## 3 Results  
### Structural Characterization of Metal Titanate Nanorods  
Figure 2 presents the powder X-ray diffraction patterns for metal titanate nanorods annealed at 600 \({}^{\circ}\)C. The structure of MgTiO\({}_{3}\) nanorods was indexed according to the standard card (JCPDS card number: 79-0831), with the diffraction lines to be at 20 = 23.90\({}^{\circ}\), 32.75\({}^{\circ}\), 35.40\({}^{\circ}\), 40.55\({}^{\circ}\), 49.05\({}^{\circ}\), 53.55\({}^{\circ}\), 62.05\({}^{\circ}\), 63.65\({}^{\circ}\), corresponding to (012), (104), (110), (11-3), (024), (11-6), (12-4), and (300) planes, respectively. In addition, the phase of CoTiO\({}_{3}\) nanorods was also identified (JCPDS card number: 77-1373) with the diffraction lines at 20= 23.90\({}^{\circ}\), 32.85\({}^{\circ}\), 35.35\({}^{\circ}\), 40.45\({}^{\circ}\), 49.00\({}^{\circ}\), 53.50\({}^{\circ}\), 61.90\({}^{\circ}\), 63.55\({}^{\circ}\), corresponding to (012), (104), (110), (11-3), (024), (11-6), (12-4), and (300) planes. The NiTiO\({}_{3}\) nanorods were indexed by JCPDS card number: 89-3743 with the diffraction lines at 20 = 24.05\({}^{\circ}\), 33.05\({}^{\circ}\), 35.65\({}^{\circ}\), 49.85\({}^{\circ}\), 49.45\({}^{\circ}\), 53.95\({}^{\circ}\), 62.40\({}^{\circ}\), 64.10\({}^{\circ}\) corresponding to (012), (104), (110), (11-3), (024), (11-6), (12-4), and (300) planes, indicative of ilmenite structure. All the above-mentioned, metal titanates are crystallized in the ilmenite structure, which is a typical example of Rhombohedral lattice system, (which belongs to the hexagonal crystal family, with space group R-3) corresponding to (012), (104), (110), (11-3), (024), (11-6), (12-4), and (300) planes. The peak at 44.50\({}^{\circ}\) for all samples is attributed to the aluminum holder. Moreover, MgTiO\({}_{3}\) nanorods has an additional peak at 25.30\({}^{\circ}\) that is attributed to secondary TiO\({}_{2}\) phase (JCPDS card No. 65-5714), a peak that could be characterized as a very small impurity as its intensity is low. The sharpness and the intensity of the diffraction peaks indicate high crystallinity. In the case of Zn- titanate nanorods (ZnTiO\({}_{3}\)) diffraction peaks at 23.55\({}^{\circ}\), 30.00\({}^{\circ}\), 31.95\({}^{\circ}\), 33.65\({}^{\circ}\), 42.90\({}^{\circ}\), 49.70\({}^{\circ}\), 53.30\({}^{\circ}\), 62.35\({}^{\circ}\) correspond to (210), (220), (300), (311), (400), (421), (422), and (440) planes and are assigned to cubic crystal system (JCPDS card No. 39-0190). The lattice parameters of all the samples were in good agreement with the theoretical ones (Table 1). However, a deviation is observed because each sample's metal in A-site has different ionic radii. Lattice parameters and volume cell of NiTiO\({}_{3}\) are smaller than MgTiO\({}_{3}\) which is smaller than CoTiO\({}_{3}\). Moreover, Mg\({}^{2+}\) has a radius of 0.72 A [61; 62] and Ni\({}^{2+}\) 0.69 A [63] thus the lattice parameters in NiTiO\({}_{3}\) are smaller than those of MgTiO\({}_{3}\). With the same notion, Co\({}^{2+}\) radius is 0.74 A [64] (larger than the radius of Mg\({}^{2+}\)) so the lattice parameters of CoTiO\({}_{3}\) are larger than those of MgTiO\({}_{3}\). Following the same trend as the lattice parameters the volume of NiTiO\({}_{3}\) cell is the smallest, the volume of CoTiO\({}_{3}\) cell is the highest, and the volume cell of MgTiO\({}_{3}\) is in-between. The volume cell of ZnTiO\({}_{3}\) is the smallest of all the four samples because it crystallizes in cubic system. The crystalline size too, follows the same trend as cell volume and lattice parameters. More specifically, NiTiO\({}_{3}\) crystalline size is the smallest, MgTiO\({}_{3}\) has slightly bigger crystalline size, and CoTiO\({}_{3}\) has the highest. The ideal perovskite structure is in cubic lattice (0.9 \(<\) t \(<\) 1). Mixed oxides with t lower than 0.8 crystallize in ilmenite structure, a distortion from perovskite structure where A and Ti cations occupy octahedron sites.