Crystallization measurement

Fig. 113. Pyroelectric coefficients of RbsNbjOFig and KsNbsOFis crystals measured in the high temperature range. Reproduced from [443], A. I. Agulyansky, J. Ravez, R Von Der Miihll, A. Simon, Ferroelectrics 158 (1994) 139, Copyright 1994, with permission of Taylor Francis, Inc., http //www. routledge-ny.com.

Figure 41. PMC potential curves for a ZnO single crystal measured in contact with propylene carbonate (0.1 M TRAP) containing 10 mM ferrocene (curve 1), and with increasing concentrations (5,10, and 20%) of water (curves 2-4). Illumination with He-Cd U V laser. 5 mW.

The isotope is almost exclusively used for the investigation of chemical compounds. The resolving power of Mossbauer spectroscopy is demonstrated by the spectra from WS2 powder and single-crystal measurements as shown in Fig. 7.48 (from [222]). On the right-hand side of the picture, the angular dependence of E2 transitions for Aw = 2, 1,0 hyperfine components is indicated. 

The crystalline lamellar thickness Dc obtained by StrobPs method is initially 1.4 nm and grows to about 2.0 nm, which is roughly equal to the crystallite size in the chain direction of 2.8 nm estimated from the wide-angle X-ray diffraction (WAXD) [7]. Interestingly, the persistence length /p = 1.45 nm just before crystallization measured by SANS (also see Fig. 11) [9,10] is almost equal to the crystal thickness. 

One of the most promising techniques for studying transition metal ions involves the use of zeolite single crystals. Such crystals offer a unique opportunity to carry out single crystal measurements on a large surface area material. Suitable crystals of the natural large pore zeolites are available, and fairly small crystals of the synthetic zeolites can be obtained. The spectra in the faujasite-type crystals will not be simple because of the magnetically inequivalent sites however, the lines should be sharp and symmetric. Work on Mn2+ in hydrated chabazite has indicated that there is only one symmetry axis in that material 173), and a current study in the author s laboratory on Cu2+ in partially dehydrated chabazite tends to confirm this observation. 

Rotating single-crystal measurements also permitted the extraction of the orientation of the magnetic tensor in the molecular reference frame and the experimental easy axis was found to coincide with the idealized tetragonal axis of the coordination dodecahedron of Dy. Crystal field calculations assuming idealized tetragonal symmetry permitted the reproduction of magnetic susceptibility data for gz = 19.9 and gxy 0 [121]. More elaborated calculations such as ab initio post Hartree-Fock CASSCF confirmed this simple analysis [119]. 

Figure 5.8 Static magnetic data for the Er(trensal) complex in the case of a powdered sample and an oriented single crystal measured in parallel or perpendicular direction to the C3 rotation axis, (a) Temperature dependence of the magnetic susceptibility...

Small amounts of tritium were added to the hydrogen growth atmosphere of some crystals. Radiation detectors fabricated from these crystals measure the energy distribution of the electrons created in the tritium decays inside the crystal (Hansen et al., 1982). These studies set a lower limit of the hydrogen concentration at a value between 1014 cm 3 and 1015 cm-3. 

Fig. 5 Schematic plot showing reported crystallization temperatures for PEO in the bulk and as a component of block copolymers of varying compositions. The morphology of the PEO block is indicated on the x-axis. The filled bars are for data where isothermal crystallization measurements were performed and Avrami indexes of 1 or less were reported. The horizontal lines indicate the maximum temperature range that can be associated with PEO homogeneous nucleation, see text...

According to experimental data, which we obtained the specific magnetization of alloy Fes2Si2Bi6 after it s crystallization measured at room temperature, does not differ of the magnetization of this alloy in amorphous... 

Ultrapure Th metal has been processed at the Ames Laboratory by solid-state electrotransport under very low pressures (on the order of 0.3 nPa), which has produced the purest Th metal known, that with a resistivity ratio of 4200 for doubly refined metal (99-101). This resistivity ratio of 4200 translates into probably <50 ppm total impurities in the metal (see footnote 1) (87-90, 104). Single crystals measuring 0.25 cm in diameter by 1.1 cm in length with resistivity ratios of 1700-1800 have also been grown (55). 

It would be best perhaps if this technique were illustrated by an example. In the case of single crystal measurements for a compound which crystallizes in the -K2S04 form (D ji-Pnma] factor group the Raman tensor for the Ag... 

IR and Raman single crystal measurements have been carried out for YVO4 61). 

Table I Experimental conditions and the ratios of concentration of L-SCMC and sodium chloride in the mother liquor or grown parts of the crystal measured from broken crystal...

Figure 3.7. TMAFM images of a (001) surface of an as-received EDT-TTF-(CONHMe)2 single crystal measured under ambient conditions (2.5 im x 2.5 j.m) (a) topography and (b) phase. The phase angle is defined as the phase shift observed between the cantilever oscillation and the signal sent to the piezo-scanner driving the cantilever.

Let y = uf, (i.e., t=ylu), where y means distance in the crystal measured from the beginning of the crystal growth then... 

No special precautions are required to prepare material of this quality. However, since the loss of conductivity in samples of (TTF)(TCNQ) has been attributed to inclusion of impurities18 it is appropriate to use purified starting materials and distilled solvents and to perform the reaction in the absence of oxygen. Although the product is easy to prepare, the crystals are small and therefore not suitable for single-crystal measurements. 

Max von Laue, 1879-1960. German physicist who in 1912 discovered the interference of X-rays diffracted by crystals, measured the wave lengths of X rays, and studied the structure of crystals. In 1914 he was awarded the Nobel Prize for physics. 

Measured on single crystals. Measured on compressed pellets. 

The apparent surfaces of poly crystals, measured geometrically, are often 2—3 times smaller than the real area because the latter is relatively rough—it has hills and valleys that are invisible to unaided sight (see Fig. 7.32). Because various metals—and different samples of the same metal—may have different roughness factors ... 

At very low oxygen pressures, Bevan and Anderson found that the graphs of conductivity against inverse temperature yield an activation energy of a few hundredths of an electron volt, and that the conductivity becomes independent of oxygen pressure. This activation energy is similar to that for ionization of the electrons from the interstitial zinc atoms, as obtained from low temperature and single-crystal measurements. This may indicate that the surface effects become unimportant at very low pressures. 

Fig. 19. Hc2(T) of a L11N12B2C single crystal measured parallel 10 the tetragonal c-axis (o). The solid curve was calculated using a two-band model (see text). Dashed lines isotropic single-band (ISB) models with two values...

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