Interlayer Ions Control Spin Canting in Low-Dimensional Manganese Trimers in 12R-BaMnO ( = Ce, Pr) Layered Perovskites.

To synthetically target a specific material with select performance, the underlying relationship between structure and function must be understood. For targeting magnetic properties, such understanding is underdeveloped for a relatively new class of layered hexagonal perovskites, the 12R-BaMnO family. Here, we perform a detailed magnetostructural study of the layered hexagonal perovskite materials 12R-BaMnO, where = diamagnetic Ce or paramagnetic ≈ 1/2 Pr.

Influence of the Rare Earth Cation on the Magnetic Properties of Layered 12R-BaMMnO (M = Ce, Pr) Perovskites.

Material design is increasingly used to realize desired functional properties, and the perovskite structure family is one of the richest and most diverse: perovskites are employed in many applications due to their structural flexibility and compositional diversity. Hexagonal, layered perovskite structures with chains of face-sharing transition metal oxide octahedra have attracted great interest as quantum materials due to their magnetic and electronic properties. BaMMnO, a member of the "12R" class of hexagonal, layered perovskites, contains trimers of face-sharing MnO octahedra that are linked by a corner-sharing, bridging MO octahedron.

Formation of BaNbMnO-6H during thermo-chemical reduction of BaNbMnO-12R.

The resurgence of inter-est in hydrogen-related technologies has stimulated new studies aimed at advancing lesser-developed water-splitting processes, such as solar thermochemical hydrogen production (STCH). Progress in STCH has been largely hindered by a lack of new materials able to efficiently split water at a rate comparable to ceria under identical experimental conditions. BaCeMnO (BCM) recently demonstrated enhanced hydrogen production over ceria and has the potential to further our understanding of two-step thermochemical cycles.

Formation of 6H-BaCeMnO during Thermochemical Reduction of 12R-BaCeMnO: Identification of a Polytype in the Ba(Ce,Mn)O Family.

The resurgence of interest in a hydrogen economy and the development of hydrogen-related technologies has initiated numerous research and development efforts aimed at making the generation, storage, and transportation of hydrogen more efficient and affordable. Solar thermochemical hydrogen production (STCH) is a process that potentially exhibits numerous benefits such as high reaction efficiencies, tunable thermodynamics, and continued performance over extended cycling. Although CeO has been the de facto standard STCH material for many years, more recently 12R-BaCeMnO (BCM) has demonstrated enhanced hydrogen production at intermediate H/HO conditions compared to CeO, making it a contender for large-scale hydrogen production.

Lateral Temperature-Gradient Method for High-Throughput Characterization of Material Processing by Millisecond Laser Annealing.

A high-throughput method for characterizing the temperature dependence of material properties following microsecond to millisecond thermal annealing, exploiting the temperature gradients created by a lateral gradient laser spike anneal (lgLSA), is presented. Laser scans generate spatial thermal gradients of up to 5 °C/μm with peak temperatures ranging from ambient to in excess of 1400 °C, limited only by laser power and materials thermal limits. Discrete spatial property measurements across the temperature gradient are then equivalent to independent measurements after varying temperature anneals.

μ-Rainbow: CdSe Nanocrystal Photoluminescence Gradients via Laser Spike Annealing for Kinetic Investigations and Tunable Device Design.

Much of the promise of nanomaterials derives from their size-dependent, and hence tunable, properties. Impressive advances have been made in the synthesis of nanoscale building blocks with precisely tailored size, shape and composition. Significant attention is now turning toward creating thin film structures in which size-dependent properties can be spatially programmed with high fidelity.