Gaston Garbarino

Polymeric nitrogen represents a long-sought class of high energy density materials, in which single-bonded nitrogen networks release large amounts of energy upon decomposition to molecular N ₂ . However, polymeric nitrogen allotropes require extreme pressures to synthesize and cannot be recovered at ambient conditions due to surface instabilities. Hydrogen has been proposed as a key element to stabilize such frameworks, yet polymeric nitrogen–hydrogen solids have until now remained the realm of theoretical calculations. Here, we report the high-pressure synthesis of polymeric N ₃ H ₂ at 134(3)–139(1) GPa from N ₂ –H ₂ mixtures. Synchrotron single-crystal X-ray diffraction, Raman spectroscopy and first-principles calculations reveal a fully single-bonded framework of 1-dimensional chains of N ₆ rings, each decorated by four H atoms. The chains of N ₆ H ₄ units are cross-linked through hydrogen bonds. Employing modern synchrotron sources, hydrogen positions are directly resolved from diffraction data at 139(1) GPa. At ambient conditions, N ₃ H ₂ exhibits an estimated energy of decomposition of 7.98 kJ/g, highlighting hydrogen-stabilized polymeric nitrogen as a promising class of energetic materials.

Using high-pressure X-ray diffraction and X-ray photon correlation spectroscopy, the authors uncover a subtle structural crossover near 3 GPa in an Au-based metallic glass, accompanied by dramatic avalanche-like atomic rearrangements. Above this pressure, a second, slower relaxation process emerges, revealing distinct dynamical environments within the glass. The simultaneous structural and dynamical signatures point to the nucleation and coexistence of two amorphous states, providing new insight into the microscopic nature of polyamorphism in metallic glasses.

Metal halide single crystals exhibit superior optoelectronic properties, promising for applications in optics and energy. However, they are inherently brittle, which has posed a major challenge for use in flexible electronics. Here, we report the elastic bending in a family of chiral lead halide crystals R-(AP)PbI₃ ∙ H₂O, S-(AP)PbI₃ ∙ H₂O, R-(AP)PbI₃, and S-(AP)PbI₃, (AP = 3-amino-1,2-propanediol) that originates from their rigid-flex structural motif. Upon mechanical bending, the AP⁺ molecular units flex and rotate, causing the molecular interactions to reorganize and effectively dissipate stress. Meanwhile, the rigid [PbI₃]⁻ metal-halide chains maintain the structural integrity of the lattice, thereby conferring exceptional elastic flexibility. The devices fabricated using these crystals with a facile nonwoven manner show significantly higher sensitivity to underwater ultrasound waves than piezoelectric ceramics. Our work paves the way for integration of bendable metal halide crystals into next-generation electronic devices.

Researchers crushed and heated ice between diamond anvils to confirm the existence of a phase of ice that could be present in the warm mantles of ice giants.

We formed two-dimensional pseudo-hexagonally ordered diamond-like carbon nano-threads by laser heating dense molecular benzene, the archetypal aromatic compound, to temperatures exceeding 1000 K at about 40 GPa in diamond anvil cells. The heated samples were then rapidly (<1 s) temperature quenched. Instead, in previous studies, carbon nano-threads were obtained by subjecting benzene to slow compression–decompression cycles (<2−3 GPa/h) at room temperature, reaching maximum pressures of 23–24 GPa. Our pressure–temperature–time reaction path for this kinetically driven transformation differs substantially from previous studies, as it is significantly more extreme and faster. Synchrotron x-ray diffraction measurements of temperature-quenched products were performed during a compression–decompression cycle from 40 to 54 to 0 GPa, allowing the determination of a one-dimensional equation of state for the characteristic interlayer spacing. This spacing reflects the van der Waals distance between neighboring threads. Comparison with previously reported ab initio equations of state constrains the local internal structure of the threads, which is otherwise elusive at high pressures due to disorder along the chain axis.

We investigate the strain response of underdoped HgBa 2 CuO 4 + δ (Hg1201), by synchrotron X-ray diffraction and corresponding simulations of thermal diffuse scattering. The compression in the crystallographic a direction leads to relatively small expansion in the b and c directions, with Poisson ratios ν ba = 0.16 and ν ca = 0.11 , respectively. However, the Cu-O distance in the c direction exhibits a notable 0.9% increase at 1.1% a -axis compression. We further find strain-induced diffuse scattering that corresponds to a new type of two-dimensional charge correlation. Interestingly, this signal is insensitive to the onset of superconductivity and instead corresponds to a short-range, nearly commensurate modulation with a wave vector close to (0.5,0,0) and a correlation length of approximately 4 unit cells. It closely resembles the charge order theoretically predicted in the phase diagram of the spin-liquid model with resonating valence bonds on a square lattice.

Y-kapellasite [ Y 3 Cu 9 ( OH ) 19 Cl 8 ], which hosts an original anisotropic kagome sublattice, is a promising candidate for studying elusive and complex correlated physics. It exhibits a theoretically predicted in-plane ( 1 / 3 , 1 / 3 ) magnetic order [Hering , ], but its magnetic interaction values place it close to a phase boundary to a spin liquid state [Chatterjee , ]. Our μ SR measurements under hydrostatic pressure demonstrate the complete suppression of static magnetism in favor of a fully dynamical ground state at 2.3 GPa. Complementary high-pressure x-ray and optical phonon measurements reveal a gradual reduction of the kagome anisotropy, enhancing magnetic frustration without structural transitions. Our results establish Y-kapellasite as a rare clean kagome model in which long-range order is suppressed by pressure-tuned frustration, the first fingerprint for the realization of a quantum spin liquid without strong disorder.