Table 1. Summary of Structural Parameters Extracted from Powder XRD Patterns by Rietveld Refinement for All Initial Samples Using the Orthorhombic Fmmm and tetragonal I4/mmm Space Groups.
| sample | parameters | Fmmm | I4/mmm |
|---|---|---|---|
| La2NiO4 | a (Å) | 5.4579(2) | 3.86119(4) |
| b (Å) | 5.4631(2) | 3.86119(4) | |
| c (Å) | 12.6874(2) | 12.6876(2) | |
| V (Å3) | 378.30(2) | 189.16(1) | |
| orthorhombicity δ × 10–4 | 4.8 | 0 | |
| Rwp | 3.9 | 4.8 | |
| Rp | 2.9 | 3.5 | |
| RB | 3.1 | 3.9 | |
| La2Ni0.9Cu0.1O4 | a (Å) | 5.4555(3) | 3.85987(5) |
| b (Å) | 5.4619(3) | 3.85987(5) | |
| c (Å) | 12.7339(3) | 12.7339(3) | |
| V (Å3) | 379.44(3) | 189.72(1) | |
| orthorhombicity δ × 10–4 | 5.9 | 0 | |
| Rwp | 2.4 | 2.8 | |
| Rp | 2.0 | 2.2 | |
| RB | 1.7 | 2.1 | |
| La2Ni0.8Cu0.2O4 | a (Å) | 5.4463(2) | 3.8535(1) |
| b (Å) | 5.4531(2) | 3.8535(1) | |
| c (Å) | 12.7768(4) | 12.7768(3) | |
| V (Å3) | 379.45(3) | 189.73(1) | |
| orthorhombicity δ × 10–4 | 6.2 | 0 | |
| Rwp | 2.7 | 3.1 | |
| Rp | 2.1 | 2.3 | |
| RB | 2.1 | 2.3 | |
| La1.8Ba0.2NiO4 | a (Å) | 5.4495(7) | 3.8540(2) |
| b (Å) | 5.4509(7) | 3.8540(2) | |
| c (Å) | 12.7977(5) | 12.7976(6) | |
| V (Å3) | 380.15(7) | 190.09(2) | |
| orthorhombicity δ × 10–4 | 1.3 | 0 | |
| Rwp | 3.9 | 3.4 | |
| Rp | 2.4 | 2.3 | |
| RB | 3.2 | 3.0 | |
| La1.8Ba0.2Ni0.9Cu0.1O4 | a (Å) | 5.4423(5) | 3.84885(8) |
| b (Å) | 5.4438(5) | 3.84885(8) | |
| c (Å) | 12.8398(3) | 12.8397(2) | |
| V (Å3) | 380.40(5) | 190.203(7) | |
| orthorhombicity δ × 10–4 | 1.4 | 0 | |
| Rwp | 4.2 | 3.8 | |
| Rp | 2.9 | 2.7 | |
| RB | 3.2 | 2.9 |