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• Optimized growth of polycrystalline VO 2 films on SiO 2 /Si substrates by Sputtering. • Appreciable insulator to metal transition (IMT) observed down to 23 nm film thickness. • Film thickness induce systematic modulation in IMT order and IMT temperature. • Low resistivity (∼10−2 Ω-cm) achieved for insulator state in 23 and 38 nm films. Engineering electronic properties of VO 2 across its insulator to metal transition enable to design wide range of electronic devices operating with low voltage such as memristor, field effect transistor, and in neuromorphic device as an active circuit element. We investigated the electrical and structural properties of sputter deposited VO 2 thin films grown on SiO 2 /Si substrates. In polycrystalline VO 2 films, we observed appreciable insulator to metal transition (IMT) down to film thickness of 23 nm. Further, thickness dependence study reveals a systematic variation in the IMT order between 30-3000, accompanied by modulation in transition temperature and hysteresis. The genesis of the modulations is attributed to morphological and structural growth dynamics. Significantly, we have attained low values for insulating states (∼10−2 Ω-cm) in low dimensional thin films (23 and 38 nm), which are desirable for Joule heating driven IMT based VO 2 devices with low voltage switching, as well as for sensing applications. [ABSTRACT FROM AUTHOR]

Ag-based semiconductors have stimulated great interest as promising photocatalysts due to their high optical absorption. While exhibiting excellent photocatalytic activity, they suffer from poor stability. On the other hand, CuI is an air-stable material with excellent optical absorption and bandgap of 3 eV, and can be an alternative to the photosensitive and expensive Ag halides for photocatalytic applications. In this study, alloying strategy was used to prepare Cu–Ag–I–Cl alloys with wide compositions Cu 1-x Ag x I 1-x Cl x (0 ≤ x ≤ 1), and their structural, optical and photodegradation properties were evaluated. X-ray diffractionmeasurements revealed the single-phase solid solution formation with systematic phase transition, from γ-phase to β-phase upon alloying of AgCl into CuI, infer the coordination effects associated with atomic size. The optical band gap has shown significant modifications with alloying, with minima of 2.65 eV at x = 0.25. The Malachite green dye photodegradation under UV-light exposure was evaluated for various Cu 1-x Ag x I 1-x Cl x alloy samples at different solution pH. Compared to pure CuI, alloying of AgCl into CuI has significantly enhanced photodegradation, with the highest degradation efficiency of 88 % at 40 minutes and pH of 3 for x = 0.25. Further, the Cu 1-x Ag x I 1-x Cl x alloy has demonstrated significant photodegradation (54 % at 100 minutes) of ofloxacin, indicating that they can be potential for other stubborn organic pollutants removal from wastewater. Through quenching experiments, the O 2 •− reactive oxygen species were identified as primarily responsible for the photodegradation in this system. The origin of high photodegradation performance in Cu–Ag–I–Cl alloy system is attributed to the configurational entropy and surface plasmon resonance of nonstoichiometric Ag on the surface. The significant efficiency achieved with an alloying strategy involving functional halides could open a novel path to develop photocatalysts alternative to complex heterogeneous and multicomponent methods. [Display omitted] • Developed Cu–Ag–I–Cl alloys for efficient photodegradation. • Achieved significant degradation (88 % at 40 min) of Malachite Green dye under UV-light exposure. • Demonstrated the stability and recyclability of the developed catalyst. • Unveiled the synergistic effects of entropy and surface plasmon resonance of Ag in photodegradation. [ABSTRACT FROM AUTHOR]

• Nanocrystalline Zn-ferrite thin film are novel magnetocaloric material for cooling on-chip devices. • Tunable magnetic transition exhibits multiple -ΔS M and RCP peaks at low and high temperatures. • A crossover from the conventional to inverse magnetocaloric effect owing to the presence of inhomogeneous magnetic grains. The novel magnetocaloric thin film material with a tunable magnetic transition is the cornerstone of magnetic refrigeration, which plays a crucial role in cooling on-chip devices. Zn-ferrite (ZnFe 2 O 4) occupies a significant place due to its interesting grain size-controlled magnetism. In this study, we investigate the magnetocaloric properties of Zn-ferrite layers consisting of a mixture of superparamagnetic (SPM), ferrimagnetic (FiM), and bulk-type antiferromagnetic (AFM) grains. Due to the co-existence of different magnetic grains, a crossover from the conventional magnetocaloric effect (MCE) to the inverse magnetocaloric effect (IMCE) is observed. The magnetic entropy change (-ΔS M) exhibits high-temperature positive values around the Curie temperature (T C) and low-temperature negative values around either the Néel temperature (T N) or blocking temperature (T B). The maximum value of -ΔS M (0.10 J/kg K) is almost double in AFM-dominant samples compared to SPM-dominant samples, while maintaining a relative cooling power (RCP) of 11.57–14.82 J/Kg under applied fields of 0 – 2T. FiM-dominant samples, with a wide working temperature window around room temperature, are suitable for large RCP applications. Thus, the discovery of new IMCE materials like single layers of Zn-ferrite is equally important in the search for suitable conventional MCE materials for magnetic refrigeration devices, which can exhibit multiple -ΔS M and RCP peaks in low and high temperatures. [Display omitted] [ABSTRACT FROM AUTHOR]

Electrode selection and its effects are extremely crucial to characterize the electrical properties and understand the colossal permittivity response of CaCu 3 Ti 4 O 12 (CCTO) ceramics. However, the specifical correlation between metal electrode and electrical performances of CCTO ceramics are not clear so far. In this study, we have systematically investigated the effects of metal electrodes (Ag, Au and Pt) on the colossal permittivity response, dielectric loss, nonlinear characteristics and dielectric relaxation behavior of CCTO ceramics prepared via solid-state reaction means. Moreover, the related physical mechanisms of electrode effect on the electrical properties of CCTO ceramics have been analyzed. As a result, it is found that the metal electrode plays a minimal effect on the dielectric constant of CCTO ceramics in low and intermediate frequencies (102–105 Hz), but the Pt-CCTO ceramic presents a reduced dielectric constant in a frequency range of 104–105 Hz due to the relatively weaker grain boundary responses and the lower Schottky barriers between Pt electrode and sample surface. Meanwhile, the dielectric constant of Pt-CCTO ceramics sharply decreases at the high frequencies, which may be attributed to the greater dipole-dominated dielectric relaxation behaviors induced by the Pt electrode. Furthermore, the influence of electrode on dielectric loss is relatively significant, especially at the intermediate and high frequencies under high temperatures. Whereas, the influences of electrode effect on the breakdown electric field strength and nonlinear coefficient of CCTO ceramics are relatively little, as revealed by nonlinear characteristics. Consequently, it is comprehensively considered that the Ag electrode is more suitable to characterize the electrical performances of CCTO ceramics. Our results may provide a guidance to select electrodes and further understand the colossal dielectric mechanism for all the dielectric ceramics. [ABSTRACT FROM AUTHOR]