Influence of the physical properties on the antibacterial and photocatalytic behavior of Ag-doped indium sulfide film deposited by spray pyrolysis

Spray pyrolysis was used to deposit indium sulfide (In2S3) films, with or without silver doping. The films are polycrystalline, and the inclusion of Ag in the In2S3 structure leads to the formation of a solid solution, with the crystallite size of the order of tens of nanometers. In2S3 films exhibit a semiconductive behavior, and the incorporation of Ag leads to an increase of the charge carrier concentration, enhancing the electrical conductivity of the films. The small polaron hopping mechanism, deduced by the fittings according to the double Jonscher variation, explains the evolution of the direct current (dc) conductivity at high temperature of the Ag-doped indium sulfide. From impedance spectroscopy, it was found that the doped film presents dielectric relaxation, and Nyquist diagrams indicate the importance of the grain and the grain boundaries’ contributions to the transport phenomena. The physical characteristics of the films have an influence on the photocatalytic performance, achieving photodegradation efficiency above 80% (85.5% in the case of Ag doping), and on the antibacterial activity. The obtained results indicate that indium sulfide films are good candidates for environmental and biological applications, confirming a multifunctional nature.Part of this work was supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UIDB/04650/2020”. D.C. and I.G. acknowledge the structural funds project PRO-DD (POS-CCE, O.2.2.1., ID123, SMIS 2637, ctr. no 11/2009) for providing some of the infrastructure used in this work. Part of this work was supported by a grant of the Romanian Ministry of Education and Research, CNCS - UEFISCDI, project number PN-III-P1-1.1-TE-2019-1209, within PNCDI III

Investigations on the Doping Effects on the Properties of Piezoelectric Ceramics

In the present paper (1-x)Pb (Zr1-yTiy)O3 – xPb (Mn1/3Sb2/3)O3 – z at%E system, with E = Pr3+, Nd5+ and Gd3+ where x = 0.12; y = 0.48; z = 0 and 0.02 ceramic synthesized by solid state reaction technique is analysed. The investigation aims studying of the effect of dopants on the dielectric and piezoelectric properties of such piezoelectric ceramic. The prepared powders have been uniaxially pressed into discs with diameter of 10 – 12 mm and thickness of 1.2 mm. Sintering has been carried out in air atmosphere at temperatures of 1150°C and 1200°C, respectively, for 2 hours each, followed by a controlled cooling at a rate of 200°C /h. The piezoelectric properties have been investigated after a suitable preparation, including polishing, metallization. The structure of the samples has been determined by X-ray diffractometry (XRD), while the morphology and grains size have been investigated by the scanning electron microscopy (SEM). The piezoelectric properties have been studied by the resonance - antiresonance method. XRD analysis reveals a perovskite tetragonal structure and, as expected for ceramic materials, SEM analysis indicates that the average grain size increases as sintering temperature increases. The dielectric and piezoelectric properties have been determined measuring the ceramic discs, and properties, as dielectric permittivity (εr), dielectric loss (tg δ), and the electromechanical coupling factor (kp) have been obtained. The acquired results indicate a significant effect of the dopants on the dielectric and piezoelectric properties of such materials

Cobalt(II) Ions Connecting [Co^II₄] Helicates into a 2‑D Coordination Polymer Showing Slow Relaxation of the Magnetization

The reactions of cobalt­(II) perchlorate with a diazine tetratopic helicand, H₄L, in the presence of sodium carbonate afford two coordination polymers constructed from tetranuclear anionic helicates as building blocks: _∞³[Co₄L₃Na₄(H₂O)₄]·4H₂O (<b>1</b>) and _∞²[Co₅L₃Na₂(H₂O)₉]·2.7H₂O·DMF (<b>2</b>). The tetranuclear triple-stranded helicates, {Co^II₄L₃}^4–, are connected in <b>1</b> by sodium­(I) ions and in <b>2</b> by sodium­(I) and cobalt­(II) ions (H₄L results from the condensation reaction between 3-formylsalicylic acid and hydrazine). The crystal structures of the two compounds have been solved. In both compounds the anionic helicates interact with the assembling cations through the carboxylato oxygen atoms. Compound <b>2</b> features chains resulting from connecting the tetranuclear helicates through cobalt­(II) ions. The analysis of the magnetic properties of compounds <b>1</b> and <b>2</b> evidenced a dominant antiferromagnetic coupling for <b>1</b>, resulting in a diamagnetic ground state. In contrast, the magnetic behavior of <b>2</b> is dominated at low temperature by the Co^II ion which connects the antiferromagnetically coupled {Co^II₄} helical moieties. The ac magnetic measurements for <b>2</b> reveal the occurrence of slow relaxation of the magnetization that is due to the single, uncorrelated cobalt­(II) ions, which are diluted in an essentially diamagnetic matrix of {Co^II₄} moieties (Δ<i><i>E</i></i>_eff = 26.7 ± 0.3 cm^–1 with τ₀ = (2.3 ± 0.2) × 10^–6 s)