Electron paramagnetic resonance of PO 2 2? and SO 2 ? radicals in barite

Ryabov, I. D.; Bershov, L. V.; Ganeev, I. G.

doi:10.1007/bf00199558

Cited by 12 publications

(5 citation statements)

References 11 publications

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“…Interestingly, the X‐ray‐irradiated sample shows one ESR signal with g = 2.0058 and a line width of 50 G, which is wider and stronger than that without irradiation (Figure a; Figure S28, Supporting Information). This signal can be assigned to the [PO 2 ] •0 radical that can form as follows

{([], {normalPO}_{2})}^{• 2 -} \to {([], {normalPO}_{2})}^{•0} + {2e}^{-}

Furthermore, the stronger intensity of the [PO 2 ] •0 radical suggests that other processes may also involve its formation. We surmise that the some ESR‐inactive phosphorus–oxygen units, such as the [PO 2 ] − unit, can be transformed into the [PO 2 ] •0 radical under X‐ray irradiation, which can be shown by the following equation

{([], {normalPO}_{2})}^{-} \to {([], {normalPO}_{2})}^{• 0} + {normale}^{-}

Besides, two weak peaks at g = 2.0682 and 2.0648 in the irradiated sample can be attributed to the O •− radical .…”

Section: Resultsmentioning

confidence: 99%

Theory‐Guided Defect Tuning through Topochemical Reactions for Accelerated Discovery of UVC Persistent Phosphors

Hong

Liu

et al. 2019

Advanced Optical Materials

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Long persistent phosphors (LPPs) have attracted enduring attention owing to their wide applications. However, the discovery of LPPs is thus far largely the results of trial and error. Here, theory‐guided defect tuning through topochemical reactions is demonstrated for accelerated discovery of emerging LPPs. First‐principles calculations are employed to identify the thermodynamic charge‐transition levels of different defect states, which help examine whether the candidate structure is a suitable host for afterglow. Rationally tuning the species and concentrations of defects through topochemical reactions is then illustrated, which leads to discovery of Pr3+‐doped LaPO4 featuring ultraviolet C afterglow with a lasting time of over 2 h. Such a strategy, in conjunction with advanced characterizations including high‐resolution synchrotron X‐ray diffraction, positron annihilation lifetime spectroscopy, and electron spin resonance, suggests a radical‐involved afterglow mechanism. Importantly, it is illustrated that this concept can be extended for the discovery of more LPPs. It is suggested that theory‐guided defect engineering enabled by topochemical reactions can be used as a powerful tool to accelerate discovery of novel LPPs with much clearer afterglow mechanisms, with implications even for the design of other optoelectronic materials.

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{([], {normalPO}_{2})}^{• 2 -} \to {([], {normalPO}_{2})}^{•0} + {2e}^{-}

{([], {normalPO}_{2})}^{-} \to {([], {normalPO}_{2})}^{• 0} + {normale}^{-}

Besides, two weak peaks at g = 2.0682 and 2.0648 in the irradiated sample can be attributed to the O •− radical .…”

Section: Resultsmentioning

confidence: 99%

Theory‐Guided Defect Tuning through Topochemical Reactions for Accelerated Discovery of UVC Persistent Phosphors

Hong

Liu

et al. 2019

Advanced Optical Materials

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“…The observed signal is attributed to the electronic SO 3 -centre (Ryabov et al, 1983;Kasuya et al, 1991) with a structure similar to the E' centre in SiO 2 and CO 2 -centre in CaCO 3 (Kasuya et al, 1991). The g factors are 2.0034, 2.0022, and 1.9995, and are consistent with those reported by Ryabov et al (1983) (Bershov et al, 1971). Therefore, the contents of a M 3+ ion in marine barite may be different from that in natural barite on land.…”

Section: Esr Signalsmentioning

confidence: 98%

“…There were several ESR studies on the signals of barite (Ryabov et al, 1983) where Kasuya et al (1991) suggested that barite is a mineral possibly suitable for ESR dating as indicated by the dose response and the thermal stability of the signal. However, so far there have been no reports on practical ESR dating of barite.…”

Section: Introductionmentioning

confidence: 99%

ESR Dating of Marine Barite in Chimneys Deposited from Hydrothermal Vents

et al. 2010

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Electron Spin Resonance (ESR) dating of marine barite in chimneys deposited from hydrothermal vents was attempted to determine the time since hydrothermal activity occurred. In this study, we used Barite (BaSO 4 ) precipitated in icroenvironments in the chimneys deposited from the hydrothermal vents at the Archaean site in South Mariana spreading centre (12°56.4'N, 143°37.9'E) and at Hakurei site in the Izena caldron (27°15'N, 127°04'E) for ESR measurements. ESR spectrum of marine barite is characterized by an electron-type centre with g values of 2.0034, 2.0022 and 1.9995 attributed to SO 3 -. The signal intensity increased with gamma ray dose. The dose rates of hydrothermal chimneys from the Archaean site and from the Hakurei site were calculated using a model that assumed a grain size and that incorporation of radionuclides after 226 Ra in U series into the chimney, and assuming the efficiency of the defect formation by alpha particles to be the same as that for OSL. The ESR ages were estimated to be 470 years old for barite from the Archaean site and 5670 years old for one from the Hakurei site, although there is a considerable difference between the present ESR ages and the 210 Pb/ 226 Ra disequilibrium ages previously reported.

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“…Previous EPR investigations on natural waterless sulphates of Ca, Sr and Ba (Ryabov et al 1983(Ryabov et al , 1989 showed the presence of the phosphorous paramagnetic defects PO~-and PO 2-ionic radicals. Their concentration turns out to be small and near to that of the corresponding isoelectronic 33SO;-and 33SO2 radicals containing the rare isotope 33S with natural abundance 0.75% (see, for example, EPR spectrum in Fig.…”

Section: Introductionmentioning

confidence: 98%

EPR and ENDOR of the PO 4 2? radical in anhydrite, celestite and barite

Ryabov¹,

Potashnyi²

1992

Phys Chem Minerals

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Abstract. Electron paramagnetic resonance (EPR) andelectron nuclear double resonance (ENDOR) low temperature measurements of natural anhydrite CaSO4, celestite SrSO4 and barite BaSO 4 have revealed the presence of PO 2-radical. The principal values of the g tensor and the A tensor [MHz] of hyperfine interaction (HFI) are found to be gxx=2.0124, gyy=2.0159, g~z=2.0098, Axx= 82.1, Ayy--81.4, A~z=77.2 in CaSO4, g~=2.0250, gyy=2.0070, g~z=2.0131, A~=84.8, Ayy=82.7, Az~ =90.5 in SrSO4, gx~=2.0302, gyy=2.0079, g~z=2.0135, A~ = 85.2, Ayy --82.3, A~ = 90.0 in BaSO4. The principal axes Axe, Ayy and A~= are parallel to the crystallographic axes a, b, c in all three matrices. In anhydrite the principal g axes coincide with the A axes. In celestite and barite such coincidence is found to be only along the b axis (a low symmetry effect). The coherence effect of splitting of ENDOR lines by a strong microwave field has been detected. From the analysis of the relative intensities of the ENDOR lines of the PO~-radical in CaSO4 the relation of probabilities of cross-relaxation processes W~/W~ = 3.5 are evaluated.

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Electron paramagnetic resonance of PO 2 2? and SO 2 ? radicals in barite

Cited by 12 publications

References 11 publications

Theory‐Guided Defect Tuning through Topochemical Reactions for Accelerated Discovery of UVC Persistent Phosphors

Theory‐Guided Defect Tuning through Topochemical Reactions for Accelerated Discovery of UVC Persistent Phosphors

ESR Dating of Marine Barite in Chimneys Deposited from Hydrothermal Vents

EPR and ENDOR of the PO 4 2? radical in anhydrite, celestite and barite

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