Table 5.
Crystallite size (calculated using Scherrer formula) and crystalline phases of thermally treated samples (NVx-TT), determined by X-ray difraction (XRD), according to the reference patterns in the ICDD PDF 4+ 2019 database.
| Sample Name | Pressure, Bar | Crystallite Size (Scherrer), nm | The Crystalline Phase Identified by XRD; Phase Content * | Formula | PDF References |
|---|---|---|---|---|---|
| NV4-TT | 20 | 81.6 | 77% Hematite 23% Magnetite |
Fe2O3 Fe3O4 |
PDF 04-003-5818 (P) PDF 04-007-2718 (*) |
| NV5-TT | 60 | 93 | 86% Hematite 14% Magnetite |
Fe2O3 Fe3O4 |
PDF 04-003-5818 (P) PDF 04-007-2718 (*) |
| NV6-TT | 100 | 82.6 | 89% Hematite 11% Magnetite |
Fe2O3 Fe3O4 |
PDF 04-003-5818 (P) PDF 04-007-2718 (*) |
| NV7-TT | 1000 | 86.4 | 72% Magnetite 28% Hematite |
Fe3O4 Fe2O3 |
PDF 04-007-2718 (*) PDF 04-003-5818 (P) |
* It should be noted that the percentage of crystalline phases calculated from XRD is a semi-quantitative estimation.