| Sample | Doping content/mol% | ||
| TiO2 | Nb2O5 | SrCO3 | |
| #1 | 99.80 | 0.10 | 0.10 |
| #2 | 99.70 | 0.15 | 0.15 |
| #3 | 99.60 | 0.20 | 0.20 |
| #4 | 99.50 | 0.25 | 0.25 |