves in this microstructure and ultimately develop an acoustic inspection method for reactor inspections. In order to account for elastic anisotropy in the material, the texture in the steel was measured as a function of radial distance though the pipe wall. Experiments were conducted on two 10 × 12.7 × 80 mm radial sections of a cast pipe using neutron diffraction scans of 2 mm slices using the HIPPO time-of-flight neutron diffractometer at the Los Alamos Neutron Science Center (LANSCE, Los Alamos, NM, USA). Strong textures dominated by a small number of austenite grains with their (100) direction aligned in the radial direction of the pipe were observed. ODF analysis indicated that up to 70% of the probed volume was occupied by just three single-grain orientations, consistent with grain sizes of almost 1 cm. Texture and phase fraction of both ferrite and austenite phases were measured along the length of the samples. These results will inform the development of a more robust diagnostic tool for regular inspection of this material.

Use of Neutron Diffraction for Describing Texture of Isostatically-Pressed Molybdite Powders

2005 ◽  
Vol 105 ◽  
pp. 83-88 ◽  
Author(s):  
H. Sitepu ◽  
Heinz Günter Brokmeier
Keyword(s):  
Crystal Structure ◽  
Neutron Diffraction ◽  
Powder Diffraction ◽  
Quantitative Description ◽  
Neutron Powder Diffraction ◽  
Powder Diffraction Data ◽  
Neutron Powder Diffraction Data ◽  
Pole Figures ◽  
Diffraction Patterns ◽  
Excellent Tool

The modelling and/or describing of texture (i.e. preferred crystallographic orientation (PO)) is of critical importance in powder diffraction analysis - for structural study and phase composition. In the present study, the GSAS Rietveld refinement with generalized spherical harmonic (GSH) was used for describing isostatically-pressed molybdite powders neutron powder diffraction data collected in the ILL D1A instrument. The results showed that for texture in a single ND data of molybdite the reasonable crystal structure parameters may be obtained when applying corrections to intensities using the GSH description. Furthermore, the WIMV method was used to extract the texture description directly from a simultaneous refinement with 1368 whole neutron diffraction patterns taken from the sample held in a variety of orientations in the ILL D1B texture goniometer. The results provided a quantitative description of the texture refined simultaneously with the crystal structure. Finally, the (002) molybdite pole-figures were measured using the GKSS TEX2 texture goniometer. The results showed that neutron diffraction is an excellent tool to investigate the texture in molybdite.

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