Negative (and very low) thermal expansion in ReO3from 5 to 300 K

2009 ◽  
Vol 42 (2) ◽  
pp. 253-258 ◽  
Author(s):  
Monica Dapiaggi ◽  
Andy N. Fitch
Keyword(s):  
Thermal Expansion ◽  
Cell Parameter ◽  
Internal Standard ◽  
Beam Current ◽  
High Energy ◽  
Low Thermal Expansion ◽  
Accuracy And Precision ◽  
Synchrotron Facility ◽  
High Beam Current ◽  
The Stability

This paper reports the accurate measurement of the ReO3cell parameter as a function of temperature. The thermal expansion is confirmed to be negative over most of the temperature range from 5 to 300 K. The main problems with the measurements are the very small variations (in the range of 10−5 Å) in the cell parameter at each temperature, requiring tight control of the stability and reliability of instrumental effects. In particular, achieving monochromator stability over time might be challenging with the high energy and high beam current variations of a third-generation synchrotron facility. On the other hand, such effects are usually checked by the addition of silicon as an internal standard, but the accuracy (and precision) of the published thermal expansion (which is not certified) might not be sufficient for its use when dealing with very small cell parameter variations.

scholarly journals Improvement of Electron Probe Microanalysis of Boron Concentration in Silicate Glasses

2019 ◽  
Vol 25 (4) ◽  
pp. 874-882 ◽  
Author(s):  
Lining Cheng ◽  
Chao Zhang ◽  
Xiaoyan Li ◽  
Renat R. Almeev ◽  
Xiaosong Yang ◽  
...  
Keyword(s):  
Electron Probe Microanalysis ◽  
Electron Probe ◽  
Pulse Height ◽  
Beam Current ◽  
High Energy ◽  
Silicate Glasses ◽  
Background Intensity ◽  
Differential Mode ◽  
Pulse Height Analysis ◽  
High Beam Current

AbstractThe determination of low boron concentrations in silicate glasses by electron probe microanalysis (EPMA) remains a significant challenge. The internal interferences from the diffraction crystal, i.e. the Mo-B4C large d-spacing layered synthetic microstructure crystal, can be thoroughly diminished by using an optimized differential mode of pulse height analysis (PHA). Although potential high-order spectral interferences from Ca, Fe, and Mn on the BKα peak can be significantly reduced by using an optimized differential mode of PHA, a quantitative calibration of the interferences is required to obtain accurate boron concentrations in silicate glasses that contain these elements. Furthermore, the first-order spectral interference from ClL-lines is so strong that they hinder reliable EPMA of boron concentrations in Cl-bearing silicate glasses. Our tests also indicate that, due to the strongly curved background shape on the high-energy side of BKα, an exponential regression is better than linear regression for estimating the on-peak background intensity based on measured off-peak background intensities. We propose that an optimal analytical setting for low boron concentrations in silicate glasses (≥0.2 wt% B2O3) would best involve a proper boron-rich glass standard, a low accelerating voltage, a high beam current, a large beam size, and a differential mode of PHA.

High energy resolution spectrometer for the dedicated STEM

1984 ◽  
Vol 42 ◽  
pp. 558-559 ◽  
Author(s):  
P.E. Batson
Keyword(s):  
Collection Efficiency ◽  
Core Loss ◽  
Beam Current ◽  
High Energy ◽  
High Energy Resolution ◽  
Acquisition Time ◽  
Good Definition ◽  
Loss Analysis ◽  
Definition Of ◽  
Acceleration Voltage

Use of the STEM to obtain precise electronic information has been hampered by the lack of energy loss analysis capable of a resolution and accuracy comparable to the 0.3eV energy width of the Field Emission Source. Recent work by Park, et. al. and earlier by Crewe, et. al. have promised magnetic sector devices that are capable of about 0.75eV resolution at collection angles (about 15mR) which are great enough to allow efficient use of the STEM probe current. These devices are also capable of 0.3eV resolution at smaller collection angles (4-5mR). The problem that arises, however, lies in the fact that, even with the collection efficiency approaching 1.0, several minutes of collection time are necessary for a good definition of a typical core loss or electronic transition. This is a result of the relatively small total beam current (1-10nA) that is available in the dedicated STEM. During this acquisition time, the STEM acceleration voltage may fluctuate by as much as 0.5-1.0V.

scholarly journals An assessment of methanolysis and other factors used in the analysis of carbohydrate-containing materials

1971 ◽  
Vol 125 (4) ◽  
pp. 1009-1018 ◽  
Author(s):  
R. E. Chambers ◽  
J. R. Clamp
Keyword(s):  
Hydrochloric Acid ◽  
Analytical Procedure ◽  
Internal Standard ◽  
Inorganic Contaminants ◽  
Rotary Evaporation ◽  
Silver Salts ◽  
Methanolic Hydrochloric Acid ◽  
Different Temperatures ◽  
The Stability ◽  
Analytical System

The stability of monosaccharides in methanolic hydrochloric acid of different strengths and at different temperatures was determined. They are generally stable for 24h in methanolic 1m- and 2m-hydrochloric acid at both 85°C and 100°C, but undergo considerable destruction in methanolic 4m- and 6m-hydrochloric acid at 100°C. Analysis of glycopeptides and oligosaccharides of known composition showed that release of carbohydrate was complete within 3h in methanolic 1m-hydrochloric acid at 85°C. Removal of methanolic hydrochloric acid by rotary evaporation resulted in considerable losses of monosaccharides, which could be prevented by prior neutralization. Methanolysis caused extensive de-N-acetylation of acetamidohexoses, so that a re-N-acetylation step is necessary in the analytical procedure. The addition of acetic anhydride for this purpose also prevented loss of internal standard by adsorption on the insoluble silver salts used in neutralization. Several trimethylsilylating agents were studied and suitable conditions are recommended. The effects on the analytical system of water and some common organic and inorganic contaminants are assessed.

scholarly journals Thermal expansion of La-based BMG studied by in situ high-energy X-ray diffraction

2010 ◽  
Vol 504 ◽  
pp. S155-S158 ◽  
Author(s):  
J. Bednarcik ◽  
C. Curfs ◽  
M. Sikorski ◽  
H. Franz ◽  
J.Z. Jiang
Keyword(s):  
Thermal Expansion ◽  
High Energy ◽  
X Ray Diffraction ◽  
X Ray

Synthesis of low thermal expansion ceramics based on CaZr4(PO4)6–Li2O system

2001 ◽  
Vol 79 (1) ◽  
pp. 6-10 ◽  
Author(s):  
Chong S. Yoon ◽  
Jae H. Kim ◽  
Chang K. Kim ◽  
K.S. Hong
Keyword(s):  
Thermal Expansion ◽  
Low Thermal Expansion

Material and application study for low thermal expansion glass-ceramic CLEARCERAM series

2005 ◽  
Author(s):  
Kousuke Nakajima ◽  
Toshihide Nakajima ◽  
Nobuo Kawasaki ◽  
Yoshiyuki Owari
Keyword(s):  
Thermal Expansion ◽  
Glass Ceramic ◽  
Application Study ◽  
Low Thermal Expansion
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