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Abstract: Solid-state battery fabrication requires the densification of solid electrolytes to achieve optimal cycling performance and high energy density. However, the underlying compaction mechanisms of these electrolytes remain poorly understood. Here, we investigate the effect of pressure consolidation on the ionic conductor Li6PS5Cl with particle size distributions (PSD) ranging from 4 to 40 µm. Heckel analysis reveals that samples with smaller PSDs exhibit higher compressibility at lower pressures. X-ray diffraction peak profiling shows that applied pressure induces lattice strain, leading to peak broadening, while pair distribution function analysis demonstrates a reduction in coherence length upon pressing. Dark-field X-ray microscopy further provides spatially resolved orientation maps, uncovering intragranular structural variations within individual Li6PS5Cl agglomerates after compression. To better understand the origin of stress fluctuations, we performed discrete element method simulations using the experimental PSDs. The results indicate that smaller particles and broader PSDs experience higher stresses, whereas monodisperse systems do not exhibit significant stress fluctuations with position or particle size. This suggests that the high strain observed cannot be attributed solely to smaller particles, but rather to size inhomogeneity. Overall, these findings highlight that both particle size and its distribution play a critical role in processing solid electrolytes for solid-state batteries.

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Abstract: Rutile-structured materials can exhibit negative linear compressibility (NLC) following ferroelastic phase transitions, expanding in one direction under uniform compression. We investigate this phenomenon in structural analogues—transition metal dicyanamides (dca) and tricyanomethanides (tcm) with single and double rutile-like structures, respectively. The pressure-induced structural behaviour of Cu(tcm)2 and Cu(dca)2 are studied using high-pressure diffraction. Both systems undergo anisotropic deformation upon compression, with Cu(dca)2 exhibiting NLC of −6.5(10) TPa−1 along the c-axis, while Cu(tcm)2 shows zero linear compressibility (ZLC) along the a-axis. This difference is attributed to the single rutile-like network with flexible dca− linkers in Cu(dca)2, in contrast to the more constrained doubly interpenetrating structure of Cu(tcm)2 with rigid tcm− linkers. We also study the interplay between structural features and electronic effects arising from the Jahn–Teller distortion in both materials, in controlling their compression behaviour.

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Abstract: Halide perovskites exhibit superior optoelectronic properties but lack precise thickness and band offset control in heterojunctions, which is critical for modular multilayer architectures such as multiple quantum wells. We demonstrate vapor-phase, layer-by-layer heteroepitaxial growth exemplified by CsPbBr3 deposition on single crystals of PEA2PbBr4 (PEA: 2-phenylethylammonium). Angstrom-level thickness control and subangstrom smooth layers enable quantum-confined photoluminescence of CsPbBr3 from monolayer, bilayer, and through to bulk. The interfacial structure controls the electronic structure from a Cs‒PEA-terminated interface (type II heterojunction) to a PEA‒PEA-terminated interface (type I heterojunction), with a layer-tunable band offset shift exceeding 0.5 electron volts. Electron transfer from CsPbBr3 to PEA2PbBr4 for a type II Cs‒PEA heterojunction results in delayed electron-hole recombination beyond 10 microseconds. Precise quantum confinement control and large band offset tunability unlock perovskite heterojunctions as platforms for scalable, superlattice-based optoelectronic applications.

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Abstract: Transition metals, including Iridium, are crucial for understanding planetary cores and developing critical technologies due to their unique properties under extreme high-pressure and high-temperature conditions. Although Ir’s room-temperature phase remains stable, its pressure-temperature phase diagram is largely unknown, with only a single experimental melting point reported previously. A notable gap in knowledge is the lack of experimental evidence for solid-solid phase transitions predicted by theoretical models. Here we show a new investigation into the phase diagram of iridium, employing a combination of resistive-heated and laser-heated diamond anvil cells coupled with synchrotron X-ray diffraction. Our findings confirm that Ir maintains its face-centered cubic structure up to 101 GPa and 5600 K. We determined five new melting points that corroborate computational predictions, providing a more robust foundation for the melting curve. The resulting thermal equation of state offers a definitive dataset that can serve as a reliable pressure standard and advance the design of technologies using Ir.

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Abstract: The low-pressure stabilization of superconducting hydrides with high critical temperatures (𝑇𝑐⁢s)remains a significant challenge, and experimentally verified superconducting hydrides are generally constrained to a limited number of structural prototypes. Ternary transition metal complex hydrides (hydrido complexes)—typically regarded as hydrogen storage materials—exhibit a large range of compounds stabilized at low pressure with recent predictions for high-𝑇𝑐 superconductivity. Motivated by this class of materials, we investigated complex hydride formation in the Mg–Pt–H system, which has no known ternary hydride compounds. Guided by ab initio structural predictions, we successfully synthesized a novel complex transition metal hydride, Mg4⁢Pt3⁢H6, using laser-heated diamond anvil cells. The compound forms in a body-centered cubic structural prototype at moderate pressures between ∼8and25GPa. Unlike the majority of known hydrido complexes, Mg4⁢Pt3⁢H6 is metallic, with formal charge described as 4⁢[Mg]2+·3⁢[PtH2]2−. X-ray diffraction measurements obtained during decompression reveal that Mg4⁢Pt3⁢H6 remains stable upon quenching to ambient conditions. Magnetic-field and temperature-dependent electrical transport measurements indicate ambient-pressure superconductivity with 𝑇𝑐 (50%)=2.9K, in reasonable agreement with theoretical calculations. These findings clarify the phase behavior in the Mg–Pt–H system, highlight important synergies between computational/experimental approaches, and provide valuable insights for transition metal complex hydrides as a new class of hydrogen-rich superconductors.