Gd systems

Commercial GD spectrometers with RF sources are available from Jobin Yvon, Inc. (www.jyhoriba.com), and from LECO (www.leco.com) DC sources are available from LECO and from Spectro Analytical Instruments (www.spectro-ai.com), among others. 

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Table 16-1. H.., Y and X... Y Hydrogen Bond Distances (A) and X—H.., Y angles (°) Calculated using ONIOM(B3LYP/6-31G(d,p) PM3) (in parentheses) and Electron Density Characteristics p (au) and V2p (au) (inner part, B3LYP/6-31G(d,p)) of Hydrogen Bonds in Dickite-GB and Dickite-GD Systems...

Reuben (291) has latterly suggested that the way round this problem is to investigate both proton and deuteron relaxation rates. In the Solomon expression for Tj [equation (17)] the deuterons are less susceptible than protons to the dipolar relaxation by a factor ( h/ d) which equals 424. Thus if Tm Tim the ratio of the induced relaxation of protons to that of deuterons is unity, but this ratio increases with increasing TimAm values until it reaches a value of 424 for the case when Tm T m- When applied to the Gd " system it is found that 0 03Tim = 3-3 X 10 s. 

McLuckey proposed the use of glow discharges coupled with quadrupole ion-trap MS for the determination of high-explosive substances in the vapor phase. The gas sampling GD system was found to be very effective at forming negative ions, e.g. from mono-, di- and trinitrophenols, mono-, di- and trinitrotoluenes, S, and others. 

The (Cuj xGax)Gd system has been investigated using magnetic susceptibility, resistivity and thermal expansion (van Dongen et al. 1983). The transition temperatures for the CsCl and FeB structures at the copper-rich end (x 0) are shown in fig. 33. 

Research on mixed trivalent chloride-iodide systems is limited. Beda et al. (1980) examined the RCI3 R = La, Gd, systems and in the lanthanum system characterized a UCl3-type phase with a doubled a lattice parameter. A structural solution based upon X-ray powder diffraction data suggested the formula La4Cl9l3 for this intermediate. An intermediate phase postulated for the R = Gd system was not characterized definitively. 

Coupling of FIA with GD is the most frequent. For example for ammonium determination several FIA—GD systems have been developed. Different detection methods coupled with GD—FIA system have been compared elsewhere [69]. Other examples are an FIA—GD system exploiting conductometric detection for Kjeldahl-produced ammonia [70], an FIA—GD system [71] applied to clinical blood samples using a bulk acoustic wave impedance sensor, a GD—FIA system using a capacitively coupled contactless conductivity detection (C4D) [72] and a GD—FIA with conductometric detection to monitor the ammonium content in open ocean seawater samples [73]. 

MSFIA—GD systems permit stop flow and flow reversal operation mode as well as implementing two flow lines simultaneously on the GD unit, and also the fact of using piston pumps provides a high precise volume control. Thus MSFIA combines benefits of both FIA and SIA techniques when being coupled to GD. In this section, two methods for determining ammonium ion by MSFIA—GD with spectrophotometric [76] and conductometric [77] determination will be described. 

Another MSFIA—GD system exploiting conductometric detection was also applied to different water samples in a wide concentration range (from 0.075 to 360 mg/1 of ammonium) [77], without sample... 

MSFIA-GD system for the conductometric determination of ammonium in water samples. Detector homemade stainless steel conductometric cell connected to a conductometer HC holding coil RC reaction coil V solenoid valve. 

Considering the above presented data it is possible to predict the existence of one liquid and two solid rows of continuous solutions in the Sc-Tb and Sc-Dy systems like in the Sc-Gd system. The occurrence of two of these solid solutions (aSc, aTb) and (aSc, oDy) has been already confirmed experimentally. 

A single crystal with the composition Sc0.075Y0.175Gd0.75 with the hep stmeture has been prepared and its magnetic properties investigated by Ito et al. (1988), however, no data about the lattice parameters were presented in this paper. These data indicate a complete miscibility of the components in the ternary system, similar to what occurs in the binary Sc-Y and Sc-Gd systems (see sect. 2.3). 

Fig. 13. Magnetic field dependence of the AFM resonances in GdjCu04 at 2 K. Branches tu, and tWj correspond to the Gd system, branches C2i and Q2 to the Cu subsystem. The magnetic field is (a) along [001] and (b) along [110]. From Stepanov et al. (1995).

Dudek, M., Rapacz-Kmita, A., Mroczkowska, M., Mosialek, M., and Mordarski, G. (2010) Co-doped ceria-based solid solution in the Ce02-M203-CaO, M=Sm, Gd system. Electrochim. Acta, 55 (14), 4387 394. 

Lundin (1966) measured heat of solution and calculated the heat of mixing for alloys in the La-Gd system. A plot of the heat of mixing versus composition for a binary system should show abrupt inflections at major phase boundaries. Lundin used a liquid-metal-soludon calorimeter that employed a liquid indium bath. The calorimeter was calibrated using solid indium sanq>les and to avoid alloying between the rare earth metals and the molten indium, the indium bath was changed after... 

The reviewers, however, suggest an alternate model for the phase equilibria in this region of the lanthanum-lutetium system. At high temperature we propose that the dhcp La and hep Lu phases form a continuous series of soHd solutions, which upon cooling form a sohd miscibility gap of the two terminal solid solutions. This construction would be essentially identical to the phase relationships observed in the Nd-Sc system by Beaudry et al. (1965) (see section 2.37 and fig. 65) and similar to that observed in the La-Gd system in that the dhcp La phase forms a continuous series of solid solutions with the hep Gd phase at high temperatures (see section 2.4 and fig. 5). Clearly a careful experimental study needs to be made of the 20 to 50 at% La region of the lanthanum-lutetium system, especially at high temperatures. 

It has been shown in section 2.1.1. that when high purity (-l-99.9at%) trivalent rare earth metals are alloyed, ideal behavior may be expected provided the atomic numbers of the component metals differ by no more than +4. The Er-Gd system fits these criteria, so fig. 83 was drawn to show the behavior expected of pure metals. It was demonstrated by Spedding et al. (1973) that Er does not have a high temperature bcc structure and when alloyed with a lanthanide metal that has a high temperature bcc form, the solvus transformation temperature line in the system... 

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