Lattice parameter measurement

Crystal defects, crystal orientations, accurate lattice parameter measurements, local strain, thin foil thickness can be identified from CBED and LACBED [7],... 

Figure 7. Lattice parameter measurement for NiO at -170°C, which has a rhomboherdal distortion. The best fit (shown at right) gives a=2.9522 A and a=60.05°.

Figure 3 shows the variation of the cubic lattice parameter, measured by x-ray powder diffraction. As can be seen, there is no volume effect or only a small negative one with an absolute value at 0 K smaller than 0.3 x 10-3. 

Different from the situation of the passive layer on Ni, passive Cr does not show a two-layered structure. Variation of the tunnel current does not cause the change from an amorphous to a crystalline structure [127], Depending on the potential one observes the amorphous granular structure of the hydroxide, or the crystalline oxide. The lattice parameter measured by STM is 0.28 nm, which corresponds to the distance in the O plane of 0001-oriented a-Cr203. Apparently, STM samples the distance of the O ions. The distance of Cr3+ ions should be 0.485 nm due to a lower density of the cations. Crystalline bulk CrO(OH) and Cr(OH)3 have a similar structure. The parameters of the hydroxide or oxyhydroxide are somewhat larger, i.e. 

The compositions of the ternary layers were evaluated from the lattice parameters measured using X-ray diffraction (see Datareview A1.2) and from the positions of the photoluminescence peaks. Both methods gave the same results, if the bowing parameters of 3.2 eV and 0.1 eV, for InGaN and AlGaN, respectively, were used (as proposed by Takeuchi et al [25] for strained layers on relaxed GaN on sapphire). 

Accurate Lattice Parameter Measurement and Strain Mapping... 

Precise lattice-parameter measurements require that there be a number of lines in the back-reflection region, while some specimens may yield only one or two. This difficulty may be avoided by using unfiltered radiation, in order to have K as well as Ka lines present. 

A detailed analysis of these various sources of error shows that they produce fractional errors in d which are very closely proportional to 0 tan (f>, where (f> is again equal to (90° - 0). This function is therefore the one to use in extrapolating lattice parameters measured with this camera. 

The parameter-composition curve, branch be of Fig. 12-8(b), thus serves as a sort of master curve for the determination of the whole solvus. For a given precision of lattice parameter measurement, the accuracy with which the solvus can be located depends markedly on the slope of the parameter-composition curve. If this curve is nearly flat, i.e., if changes in the composition of the solid solution produce very small changes in parameter, then the composition, as determined from the parameter, will be subject to considerable error and so will the location of the solvus. However, if the curve is steep, just the opposite is true, and relatively crude parameter measurements may suffice to fix the location of the solvus quite... 

Horvatti, J. (1983). Lattice parameter measurements of PbHP04 single crystals by ttie ration method. 

Data at other temperatures can easily be obtained by using Eqn (1) and the lattice parameter measurements as a function of temperature from [1],... 

Examples of Lattice Parameter Measurements with Polymers... 

Ere] Lattice parameter measurement, XRD 1350°C, Cr2iFe62Moi7, ti phase... 

TbAljSij adopts the structure type La O S [space group P3ml Muravyova et al. (1972), from X-ray powder diffraction analysis]. For sample preparation and atom parameters, see Sm-Al-Si. The lattice parameters measured were a = 4.18 and c = 6.60 A. 

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