The synthesis is presented of highly fluorescent hexamine-derived carbonized polymer dots (HACDs), which are made possible by ethylenediamine and folic acid. Density functional theory is used to clarify the formation mechanism and optimize the electronic structure of HACDs that resemble polymers. Our study reveals effective intramolecular charge transfer pathways and a favorable reaction coordinate, supported by electrostatic potential mapping and HOMO-LUMO transitions. The resulting HACDs have a ∼3.3 eV optical bandgap, an extraordinary quantum yield of 80.1
We report proximate quantum spin liquid behavior in K2Co2(SO4)(3) with the magnetic Co2+ ions embedded on a highly frustrated three-dimensional double trillium lattice. Single-crystal and high-resolution synchrotron powder x-ray diffraction experiments reveal a structural phase transition at T-t similar or equal to 125 K from high-temperature cubic to low-temperature monoclinic phase with the threefold superstructure. Magnetization and heat capacity consistently show the formation of the J(eff) = 1/2 state of Co2+ below 50 K. In zero field, K2Co2(SO4)(3) shows signatures of static magnetic order formed below T* similar or equal to 0.6 K, but muon spin relaxation experiments reveal a large fluctuating component that persists down to at least 50 mK, reminiscent of quantum spin liquid (QSL). Static order is completely suppressed in the small magnetic field of similar to 1 T, and low-temperature heat capacity demonstrates the T-2 behavior above this field, another fingerprint of QSL. Ab initio calculations show a competition of several antiferromagnetic couplings that render K2Co2(SO4)(3) a promising pseudospin-12 material for studying quantum magnetism in the double trillium lattice geometry.
The lead-free flexible polymer magneto-electrics (PME) composed of ([Formula: see text] (CoFe 2 O[Formula: see text] - (1[Formula: see text] polyvinylidene fluoride (PVDF), where x varies from 0 to 1 in increments of 0.1, is developed using a co-precipitation and novel cold-pressed route. The percolation, dielectric, ferroelectric, magnetic, and magnetoelectric properties are systematically investigated. The highest crystallite size of 15.4[Formula: see text]nm and the least strain of approximately 0.00156 are noticed from the Williamson–Hall (W–H) plot in CoFe 2 O 4 (CF). At the percolation threshold of [Formula: see text], scaling exponents were obtained as [Formula: see text] and [Formula: see text], which lie within the universal region. The low dielectric loss ([Formula: see text]1 at 10[Formula: see text]kHz) and KWW-fitted modulus show the values of stretching coefficient ([Formula: see text] as 0.004, 0.005, and 0.012 for [Formula: see text], 0.4, and 0.5 compositions, respectively, suggesting non-Debye type relaxation. P–E hysteresis confirmed ferroelectric characteristics at 10[Formula: see text]Hz, and the Weibull distribution function showed high breakdown strength for 0.9PVDF–0.1CF. Further, the magnetization is about 72.6[Formula: see text]emu/gm for CF. Moreover, the ferromagnetic nature of PME is confirmed by the positive slope in the Arrott plot. Significant magnetoelectric coupling is observed of approximately 13.20[Formula: see text]mV/cm[Formula: see text]Oe for the composition 0.9PVDF–0.1CF at an AC field of 20[Formula: see text]Oe at a frequency of 540 Hz at room temperature due to the charge transfer between the phases, conductivity, and dielectric constant of the composite. The magnetoelectric coupling response is reported in varying the frequency from 23[Formula: see text]kHz to 1[Formula: see text]kHz as well as temperatures up to 295–353[Formula: see text]K.
Tin (Sn) thin films are deposited on BiSe substrate via vapor deposition under ultrahigh vacuum conditions, and the surface electronic structure and interface chemistry are systematically investigated using X‐ray and ultraviolet photoemission spectroscopy (XPS and UPS) measurements. Spectroscopy analysis reveals the formation of SnSe bonds along with a reduction of Bi, leading to the emergence of multiple Sn‐based interfacial phases such as SnSe and SnSe. Thus, our study estabilishes predominance of interfacial chemistry over epitaxial stanene growth on BiSe at room temperature, highlighting the challenges associated with the interface engineering in layered topological systems.
In this communication, the effect of dysprosium (Dy) substitution on the structural and thermoelectric properties of LaCoO3 in the low-temperature regime (90-325 K) have been investigated. Dy3+, with its smaller ionic radius and 4f electrons, induces lattice contraction, strain, phonon scattering, and modifies carrier concentration and Co3+ spin states, affecting both phonon and electronic transport. Polycrystalline samples La1_ xDyxCoO3 (x = 0, 0.1, 0.2, 0.3, and 0.4) were synthesized using solid-state reaction route. XRD showed pristine LaCoO3 has a rhombohedral R3c structure, while Dy-doped samples (x >= 0.2) exhibited Dy2O3 secondary phase (Ia3). SEM revealed distinct grains and well-defined boundaries affecting transport properties. Electrical resistivity decreased with temperature, showing semiconducting behavior, and was described using variable range and small polaron hopping models. Dy doping increased resistivity and thermopower, reducing the power factor, with higher activation energy and carrier concentration contributing to rise in the electrical resistivity. The pristine sample had a maximum power factor of 25 mu W/mK2 at 325 K. Overall, this systematic study establishes how Dy doping modifies the spin-charge-lattice interactions in LaCoO3, highlighting its limited potential for improving thermoelectric performance in the low-temperature regime.
