Variation of X-Ray Spectral Line Position with Ambient-Temperature Change: A Source of Error in X-Ray Spectrography

1964 ◽  
Vol 8 ◽  
pp. 431-442
Author(s):  
Frederick S. Lee ◽  
William J. Campbell
Keyword(s):  
Thermal Expansion ◽  
Spectral Line ◽  
Ambient Temperature ◽  
Temperature Change ◽  
Silicon Germanium ◽  
Peak Shift ◽  
Effect Of Temperature ◽  
Bragg Angle ◽  
X Ray ◽  
Principal Axes

AbstractThe effect of temperature change on LiF, ADP, and EDDT analyzing crystals was studied by measuring the change In intensity of a selected X-ray spectral line while maintaining a constant 2θ position on the spectrometer. A change in interplanar spacing due to thermal expansion and contraction satisfactorily account for experimentally observed line shifts for LiF and ADP. EDDT showed a large unexplained decrease in reflectivity with increasing ambient temperature.An equation was developed to express the change in intensity at a constant 2θ position as an exponential function of temperature. In this equation the thermal expansion coefficients of the principal axes of the crystal, the width of the spectral line at half-height, and the Bragg angle appear as factors. Intensity changes due to peak shift were tabulated for LiF, ADP, NaCl, silicon, germanium, quartz, calcite, fiuorite, and topaz.

Thermal expansion coefficients and Gruneisen parameters of quartz at high temperature by X-ray method

1994 ◽  
Vol 9 (2) ◽  
pp. 148-150
Author(s):  
Nabil N. Rammo ◽  
Saad B. Farid
Keyword(s):  
Thermal Expansion ◽  
High Temperature ◽  
Ambient Temperature ◽  
Least Squares ◽  
Temperature Variation ◽  
Ray Method ◽  
X Ray ◽  
Least Squares Fitting ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients

The temperature variation of the interplanar spacings (101), (112), and (211) of 325 mesh quartz was determined in the range 300–966 °K using X-ray powder diffractometry. The measured lattice parameters have been found to increase nonlinearly with temperature, and the dependence has been expressed by a polynomial of second degree from the least-squares fitting of the data, the results of which are presented herein. Values are given for the thermal expansion coefficients and Gruneisen parameter in the range 300 to 768 °K. In the range 768–966 °K, the expansion is zero. The derivatives dαa/dT, dαc/dT, and dαv/dT at ambient temperature are also given.

Shifts of peak positions due to specimen geometry and beam divergence in X-ray diffractometer

1996 ◽  
Vol 11 (4) ◽  
pp. 276-280 ◽  
Author(s):  
Bing H. Hwang
Keyword(s):  
Incident Beam ◽  
Peak Shift ◽  
Specimen Geometry ◽  
Beam Divergence ◽  
Specimen Surface ◽  
Bragg Angle ◽  
Curvature Radius ◽  
Analytical Geometry ◽  
X Ray ◽  
Lattice Strains

Plane analytical geometry has been used to derive formulas of peak shifts due to specimen geometry and beam divergence of X-ray diffractometers in a Seemann–Bohlin configuration. When the attenuated diffraction below the specimen surface is not considered, peak shifts depend on Bragg angle (θ), incident beam divergence (2α), curvature radius of the specimen surface (r), and the tilt angle of the specimen (ψ). Numerical results show that at any fixed Bragg angle value, the peak shift increases with 2α whatever the combination of r and ψ values are. Moreover, at any fixed value of both Bragg angle and beam divergence, the peak shift depends directly on |ψ| and inversely on |r|. Shifts of peaks have been compared on both goniometer circle (Δ2θS) and focusing circle (Δ2θP). The results show that when ψ>0, then (Δ2θS) is less than (Δ2θP). On the contrary, when ψ<0, then (Δ2θS) is greater than (Δ2θP). Both (Δ2θS) and (Δ2θP) increase when the Bragg angle is decreased under the same fixed set of ψ, 2α, and r values. These peak shifts are so high that lattice strains may be masked at either high values of |ψ| and 2α, or small |r| values.

Effect of Temperature on Fe3O4 Magnetic Nanoparticles Prepared by Coprecipitation Method

2014 ◽  
Vol 900 ◽  
pp. 172-176 ◽  
Author(s):  
Ji Mei Niu ◽  
Zhi Gang Zheng
Keyword(s):  
Magnetic Nanoparticles ◽  
Coprecipitation Method ◽  
Effect Of Temperature ◽  
Vibrating Sample Magnetometer ◽  
X Ray Diffraction ◽  
X Ray ◽  
Magnetic Carriers ◽  
Average Grain Size ◽  
Or Gene ◽  
Block Temperature

The Fe3O4 magnetic nanoparticles obtained by the aqueous coprecipitation method are characterized systematically using scanning electron microscope, X-ray diffraction and vibrating sample magnetometer. These magnetic nanoparticles are spheric, dispersive, and have average grain size of 50 nm. The size and magnetic properties of Fe3O4 nanoparticles can be tuned by the reaction temperature. All samples exhibit high saturation magnetization (Ms=53.4 emu·g-1) and superparamagnetic behavior with a block temperature (TB) of 215K. These properties make such Fe3O4 magnetic nanoparticles worthy candidates for the magnetic carriers of targeted-drug or gene therapy in future.

Synchrotron X-Ray Topography Study on the Relationship between Local Basal Plane Bending and Basal Plane Dislocations in PVT-Grown 4H-SiC Substrate Wafers

2020 ◽  
Vol 1004 ◽  
pp. 393-400
Author(s):  
Tuerxun Ailihumaer ◽  
Hongyu Peng ◽  
Balaji Raghothamachar ◽  
Michael Dudley ◽  
Gilyong Chung ◽  
...  
Keyword(s):  
Basal Plane ◽  
Local Strain ◽  
Grazing Incidence ◽  
Peak Shift ◽  
Linear Mapping ◽  
Incidence Geometry ◽  
Convex Shape ◽  
X Ray ◽  
Black And White ◽  
Plane Bending

Synchrotron monochromatic beam X-ray topography (SMBXT) in grazing incidence geometry shows black and white contrast for basal plane dislocations (BPDs) with Burgers vectors of opposite signs as demonstrated using ray tracing simulations. The inhomogeneous distribution of these dislocations is associated with the concave/convex shape of the basal plane. Therefore, the distribution of these two BPD types were examined for several 6-inch diameter 4H-SiC substrates and the net BPD density distribution was used for evaluating the nature and magnitude of basal plane bending in these wafers. Results show different bending behaviors along the two radial directions - [110] and [100] directions, indicating the existence of non-isotropic bending. Linear mapping of the peak shift of the 0008 reflection along the two directions was carried out using HRXRD to correlate with the results from the SMBXT measurements. Basal-plane-tilt angle calculated using the net BPD density derived from SMBXT shows a good correlation with those obtained from HRXRD measurements, which further confirmed that bending in basal plane is caused by the non-uniform distribution of BPDs. Regions of severe bending were found to be associated with both large tilt angles (95% black contrast BPDs to 5% white contrast BPDs) and abrupt changes in a and c lattice parameters i.e. local strain.

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