TEM– i TED–istraživanja tankih dvoslojeva Ag/PbTe

Morphology and phase structure of Ag/PbTe thin film bilayers were investigated. This system was of particular interest because of interfacial reaction observed previously in an analogous Ag/SnTe system. Reaction products due to the interdiffusion of Ag with the substrate were determined as well as their orientations. They were discussed in view of the reaction products\u27 structural relations to the PbTe.Istraživala se je morfologija i fazna struktura tankih dvoslojeva Ag/PbTe. Taj je sustav posebno zanimljiv zbog graničnih reakcija koje su se ranije opazile u sličnom sustavu Ag/SnTe. Odredili su se reakcijski produkti koji nastaju uzajamnom difuzijom Ag i podloge kao i njihove orijentacije, te raspravljaju strukturni odnosi s PbTe

TEM– i TED–istraživanja tankih dvoslojeva Ag/PbTe

Morphology and phase structure of Ag/PbTe thin film bilayers were investigated. This system was of particular interest because of interfacial reaction observed previously in an analogous Ag/SnTe system. Reaction products due to the interdiffusion of Ag with the substrate were determined as well as their orientations. They were discussed in view of the reaction products\u27 structural relations to the PbTe.Istraživala se je morfologija i fazna struktura tankih dvoslojeva Ag/PbTe. Taj je sustav posebno zanimljiv zbog graničnih reakcija koje su se ranije opazile u sličnom sustavu Ag/SnTe. Odredili su se reakcijski produkti koji nastaju uzajamnom difuzijom Ag i podloge kao i njihove orijentacije, te raspravljaju strukturni odnosi s PbTe

SURFACE SEGREGATION STUDIES OF SELENIUM ON FeSiAl ALLOY RAZISKAVE POVR[INSKE SEGREGACIJE SELENA NA FeSiAl ZLITINI

Surface segregation of selenium in a polycrystalline FeSiAl alloy with 0.05% Se was investigated by high resolution Auger Electron Spectroscopy and X-ray Photoelectron Spectroscopy. Surface segregation measurements of selenium and impurities e.g. carbon, phosphorus and sulfur, were performed in situ under UHV conditions in the temperature range from 200 to 900°C. In the low temperature range, 200<T<550°C, carbon segregated due to its high diffusion and segregation enthalpy. Carbon segregated in the form of graphite clusters. At higher temperature T>850°C sulfur and selenium segregated. The selenium segregation rate was low, probably due to its low solubility in αFe and its high vapor pressure. The grain boundary segregation of selenium was negligible. The fracture facets were practically transgranular, only on some areas intergranular decohesion was noticed. Key words: equilibrium segregation, cosegregation, diffusion, surface precipitates, selenium, HR AES, XPS Povr{insko segregacijo selena na polikristalini~ni zlitini FeSiAl legirani z 0,05% Se, smo raziskali z visokolo~ljivo spektroskopijo Augerjevih elektronov na poljsko emisijo (HR AES) in z rentgensko fotoelektronsko spektroskopijo (XPS). Meritve povr{inske segregacije selena in elementov ne~isto~ kot so ogljik, fosfor in 'veplo so potekale v temperaturnem podro~ju od 200 do 900°C in situ v ultravisokem vakuumu. V nizko temperaturnem podro~ju 200<T<550°C, ogljik segregira na povr{ini zaradi visokega difuzijskega koeficienta in entalpije segregacije. Ogljik je na povr{ini segregiral kot grafit v oto~kih. Pri v i{jih temperaturah T>850°C sta na povr{ini segregirala 'veplo in selen. Stopnja sergegacije selena je bila nizka, predvidevamo da je vzrok temu nizka topnost selena v αFe in visok parni tlak. Segregacija selena po mejah zrn je zanemarljivo majhna. Skoraj vse prelomljene facete so bile transkristalne, le nekaj je bilo interkristalnih prelomov. Klju~ne besede: povr{inska segregacija, segregacija po mejah zrn, povr{inski precipitati, kosegregacija selen, HR AES, XP

SEM, AES, WDS i korozijsko testiranje oksidnih i nitridnih zaštitnih slojeva oblikovanih toplinskom obradom nerđajućeg čelika

Protective oxide and/or nitride layers on AISI 321 stainless steel were prepared by thermal treatment in air and two controlled atmospheres in a laboratory simulation of an actual technological procedure. Samples’ surface was imaged by Scanning Electron Microscopy (SEM), elemental composition of the substrates was checked by Wavelength Dispersive Spectroscopy (WDS) and depth profiles of the samples were measured by Auger Electron Spectroscopy (AES). Since protective layer thicknesses were found to be of the order of hundreds of nanometers an attempt was made to obtain some fast averaged information about layers composition by Wavelength Dispersive Spectroscopy (WDS) with appropriately adjusted primary beam energy. Electrochemical corrosion testing was also performed on samples.Zaštitne oksidne i/ili nitridne slojeve na AISI 321 nerđajućem čeliku pripremljen toplinskom obradom materijala na zraku i u 2 kontrolirana tipa atmosfera kao laboratorijsku simulaciju stvarnog tehnološkog procesa. Slike površine uzoraka dobijene tehnikom SEM, sastav substrata metodom WDS a za profilnu analizu upotrijebljena je spektroskopija Augerovih elektrona (AES). Kako je ustanovljeno da su debljine formiranih zaštitnih slojeva reda veličine nekoliko stotina nanometara pokušalo se doći do ocjene o prosječnom sastavu unutar sloja upotrijebom tehnike WDS uz odgovarajuće odabranu energiju primarnog elektronskog snopa. Na uzorcima je provjereno i korozijsko testiranje

Specola 2000: A Project for the Preservation of the Historical Archives of the Twelve Italian Astronomical Observatories

The historical archives of the Italian Astronomical Observatories contain valuable information on their institutional and scientific life. Due to the lack of proper inventories, however, the wealth of historical data contained in the archives has not always been used to its full extent. A joint effort started in 1999 by the former Ufficio Centrale Beni Archivistici (now Direzione Generale per gli Archivi) of the Italian Ministero per i Beni e le Attività Culturali, Società Astronomica Italiana and the former Consorzio Nazionale per l'Astronomia e l'Astrofisica, aimed at the inventorying and preservation of the archives. Seven years after its start, the project has reached the second of four planned phases

Auger-spektroskopija visoke resolucije u metalurgiji: moderna tehnika površinske analize

A brief review of the high spatial resolution Auger electron spectroscopy (HRAES) and its usage in metallurgy is presented. A combination of HRAES and X-ray photoelectron spectroscopy makes a powerful combination to resolve a large number of problems encountered in metallurgy. Several selected examples of such problems studied in the authors’ laboratory are presented: influence of surface active impurities on the surface properties and structure, chemical composition of nano-scaled inclusions, homogeneity of oxide layers formed by decarburization, chemical composition of inter- and intra-grain surfaces obtained by fracture in vacuum and interfacial study of 19Cr-13Ni austenitic stainless steel after treatment at elevated temperatures.Predočen je kratki pregled Auger-ove elektronske spektroskopije (HREAS) visoke spacijalne resolucije i njene primjene u metalurgiji. Kombinacija HREAS i röntgenske fotoelektronske spektroskopije učinkovita je pri rješavanju velikog broja problema koji se susreću u metalurgiji. Predočeno je nekoliko odabranih primjera takvih problema studiranih u laboratoriju autora: utjecaj površinski aktivnih nečistoća na svojstva i strukturu površine, kemijski sastav “nano-uključaka”, homogenost oksidnih slojeva nastalih odugljičenjem, kemijski sastav površina u zrnu i među zrnima nastalih lomljenjem u vakuumu te međufazna studija 19Cr-13Ni nehrđajućeg austenitnog čelika nakon obrade kod povišenih temperatura

IR AND X-RAY PHOTOELECTRON SPECTROSCOPY OF V 2 O 5 , TiO 2 AND V/Ti-OXIDE SOL-GEL DERIVED FILMS INFRARDE^A IN RENTGENSKA FOTOELEKTRONSKA SPEKTROSKOPIJA V 2 O 5 , TiO 2 IN V/Ti-OKSIDNIH SOL-GEL FILMOV

Prejem rokopisa -received: 1998-12-06; sprejem za objavo -accepted for publication: 1998-12-14 V/Ti-oxide films were prepared by dip-coating from sols made by mixing of V-oxoisopropoxide and Ti-propoxide in V:Ti molar ratio in precursors 3:1, 1:1 and 1:3. Amorphous films were obtained after annealing at 300°C (1 h). IR spectroscopic analysis revealed that V=O stretching modes appeared at 1020 cm -1 in the IR spectrum of powder (V:Ti=1:1). However, in the IR spectra of a film with the same molar ratio the bands at 1008 and 914 cm -1 appeared suggesting the presence of V 4+ -O bonds. The new band at 790 cm -1 signalled the V-O-Ti bridging bonds connecting V-O and Ti-O polyhedra. XPS measurements confirmed that initial-state films contained V 5+ , V 4+ and Ti 4+ species, but at the film surface only V 5+ species existed. Sequential depth analysis of films performed with Ar + sputtering showed that the vanadium is reduced to 3+ oxidation state with progressive exposure while titanium is not affected. Key words: electrochromic (EC) devices, oxide films, IR spectroscopy, XPS, oxidation states, sputtering, sol-gel V/Ti-oksidne filme smo pripravili iz koloidnih raztopin V-oksoizopropoksida in Ti-propoksida v 2-propanolu s tehniko potapljanja. Molska razmerja V:Ti v prekurzorjih so zna{ala 3:1, 1:1 in 1:3. Amorfni filmi so nastali po segrevanju na 300°C (1h). V IR spektru pra{kastega vzorca (V:Ti = 1:1) so se valen~na nihanja V=O pojavila pri 1020 cm -1 . V IR spektru filma z istim molskim razmerjem pa se pojavita trakova pri 1008 c