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Recently, room-temperature phosphorescence (RTP) in 2D hybrid perovskites has proved due to energy transfer from inorganic sheets to conjugated organic cations harnessing the triplet states. Thus far, only the sensitization of triplet states by inorganic excitons has been demonstrated. Herein, we report a novel (110)-oriented lead bromide perovskite, (C3H8N6)PbBr4 [abbreviated (H2mela)PbBr4], where within the inorganic sheets the self-trapped excitons generate broad-band emission and the Br−⋯π+ interactions harness the triplet excitons of organic components, via intersystem crossing (ISC), leading to dual fluorescence emission and RTP. To the best of our knowledge, based on the strategy of heavy-atom-participated anion–π+ interactions, the first RTP-active 2D-perovskite was successfully stabilized. The solid-state photoluminescence studies showed that the color rendering index (CRI) and chromaticity coordinates (x,y) as well as the correlated color temperature (CCT) of the white-light emission can be tuned via excitation energy variation. The emission of light varies from “cold” white light to “warm” white light by decreasing the excitation energy. When excited at 365 nm and 375 nm, our perovskite yielded “cold” white-light emission with the highest CRI of 97 and 99.

A 1-D Cu(ii)-based perovskite (C5H8N3)[CuCl3], with gap energy “Eg” of 2.21 eV, has been successfully investigated as a good UV–Vis–NIR absorber. The magnetic analysis suggests that this material can be described by the model of S = 1/2 AFM dimers.

The present work reports a detailed study of the spin dynamics, magnetocaloric effect and critical behaviour near the magnetic phase transition temperature, of a ferrimagnetic spinel Cu1.5Mn1.5O4. The dynamic magnetic properties investigated using frequency-dependent ac magnetic susceptibility fitted using different phenomenological models such as Neel–Arrhenius, Vogel–Fulcher and power law, strongly indicate the presence of a cluster-glass-like behavior of Cu1.5Mn1.5O4 at 40 K. The magnetization data have revealed that our compound displays an occurrence of second-order paramagnetic (PM) to ferrimagnetic (FIM) phase transition at the Curie temperature TC = 80 K as the temperature decrease. In addition, the magnetic entropy change (ΔSM) was calculated using two different methods: Maxwell relations and Landau theory. An acceptable agreement was found between both sets of data, which proves the importance of both electron interaction and magnetoelastic coupling in the magnetocaloric effect (MCE) properties of Cu1.5Mn1.5O4. The relative cooling power (RCP) reaches 180.13 (J kg−1) for an applied field at 5 T, making our compound an effective candidate for magnetic refrigeration applications. The critical exponents β, γ and δ as well as transition temperature TC were extracted from various techniques indicating that the magnetic interaction in our sample follows the 3D-Ising model. The validity of the critical exponents is confirmed by applying the Windom scaling hypothesis.

International audience; Crystals of (H2AMP)2[FeIIIBr4]Br3, where AMP refers to the 2-(Ammoniomethyl)pyridinium ligand, have been successfully synthesized through redox chemistry and analyzed using X-ray crystallography. The new complex crystallizes as red needles in the monoclinic space group, P21/c, with eight formula weights in a unit cell of dimensions: a = 12.358 (13), b = 28.572 (3), c = 13.544 (14) Å and β=92.009(5) °. Analysis of absorption and reflectance data through the visible and near-infrared provide insight into the optical properties of the material. The structural data and the BVS (Bond Valence Sum) calculations are in agreement with the iron (III) oxidation. In this work, the experimental and theoretical study on molecular structure and vibrational spectral analysis of the new product has been reported. Theoretical calculations were performed by using density functional theory (DFT) at the B3LYP/LAN2DZ basis set levels. The electronic parameters such as frontier molecular orbital, electrostatic potential and HOMO-LUMO energy were calculated. Also, NLO were studied with the same level of DFT. The theoretical values show good agreement with experimental values. In addition, (H2AMP)2[FeIIIBr4]Br3 reveals broad absorption across the visible spectrum and an optical bandgap of 1.06 eV. Then the obtained material can be a promising eco-friendly light absorber in solar cell application. Finally, the thermal behavior of this material has been performed by TGA/DTA. In addition, two phase transitions at T1 = 108 °C and T2 = 170 °C were evidenced by DSC measurements.

We report on structural, magnetic properties of Na-doped La0.8Sr0.15Na0.05MnO3 (LSNMO) nanoparticles (NP) with size about 50 nm elaborated via sol-gel route. The chemical composition was verified using the energy dispersive X-ray analysis (EDAX) and by X-ray photoelectron spectroscopy (XPS). Magnetic characterizations demonstrate that LSMNO exhibits a coexistence of interacting superparamagnetic (ISPM) phase with blocking temperature T-B = 194 K and a ferromagnetic phase with Curie temperature T-C = 255.5 K. At low temperatures, the SPM state undergoes a collective freezing state at T-f = 46 K. the high-temperature regime (well above TC) reveals that NP-LSNMO has a strengthened Griffiths-like phase compared to their bulk counterpart. An itemized investigation of the critical behavior of the material was carried out in the vicinity of T-C. The critical exponents [beta = 0.546(7), gamma = 0.972(6), and delta = 2.94 (5)] were found to be in close agreement with of the mean-field theory. The maximum magnetic entropy change (-Delta(pk)(M)) is about 1.41 Jkg(-1) K-1 and the refrigeration capacity (RC) is 288 Jkg(-1) for a field change of 5 T at T = 215 K. This magnetocaloric response is reasonably high for nanomaterials and, together with its cost-effectiveness, makes NP LSMNO a potential candidate material for active magnetic refrigerators. Besides, the ISPM properties are desirable for hyperthermia applications. Our findings suggest that the magnetic inhomogeneity and the dipolar interaction between the SPM and FM phases in the range T-B < T < T-C are crucial factors in determining the magnetic properties of NP-LSNMO. (C) 2021 Elsevier B.V. All rights reserved. Portuguese Foundation for Science and Technology European Commission QREN-Mais Centro Project Deanship Scientific Research at Jouf University central laboratory at Jouf University

We report on the magnetocaloric effect and critical phenomenon on La0.8K0.2MnO3 nanoparticle through a systematic magnetic and electrical measurement. The magnetic entropy change (ΔSM) presents close values obtained from resistivity and magnetic measurements, however, with a discrepancy in the magnetic entropy maximum values. This discrepancy is due to the presence of an extrinsic effect associated with the nanometric grain size affecting the electrical behavior. Interestingly, our results show a good agreement with the calculation of the critical exponents and the temperature coefficient of resistance shows positive and negative values. The obtained critical exponents are close to that of the mean-field theory (with β = 0.5, γ = 1, and δ = 3). This indicates a long-range interaction between spins a consequence of the presence the presence of dipole- dipole interaction in this system.