Search results for " ceramic"

Production and properties of doped PSN electro-optical ceramics

1997

Due to multifunctionality the transparent ferroelectric ceramics is attractive to solid state chemistry and physics as a promising material for active electro-optic elements. To study doping effects on the technological processing and properties, ceramic samples of Pb1-xZxSc1/2Nb1/2O3, have been prepared, where Z: (1) Ba (0 less than or equal to x less than or equal to 1), (2) rare-earth elements: Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu (x equals 0.1), (3) PbSc1/2Nb1/2O3 doped with 5 wt.% of rare-earth oxides. Ceramic characteristics, dielectric and electro-optical parameters have been measured. Differential thermal analysis (DTA), and x-ray diffraction are used to study the infl…

Study of low-pressure suspension plasma spray nanostructured coating : structural characteristics and application in solid oxide fuel cell

2021

Suspension plasma spraying (SPS) has attracted more and more attention in terms of the preparation of nanostructured / sub-microstructured ceramic coatings. However, conventional SPS techniques are conducted under atmospheric pressure, which inevitably causes some disadvantages. Recently, a novel suspension spraying technology – low-pressure suspension plasma spraying (LPSPS) – was proposed, in which the sus-pension spraying process is conducted under low environmental pressure. Benefit from the significant impact of low pressure on the coating deposition, LPSPS is expected to improve the disadvantage of SPS as well as to obtain distinct coating structures not achievable in conventional SPS…

Evaluation of Rhodamine B Photocatalytic Degradation over BaTiO

2021

This research was funded by UIDB/50006/2020 with funding from FCT/MCTES through national funds and from the Institute of General and Ecological Chemistry of Lodz University of Technology. Susana L.H. Rebelo and Iwona Kuźniarska-Biernacka thank FCT (Fundação para a Ciência e Tecnologia) for funding through program DL 57/2016–Norma transitória (RE-QUIMTE/EEC2018/30 (SLHR) and REQUIMTE/EEC2018/14 (IKB)).

Termini Imerese (PA) [Sito 88]

2016

This work will examine the imports of African pottery at Termae Himeraeae, pointing to the atelier of origin and identifying local imitations of African types, according to archaeometrical analyses.

A new eco-friendly chemical treatment of natural fibres: Effect of sodium bicarbonate on properties of sisal fibre and its epoxy composites

2016

Abstract Several researchers have shown how sisal fibres possess remarkable tensile properties that yield them good candidates as reinforcement in biocomposite materials. This work aims to evaluate the effect of an eco-friendly and cost effective surface treatment method based on the use of commercial sodium bicarbonate (i.e. baking soda) on properties of sisal fibre and its epoxy composites. In particular, raw sisal fibres were treated with a 10%w/w of sodium bicarbonate solution for different periods (24, 120 and 240 h), at room temperature. Changes occurring in sisal fibres were characterized through scanning electron microscope, Fourier transform infrared spectroscopy, thermogravimetric…

Innovative experimental approaches applied to the study of ceramics from underwater archaeological excavations

2012

Pantellerian ware: a comprehensive archaeometric review.

2007

Pantellerian ware is a Late Roman cooking ware whose production centre was established on the island of Pantelleria by the pioneering research of Fulford and Peacock almost 20 years ago (Peacock 1982; Fulford and Peacock 1984). Archaeological and archaeometric studies carried out by the authors of the present contribution during the past four years have aimed to fully characterize this ceramic class. Recurrent ceramic forms, their distribution over time and space, their petrographic characteristics and their chemical identity, as well as possible raw materials and their technological properties, were considered. The present paper is a comprehensive review of this archaeometric work and aims…

X-ray Spectroscopy of (Ba,Sr,La)(Fe,Zn,Y)O3-δIdentifies Structural and Electronic Features Favoring Proton Uptake

2020

Mixed protonic–electronic conducting oxides are key functional materials for protonic ceramic fuel cells. Here, (Ba,Sr,La)(Fe,Zn,Y)O3−δ perovskites are comprehensively investigated by X-ray spectroscopy (in oxidized and reduced states). Extended X-ray absorption fine structure shows that Zn,Y doping strongly increases the tendency for Fe–O–Fe buckling. X-ray absorption near-edge spectroscopy at the Fe K-edge and X-ray Raman scattering at the O K edge demonstrate that both iron and oxygen states are involved when the samples are oxidized, and for the Zn,Y doped materials, the hole transfer from iron to oxygen is less pronounced. This can be correlated with the observation that these material…

Metodi non distruttivi per la diagnosi dei Beni Culturali

2013

La conoscenza dei materiali, in termini di composizione, di morfologia e di struttura, costituenti manufatti di varia natura è, oggi, di grande importanza in vari settori scientifici e tecnologici. La comprensione dei processi che possiamo, genericamente, raggruppare secondo la definizione “interazione radiazione-materia” ha portato allo sviluppo di una serie di tecniche di caratterizzazione spettroscopica e strutturale della materia che trovano applicazione nello studio di materiali dai più nuovi e innovativi a quelli archeologici. Negli ultimi decenni, l’approfondimento delle problematiche legate alla comprensione dei processi di sviluppo delle conoscenze ha promosso un connubio sempre pi…

ZnO – Yb2O3 composite optical ceramics: Synthesis, structure and spectral-luminescent properties

2022

International audience; Zinc oxide optical ceramics containing 0 – 2 wt% ytterbium are prepared byuniaxial hot pressing of commercial oxides at 1150 and 1180 °C. The ceramics have themain crystalline phase of hexagonal wurtzite-type ZnO. Ytterbium ions do not enter theZnO crystals but form a cubic sesquioxide phase of Yb2O3 located at the ZnO grainboundaries. Yb acts as an inhibitor for the ZnO grain growth. The ceramics exhibittransmittance up to 60% in the visible. Their transmission in the infrared is determinedby the free charge carrier absorption. The Yb3+ ions are found in C2 and C3i sites in Yb2O3crystals. Under X-ray excitation, the ceramics exhibit intense luminescence bands in the…