| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 859252 | Procedia Engineering | 2014 | 8 Pages |
Synthesis of Bi2+x Gax Pd4-3x O7+δ (S1-S4:x=0.15, 0.30, 0.45, 0.60) composite oxides were performed by sol-gel method. Powder XRD results show tetragonal unit cell with lattice parameters: A = 8.6354, 8.6420, 8.6241 and 8.6272 Å; C = 5.8786, 5.9099, 5.9122 and 5.9161 Å in S1-S4, respectively, space group I4/mcm and Z = 1. Unit cell structures were developed on space group I4/mcm with Wycoff sites: Bi3+(Ga3+) in 4(c), Pd2+(Ga3+) in 4(b), and O2− in 8(c). On Rietveld refinement the agreement factors were lowered to: Rp = 94.88, 93.78, 95.55, 93.43%; Rwp = 95.81, 95.88, 96.63, 94.45% and Rexp = 0.22, 0.91, 0.20, 0.26% in S1-S4, respectively. Calculated electronic energy band gaps by CASTEP programme package ∼ 0.02 eV show semiconductor-like nature of S1-S4. Observed EPR lineshapes at 300 K show two giso -values: g1= 2.024, 2.018, 2.010, 2.033; g2= 4.260, 4.201, 4.184, 4.186 at 300 K and two g-values: g3 = 2.148, 2.148, 2.041, 2.051; g4 = 4.423, 4.186, 4.209, 4.204 at 77 K in S1-S4, respectively. giso -values ∼2.0 is attributed to Pd+ and Pd2+(4d8) sites. Presence of hysteresis loops at 300 K show ferromagnetic nature of the samples. Optical absorption ∼400 - 500 nm is assigned to d–d transitions in Pd2+ ions.
