Separation of99Mo from132Te using thiourea as complexing agent. Application to the separation of99Mo from fission products

A radiochemical method to isolate⁹⁹Mo from¹³²Te, both produced in the fission of²³⁵U, has been developed. The method is based on the formation of a cationic complex of tellurium with thiourea in acid medium which is retained (98.7±0.5)% on a cation exchange resin (Dowex 50W-X8, 100–200 mesh), while (99.8±0.05)%⁹⁹Mo passes through it, due to the non-formation of such complex in the same experimental conditions. The radionuclidic purity of⁹⁹Mo was found to be suitable for the preparation of⁹⁹Mo–^99mTc generators. The retention of⁹⁹Mo on an alumina column as a function of pH was investigated and the best pH range for this purpose was found to be 4.0–4.5.     

Hydrogen absorption effects in the Zr(Fe0.5Cr0.5)2 compound

Zr(Fe_0.5Cr_0.5)₂ Laves phase samples have been made to absorb different hydrogen amounts up to 3.3 H/f.u. XRD showed all ZrFeCrH _y samples to have the C14 structure and, for 0 < y < 2.6, to be composed of a H-poor α-phase and a H-rich β-phase having different c/a ratios. Both phases could be distinguished in the Mössbauer spectra. The β-phase fraction was determined both from X-ray and Mössbauer analysis, with excellent agreement. β-phase lattice constants and hyperfine parameters vs. y exhibited a small jump at y ≈ 1.75, suggesting a phase transition. Mössbauer spectra of ZrFeCrH_3.3 in the 78–350 K range revealed that, for Fe at the 6h site, quadrupole splitting and linewidth increased for decreasing temperature. These effects were attributed to H atomic jump diffusion, and an activation energy of ≈70 meV was estimated.     

Production of123I using the CV-28 cyclotron at IPEN-CNEN/SP

These studies had the purpose of establishing the optimal conditions for the production of¹²³I through the¹²⁴Te (p, 2n)¹²³I reaction, using the CV-28 Cyclotron (E_max=24 MeV for protons) at IPEN-CNEN/SP. Two different targets (TeO₂ and TeO₂+2% Al₂O₃) were irradiated in order to check their physical resistance against beam current (up to 12 A) and length of irradiation (10 min — 2h), and to evaluate the recovery of the radioiodine produced, by a dry distillation process with a high frequency induction furnace. Later on, enriched¹²⁴TeO₂ (96.2%) targets were irradiated, and¹²³I was produced routinely with a production yield of (3. 31±0.07) mCi/Ah, 1.7% of¹²⁴I at EOB and radiochemically pure.     

Metal-nonmetal transition in the Cu2-xAgxSe system

Cu_2-xAg_xSe system shows metal-nonmetal transition in the sense that positive temperature coefficient of electrical conductivity at low x passes into a negative coefficient at higher x. The energy gap in the nonmetallic region increases with x. For x=0.96 it is equal to about 0.26 eV, and for x=1.21 to about 0.31 eV.     

Hyperfine Interactions in CeT2Ge2 (T = Mn,Co) Heavy Fermions Compounds Measured by TDPAC

Time Differential Perturbed γ–γ Angular Correlation (TDPAC) technique was used to measure the magnetic hyperfine field at both Ge and Ce sites in CeMn₂Ge₂ and CeCo₂Ge₂ intermetallic compounds. The ¹¹¹In (¹¹¹Cd) probe nuclei was used to investigate the hyperfine interaction at Ge sites, while the ¹⁴⁰La (¹⁴⁰Ce) nuclei was used to measure the magnetic hyperfine field at Ce site. The present measurements cover the temperature ranges from 10–460 K for CeMn₂Ge₂ and 9–295 K for CeCo₂Ge₂, respectively. The result for ¹¹¹Cd probe showed two distinct electric quadrupole frequencies above magnetic transition temperatures, in both compounds and a combined interaction in the magnetic region. The temperature dependence of the magnetic hyperfine field at ¹¹¹Cd at Mn site for the CeMn₂Ge₂ compound showed a transition from ferromagnetic to antiferromagnetic phase around 320 K and from antiferromagnetic to paramagnetic phase at 420 K. While a small magnetic field was measured on ¹¹¹Cd at Co site, no magnetic field on ¹⁴⁰Ce site was observed in CeCo₂Ge₂. This revised version was published online in September 2006 with corrections to the Cover Date.