Temperature Dependence of Debye-Waller Factors in bcc Metals. I

Kharoo, H. L.; Gupta, O. P.; Hemkar, M. P.

doi:10.1143/jpsj.43.2030

Cited by 7 publications

(9 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…In the present work, the values were obtained by fitting the Fe {220} Bragg edges, selected because they make the minimum contribution of magnetic scattering to the transmission spectra at shorter wavelengths (Powers, 1938). The present result is compared against previous experimental values from Debrunner & Morrison (1965) as mentioned by Prakash et al (1975) and Kharoo et al (1977), and from Haworth (1960), who used X-ray diffraction and similarly focused on the Fe {220} diffraction peak covering the temperature range of 286-1190 K. Theoretical values calculated by Prakash et al (1975) and Kharoo et al (1977) are also shown. The values from the present work agree well with the previous experimental values, considering the scatter in the results by Haworth.…”

Section: Debye-waller Factor Analysismentioning

confidence: 95%

“…The data were derived from the Fe powder data collected at different temperatures as described in Section 3.3. Previously Haworth (1960), Prakash et al (1975) and Kharoo et al (1977) compared the Debye-Waller-factor dependencies on temperature in terms of the temperature parameter Y, which is defined by Y ¼ log 10 exp ð= sin Þ 2 ð2W T 0 À 2W T Þ ¼ ð= sin Þ 2 log 10 ð T = T 0 Þ;…”

Section: Debye-waller Factor Analysismentioning

confidence: 99%

“…Temperature parameter Y of Fe obtained at different temperatures through Bragg-edge analysis, compared with literature values measured by -ray resonant absorption (Debrunner & Morrison, 1965) and X-ray diffraction (Haworth, 1960). Theoretical values from Prakash et al (1975) and Kharoo et al (1977) are shown for comparison as solid and dashed lines, respectively. approach often struggles to describe the Bragg-edge shape, the cross-correlation method was shown to provide accurate results.…”

Section: Figure 18mentioning

confidence: 99%

See 2 more Smart Citations

Characterization and application of Bragg-edge transmission imaging for strain measurement and crystallographic analysis on the IMAT beamline

et al. 2019

View full text Add to dashboard Cite

This paper presents a series of experiments to characterize the performance of the new IMAT beamline at the ISIS pulsed neutron source and provides examples to showcase the potential applications of Bragg-edge transmission imaging on the instrument. The characterization includes determination of the IMAT spectral and spatial resolutions through calibration measurements, and also determination of the precision and the accuracy of Bragg-edge analysis for lattice parameters of ceramics, metals and textured engineering alloys through high-temperature measurements. A novel Bragg-edge analysis method based on the cross-correlation of different Bragg edges has been developed to provide an estimate of the change in lattice parameter, which is especially useful for measurements of textured samples. Three different applications of the Braggedge transmission imaging technique are presented, including strain mapping, texture mapping and obtaining crystallographic information, i.e. the dependence on temperature of the Debye-Waller factor. The experimental results demonstrate the ability of the IMAT beamline to provide accurate strain measurements with uncertainties as low as 90 m" with reasonable measurement time, while characteristic materials parameters can be mapped across the sample with a spatial resolution of 300-600 mm for a strain map and down to $90 mm for a texture map.

show abstract

Section: Debye-waller Factor Analysismentioning

confidence: 95%

Section: Debye-waller Factor Analysismentioning

confidence: 99%

Section: Figure 18mentioning

confidence: 99%

See 1 more Smart Citation

Characterization and application of Bragg-edge transmission imaging for strain measurement and crystallographic analysis on the IMAT beamline

et al. 2019

View full text Add to dashboard Cite

show abstract

“…The (311) planes are nearly independent of the anions. The intensities I 220 , I 311 , I 222 , I 400 , I 422 , I 511 and I 440 were calculated using equation (17). The calculated and observed relative results were obtained by normalizing with respect to the most intensive reflection I 311 , which has been taken as 100%.…”

Section: Debye-waller Factor (Dwf)mentioning

confidence: 99%

“…The temperature variation of the DWF for alkali and nobel metals have been reported [14]. The DWF have been calculated for five FCC metals: copper, silver, gold, aluminum and nickel [15,16] and for three bcc metals: sodium, α-iron and chromium [17][18][19]. The Debye-Waller factor of molybdenum has been determined by the powder neutron diffraction technique with a double-axis neutron diffractometer [20].…”

Section: Introductionmentioning

confidence: 99%

Effects of Zn Substitution on Structure Factors, Debye-Waller Factors and Related Structural Properties of the Mg1-xZnxFeNiO4 Spinels

Khalaf¹

2019

View full text Add to dashboard Cite

The effects of Zn 2+ ions substitutions on the Debye-Waller Factors, structure factor and other related structural properties of the Mg 1-x Zn x NiFeO 4 (where 0.0≤x≤1.0) spinels have been investigated using the XRD, TEM, SEM and FT-IR tools. The Mg 1-x Zn x NiFeO 4 samples were prepared using the conventional ceramic solid state sintering techniques at temperatures around 1100°C. The Mg 1-x Zn x NiFeO 4 spinels have predominantly inverse type structure with inversion factor, λ in the range 0.69 to 0.36. The X-ray diffraction (XRD) patterns of all compositions showed the formation of cubic spinel structure. The lattice constant "a" increases from 8.3397Å for MgFeNiO 4 to 8.3855Å for ZnFeNiO 4 spinels. The increases in lattice parameters have been attributed to the replacement of small Mg 2+ ions (0.66 Å) with the Zn 2+ (0.74 Å) ions of a larger ionic radius. The IR spectra confirm the existence of two main absorption bands υ 1 and υ 2 in the frequency range of (400-1000 cm-1), arising due to the tetrahedral (A) and octahedral (B) stretching vibrations respectively. Values of both υ 1 and υ 2 decrease as Zn content increases. The scanning electron microscope (SEM) and transmission electron microscope (TEM) images showed aggregates of stacked grains. The normalized XRD intensities of the main (hkl) planes were used in the estimation of the Debye-Waller factor. Values of the Debye-Waller factors were estimated to be in the range (0.77-1.44A 2). The calculated and observed relative intensities and areas of the most related plains to cation distributions (i.e.: the (220), (311), (222), (400), (422), (511) and (440) plains) were obtained by normalizing with respect to the most intensive reflection from the (311) plane. An inverse relation between the ordering, Q and inversion, λ factors exists in these partially inverse spinels. Both Q and λ decrease as Zn content (x) increases in the sample. The cation distributions indicate that the sample, MgFeNiO 4 with x=0, λ=2/3 and maximum configurational entropy Sc(=15.876 J/mol, K) should represents the sample of the complete randomness of cation distributions in these spinels and can be written as (Mg 1/3 Fe 2/3)[Mg 2/3 Fe 1/3 Ni 3/3)O 4. In general the variation of the different structural parameters with Zn content lie on two different regions, the first region for x values (0.0-0.6) the "highly normal" and the second region for x values (0.6-1.0) the "highly inverse" type structure.

show abstract

Microscopic nonequilibrium energy transfer dynamics in a photoexcited metal/insulator heterostructure

et al. 2019

View full text Add to dashboard Cite

The element specificity of soft X-ray spectroscopy makes it an ideal tool for analyzing the microscopic origin of ultrafast dynamics induced by localized optical excitation in metal-insulator heterostructures. Using [Fe/MgO]n as a model system, we perform ultraviolet pump/soft X-ray probe experiments, which are sensitive to all constituents of these heterostructures, to probe both electronic and lattice excitations. Complementary ultrafast electron diffraction experiments independently analyze the lattice dynamics of the Fe constituent, and together with ab initio calculations yield comprehensive insight into the microscopic processes leading to local relaxation within a single constituent or non-local relaxation between two constituents. Besides electronic excitations in Fe, which are monitored at the Fe L3 absorption edge and relax within 1 ps by electron-phonon coupling, soft X-ray analysis identifies a change at the oxygen K absorption edge of the MgO layers which occurs within 0.5 ps. This ultrafast energy transfer across the Fe-MgO interface is mediated by high-frequency, interface vibrational modes, which are excited by hot electrons in Fe and couple to vibrations in MgO in a mode-selective, non-thermal manner. A second, slower timescale is identified at the oxygen K pre-edge and the Fe L3 edge. The slower process represents energy transfer by acoustic phonons and contributes to thermalization of the entire heterostructure. We thus find that the interfacial energy transfer is associated with non-equilibrium behavior in the phonon system. Because our experiments lack signatures of charge transfer across the interface, we conclude that phonon-mediated processes dominate the competition of electronic and lattice excitations in these non-local, non-equilibrium dynamics.

show abstract

Temperature Dependence of Debye-Waller Factors in bcc Metals. I

Cited by 7 publications

References 30 publications

Characterization and application of Bragg-edge transmission imaging for strain measurement and crystallographic analysis on the IMAT beamline

Characterization and application of Bragg-edge transmission imaging for strain measurement and crystallographic analysis on the IMAT beamline

Effects of Zn Substitution on Structure Factors, Debye-Waller Factors and Related Structural Properties of the Mg<sub>1-x</sub>Zn<sub>x</sub>FeNiO<sub>4</sub> Spinels

Microscopic nonequilibrium energy transfer dynamics in a photoexcited metal/insulator heterostructure

Contact Info

Product

Resources

About

Temperature Dependence of Debye-Waller Factors in bcc Metals. I

Cited by 7 publications

References 30 publications

Characterization and application of Bragg-edge transmission imaging for strain measurement and crystallographic analysis on the IMAT beamline

Characterization and application of Bragg-edge transmission imaging for strain measurement and crystallographic analysis on the IMAT beamline

Effects of Zn Substitution on Structure Factors, Debye-Waller Factors and Related Structural Properties of the Mg&lt;sub&gt;1-x&lt;/sub&gt;Zn&lt;sub&gt;x&lt;/sub&gt;FeNiO&lt;sub&gt;4&lt;/sub&gt; Spinels

Microscopic nonequilibrium energy transfer dynamics in a photoexcited metal/insulator heterostructure

Contact Info

Product

Resources

About

Effects of Zn Substitution on Structure Factors, Debye-Waller Factors and Related Structural Properties of the Mg<sub>1-x</sub>Zn<sub>x</sub>FeNiO<sub>4</sub> Spinels