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A Pd-vacancy ͑Pd-V − ͒ complex in Si has been identified with the perturbed angular correlation technique using the radioactive 100 Pd probe produced by recoil implantation. The fraction of Pd probes in the complex has been determined as a function of dopant type ͑B, P, As, and Sb͒, dopant concentration ͑10 15 -6 ϫ 10 19 cm −3 ͒ and annealing temperature ͑21-500°C͒. The Pd-V − complex, with a unique interaction frequency of 13.1͑2͒ MHz, was observed only in n + -Si with a maximum relative fraction of ϳ52% achieved between 200-300°C while a broad distribution of interaction frequencies was apparent in n-, p-, and p + -Si. Annealing beyond 300°C yielded a reduction in the Pd-V − fraction with a dissociation energy of 2.5͑7͒ eV. Density functional theory calculations of the electric field gradient for the given defect configuration were consistent with a measured value of 3.58ϫ 10 21 V/m 2 .

The time differential perturbed angular correlation (TDPAC) technique was used to study the temperature dependence of electric field gradient (EFG) in LaCoO 3 perovskite using 111 In → 111 Cd and 181 Hf → 181 Ta nuclear probes. The radioactive parent nuclei 111 In and 181 Hf were introduced into the oxide lattice through a chemical process during sample preparation and were found to occupy only the Co sites in LaCoO 3 . The PAC measurements with 111 Cd and 181 Ta probes were made in the temperature range of 4.2-1146 K and 4.2-1004 K, respectively. No long-range magnetic order was observed up to 4.2 K. The EFGs at 111 Cd and 181 Ta show very similar temperature dependences. They increase slowly between 4.2 and about 77 K and then decrease almost linearly with increasing temperature until about 500-600 K, where a broad peak-like structure is observed, followed by linear decrease at still higher temperatures. These discontinuities at about 77 K and 500-600 K have been interpreted as thermally activated spin state transitions from the low-spin (t 6 2g e 0 g ) ground state configuration to the intermediate-spin (t 5 2g e 1 g ) state and from the intermediate-spin to the high-spin (t 4 2g e 2 g ) state of the Co 3+ ion, confirming previous observation in other recent studies. An indication of a Jahn-Teller distortion, which stabilizes the intermediate-spin state with orbital ordering, is also pointed out.

In the present study, the synthesis of novel semi‐interpenetrating network (Semi‐IPN) hydrogel based on gum rosin alcohol‐psyllium (GrA‐Psy) has been reported. (Gum rosin alcohol‐psyllium)‐crosslinked‐poly(acrylic acid) [termed as (GrA‐Psy)‐cl‐poly (AA)] was synthesized using potassium persulphate (KPS) as an initiator and N, N′−methylene‐bis‐acrylamide (MBA) as crosslinker by free radical graft co‐polymerization technique. The prepared semi‐IPN was characterized using FTIR, XRD, and FE‐SEM. Further, the synthesized hydrogel was evaluated for the removal of malachite green (MG) dye from aqueous solution. Dye adsorption data was analyzed through various isotherm and kinetic models. Thermodynamic parameters and reusability of the synthesized adsorbent were also assessed. POLYM. ENG. SCI., 59:1416–1427 2019. © 2019 Society of Plastics Engineers