Vimal Kumar Jain

Electron paramagnetic resonance of VO2+ in hydrated crystals

The electron paramagnetic resonance of VO2+ ion impurities in single crystals of M″Rb2(SO4)2⋅6H20 where M″=Mg, Fe; MgSO4⋅7H2O; NaKC4H4O6⋅4H2O; and (NH4)2C2O4⋅H2O has been studied at room temperature and at X‐band frequency region. Multiple trapping sites for vanadyl are observed in all the crystals. The vanadyl ions enter the lattices at substitutional sites and a correlation is found to exist between the directions of the metal–oxygen bonds and the V–O bonds. The spin‐Hamiltonian parameters have been evaluated from single crystal as well as from powder spectra.

Electron paramagnetic resonance studies of vo2+ impurities in ferroelectric LiH3 (SeO3)2

Abstract The electron paramagnetic resonance of VQ 2+ impurities in ferroelectric lithium trihydrogen selenite has been studied in the X-band microwave frequency region and at 298 K. The ions reside in at least three chemically distinct sites. The principal values of the g and A tensors and the direction cosines which the principal axes make with the crystallographic axes are determined. A correlation is found to exist between the direction of the V-O bond and of the Li-O bond.

Electron paramagnetic resonance of Cr3+ in (NH4)xTl1−xAl(SO4)2⋅12H2O

The electron paramagnetic resonance EPR of Cr3+ has been studied in ammonium aluminium alum and thallium aluminium alum. The zero‐field splitting has been studied with variations of composition. (AIP).

Electron paramagnetic resonance and phase transition in (NH4)2SeO4:Mn2+ single crystals

The electron paramagnetic resonance of Mn2+ in ammonium selenate has been studied at X‐band and at various temperatures between 77 and 395 K. The spectrum consists of a set of 30 lines corresponding to single type of Mn2+ environment. The principal y axis is along the b axis and the principal z axis makes an angle 54°±2° with the c axis in the ac plane. Around 390 K the spectrum shows an anomalous change in line shapes followed by a complete collapse of the spectrum which is found to be reversible. This has been discussed in terms of a possible first‐order phase transition. The spectra at 77 K and at 300 K (including fine structure ΔM=±1 and Δm=0 hyperfine structure) are satisfactorily described by a spin Hamiltonian appropriate for Mn2+ in a rhombic crystal field. The parameters are determined at 77 and 300 K. Forbidden hyperfine transitions Δm=±1 and Δm=±2 have been observed. From the unequal separations between Δm=±1 doublets in M=+1/2→−1/2 transition, the values of the axial and rhombic parts of the q...

ESR of Cr3+ in CsAl(SO4)2 · 12H2O

The angular variation of the ESR spectrum of Cr3+ in CsAl(SO4)2 · 12H2O has been studied. In addition to the allowed fine structure lines some weak low field lines, identified as forbidden transitions, have been observed.

ESR of VO2+ in NaH3(SeO3)2

Abstract The ESR spectra of VO 2+ in NaH 3 (SeO 3 ) 2 have been investigated. Three vanadyl centres of different intensities are observed. A correlation is found to exist between the direction of the VO bond and of the NaO bond for the predominant centre.