Electron paramagnetic resonance study of the proton-assisted thermal decompositions of MnO4−and CrO42− doped into (NH4)2SO4 and LiNH4SO4 crystals

Yu, Jiang Tsu; Chou, Shen Yuan

doi:10.1016/0022-3697(90)90002-w

Cited by 11 publications

(2 citation statements)

References 24 publications

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“…phase II exhibits similar unit-cell parameters as those of phase I [8]; phase III has a monoclinic structure [4,9]; and finally, phase IV has a monoclinic unit cell [10][11][12]. Moreover, Watton et al [13] reported a new phase transition for this compound (at 133 K), in addition to those previously observed at 27, 284.5 and 459.5 K. On the other hand, KNH 4 SO 4 crystals do not exhibit any phase transitions.…”

Section: Introductionmentioning

confidence: 99%

Study of the phase transitions by observation of the A and¹H nuclear magnetic resonance in ANH₄SO₄(A =⁷Li,³⁹K and⁸⁷Rb) single crystals with excellent optical quality

Lim¹,

Kim²

2008

J. Phys.: Condens. Matter

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ANH 4 SO 4 (A = Li, K and Rb) single crystals were grown using the slow evaporation method. We studied the spectra, spin-lattice relaxation times, T 1 , and spin-spin relaxation times, T 2 , of the 1 H, 7 Li, 39 K and 87 Rb nuclei in these three types of single crystals. The nuclear magnetic resonance observations provided a consistent description of the dynamics of the studied nuclei in these materials. The T 1 values for the 1 H nuclei are similar in all three crystals and the 1 H spin-lattice relaxation times increase with increasing temperature. However, as the radii of the metal ions increase, a corresponding decrease in the spin-lattice relaxation times of the A nuclei is observed. The differences observed in the spin-lattice relaxation times of the A nuclei upon changing the alkali-metal ion may be related to the ionic radius and the lengths of the A-O bonds. Therefore, the occurrence of phase transitions in these materials seems to be essentially dependent on the presence of the metal ions.

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Section: Introductionmentioning

confidence: 99%

Study of the phase transitions by observation of the A and¹H nuclear magnetic resonance in ANH₄SO₄(A =⁷Li,³⁹K and⁸⁷Rb) single crystals with excellent optical quality

Lim¹,

Kim²

2008

J. Phys.: Condens. Matter

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“…It has been found that the Cr 3þ complexes in the LCS [26] and LAS [27] crystals can be produced only by the thermal decomposition of CrO 2À 4 in the assistance of the ammonia hydrogens released by the ammonium groups (through doping with ammonium chromate). In this article it was shown that the EPR spectra of Cr 3þ ions in LCS could be observed without any additional sample treatment like irradiation or thermal decomposition.…”

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confidence: 99%

CsLiSO₄/NH₄LiSO₄system investigated by EPR

Zapart

Czaja

et al. 2006

Phase Transitions

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The single crystals of CsLiSO 4 and the solid solutions Cs x (NH 4 ) (1Àx) LiSO 4 have been investigated using the EPR technique. Two kinds of vanadyl doped samples were considered -as-grown from the aqueous solutions of appropriate compounds and after a thermal treatment. It has been established that in as-grown crystals the EPR spectra of vanadyl ions were very complex due to the presence of more than one paramagnetic site in the lattice. At least two such sites were identified and spin Hamiltonian parameters were calculated for all the sites. After annealing the crystals at about 400 K, a significant decrease in the intensities of the EPR lines of VO 2þ complexes was observed. In well-annealed samples the complexity of the EPR spectra has been found to disappear. Additionally, the third kind of vanadyl complexes were created during this treatment. It has also been shown that the EPR spectra of Cr 3þ ions in CsLiSO 4 could be observed without any additional sample treatment reported in literature like an irradiation or thermal decomposition. It was established that the VO 2þ and Cr 3þ , being sensitive to structural phase transition in the CsLiSO 4 , can be used as a probe for the structural changes in the CsLiSO 4 /NH 4 LiSO 4 system.

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39a-1 (Nh4)2so4 [F]

Deguchi¹,

Hasebe²,

Gesi³

et al.

Inorganic Substances Other Than Oxides

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Electron paramagnetic resonance study of the proton-assisted thermal decompositions of MnO4−and CrO42− doped into (NH4)2SO4 and LiNH4SO4 crystals

Cited by 11 publications

References 24 publications

Study of the phase transitions by observation of the A and¹H nuclear magnetic resonance in ANH₄SO₄(A =⁷Li,³⁹K and⁸⁷Rb) single crystals with excellent optical quality

Study of the phase transitions by observation of the A and¹H nuclear magnetic resonance in ANH₄SO₄(A =⁷Li,³⁹K and⁸⁷Rb) single crystals with excellent optical quality

CsLiSO₄/NH₄LiSO₄system investigated by EPR

39a-1 (Nh4)2so4 [F]

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Electron paramagnetic resonance study of the proton-assisted thermal decompositions of MnO4−and CrO42− doped into (NH4)2SO4 and LiNH4SO4 crystals

Cited by 11 publications

References 24 publications

Study of the phase transitions by observation of the A and1H nuclear magnetic resonance in ANH4SO4(A =7Li,39K and87Rb) single crystals with excellent optical quality

Study of the phase transitions by observation of the A and1H nuclear magnetic resonance in ANH4SO4(A =7Li,39K and87Rb) single crystals with excellent optical quality

CsLiSO4/NH4LiSO4system investigated by EPR

39a-1 (Nh4)2so4 [F]

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Study of the phase transitions by observation of the A and¹H nuclear magnetic resonance in ANH₄SO₄(A =⁷Li,³⁹K and⁸⁷Rb) single crystals with excellent optical quality

Study of the phase transitions by observation of the A and¹H nuclear magnetic resonance in ANH₄SO₄(A =⁷Li,³⁹K and⁸⁷Rb) single crystals with excellent optical quality

CsLiSO₄/NH₄LiSO₄system investigated by EPR