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Phase relations in the MgSiO3–MgAl2O4–Al2O3 system are investigated at 27 GPa and 2000–2600 K using a multi‐anvil apparatus. The AlAlO3 content in the bridgmanite increases from 8.6 to 20.0 mol% with increasing temperature from 2000 to 2600 K, while the MgAlO2.5 content remains nearly constant, that is, 3–4 mol% at these temperatures. Therefore, the presence of an additional Al‐bearing phase suppresses the oxygen vacancy substitution for Al3+ in bridgmanite. Conversely, significant amounts of the Al8/3O4 component can be dissolved into the calcium‐ferrite type MgAl2O4–Mg2SiO4–Al8/3O4 phase (CF‐phase), implying that the CF‐phase likely contains some amount of vacancies. Therefore, the CF‐phase could also be a candidate mineral for transporting volatiles into the lower mantle. Our results, combined with previous studies on Al‐bearing bridgmanite, indicate that, once the Al per formula unit exceeds 0.12 in bridgmanite, the MgAlO2.5 content remains nearly constant and the AlAlO3 component becomes dominant. Plain Language Summary: Bridgmanite, the most abundant mineral in the Earth's mantle, can contain Al3+ in the forms of MgAlO2.5 and AlAlO3. To constrain the substitution mechanism of Al3+ in bridgmanite, we investigate the MgAlO2.5 and AlAlO3 contents in bridgmanite coexisting with a calcium‐ferrite type phase and corundum at different temperatures. Our results demonstrate that the MgAlO2.5 content reaches saturation (3–4 mol%) when an additional Al‐bearing phase exists in the system. Key Points: The MgAlO2.5 content in bridgmanite remains constant with temperature when bridgmanite coexists with corundum and the CF‐phaseThe MgAlO2.5 content in bridgmanite reaches a solubility of 3–4 mol% when bridgmanite coexists with an additional Al‐bearing phaseA significant amount of the Al8/3O4 component can be dissolved into the CF‐phase [ABSTRACT FROM AUTHOR]

Bridgmanite may contain a large proportion of ferric iron in its crystal structure in the forms of FeFeO3 and MgFeO2.5 components. We investigated the pressure dependence of FeFeO3 and MgFeO2.5 contents in bridgmanite coexisting with MgFe2O4‐phase and with or without ferropericlase in the MgO‐SiO2‐Fe2O3 ternary system at 2,300 K, 33 and 40 GPa. Together with the experiments at 27 GPa reported in Fei et al. (2020, https://doi.org/10.1029/2019GL086296), our results show that the FeFeO3 and MgFeO2.5 contents in bridgmanite decrease from 7.6 to 5.3 mol % and from 2 to 3 mol % to nearly zero, respectively, with increasing pressure from 27 to 40 GPa. Accordingly, the total Fe3+ decreases from 0.18 to 0.11 pfu. The formation of oxygen vacancies (MgFeO2.5 component) in bridgmanite is therefore dramatically suppressed by pressure. Oxygen vacancies can be produced by ferric iron in Fe3+‐rich bridgmanite under the topmost lower mantle conditions, but the concentration should decrease rapidly with increasing pressure. The variation of oxygen‐vacancy content with depth may potentially affect the physical properties of bridgmanite and thus affect mantle dynamics. Plain Language Summary: Bridgmanite is the most abundant mineral in the Earth's lower mantle. Although its basic chemical formula is MgSiO3, large amounts of Fe3+ can be added in the following two ways: (1) Two Fe3+ replace Mg2+ and Si4+ and form the FeFeO3 component. This is called charge‐coupled substitution because the overall charge does not change. (2) One Fe3+ replaces one Si4+ and forms the MgFeO2.5 component. Here the loss of positive charge is compensated by a loss of oxygen and is therefore called oxygen‐vacancy substitution. In this study, we measured the effect of pressure on the abundance of these two components of bridgmanite. We found that the MgFeO2.5 content decreases greatly with increasing pressure. Some oxygen sites may therefore be vacant in bridgmanite at the top of lower mantle, but the concentration of oxygen vacancies should decrease rapidly in deeper regions. The decrease of oxygen‐vacancy concentration in bridgmanite will change the nature of the lower mantle, for example, rocks will become harder, and electrical conductivity will decrease with increasing depth. Key Points: MgFeO2.5, FeFeO3, and total Fe3+ contents in bridgmanite decrease with increasing pressureFe3+‐linked oxygen vacancies in bridgmanite are destabilized by increasing pressureMgFeO2.5 can be formed in Fe3+‐rich bridgmanite under the topmost lower mantle conditions [ABSTRACT FROM AUTHOR]

MgSiO3 majorite is the most significant endmember of the Al‐deficient majorite garnets that form at depths higher than ∼400 km, in the mantle transition zone (MTZ). Here, we report elastic wave velocity measurements on polycrystalline MgSiO3 majorite samples, up to 18.4 GPa and 2000 K by ultrasonic interferometry techniques combined with in situ X‐ray diffraction measurements in a multianvil apparatus. Our data show MgSiO3 majorite has the lowest elastic moduli among silicate garnet endmembers, under the pressure and temperature conditions of the MTZ. These new data combined with those of other garnet endmembers allowed to estimate VP and VS of majorite with compositions relevant to the MTZ. The results suggest that variation of MgSiO3 component in garnet may play a role for interpreting seismic gradients atop the 410‐km discontinuity while below ∼520 km, the velocity contrasts hold too low values to explain the discrepancy between mineral physics data and seismological observations. Plain Language Summary: Majorite is an important constituent of mantle garnet that form at depths higher than ∼400 km, in the Earth's mantle transition zone. Here, we report elastic wave velocity measurements on polycrystalline MgSiO3 majorite samples, up to 18.4 GPa and 2000 K by ultrasonic interferometry techniques combined with in situ X‐ray diffraction measurements in a multianvil apparatus. Our data show MgSiO3 majorite has the lowest elastic moduli among other silicate garnets and therefore may play a role for interpreting the steep seismic gradients across the 410‐km discontinuity while below ∼520 km, it holds too low seismic contrast to explain the discrepancy between mineral physics data and seismological observations. Key Points: Sound velocities of MgSiO3 majorite were measured up to 18.4 GPa and 2000 KElastic softening increase gradually upon increasing MgSiO3 content in mantle garnetsPyrolite and mid‐ocean ridge basalts majorite are unlikely to explain the high VP and VS of the bottom mantle transition region [ABSTRACT FROM AUTHOR]

(Mg, Fe, Al)(Si, Al)O3 bridgmanite is the most abundant mineral of Earth′s lower mantle. Al is incorporated in the crystal structure of bridgmanite through the Fe3+AlO3 and AlAlO3 charge coupled (CC) mechanisms, and the MgAlO2.5 oxygen vacancy (OV) mechanism. Oxygen vacancies are believed to cause a substantial decrease of the bulk modulus of aluminous bridgmanite based on first‐principles calculations on the MgAlO2.5 end‐member. However, there is no conclusive experimental evidence supporting this hypothesis due to the uncertainties on the chemical composition, crystal chemistry, and/or high‐pressure behavior of samples analyzed in previous studies. Here, we synthesized high‐quality single crystals of bridgmanite in the MgO–AlO1.5–SiO2 system with different bulk Al contents and degrees of CC and OV substitutions. Suitable crystals with different compositions were loaded in resistively heated diamond anvil cells and analyzed by synchrotron X‐ray diffraction at pressures up to approximately 80 GPa at room temperature and 35 GPa at temperatures up to 1,000 K. Single‐crystal structural refinements at high pressure show that the compressibility of bridgmanite is mainly controlled by Al–Si substitution in the octahedral site and that oxygen vacancies in bridgmanite have no detectable effect on the bulk modulus in the compositional range investigated here, which is that relevant to a pyrolytic lower mantle. The proportion of oxygen vacancies in Al‐bearing bridgmanite has been calculated using a thermodynamic model constrained using experimental data at 27 GPa and 2,000 K for an Fe‐free system and extrapolated to pressures equivalent to 1,250 km depth using the thermoelastic parameters of Al‐bearing bridgmanite determined in this study. Plain Language Summary: Earth′s lower mantle, spanning from approximately 660 to 2,890 km depth, is mainly composed of bridgmanite, (Mg, Fe, Al)(Si, Al)O3 with a distorted perovskite‐type structure. In the topmost 500 km of the lower mantle, experiments showed that an MgAlO2.5 oxygen vacancy component may be present in bridgmanite. However, the effect of oxygen vacancies on the thermoelastic properties of bridgmanite is still not well constrained. These parameters are of crucial importance not only to model the thermodynamic stability of bridgmanite components at high‐pressure and high‐temperature but also to calculate the physical properties of lower mantle rocks. Here, we have determined the high‐pressure and high‐pressure‐temperature equations of state of three bridgmanite samples having different concentrations of Al and oxygen vacancies using X‐ray diffraction in diamond anvil cells. These data are complemented by the analysis of the bridgmanite crystal structure as a function of pressure, which revealed that oxygen vacancies have a minor effect on the elastic properties of bridgmanite at concentrations relevant for the lower mantle. Combining our results with experimental data on the stability of bridgmanite in the MgO–AlO1.5–SiO2 system, we have modeled the thermodynamic stability of the MgAlO2.5 component as a function of pressure and bulk Al content. Key Points: The thermal equation of state of Al‐bearing bridgmanite was determined for the first time using single crystalsThe bulk compressibility of Al‐bearing bridgmanite is mostly controlled by Al‐Si substitution in the octahedral siteUsing the obtained equation of state parameters, we modeled the pressure dependency of oxygen vacancies in bridgmanite in MgO–AlO1.5–SiO2 [ABSTRACT FROM AUTHOR]

Objective: To analyze the associations between gestational weight gain (GWG) and perinatal outcomes based on the GWG guidelines of the Chinese Nutrition Society (CNS) and the Institute of Medicine (IOM). Methods: This was a retrospective study with 9075 low‐risk singleton pregnant women. Logistic regression model was used to analyze associations between GWG categories and perinatal outcomes. Sensitivity analyses were performed based on pre‐pregnancy body mass index (calculated as weight in kilograms divided by the square of height in meters). Results: Excessive GWG as defined by the two guidelines was associated with a higher risk of adverse perinatal outcomes. Inadequate GWG was associated with higher risks of small for gestational age (adjusted odds ratio [aOR] 1.34, 95% confidence interval [CI] 1.10–1.64) and preterm birth (aOR 1.70, 95% CI 1.22–2.36), but a lower risk of large for gestational age (LGA) (aOR 0.77, 95% CI 0.63–0.95) according to the IOM guidelines. When using the CNS guidelines, inadequate GWG was associated with only a lower risk of preterm birth (aOR 1.80, 95% CI 1.19–2.70). Sensitivity analyses suggested that excessive GWG was associated with a higher risk of LGA in underweight women. Conclusions: Both guidelines could demonstrate the relationship between GWG and adverse perinatal outcomes. The CNS guidelines were more suitable for the Chinese population with underweight or normal weight before pregnancy, whereas IOM was more suitable for pregnant women with inadequate GWG. Synopsis: Chinese Nutrition Society guidelines were generally better for Chinese woman, but IOM guidelines were more appropriate for pregnant women with inadequate gestational weight gain. [ABSTRACT FROM AUTHOR]

The emergence of metal‐organic frameworks (MOFs) provides a new platform of low‐cost and color‐saturated blue light‐emitting diodes ideal for display and solid‐state lighting applications. However, numerous established MOFs still exhibit weak deep‐blue‐light emission (<450 nm) owing to low energy/charge transfer efficiency. Here a pressure‐treated strategy to greatly enhance photoluminescence performance of deep‐blue light‐emitting Y(BTC)(H2O)6 (H3BTC: benzene‐1,3,5‐tricarboxylic acid) is reported. Pressure‐treated Y(BTC)(H2O)6 exhibits a bright emission at 409 nm with a photoluminescence quantum yield from the initial 2.8% increasing to 75.0%. The hydrogen bonding cooperativity effect increases hydrogen bond binding energy after pressure treatment and thus the planarization structure is locked. The increased electronic transition diversity and oscillator strength originating from the planarization structure are highly responsible for boosting metal‐to‐ligand charge transfer. The findings in this study provide significant insights into the underlying mechanism of the structure‐property relationship in Y(BTC)(H2O)6 and offer a promising strategy to harvest deep‐blue‐emitting MOFs materials. [ABSTRACT FROM AUTHOR]

Introducing nanostructures into diamonds is quite appealing for the synthesis of superhard materials with superior properties. However, as the grain size decreases to nanoscale, grain boundary effects become crucial yet complicated in the nanopolycrystalline diamond (NPD), making it challenging to tailor nanostructures. Here, atomistic simulations are combined with experiment to demonstrate a strengthening strategy for the sintered NPD by introducing thin amorphous grain boundary (AGB). The additive of small percentage of fullerene into precursors during sintering can significantly reduce crushed amorphous‐like nanodomains in diamond nanocrystals, leading to the formation of thin AGB. Such sintered NPD exhibits a significant hardness and fracture toughness enhancement, exceeding that of single crystal diamonds. These atomistic simulations show that upon straining the plastic deformation, crack initiation and propagation in NPD is AGB thickness dependent, and thin AGB can reduce crack nucleation and block crack propagation, well explaining the experimental observations. This study indicates that grain boundary modulation provides a promising approach for rational designs of high‐performance superhard materials with desired high strength. [ABSTRACT FROM AUTHOR]

Lanthanide metal–organic frameworks are of great interest in the development of photoluminescence (PL) materials owing to their structural tunability and intrinsic features of lanthanide elements. However, there exists some limitations arising from poor matching with metal ions, thereby exhibiting a weak ligand‐to‐metal energy transfer (LMET) process. Here we demonstrate a pressure‐treated strategy for achieving high PL performance in green‐emitting Tb(BTC)(H2O)6. The PL quantum yield of pressure‐treated sample increased from 50.6 % to 90.4 %. We found that the enhanced hydrogen bonds locked the conjugated configuration formed by two planes of carboxyl group and benzene ring, enabling the promoted intersystem crossing to effectively drive LMET. Moreover, the optimized singlet and triplet states also validated the facilitated LMET process. This work opens the opportunity of structure optimization to improve PL performance in MOFs by pressure‐treated engineering. [ABSTRACT FROM AUTHOR]

Lanthanide metal–organic frameworks are of great interest in the development of photoluminescence (PL) materials owing to their structural tunability and intrinsic features of lanthanide elements. However, there exists some limitations arising from poor matching with metal ions, thereby exhibiting a weak ligand‐to‐metal energy transfer (LMET) process. Here we demonstrate a pressure‐treated strategy for achieving high PL performance in green‐emitting Tb(BTC)(H2O)6. The PL quantum yield of pressure‐treated sample increased from 50.6 % to 90.4 %. We found that the enhanced hydrogen bonds locked the conjugated configuration formed by two planes of carboxyl group and benzene ring, enabling the promoted intersystem crossing to effectively drive LMET. Moreover, the optimized singlet and triplet states also validated the facilitated LMET process. This work opens the opportunity of structure optimization to improve PL performance in MOFs by pressure‐treated engineering. [ABSTRACT FROM AUTHOR]

Penetrating, high‐energy synchrotron X‐rays are in strong demand, particularly for high‐pressure research in physics, chemistry and geosciences, and for materials engineering research under less extreme conditions. A new high‐energy wiggler beamline P61 has been constructed to meet this need at PETRA III in Hamburg, Germany. The first part of the paper offers an overview of the beamline front‐end components and beam characteristics. The second part describes the performance of the instrumentation and the latest developments at the P61B endstation. Particular attention is given to the unprecedented high‐energy photon flux delivered by the ten wigglers of the PETRA III storage ring and the challenges faced in harnessing this amount of flux and heat load in the beam. Furthermore, the distinctiveness of the world's first six‐ram Hall‐type large‐volume press, Aster‐15, at a synchrotron facility is described for research with synchrotron X‐rays. Additionally, detection schemes, experimental strategies and preliminary data acquired using energy‐dispersive X‐ray diffraction and radiography techniques are presented. [ABSTRACT FROM AUTHOR]

GLO:44U/25nov22:anie202215826-toc-0001.jpg PHOTO (COLOR): . gl GLO:44U/25nov22:anie202215826-toc-0001.jpg PHOTO (COLOR): . gl B A pressure-treatment strategy b for achieving high photoluminescence performance in a green-emitting Tb-based metal-organic framework is reported by Xinyi Yang, Qianrong Fang, Banglin Chen, Bo Zou et al. in their Research Article (e202210836). Fluorescent Monochromaticity, Green Photoluminescence Enhancement, Lanthanide Metal-Organic Frameworks, Ligand-to-Metal Energy Transfer, Pressure-Treated Engineering Cover Picture: Maximized Green Photoluminescence in Tb-Based Metal-Organic Framework via Pressure-Treated Engineering (Angew. [Extracted from the article]

Keywords: Fluorescent Monochromaticity; Green Photoluminescence Enhancement; Lanthanide Metal-Organic Frameworks; Ligand-to-Metal Energy Transfer; Pressure-Treated Engineering EN Fluorescent Monochromaticity Green Photoluminescence Enhancement Lanthanide Metal-Organic Frameworks Ligand-to-Metal Energy Transfer Pressure-Treated Engineering 1 1 1 11/22/22 20221125 NES 221125 B Die Photolumineszenzausbeute b in einem grün-emittierenden metallorganischen Gerüst auf Tb-Basis lässt sich mittels Druckbehandlung steigern, wie Xinyi Yang, Qianrong Fang, Banglin Chen, Bo Zou und Mitarbeiter in ihrem Forschungsartikel berichten (e202210836). Die verstärkten Wasserstoffbrücken verriegeln die konjugierte Konfiguration und ermöglichen Intersystem-Crossing, was den Metall-zu-Ligand-Energietransfer beschleunigt. Fluorescent Monochromaticity, Green Photoluminescence Enhancement, Lanthanide Metal-Organic Frameworks, Ligand-to-Metal Energy Transfer, Pressure-Treated Engineering. [Extracted from the article]