EPR Study of Fe3+- and Ni2+-Doped Macroporous CaSiO3 Ceramics

Abstract

Abstract. Thermally stable macroporous CaSiO 3 , Fe 3! -and Ni 2! -doped (0.5 to 5 mol%) ceramics have been prepared by solution combustion process by mixing respective metal nitrates (oxidizers), fumed silica. Diformol hydrazine is used as a fuel. The combustion products were identified by their X-ray diffraction and thermal gravimetry/differential thermal analysis. Single phases of b-CaSiO 3 and a-CaSiO 3 were observed at 950 and 1200 °C, respectively. The phase transition temperatures of combustion-derived CaSiO 3 were found to be lower compared to those obtained via solid-state reaction method. It is interesting to note that with an increase in the calcination temperature the samples become more porous with an increase in the pore diameter from 0.2 to 8 µm. The electron paramagnetic resonance (EPR) spectrum of Fe 3! ions in CaSiO 3 exhibits a weak signal at g " 4.20 ) 0

Structural characterization, EPR and thermoluminescence properties of Cd1−xNixSiO3 nanocrystalline phosphors

“…due to the moderately high spin orbit coupling of octahedrally coordinated Ni 2+ . A similar g value of g = 2.23 is reported for Ni 2+ ions in porous CaSiO 3 [28]. The presence of a weak resonance signal in the vicinity of g = 4.090 may be due to the presence of a trace amount of iron impurity.…”

Effect of γ-Irradiation on the Dielectric and Conductivity Properties of Nano-Wollastonite

“…The image shows that the sintered sample before irradiation is porous. On the other hand, the irradiated sample exhibits sheet morphology consisting of regularly arranged nanorods due to chain like structure of (SiO 4 ) −4 ions increasing the porosity [8]. Similar type of sheet morphology in SEM image of CaSiO 3 has been reported earlier by Zhou and Yan [9].…”

Oxygen defect assisted paramagnetic to ferromagnetic conversion in Fe doped TiO2nanoparticles

“…The signal at g ¼ 1.998 is due to transition from lowest Krammers doublet in case of D s 0 and E ¼ 0. 35,36 This signal is for Fe 3+ in high symmetry octahedral eld of TiO 2 . In the octahedral coordination Fe 3+ interacts with the nearest Fe 3+ on the lattice site and undergoes spin-spin coupling resulting in the intense signal at g ¼ 1.998.…”