X and Q band EPR studies of paramagnetic centres in natural and heated tourmaline

Babińska, Joanna; Dyrek, K.; Pieczka, Adam; Sojka, Zbigniew

doi:10.1127/0935-1221/2008/0020-1790

Cited by 11 publications

(5 citation statements)

References 19 publications

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“…In the absence of fine splitting, their EPR identification is not possible. In fact, such signals can belong to ions of Fe(III), Mn(II), 20 Cu(II), 21 or even Zr(III). 22 In spite of this uncertainty, the EPR data justify completely the biexponential character of 31 P relaxation in Zr(IV)/ZrP, Zr(IV)/DOX@ZrP, and m-PEG-PO 3 /Zr(IV)/DOX@ZrP(2) materials and the presence of short 31 P T 1 components.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

³¹P NMR Relaxation and Motions of Phosphate Groups in Layered Zirconium Phosphate Materials

Bakhmutov

Clearfield

2016

J. Phys. Chem. C

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There is little systematic understanding of the motions of phosphate groups in layered zirconium phosphate (α-ZrP) materials applied in chemistry, industry, and nanomedicine for drug delivery. In this paper, we show how to quantitatively characterize correlation times of motions in the zirconium phosphate network on the basis of NMR 31 P relaxation time measurements. By studies of α-ZrP phosphates and their intercalated and decorated derivatives, we have established that room-temperature 31 P relaxation is governed by rotations of HPO 4 − groups with correlation times of (1.1− 4.7) × 10 −8 s restricted by H-bonding with water molecules in ordered and locally disordered areas. The disordered areas have been found by the 1 H spin-lock proton−phosphorus cross-polarization 31 P{ 1 H} MAS NMR experiments.

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Section: ■ Results and Discussionmentioning

confidence: 99%

³¹P NMR Relaxation and Motions of Phosphate Groups in Layered Zirconium Phosphate Materials

Bakhmutov

Clearfield

2016

J. Phys. Chem. C

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“…Here, like in the case of the previous study, 10 traces of paramagnetic centers in α-zirconium phosphate, prepared in this work, have been found as a wide signal at a g-factor of 2.0− 2.5 in the EPR spectrum. This g-factor corresponds to the presence of paramagnetic ions of Fe(III), Mn(II), 30 or Cu(II). 31 Since the signal is observed after 16 EPR scans, their concentration is obviously small.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

³¹P, ¹H NMR Relaxation and Molecular Mobility in Layered α-Zirconium Phosphate: Variable-Temperature NMR Experiments

Bakhmutov

Clearfield

2016

J. Phys. Chem. C

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Internal rotations in HPO4 – groups and proton transfer between them have been characterized in static α-zirconium phosphate by variable-temperature measurements of 31P T 1 and 1H T 1ρ times. The 1H T 1ρ times have been obtained by the kinetic of phosphorus–proton cross-polarization treated with the I-I*-S model. The calculations of the temperature T 1 relaxation dependences have resulted in the rotational activation energy of 2.6 kcal/mol (or 3.9 kcal/mol in account for the τC distribution) and the proton transfer activation energy of 5.5 kcal/mol. Thus, two types of motions have been found in α-zirconium phosphate: the low-frequency proton transfer with the correlation time τc of 1.5 × 10–5 s at 295 K and the high-frequency rotation in P–OH groups with the correlation time τc of 2.2 × 10–8 s at 295 K.

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“…Spectroscopic methods were widely used in studying the colour genesis of pink-red tourmaline, e.g., X-ray photoelectron spectroscopy by Hong et al [16], Li et al [17]; UVvisible, NIR, IR and Raman spectroscopy by Reddy et al [18], EPR spectroscopy by Babińska et al [19]. However, the understanding about pink-red tourmaline remains inconclusive and it still needs further research.…”

Section: Introductionmentioning

confidence: 99%

Gem Elbaite as a Recorder of Pegmatite Evolution: In Situ Major, Trace Elements and Boron Isotope Analysis of a Colour-Zoning Tourmaline Crystal

Zheng

Chen

2021

Crystals

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Few studies have focused on gem-quality tourmaline acting as a petrogenetic recorder, and the colour genesis of pink elbaite is still controversial. We carry out in situ major, trace element and boron isotope composition analyses on a single tourmaline crystal. This crystal is characterized by sudden transformation from colourless to pink, which can represent full pegmatite magma evolution. According to the analysis results, all spots are divided into alkali groups according to X-site occupancy and subdivided into elbaite series. The pink part accommodates higher concentrations of volatile and incompatible elements. The result is most consistent with successive pegmatite evolution in which the colourless part crystallized from the early stage, while the pink part crystallized from the late stage. The relatively consistent δ11B value between the colourless and the pink part suggests no fluid exsolution occurred during pegmatite evolution. The slight increase of δ11B values within the pink part and the colourless part may be due to mica crystallization. The combination of (Li++Mn2+) (Al3++Xvac)-1 and the exclusive positive linear relationship of Mn2+ vs. Ti4+ indicate that Mn2+ is the main cause of pink, while Mn2+-Ti4+ intervalence charge transfer also plays an important role.

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X and Q band EPR studies of paramagnetic centres in natural and heated tourmaline

Cited by 11 publications

References 19 publications

³¹P NMR Relaxation and Motions of Phosphate Groups in Layered Zirconium Phosphate Materials

³¹P NMR Relaxation and Motions of Phosphate Groups in Layered Zirconium Phosphate Materials

³¹P, ¹H NMR Relaxation and Molecular Mobility in Layered α-Zirconium Phosphate: Variable-Temperature NMR Experiments

Gem Elbaite as a Recorder of Pegmatite Evolution: In Situ Major, Trace Elements and Boron Isotope Analysis of a Colour-Zoning Tourmaline Crystal

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X and Q band EPR studies of paramagnetic centres in natural and heated tourmaline

Cited by 11 publications

References 19 publications

31P NMR Relaxation and Motions of Phosphate Groups in Layered Zirconium Phosphate Materials

31P NMR Relaxation and Motions of Phosphate Groups in Layered Zirconium Phosphate Materials

31P, 1H NMR Relaxation and Molecular Mobility in Layered α-Zirconium Phosphate: Variable-Temperature NMR Experiments

Gem Elbaite as a Recorder of Pegmatite Evolution: In Situ Major, Trace Elements and Boron Isotope Analysis of a Colour-Zoning Tourmaline Crystal

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³¹P NMR Relaxation and Motions of Phosphate Groups in Layered Zirconium Phosphate Materials

³¹P NMR Relaxation and Motions of Phosphate Groups in Layered Zirconium Phosphate Materials

³¹P, ¹H NMR Relaxation and Molecular Mobility in Layered α-Zirconium Phosphate: Variable-Temperature NMR Experiments