Thermochemical Mechanism of Optimized Lanthanum Chromite Heaters for High-Pressure and High-Temperature Experiments.

High-pressure heaters in large volume presses must reconcile potentially contradictory properties, and the whole high-pressure and high-temperature (HPHT) community has been engaged for years to seek a better heater. LaCrO3 (LCO)-based ceramic heaters have been widely applied in multianvil apparatus; however, their performance is far from satisfactory, motivating further research on the chemical optimization strategy and corresponding thermochemical mechanism. Here, we adopted a chemical-screening strategy and manufactured tubular heaters using the electrically, chemically, and mechanically optimized Sr-Cu codoped La0.9Sr0.1Cr0.8Cu0.2O3-δ (LSCCuO-9182). HPHT examinations of cylindrical LSCCuO-9182 heaters on Walker-type multianvil apparatuses demonstrated a small temperature gradient, robust thermochemical stability, and excellent compatibility with high-pressure assemblies below 2273 K and 10 GPa. Thermochemical mechanism analysis revealed that the temperature limitation of the LSCCuO-9182 heater was related to the autoredox process of the Cu dopant and Cr and the exchanging ionic migration of Cu and Mg between the LSCCuO-9182 heater and the MgO sleeve. Our combinatorial strategy coupled with thermochemical mechanism analysis makes the prioritization of contradictory objectives more rational, yields reliable LCO heaters, and sheds light on further improvement of the temperature limitation and thermochemical stability.

Robust Yellow-Violet Pigments Tuned by Site-Selective Manganese Chromophores.

The rational design of multifunctional inorganic pigments relies on the manipulation of ionic valence and local surroundings of a chromophore in structurally and chemically habitable hosts. To date, the development of environmentally benign and intense violet/purple pigments is still a challenge. Here we report a family of A3-xMnxTeO6 and A3-2xMnxLixTeO6 (A = Zn, Mg; x = 0.01-0.15) pigments colored by site-selective Mn2+O4 yellow and Mn3+O5-6 violet chromophores. Zn2.9Mn0.1TeO6 is intense bright yellow, comparable with commercial BiVO4, and has better near-infrared reflectivity (∼89%) in comparison to commercial TiO2. The codoped Li+ "activator" generates holes and charge-balanced Mn3+ (Mn3+O5-6), realizing a color transformation from yellow to the bright violet pigments of A3-2xMnxLixTeO6. The most vivid Mg2.8Mn0.1Li0.1TeO6 is probably the best violet pigment known to date, exhibits excellent chemical and thermodynamic stability, and demonstrates pressure-dependent stability up to 5-7 GPa, before a (reversible) phase transition to pink. Theoretical calculations revealed the correlation between site-preference occupancy and chromophore motifs and predicted a wide color gamut of pigments in Zn3TeO6-hosted 3d transition-metal ions other than manganese.

Data-driven computational prediction and experimental realization of exotic perovskite-related polar magnets.

Rational design of technologically important exotic perovskites is hampered by the insufficient geometrical descriptors and costly and extremely high-pressure synthesis, while the big-data driven compositional identification and precise prediction entangles full understanding of the possible polymorphs and complicated multidimensional calculations of the chemical and thermodynamic parameter space. Here we present a rapid systematic data-mining-driven approach to design exotic perovskites in a high-throughput and discovery speed of the A 2 BB'O6 family as exemplified in A 3TeO6. The magnetoelectric polar magnet Co3TeO6, which is theoretically recognized and experimentally realized at 5 GPa from the six possible polymorphs, undergoes two magnetic transitions at 24 and 58 K and exhibits helical spin structure accompanied by magnetoelastic and magnetoelectric coupling. We expect the applied approach will accelerate the systematic and rapid discovery of new exotic perovskites in a high-throughput manner and can be extended to arbitrary applications in other families.

NH2-Ni-MOF electrocatalysts with tunable size/morphology for ultrasensitive C-reactive protein detection via an aptamer binding induced DNA walker-antibody sandwich assay.

Here we report a general approach for synthesizing size/morphology-controlled NH2-Ni-MOFs by optimizing the solvent composition in the reaction system, and their correlating catalytic performances are clearly explored for the first time. Interestingly, the electrocatalytic performance was found to increase 2.7 fold when the particle size is reduced from 1.5 µm for NH2-Ni-MOF(a) to 300 nm for NH2-Ni-MOF(c). Subsequently, this work exhibits an example of a high-performance NH2-Ni-MOF(c) electrocatalyst for application in constructing an electrochemical aptasensor to achieve sensitive C-reactive protein (CRP) detection based on an aptamer binding induced DNA walker-antibody sandwich assay. The proposed aptasensor shows a wide linear range from 0.1 pg mL-1 to 100 ng mL-1 with a low detection limit of 0.029 pg mL-1. The work presented here can thus offer an atypical approach to size- and morphology-controlled MOFs in electrocatalysis and biosensing.