Electron paramagnetic resonance study of Cr3+ ions in (NH4)1-xMxAl(SO4)2 · 12H2O (M = K, Na) mixed alums

Chand, Prem; Krishna, R. M.; Rao, J.L.; Lakshman, S.V.J.

doi:10.1016/0038-1098(89)90106-3

Cited by 5 publications

(6 citation statements)

References 13 publications

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“…Thus one would expect a different EPR spectum for each set of mixed near neighbours and perhaps further differention due to the second neighbour substitution. One reason for not observing the multiplet spectra by Chamd et al [8] is probably due to the fact that the component of species is not resolved because of a small difference in the values of the ZFS of Cr 3 + in pure alums and a large linewidth.…”

Section: Resultsmentioning

confidence: 99%

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Electron Paramagnetic Resonance of Cr³⁺in Rb_x(NH₄)_1-xAl(SO₄)₂·12H₂O

Takhur

Jain

1994

Acta Phys. Pol. A

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The EPR of Cr3+ in mixed alum Rbx(NH4)1-xAl(SO4)2 . 12H2 O has been studied at ca. 300 K and ca. 9.45 GHz. The EPR spectrum for x between 30 to 70% shows more than one kind of chromium complexes. The variation in magnitude of zero-field splitting parameter D indicates that the monovalent ions probably play an important role in the trigonal distortion of the water octahedron around the trivalent metal ion in alums.

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Section: Resultsmentioning

confidence: 99%

“…Chand et al [8] have studied the EPR of Cr 3 + in mixed alums (NH4)M1-x A l(SO4)2.12H2O (M = Na, K) and have observed only one specie. This would imply that the trigonal distortion about the chromium ion (at the Al site) depends on the average occupancy of neighbouring M 1 + sites.…”

Section: Resultsmentioning

confidence: 99%

Electron Paramagnetic Resonance of Cr³⁺in Rb_x(NH₄)_1-xAl(SO₄)₂·12H₂O

Takhur

Jain

1994

Acta Phys. Pol. A

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“…Thus the variation of the ESR spectra with composition is probably a sequential growth and diminuition of spectra corresponding to specific configurations of near neighbours. Chand et al [5] have studied the ESR of Cr 3+ in mixed alums of ammonium and potassium (sodium) and have observed only one species. One of the reasons for not observing multiplet spectra may be that the components of the species are not resolved because of the small difference in the ZFS's of Cr 3+ in pure alums, and the large linewidths.…”

Section: Methodsmentioning

confidence: 99%

“…Garrett and Boop [4] concluded those from the ESR of powder spectra the presence of other chromium complexes beside those observed by Jain [3]. Chand et al [5] have studied the ESR of Cr 3+ in the mixed alums (NH 4 ) x M 1−x Al(SO 4 ) 2 ·12H 2 O (M=Na,K) and have observed only one kind of chromium complexes. It seemed of interest to investigate the ESR of Cr 3+ diluted in K 1−x Tl x Al(SO 4 ) 2 ·12H 2 O (PotaniumThallium-Alum = PTA) in order to understand the variation of the ZFS with composition.…”

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Electron Spin Resonance of Cr³⁺ in K_1–xTl_xAl(SO₄)₂ · 12 H₂O

Jain

2003

Zeitschrift Für Naturforschung A

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The electron spin resonance (ESR) of Cr 3+ in K 1−x Tl x Al(SO 4 ) 2 ·12H 2 O has been studied at 300 K and 9.45 GHz. The ESR spectrum for x between 30 and 90% shows several chromium complexes. The variation of the zero-field splitting parameter D suggests that monovalent ions play an important role in the trigonal distortion of the water octahedron around the trivalent metal ion in alums. O (PotaniumThallium-Alum = PTA) in order to understand the variation of the ZFS with composition. The ESR of PTA for x = 0 and 1 has been previously studied [6,7]. The potassium aluminium and thallium aluminium alums which belong to the α type of alum [8,9], form a continuous series of solid solutions [1,10].The alum belongs to the cubic system with space group T h 6 (Pa3). Because of different atomic arrangements they exists in three types, namely α, β , and γ [8]. The K and Tl alum belong to the α type. The lattice constant a of the K alum is 1.2158 nm, and of the Tl alum is 1.2232 nm [9]. The Al 3+ has six water ExperimentalSingle crystals of PTA (x = 0 to 1) were grown at ∼ 300 K by slow evaporation of the saturated aqueous solutions of appropriate metal sulphates. Cr 3+ was introduced into the host lattice by adding chromic sulphate (1% by weight). The ESR experiments were performed on a JEOL FE-3X homodyne spectrometer operating at ∼ 9.45 GHz equipped with a TE 011 cylindrical cavity and 100 kHz field modulation. A speck of powdered diphenyl picrylhydrazil (DPPH) used as a field marker (taking g DPPH = 2.0036) was inserted simultaneously into the sample cavity. The crystals were mounted on quartz rods. The angular variation studies were made using a JES-UCR-2X sample angular rotating device. Powder spectra were recorded from powder in quartz tubes. Each powdered ESR sample was obtained by grinding an individual untwinned crystal.For an arbitrary orientation of the crystal, the ESR spectrum consists of a number of intense lines besides some weak lines on the low magnetic field side of the spectrum in all the crystals studied. For x = 0

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“…Chand et al [9] have studied the EPR of Cr3+ in mixed alums (NH,),M,~,Al(SO,), . 12 H,O (M = Na, K) and have observed only one species.…”

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Electron Paramagnetic Resonance of Cr^{3 +} in Rb_xK_1−xAl(SO₄)₂·12 H₂O

Jain¹

1994

Physica Status Solidi (b)

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The alums with the general formula M' +M3+(X04), . 12 H,O (X = S, Se), where M" is a monovalent cation (NH,, K, Rb, Cs, T1) and M 3 + a trivalent cation (Al, Ga, In, Cr, Fe) form an interesting isomorphous series of salts. It is easy to prepare solid solutions of the paramagnetic salts in diamagnetic ones over a wide range (0 to 100%) of relative concentration. There has been a considerable interest in the electron paramagnetic resonance (EPR) of these salts because they contributed significantly to the understanding of the location of the paramagnetic ion, high-order transitions, and phase transitions [l to 51. In this note we report the EPR of Cr3' in solid solutions of RbAl(SO,), . The alums belong to the cubic system with space group T,6(Pa3). Because of different atomic arrangements they exist in three types, namely a, p, and y [6]. The K alum and the Rb alum belong to the a-type. The lattice constant a of K alum is 1.2158 nm [7] and of Rb alum 1.2243 nm [7]. The unit cell contains four formula units. The A13+ have six water molecules as nearest neighbours forming a nearly regular octahedron. On the other hand, the octahedron of water molecules about the M" is strongly distorted. The six near neighbour M' + sites about an M3+ are ocatahedrally disposed, while the second neighbour M1 + sites are eightfold cubic. The [l 1 11 axis of the octahedron surrounding A1 coincides with the [ l l l ] axis of the crystal, but the axes of the octahedron deviate from the cubic axes of the crystal by an angle of rotation ~9 . 5 " about the [lll] direction.Single crystals of Rb,K1-,A1(SO,), . 12 H,O (x = 0.1 to 0.9) were grown at ~3 0 0 K by slow evaporation of the saturated aqueous solution of the component alums. Cr3+ was introduced into the host lattice by adding chromic sulfate (1 wt%).The EPR experiments were performed on a JEOL FE-3X homodyne spectrometer operating at ~9 . 4 5GHz equipped with a TE,,, cylindrical cavity and 100 kHz field modulation. A speck of powdered DPPH used as a field marker (taking g,,,,, = 2.0036) was inserted simultaneously into the sample cavity. The crystals were mounted on quartz rods.For an arbitrary orientation of the crystal, the EPR spectrum consists of a number of intense lines besides some weak lines on the low magnetic field side of the spectrum in all the crystals studied. Angular variation studies reveal the presence of four magnetically inequivalent but chemically equivalent Cr3 + complexes (formed by the substitution of A13 + ') Rohtak 124001, India.

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Electron paramagnetic resonance study of Cr3+ ions in (NH4)1-xMxAl(SO4)2 · 12H2O (M = K, Na) mixed alums

Cited by 5 publications

References 13 publications

Electron Paramagnetic Resonance of Cr³⁺in Rb_x(NH₄)_1-xAl(SO₄)₂·12H₂O

Electron Paramagnetic Resonance of Cr³⁺in Rb_x(NH₄)_1-xAl(SO₄)₂·12H₂O

Electron Spin Resonance of Cr³⁺ in K_1–xTl_xAl(SO₄)₂ · 12 H₂O

Electron Paramagnetic Resonance of Cr^{3 +} in Rb_xK_1−xAl(SO₄)₂·12 H₂O

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Electron paramagnetic resonance study of Cr3+ ions in (NH4)1-xMxAl(SO4)2 · 12H2O (M = K, Na) mixed alums

Cited by 5 publications

References 13 publications

Electron Paramagnetic Resonance of Cr3+in Rbx(NH4)1-xAl(SO4)2·12H2O

Electron Paramagnetic Resonance of Cr3+in Rbx(NH4)1-xAl(SO4)2·12H2O

Electron Spin Resonance of Cr3+ in K1–xTlxAl(SO4)2 · 12 H2O

Electron Paramagnetic Resonance of Cr3 + in RbxK1−xAl(SO4)2·12 H2O

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Electron Paramagnetic Resonance of Cr³⁺in Rb_x(NH₄)_1-xAl(SO₄)₂·12H₂O

Electron Paramagnetic Resonance of Cr³⁺in Rb_x(NH₄)_1-xAl(SO₄)₂·12H₂O

Electron Spin Resonance of Cr³⁺ in K_1–xTl_xAl(SO₄)₂ · 12 H₂O

Electron Paramagnetic Resonance of Cr^{3 +} in Rb_xK_1−xAl(SO₄)₂·12 H₂O