An isothermally jacketed calorimeter has been constructed to measure the changes in heat content accompanying the solution of somerareearthmetals and compounds. To check the performance of the apparatus, the integral heats of solution of potassium nitrate in water at 25°C have been measured. The values corrected to infinite dilution by use of relative apparent molal heat content data in the literature give 8384 +/- 12 cals/mole. The result agrees well with the values reported by others.
The task was to find out the most appropriate expandable graphite intercalation compound GIC for intumescent seals. The application in fire seals required GICs, which exerted high expansion at low burning rates. Therefore graphite was treated with nitric, sulphuric, phosphoric acids and ferric chloride. Phosphoric acid with its flame retardant properties was the favourite, but graphite treated with it, did not exfoliate, therefore expandable graphite was post treated with phosphoric acid. Elemental analysis and thermogravimetric measurements led to chemical formulas of GICs. Their heats of exfoliation were determined by differential scanning calorimetry, by the work done given by the product of increased specific volume and atmospheric pressure, by the Arrhenius plot of exfoliated specific volume dependent on temperature and were calculated in a complete balance of weights and heats of formation. It turned out that the sum of heats of intercalation and exfolia- tion corresponded with the heats of decomposition and gasification of the intercalated compounds. When the heat of intercalation was added to the lattice energy of graphite, the lattice energy of GIC was obtained. Electron microscopy indicated that expansion did not happen in monolayers but in nanoplatelets consisting of about 40 atomic layers. The expandable GICs were incorporated into polyvinyl acetate strips and applied as fire gaskets in gaps. In a fire test, the gap protected by the strip comprising the GIC treated with sulphuric and phosphoric acid showed the best performance, which corresponded with the highest observed expansion and with the second highest tempera- ture of maximum speed of combustion.
Now day’s different routes such as mechanical alloying, combustion synthesis, plasma forming, explosive form- ing, electro deposition and sol-gel process are used for producing nano-sized ceramics or metals. Among them, high energy ball milling and combustion synthesis are the most useful techniques for producing nano-sized ce- ramics and ceramic-composites. The ball milling tech- nique is more environmentally safe than the method of chemical synthesis, producing far less chemical waste . A number of nanostructured metal oxides and their solid solutions such as Fe 2 O 3 -SnO 2 , ZrO 2 -Fe 2 O 3 , TiO 2 -
good agreement with specific heat data of Ref. 39. Thus there is complete agreement within the magnetic, spe- cific heat and neutron scattering that stoichiometric YbN is a classical antiferromagnet. On an undefined poly- crystalline sample of YbN a heavy fermion characteristic has been proposed , but we have shown that this characteristic is typical for non-stoichiometric samples, where the large carrier concentration fills up partially the usually empty 4f 14 state, whereas stoichiometric single crystals are definitely non heavy fermion. However, all other Yb pnictides, especially also non-stoichiometric YbN, with their large free carrier contribution, fill somewhat the 4f 14 or one hole state (see Figure 27) and result in some intermediate valence   or dense Kondo effect. This usually has also an effect in the electrical resistivity, but the one of stoichiometric YbN is a very smooth curve, in contrast to YbP and YbAs . However, all Yb pnictides show antiferromagnetic order  , although in YbP 0.41 K  is observed, in contrast to 0.7 K in Ref. 52.
In the metallic state rare earths use to occur as trivalent ion cores, each of the localized magnetic moments, which interact indirectly via conduction bands. Within their period, the magnetic moments of the rareearth atoms are tuned with increasing atomic number. The interplay of local magnetic moments, spatial electron distribution and periodic exchange coupling nurtures 6 exotic nating in the helical ordering of holmium. As exchange interaction is strongly influenced by the shape of the Fermi surface, those extraordinary magnetic properties are also reflected in the electron transport properties. be investigated at different temperatures. Note that in contrast to the state of affairs within transition metals the 4f electrons of rareearth ion cores are fully localized and surrounded by the filled 5s and 5p shells they are well screened from
Weight loss of the samples was plotted against immersion time for 400ppmof rareearthmetals are demonstrated in Figure (1) at 25 o C. The resulted curves in the existence of 400 ppmof rareearth metalsfall significantly below that of blank solution. Additionally, it is clear that the mass loss of mild steel in the presence of rareearthmetals varies linearly with time. This can be outlined as theprecipitation of insoluble surface filmwhich isolated the coupon surface from the corrosive media  (i.e. these compounds behave as inhibitors). However, for all the concentrations tested, it is appeared to devote metal dissolution and displayed a corrosion rate worse than that of the control sample. It was also noted that the coupon initially took on a reddish appearanceconsistent with the formation of a complex oxide film of iron and rareearthmetals.
E-beam evaporation utilizes the energy from an electron beam to melt and evaporate a material contained in a crucible. Deposition rates can be easily adjusted by changing the current and energy of the electron beam . Film thicknesses and deposition rates are determined in the systems used by a quartz crystal. Our e-beam evaporator capabilities allow deposition of up to five different materials in situ. Deposition of multiple materials is necessary because capping layers are required to prevent oxidation of magnetic metals. Multiple layers are also necessary to create spin valve structure which can be used to determine the presence and position of a domain wall as described in the next section. E- beam evaporation is a very directional process and consequently is good for lift-off applications. However, one of the limitations of e-beam evaporation is that it is difficult to deposit an alloy because the vapor pressures of the materials are not the same.
The following thermal data have been measured f or some of t he compounds and metals of cerium and neodymiumz (1) the heats of solution and dilution of the anhydr ous chlorides i n aqueous solution; (2) the changes in heat capacities of solution and dilution of the anhydrous chlorides in aqueous solution; (3) the heats of solution of the anhydrous chlorides and metals in aqueous hydrochloric acid; (4) the heats of solution of the hydrated chlorides in aqueous solution; ( 5) the heats of precipitation of the oxalates in aqueous oxalic acid solution; and (6) the heat capacity of neodymium metal in the temperature range of 0° to 250°C. In addition, the heats of solution and dilution of potassium chloride and oxalic acid hydrate in aqueous solution, and the heat capacity of tantalum metal from 0°C to 425°C have been measured.
Another factor needs to be considered: the pH. Indeed, as the TOAH is an ammonium, the acidic proton on the ammonium can be removed if the pH isn’t acid enough. With that optic, Katsuka and co-workers have studied the power of pH on the extractability for several transition metals. The following table is giving results for some of them.
concentration range between 0.02 molal and saturation. Density measurements on solutions of lanthanum, neodymium, samarium, gadolinium, dysprosium, erbium, and ytterbium chlorides were carried out by a pycnometric method with an estimated accuracy of 1 x 10-5 gm.per ml. From the density data the apparent molal volumes for these rare-earth chlorides were calculated. The apparent molal volume data for each rare- earth chloride were expressed as a function of the square root of the molality by a five-parameter power series from which partial molal volumes were calculated. Conductance measurements on solutions of these rare- earth chlorides were carried out over the same concentration range using the conventional alternating-current technique. In addition, the solubilities of the rare-earth chlorides at 25° c. were determined.
»■*> \jl\ is known as the paramagnetic moment and both the theoretical and observed values are tabulated in table 2.1 in units of //b per ion. The values of the theoret ical and observed saturation moment for each rareearth, gJ, are also tabulated in the same units. The paramagnetic Curie tem peratures parallel and perpen dicular to the c-axis, 6\\ and 6_i respectively, are also tabulated along with the Neel tem peratures, Tjv, of the hexagonal and cubic sites of the DHCP lattice (not all of the rare earths adopt this structure, for example the heavy rare earths are HOP which only contain hexagonal sites), along with the Curie tem perature Tc- When one considers ions in condensed m atter they will experience interactions th a t derive from the nature of their surroundings. Two classes of interactions exist. There are those known as single-ion interactions whose effect at one site does not depend upon the state of ions at another site, and there are those known as two-ion interactions which couple together the 4 / electrons on two different sites i and j.
However, the widespread use of magnetic materials created of inter metallic compounds of the rareearthmetals with metals of the iron subgroup is limited by their extreme fragility and low technology. Therefore, the search of ways of strengthening intermetallic compounds of rareearthmetals and improvement of their adaptability is an extremely urgent task.
of 1.0 ml of the water samples to 10.0 mL with 0.3% ultrapure nitric acid and analyzed by ICP/MS. Each sample was analyzed three times and the results are expressed as mean ± SD (SD: standard deviation). Relative standard deviation (RSD) of the three results are calculated and found to be less than 5% for all samples for all heavy metals analyzed in this study, reflecting the precision of the method for the analysis of these heavy metals. Calibration curves for all heavy metals analyzed were constructed by plotting the ratio of the intensity of the analyte heavy metal to that of the internal stan- dard vs. concentration of the heavy metal (in ppb), and results showed that the calibra- tion curves are linear with correlation coefficient (r 2 ) greater than 0.999 for the heavy
The results of the research interaction between ash and slag samples from Vladivostok TPP’s landfills saturated with underburning and ammonium hydrodifluoride were given. It was found out that the reactions of the main components of a concentrate with NH 4 HF 2 are flowing with creation of complex ammonium fluoro-metalate. It is shown that the distribution of REM (rareearthmetals) between foam and heavier products is going during the flotation process of carbon-containing ash and slag samples without significant concentrating. It is shown that the water leaching of fluoridated product lets transfer silicone, aluminum and iron salts into solution and concentrate rareearth elements in insoluble residue in the form of complex salts of NaLnF 4 general formula. We propose a schematic diagram of hydrodifluoride recycling of carbon-containing sample, which provides concentrating of REM with incomplete separation of macro-components.
Supposing that FeAl, FeB, FeZn and FeCo compounds (with varying stoichiometry) would not dissolve in the mol- ten salt, it is expected that only rareearth deposition will oc- cur during the electrolysis process. However, as was dis- cussed earlier, in the case of cryolite treatment, co-deposition of Na and Al along with the rare earths can be expected.
The Periodic Table can be arrange by The Periodic Table can be arrange by subshells. The s-block is Group IA and subshells. The s-block is Group IA and & IIA, the p-block is Group IIIA - VIIIA. & IIA, the p-block is Group IIIA - VIIIA. The d-block is the transition metals, The d-block is the transition metals, and the f-block are the Lanthanides and the f-block are the Lanthanides and Actinide metals