Heteroatom doping in hexagonal boron nitride (h-BN) films has been regarded as an effective solution to adjust their electrical and optical properties for realizing applications in various technologies. A high-temperature annealing process is routinely utilized to enhance the doping efficiency following film growth, which is, however, accompanied by other unexpected effects. Thus, understanding the dopant behavior induced by temperature is crucial for unlocking unprecedented development of h-BN. Here, we report the thermally induced mutual diffusion in Si-doped h-BN films grown on sapphire substrates, which can facilitate the transition from the hexagonal to the cubic phase. Spectral analysis indicates that as the annealing temperature increases, the doped films undergo a phase transition from hexagonal to cubic BN phases via an intermediate of explosive BN. Combined x-ray photoelectron spectroscopy and secondary ion mass spectrometry reveal that the thermal annealing above 1000 °C induces the interdiffusion of Si and Al through the interface, where the latter originates from the decomposition of the sapphire substrate. First-principles calculations reveal that the substitution of Si within BN reduces the energy barrier from sp2 to sp3 phase transformation by supplying electrons to adjacent N atoms. This work provides novel insights into understanding the doping behavior in h-BN films and the development of h-BN based devices.

Crown ether-ammonium inclusion compounds have attracted great interest in the fields of supramolecular chemistry, crystal engineering, and molecular switches due to their tunable host-guest dynamics and stimuli-responsive phase transitions. However, most reported systems exhibit phase transitions only below room temperature, limiting practical applications, and their luminescence properties remain largely unexplored. Herein, we report a host-guest inclusion compound, [(2-fluorophenethylaminium)(18-crown-6)][PF6] (1) that undergoes a reversible phase transition at 404 K, approaching the highest values reported in crown ether-based systems. Single-crystal X-ray diffraction confirms that the ammonium cation is tightly anchored within the 18-crown-6 cavity through N-H⋯O hydrogen bonds. Remarkably, the regioisomeric 3-fluoro (2) and 4-fluoro (3) analogues show no detectable phase transition, yet all three isomers display intense blue emission under 365 nm UV irradiation. This contrast demonstrates that 2-fluorine substitution is essential for the high-temperature transition, while luminescence arises from supramolecular confinement and does not depend on the fluorine substitution position. Density functional theory calculations support an intermolecular charge-transfer mechanism: the HOMO is localized on the crown ether oxygen atoms, the LUMO on the aromatic ring of the cation, with a calculated HOMO-LUMO gap of 4.49 eV. Collectively, these results demonstrate decoupling of the two functions, where the phase transition is governed by fluorine regiochemistry and emission is controlled by confinement effects. This decoupling provides a design principle for independently tuning thermal and optical properties in multifunctional molecular crystals.

The Riemann Hypothesis (RH), one of the most profound unsolved problems in mathematics, concerns the nontrivial zeros of the Riemann zeta function. Linking these zeros to physical phenomena offers new perspectives on their origin and verification. Here we establish a direct correspondence between these zeros and dynamical quantum phase transitions in two complementary engineered quantum many-body systems, characterized by the average accumulated phase factor and the Loschmidt amplitude, respectively. This precise correspondence recasts the RH as the occurrence of phase transitions at a unique temperature and identifies it as a previously unknown transition mechanism. We demonstrate this correspondence in a proof-of-principle experiment on a quantum processor. Moreover, we propose a quantum computational framework that implements both systems with polynomial resources, suggesting quantum advantage in probing the hypothesis. Our work bridges nonequilibrium quantum dynamics and number theory, positioning quantum computing as a powerful platform for exploring mathematical conjectures, phase transitions and beyond.

Resource utilization strategy for refractory iron‑aluminum symbiotic resource based on reduction sintering: Phase transition and element migration mechanism

Li/Cu synergistic stabilization surface in P2-type Mn-based layered oxides: inhibiting Jahn-Teller effect via regulating spin state for stable sodium-ion batteries.

Pore-structure responses of polyethylene microplastic-amended Malan loess under different thermal regimes.

Unraveling the effect of oxygen vacancies on the phase transition and mid-infrared optical properties of VO2 thin films

Impact of swimming intensity on spatiotemporal kinematics of lower-limb breaststroke actions in national-level male swimmers: A discrete variable and time-series analysis.

Infrared and terahertz spectroscopy performed at synchrotron facilities offers unique opportunities for probing matter under extreme and well controlled conditions. At the AILES beamline of Synchrotron SOLEIL, two complementary experimental setups have recently been developed to enable spectroscopy of submillimetric samples across a broad range of temperatures and pressures. These platforms operate from 10 K to 600 K and from vacuum up to 100 GPa, while accommodating a variety of sample environments, including liquid cells, diamond anvil cells and uniaxial strain devices. Combined with the high brilliance and stability of synchrotron radiation and advanced detection schemes, these setups are particularly suited for in situ and operando investigations, allowing real-time monitoring of structural changes, phase transitions and reaction dynamics under external stimuli. Their performance is illustrated through far-infrared measurements of water and ice over different thermodynamic states, demonstrating sensitivity to structural reorganizations and hydrogen-bond dynamics. These developments significantly expand the experimental capabilities of the AILES beamline and provide versatile tools for a wide user community, opening new perspectives for studies of functional materials, molecular systems and emerging phenomena under extreme conditions.

Thermotropic and barotropic phase behavior of phospholipid bilayers: A thermodynamic phase-diagram perspective incorporating modular lipid architecture.

Interfracture disturbance effects on multiple fracture propagation caused by CO2 phase transition blasting: A phase field method analysis

The energy landscapes and electronic properties of non-polar and polar nanofilms of silicon carbide are studied using periodic hybrid density functional calculations. Relative energies and electronic properties are reported as a function of film thickness for a set of structures derived from those of wurtzite, zinc blende and graphite. The energy landscape of the films is complex with pronounced nano-polymorphism. Across polar films different mechanisms in different cases remove or reduce the dipole moment, including charge transfer and phase transitions to the graphitic-like structures which are stable for the thinnest films. Graphitic structures are lowest in energy for the thinnest films. For ten layers non-polar films-zinc blende (110) and wurtzite(101-0) with tetrahedrally-coordinated Si and C in Si3C3rings in chair conformations-are lowest in energy, followed, ≈0.1 eV per formula unit higher in energy, by a body-centered tetragonal structure containing Si3C3rings in boat conformations. In the planar graphene structure the energy of the anti-site defect CSi-SiC(≈0.3 eV)) is more than an order of magnitude lower than in the bulk, suggesting a much higher degree of disorder in such films. One staggered graphitic-like structure with ABC stacking, a local minimum in the energy landscape, is of particular interest, since it lies in a regime of uncompensated polarity and possesses a direct band gap that decreases linearly with film thickness., from ≈2 eV (3 layers) to zero (6 layers).

Cross-layer plasticity of InSe van der Waals crystals derived from continuous phase transitions

Experimental investigation on wear-vibration mechanism induced by the friction and phase transition for ring-ring end-face pairs under cryogenic conditions

Strong electron-lattice coupling in 1T-MX2 (M = Nb, Ta; X = S, Se) enables diverse quantum phenomena. Using first-principles calculations, we reveal temperature-dependent orbital textures of midgap states in monolayer 1T-NbSe2 with a star-of-David charge-density-wave superstructure. A mere 0.1% thermal lattice expansion drives a sharp nonmagnetic-to-ferromagnetic transition. In the ferromagnetic phase, midgap states localize at the supercell center, while in the nonmagnetic phase, high-energy Rydberg-like states generate weak in-gap signals and characteristic six-petal orbital patterns. These findings resolve long-standing theory-experiment discrepancies and establish Rydberg fingerprinting as a method to probe high-energy electronic structures via low-bias scanning tunneling spectroscopy, offering new insights into coupled electronic and magnetic degrees of freedom in two-dimensional transition metal dichalcogenides.

Mineralization regeneration of NH3–CO2 absorption solution and crystalline phase transition pathways of calcium carbonate

Through first-principles calculations, the structural evolution, carrier mobility, and superconductivity of anti-perovskite Ca3BiX (X = H, N, P) have been investigated in the 0-100 GPa range. Results indicate that Pm3̄m, R3̄m, P63/mmc, P4/mmm, Cmcm, Pnma, and C2/m are stable phases in the corresponding pressure regions. Moreover, phase transitions occur in Ca3BiH from Pnma to Pm3̄m and R3̄m phases at 8 GPa, in Ca3BiN from Pm3̄m and P4/mmm to P63/mmc phases at 73 GPa, and in Ca3BiP through three transitions: Pnma → C2/m at 5 GPa, C2/m → Cmcm at 10 GPa, and Cmcm → C2/m at 22 GPa. More importantly, the electron mobility of the Pnma phase of Ca3BiP is anisotropic and reaches 7.1 × 104 cm2 V-1 s-1 in the x direction, exceeding the recently reported result of the anti-perovskite Rb4I2O (5.3 × 104 cm2 V-1 s-1) in the z direction. Meanwhile, electron-phonon coupling calculations show that the superconducting transition temperature (Tc) of the Pm3̄m phase of Ca3BiH reaches 7.2 K at 50 GPa, which is higher than that of the comparable Ca-based anti-perovskite Ca3PN (4 K). These results not only enrich research on Ca-based anti-perovskites under high pressure, but also provide theoretical support for further studies of the mobility and Tc of Ca-based anti-perovskites.

Investigation of Freeze–Thaw Damage Mechanisms of Asphalt Mixtures Using the Coupled Water–Ice Phase Transition and Expansion Theory

Colossal barocaloric effect of water-ice phase transition

Enhancement of fly ash carbonation by mechanical ball milling: From lab-scale characterization to pilot‑scale validation.