Nanosized silver sulfide (α-Ag(2)S) particles were identified in the final stage sewage sludge materials of a full-scale municipal wastewater treatment plant using analytical high-resolution transmission electron microscopy. The Ag(2)S nanocrystals are in the size range of 5-20 nm with ellipsoidal shape, and they form very small, loosely packed aggregates. Some of the Ag(2)S nanoparticles (NPs) have excess S on the surface of the sulfide minerals under S-rich environments, resulting in a ratio of Ag to S close to 1. Considering the current extensive production of Ag NPs and their widespread use in consumer products, it is likely that they are entering wastewater streams and the treatment facilities that process this water. This study suggests that in a reduced, S-rich environment, such as the sedimentation processes during wastewater treatment, nanosized silver sulfides are being formed. This field-scale study provides for the first time nanoparticle-level information of the Ag(2)S present in sewage sludge products, and further suggests the role of wastewater treatment processes on transformation of Ag nanoparticles and ionic Ag potentially released from them.

Articles you may be interested in Self-biased large magnetoelectric coupling in co-sintered Bi0.5Na0.5TiO3 based piezoelectric and CoFe2O4 based magnetostrictive bilayered composite J. Appl. Phys. 116, 244101 (2014) This study reports the experimental observation and analysis of self-biased magnetoelectric ͑ME͒ effect in three-phase laminates. The 2-2 L-T mode laminates were fabricated by attaching nickel ͑Ni͒ plates and ME particulate composite plates having 3-0 connectivity with 0.948Na 0.5 K 0.5 NbO 3 -0.052LiSbO 3 ͑NKNLS͒ matrix and Ni 0.8 Zn 0.2 Fe 2 O 4 ͑NZF͒ dispersant. The presence of two types of ferromagnetic materials, Ni and NZF, results in built-in magnetic bias due to difference in their magnetic susceptibilities and coercivity. This built-in bias ͑H bias ͒ provides finite ME effect at zero applied magnetic dc field. The ME response of bending mode trilayer laminate NKNLS-NZF/Ni/NKNLS-NZF in off-resonance and on-resonance conditions was shown to be mathematical combination of the trilayers with configuration NKNLS-NZF/Ni/NKNLS-NZF and NKNLS/Ni/NKNLS representing contributions from magnetic interaction and bending strain.

In this manuscript, we investigate the sintering behavior of (K,Na)NbO 3 (KNN)-based ceramics covering unmodified KNN, (K,Na,Li)NbO 3 (KNLN), and KNLN-xBaTiO 3 (KNLN-BT) systems. Three stages of sintering were identified using detailed temperature and time dependent microscopy. The first stage corresponds to rearrangement of random shape particle to form stack of plate type particles. The second stage is characterized by rapid grain growth promoted by formation of liquid phase. The liquid phase was identified to be Na-deficient composition. In the final stage of sintering, densification slows and microstructural coarsening becomes the dominant process. The fraction control of liquid phase was an important factor to obtain dense and uniform microstructure by completely filling the voids between the plate-shaped particle stacks. II. Experimental ProcedureCeramics in the system (K 0.5 Na 0.5 )NbO 3 (0.5KNN), (K 0.5(1Àx) Na 0.5(1Àx) Li x )NbO 3 (xKNLN, e.g. 0.04KNLN 5 (K 0.48 Na 0.48 Li 0.04 )NbO 3 , and 0.05KNLN 5 (K 0.475 Na 0.475 Li 0.05 ) NbO 3 ), and (1Àx)(K 0.48 Na 0.48 Li 0.04 )NbO 3 -xBaTiO 3 [(1Àx) KNLN-xBT] were synthesized from oxides of 499% purity by conventional solid-state route. The powders of K 2 CO 3 , Na 2 CO 3 , Nb 2 O 5 , Li 2 CO 3 , BaCO 3 , and TiO 2 (all obtained from Alfa Aesar, Ward Hill, MA) were mixed for 24 h in a polypropylene jar with zirconia balls. Mixed powders were dried J. Roedel-contributing editor This work was financially supported by Office

In this manuscript, we review the progress made in the synthesis of thick film-based piezoelectric and magnetoelectric structures for harvesting energy from mechanical vibrations and magnetic field. Piezoelectric compositions in the system Pb(Zr,Ti)O3–Pb(Zn1/3Nb2/3)O3 (PZNT) have shown promise for providing enhanced efficiency due to higher energy density and thus form the base of transducers designed for capturing the mechanical energy. Laminate structures of PZNT with magnetostrictive ferrite materials provide large magnitudes of magnetoelectric coupling and are being targeted to capture the stray magnetic field energy. We analyze the models used to predict the performance of the energy harvesters and present a full system description.

In this manuscript, we report the polymorphic phase transitions, structural changes and piezoelectric properties of alkali niobate based lead-free ceramics. The phase transitions were characterized as a function of alkali niobate content at room temperature. The results clearly demonstrate that in this system high piezoelectric properties are achieved for a specific fraction of ferroelectric orthorhombic (O) and tetragonal (T) phases. Using Rietveld and powder diffraction analysis, a correlation was established among the piezoelectric response, the fraction of O and T phases, and KNN ratio for three different systems of (K,Na)NbO 3 -BaTiO 3 (KNN-BT), KNN-LiNbO 3 (LN), and (K,Na,Li)NbO 3 (KNLN)-BT.