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Paul Scherrer i Peter Debye izradili su 1916. kameru s pomoću koje su uspjeli ostvariti prvu rendgensku difrakciju u prahu LiF. Neovisno o njima, A. W. Hull je iste godine uspio ostvariti difakciju u prahu željeza. Zajedno s W. P. Daveyjem izračunao je i nacrtao posebne logaritamske krivulje s pomoću kojih je uspio indicirati mnoge metalne strukture. Te krivulje, kasnije nazvane Hull-Daveyjeve, bile su u upotrebi sve do sedamdesetih godina prošloga stoljeća i tek su pojavom snažnih računala polako pale u zaborav. Zahvaljujući P. Scherreru, već se 1918. moglo određivati veličinu kristalita iz proširenja difrakcijskih linija (Scherreova jednadžba). Rendgenska difrakcija u prahu omogućila je procvat istraživanja višefaznih materijala što je pospješilo određivanje kristalne strukture kao i definiranje faznih dijagrama. Kasnije je primjena elektronske difrakcije omogućila istraživanje vrlo sitnih uzorka, a neutronska difrakcija istraživanje magnetskog uređenja u materijalu. H. Rietveld je 1966. predložio matematičku obradu cijele difrakcijske slike polikristala s ciljem određivanja kristalne strukture, a to je bilo omogućeno razvojem računalne tehnike i suvremene instrumentacije. Bitni napredak u nizu istraživanja kristalne strukture i mikrostrukture polikristala kao i vremensko razlučivanje dimamičkih procesa u kristalu ostvaren je sinkrotronskim zračenjem nakon 1970. Mogućnosti difrakcije u polikristalu ilustrirane su primjerima iz znanstvenih radova autora

U e-biblioteci Terminološki rječnici Strune objavljuju se terminološke zbirke koje su nastale kao rezultat pojedinih projekata u okviru programa Izgradnja hrvatskog strukovnog nazivlja - Struna. U ovom se svesku donosi nazivlje obrađeno u okviru projekta HRZZ Izgradnja, odabir i usuglašavanje hrvatskog nazivlja u fizici koji je vodila prof.dr.sc. Vjera Lopac.

Difrakcija u polikristalu je jedna od najmoćnijih tehnika u istraživanju mikrostrukture i kristalne strukture čvrstoga stanja. Ta tehnika omogućuje, u sinergiji sa spektroskopskim i mikroskopskim tehnikama, potpunu analizu jednofaznih i višefaznih tvari od važnosti u nizu znanstvenih i tehnologijskih područja. Informacije o kristalnoj strukturi i mikrostrukturi tvari pohranjene su u njenoj difrakcijskoj slici ; da se te informacije dobiju potrebno je difrakcijsku sliku dekodirati prikladnim, često složenim, matematičkim postupcima. Difrakcija u polikristalu doživljava ubrzani razvoj uvođenjem suvremene sofisticirane instrumentacije te snažnih i brzih računala, kao i uporabom sinkrotronskoga zračenja, što omogućuje prikupljanje obimnih difrakcijskih podataka u realnome vremenu te vremensko razlučivanje dinamičkih procesa u tvari. Prikazane su mogućnosti difrakcije u polikristalu koje su ilustrirane primjerima iz znanstvenih radova autora.

Rječnik je namijenjen kristalografima, eksperimentalnim i teorijskim fizičarima, anorganskim i organskim kemičarima, biokemičarima i biolozima, mineralozima, matematičarima, farmaceutima, tehnolozima i drugim stručnjacima te polaznicima diplomskih i doktorskih studija prirodnih, matematičkih i tehnologijskih znanosti. Isto tako Rječnik će biti koristan i stručnjacima koji se u prvome redu bave terminologijom, hrvatskim jezikom i jezikoslovljem te se nadamo da će doprinijeti promicanju znanosti u Hrvatskoj i izgradnji hrvatskoga znanstvenog nazivlja.

Sredinom šezdesetih godina prošlog stoljeća znanstvenici s Fizičkog zavoda PMF-a izradili su uređaj, nazvan metoda dvostrukog klipa, za vrlo brzo kaljenje talina, s pomoću kojega su se na Institutu za fiziku Sveučilišta proizvodile prezasićene čvrste otopine, pretežno na bazi aluminija i ispitivale rentgenskom difrakcijom i transmisijskom elektronskom mikroskopijom radi utvrđivanja povećanja metastabilne topivosti i ispitivanja pretvorbe prezasićenih čvrstih otopina u ravnotežne faze.

Izgradnja strukovnoga nazivlja vlastite struke važno je područje djelovanja znanstvenika svih struka. Pri uspješnoj izgradnji nazivlja pojedine struke trebali bi sudjelovati znanstvenici te struke i jezikoslovci jer nazivlje neke struke pripada i toj struci i hrvatskome standardnom jeziku. To je bila temeljna misao vodilja koja je dovela do pokretanja projeta STRUNA i projekta Izgradnja, usuglašavanje i odabir hrvatskoga nazivlja u fizici. Nositelj projekta za fiziku ( dalje: STRUNA fizika ) bio je Fakultet kemijskog inženjerstva i tehnologije Sveučilišta u Zagrebu, a voditeljica projekta prof.dr.sc. Vjera Lopac. U radnoj skupini projekta za fiziku, uz dvoje jezikoslovaca i jedanaest fizičara sa Sveučilišta u Zagrebu i znanstvenih instituta, sudjelovali su i stručnjaci za elektrotehniku, strojarstvo, mjeriteljstvo i izdavačku djelatnost u fizici. U rad na tome projektu uložen je velik trud i entuzijazam i voditeljice projekta i svih suradnika, te izražena želja da se u relativno kratkom vremenu od jedne godine ostvari najbolji učinak. Stoga smo kao suradnici na projektu STRUNA fizika sa zanimanjem dočekali rad Interdisciplinarni projekt STRUNA – o nazivlju u prirodnim znanostima autorice prof.dr.sc. Vjere Lopac, objavljen u časopisu Kemija u industriji1, u rubrici Imenje i nazivlje u kemiji i kemijskom inženjerstvu koju uređuje prof.em.dr.sc. Marija Kaštelan-Macan2.

In this article we report on HRTEM and SAED examination of samples ZrO2–CuO having 0 and 0.2 mol % CuO content and calcinated at temperatures 400 and 5000C (samples named ZCuO-400, ZCuO2-400, ZCuO-500, ZCuO2-500). Measurements were performed on JEOL JEM 2010 200kV high resolution transmission electron microscope. Previously the samples were examined by low frequency Raman spectroscopy (LFRS) [1] and other characterization methods [2]. LFRS can be applied to nanoparticles having spherical microstructure and having constant that depends on the ratio of the longitudinal and transversal velocities of sound within the particles. The particle size distribution measured by LFRS and HRTEM is in very good agreement for number of materials whether the particles are amorphous, nanocrystaline, nanoscrystaline in amorphous matrix in thin films or in the form of powder [3]. In Figure 1. we give evidence about the existence amorphous nanoparticles, what is evidenced in BF as well in SAED, were the first amorphous ring is very well observed. By prolonged heating in SAED, monoclinic and tetragonal ZrO2 can be observed (sample ZCu0). The samples ZCuO-400 and ZCuO2-500 are fully amorphous (Figures 1b. and 2d), but with heating in EM during observation by SEAD, the first spot of new phase appeared in amorphous part of sample. The monoclinic ZrO2 (-111) with d =0.314 nm and (111) with d=0.284 nm are identified. In Figure 1c. in the same region of the sample amorphous spherical and crystalline particles as well the holes (H) are observed in HRTEM image. For lower magnification particle size distribution, the size of particles are D=(6.70.3) nm, while hole sizes are (5.70.3) nm. The crystalline phases are identified in SAED in Figures 1b. and 2b. as amorphous and monoclinic ZrO2 . In Figure 2. (sample ZCu2) particle sizes are smaller D= (3.40.6)nm (from the HRTEM image from Figure 2a.). This result is in accordance with previous measurements, obtained on series of samples having different doping concentration of CuO, in which the grain sizes increase with increasing calcinations temperature [1]. Also, the results show that with increasing dopant concentration, nanoparticles become smaller, as observed in In2O3 doped with Sn (ITO) [4].

Rad je ostvaren u okviru projekta Izgradnja, usuglašavanje i odabir hrvatskoga nazivlja u fizici (dalje: STRUNA fizika). STRUNA fizika jedan je od projekata STRUNA-e (Hrvatsko strukovno nazivlje) na kojima surađuju znanstvenici pojedinih struka uključeni u različite projekte (antropologija, brodostrojarstvo, građevinarstvo, fizika, kemija, matematika, korozija i zaštita materijala, stomatologija, strojni elementi, zrakoplovstvo i dr.) i jezikoslovci iz Instituta za hrvatski jezik i jezikoslovlje (IHJJ). IHJJ je koordinator projekta STRUNA, koji se ostvaruje uz potporu Hrvatske zaklade za znanost. Obrađeni i uneseni nazivi mogu se pregledati na mrežnoj stranici http://struna.ihjj.hr.

Practical applications of the XBroad program for Warren-Averbach-Bertaut and Willamson-Hall analysis on XRD data of selected materials

NiCoB nanioparticles, uncoated and coated in SiO2 were synthesized and investiged by XRD, FE-SEM and EDS.

Materials composed of fine magnetic particles exhibit unique properties which are strongly affected by morphology (i.e. size and shape) and composition of incorporated nanoparticles. Such materials offer a wide range of versatile applications (i.e. medicine diagnostic and drug delivery, chemical catalysts, memory storage, solar cells etc.). Our research was based on the idea of enhancement of electro-magnetic properties of MgB2 superconductor (T ≈ 39 K) by doping it with ternary transition metal-boron alloy magnetic nanoparticles. We used NiCoB nanoparticles with mean diameter d = 19 ± 4 nm, which were amorphous according to previously XRD measurements. Magnetic measurement of these particles showed the superparamagnetic behaviour. MgB2 wires doped with NiCoB particles were prepared by the in-situ powder in tube method (PIT). The resulting microstructures were characterized by X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray analysis (EDS). The SEM-EDS elemental mapping was used for determination of distribution of constituent elements. The analysis of FE-SEM micrographs of doped MgB2/NiCoB sample revealed nearly uniaxial nanoparticles (d = 20 ± 1 nm) along with hexagonal shaped forms (d = 290 ± 20 nm). The X-ray diffraction showed the existence of MgB2 and MgO phases and Si. We suppose that MgO is the result of oxidation of the sample and Si is from the sample holder. The existence of Mg, B and O elements was also confirmed by EDS results. The hexagonal shaped forms were mainly composed of these elements. Small quantities of Ni and Co elements were also detected, obviously due to the using of 1.25 wt. % of NiCoB powder for doping. The quantitative EDS analysis showed that the ratio of detected Mg and B elements was very close to 1:2 and ratio of Mg and O elements was ≈ 1:1. The mean crystallite size of MgB2 phase calculated from MgB2/NiCoB X-ray diffraction pattern was ≈ 30 - 40 nm. These results along with earlier obtained from FE-SEM micrographs indicate that hexagonal forms are in fact MgB2 polycrystals. According to EDS results nearly uniaxial particles seem to be NiCoB particles. Also, the electrical transport measurements performed on doped MgB2/NiCoB superconductor showed an improvement of electro-magnetic properties in respect to pure MgB2 superconductor.

Magnezij diborid (MgB2) je supravodič koji se uz razna iznimna svojstva (velika duljina koherencije, relativno velike vrijednosti gustoće kritične struje itd.) odlikuje i relativno visokom temperaturom prijelaza u supravodljivo stanje (39 K), što ga čini jako dobrim kandidatom za široki spektrar primjena. Kako bi se poboljšala elektro-magnetska svojstva tog supravodiča isti je dopiran magnetskim nanočesticama raznih kemijskih sastava pripravljenih metodom kemijske redukcije. Budući da svojstva dopiranog MgB2, osim o kemijskom sastavu, ovise i o morfologiji (tj. obliku i veličini) nanočestica kojima se dopira supravodič, prvi korak u istraživaju je stavljen upravo na strukturnu analizu istih (u ovom slučaju NiCoB nanočestica, budući da su one pokazale željena strukturna i magnetska svojstva). Tim je nanočesticama zatim izvršeno dopiranje MgB2 supravodiča. Za pripremu MgB2/NiCoB uzorka korištena je metoda praha u cijevi (eng. powder in tube method). NiCoB nanočestice i dopirani MgB2 supravodič su ispitivani metodom rentgenske difrakcije (eng. XRD), pretražne elektronske mikroskopije (eng. SEM) te energijske disperzivne mikroskopije (eng. EDS). U SEM modu rada je također izvršeno mapiranje uzorka u svrhu utvrđivanja raspodjele pojedinih kemijskih elemenata koji čine uzorak.

Correlations between electrical and mechanical properties of the Al-(Nb, Mo, Ta, W) binary alloys

In the last years considerable attention has been devoted to materials composed of fine magnetic particles because of their novel properties (superparamagnetism) and technological applications. Magnetic nanomaterials are also very intriguing due to their potential application in biomedicine [1-3]. A well known method for preparation of alloys in the form of fine particles (particularly ternary transition metal-boron alloys e.g. NiCoB) is the chemical reduction of aqueous solution of metal salts, with an alkali metal borohydride as the reducing agent. By changing the composition and synthesis conditions it is possible to control the morphology (i. e. size and shape) of these nanoparticles. It is known that magnetic particles smaller than 100 nm could exhibit superparamagnetism [4], and we suppose that such particles embedded in MgB2 superconductor (Tc39 K) could enhance the critical current density. At this stage of research we have tried to synthesize amorphous nanosized particles with well defined dimensions and with narrow and reproducible size distribution in order to obtain superparamagnetic behaviour. Two series of samples were prepared and analyzed, namely NiCoB without and with SiO2 coating. We suppose that particles with SiO2 coating could be more appropriate for embedding in MgB2 superconductor because the SiO2 coating could prevent a direct contact among NiCoB particles and decrease the magnetic interaction among the particles. The resulting microstructures were characterized by X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray analysis (EDX). For magnetic measurements superconducting quantum interference device (SQUID) magnetometer was used. The analysis of FE-SEM micrographs of NiCoB/NiCoB-SiO2 nanoparticles showed that the particles were nearly uniaxial ( ili: particle shapes were roughly spheres ), with sizes from 12 to 24 nm for NiCoB sample and from 12 to 32 nm for the SiO2 coated NiCoB sample, showing relatively narrow log normal distribution. X-ray diffraction patterns showed that the samples were amorphous. EDX results confirmed the existence of expected elements (Ni, Co, B, Si and O). Also, the preliminary magnetic measurements for both samples confirmed the superparamagnetic behaviour. [1] A. K. Gupta, S. Wells, IEE Trans. Nanobiosci. 3 (2004) 66-73 [2] A. H. Lu, E. L. Salabas, F. Shuf, Angew. Chem. Int. Edn 46 (2007) 1222-44 [3] J. F. Lutz, S. Stiller, A. Hoth, L. Kaufner, U. Pison, R. Cartier, Biomacromolecules 7 (2006) 3132-8 [4] A. G. Roca, R. Costo, A. F. Rebolledo, S. Veintemillas-Verdaguer, P. Tartaj, T. González-Carreño, M. P. Morales , C. J. Serna, J. Phys. D:Appl. Phys. 42 (2009)

In the last years considerable attention has been devoted to materials composed of fine magnetic particles because of their novel properties (superparamagnetism) and technological applications. A well known method for preparation of alloys in the form of fine particles is the chemical reduction of aqueous solution of metal salts, with an alkali metal borohydride as the reducing agent. By changing the composition and synthesis conditions it is possible to control the morphology (i. e. size and shape) of these nanoparticles. It is known that magnetic particles smaller than 100 nm could exhibit superparamagnetism, and we suppose that such particles embedded in MgB2 superconductor (Tc39 K) could enhance the critical current density. At this stage of research we have tried to synthesize amorphous nanosized particles with well defined dimensions and with narrow and reproducible size distribution. Two series os samples were prepared and analyzed, namely NiCoB without and NiCoB with SiO2 coating. We suppose that particles with SiO2 coating could be more appropriate for embedding in MgB2 superconductor because the SiO2 coating could prevent a direct contact among NiCoB particles and decrease the magnetic interaction among the particles. The resulting microstructures were characterized by X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray analysis (EDX). For magnetic measurements superconducting quantum interference device (SQUID) magnetometer was used. The analysis of FE-SEM micrographs of NiCoB/NiCoB-SiO2 nanoparticles showed that the particles were nearly uniaxial, with sizes from 12 to 24 nm for NiCoB sample and from 12 to 32 nm for the SiO2 coated NiCoB sample, showing relatively narrow log normal distribution. X-ray diffraction patterns showed that the samples were amorphous. EDX results confirmed the existence of expected elements (Ni, Co, B, Si and O). Also the preliminary magnetic measurements for both samples confirmed the superparamagnetic behaviour.

Metodama rendgenske difrakcije (RTG), energetske analize spektara (EDS), transmisijske elektronske mikroskopije (TEM), pratili smo pojavljivanje kristalnih faza u uzorcima Aplysia punctata (A.p.) starosti 1 do 24 dana. Morfološke promjene koje se događaju prilikom razvoja opažane su u prethodnim radovima rasterskim elektronskim mikroskopom i EDS-om. Potanje su ispitivani uzorci 9 dana stari, koji su bili amorfni prema rendgenskoj difrakciji. Transmisijskom elektronskom mikroskopijom i difrakcijom, grijanjem uzoraka u elektronskom mikroskopu, uočeni su prvi kristalići faza dolomita i aragonita. Prema našim opažanjima biomineralizacija ove vrste morskog zekana (A.p.) odvija se prijelazom amorfnih faza koje sadrže Mg i Ca u dolomit i aragonit.

Transmission electron microscopy (TEM), SAED and HRTEM were used in order to find and locate starting biominerals [1] in the early embryos of the sea hare species Aplysia punctata. The former results obtained by scanning electron microscopy (ESEM) with energy dispersive X-ray analysis (EDS) showed morphological changes during development of numerous (about 40 in each capsule) embryos incorporated in a jelly-like egg-string immediately after deposition on the substratum (in a form of a spaghetti-like tissue) until hatch of the veliger larvae [2]. X-ray diffraction patterns of A. punctata embryos confirmed that the very first aragonite crystals appeared 12 days after egg-strings deposition. Fully formed aragonite crystals [2] were recorded in a further stage of embryo developments even before hatching, which occurred 23 days after deposition. The same series of powdered samples of egg-strings and embryos were also used for TEM, SAED and HRTEM investigation. A special attention was paid to the sample of 9 days old embryos (sample C4 in Figures 1 and 2) that appeared amorphous in XRD (Figure 1d). During observation of the amorphous area A by TEM, the appearance of the precipitation of first grains of a nanocrystalline phase was marked, showing a diffraction effect in SAED. This precipitation of the first nucleated phase was induced by the electron beam in the amorphous phase. Three separate regions were analyzed in order to give confidence of appearance of crystallographic phases. At higher magnification (area of 100x100 nm2), after disappearance of the amorphous area, layers of monocrystalline dolomite in [010] orientation were noticed by SAED (Figure 2). In all regions faint nanocrystalline diffraction rings of calcite or aragonite were observed. It appears from our observation and measurements by SAED that in A. punctata biomineralization process starts by formation of the dolomite crystals which serve as centers of crystallization for further aragonite deposition in the larval shell.

Structural relaxation and crystallization of the Al-(Nb, Mo, Ta, W) amorphous thin films under isochronal and isothermal condition was examined by continuous in situ electrical resistance measurements in vacuum. Films have been prepared by magnetron codeposition in the CMS 18 sputtering system onto various substrates held at room temperature and in a wide range of composition. Average film thickness was from 325 to 400 nm, depending on the film composition. The structure of the as-deposited and heated films was examined by the XRD. The adaptation of the JMA model to the non-isothermal kinetics was used for calculation of kinetic parameter n for both, relaxation and crystallization processes inside the same model. The calculated results indicated that the “ relaxation” kinetic parameter n in AlW amorphous thin films increases from approximately 0.4 to 0.8, while the “ crystallization” kinetic parameter increases from 1.5 to 2.8 with increasing of the aluminum content. For AlMo the “ relaxation” kinetic parameter n vary from 0.5 to 1.0 and the “ crystallization” kinetic parameter increases from 2.0 to 2.6. The results suggests that the relaxation of the Al-(Mo, W) amorphous structure changes interatomic distances and thus increases the chemical short range order (CSR). Due to sp-d hybridization the change in inter-atomic distances strongly affects the electrical properties of Al-(early transition metals) amorphous alloys. This view is strongly supported by the Hall effect results which were measured for Al-W thin films. Preliminary experimental results suggests that relatively high relaxation effects, as observed in the electrical resistivity, in the Al-W and Al-Mo have a maximum for the films with about 70-80 at% Al. Measurements on the Al-W amorphous films have shown that the relaxation effects decrease with an increase of the heating rate. For Al-Nb and Al-Ta amorphous films relaxation effects were not so clear, probably due to the remarkable low crystallization temperatures which are around or below 300OC.

Thin films of AlxNb1-x (95 ≥ x ≥ 20), have been prepared by magnetron codeposition in the CMS-18 sputtering system at room temperature. The structure of the as-deposited films was examined by the XRD and the AlNb films were amorphous in the range of composition from 30% to 85% aluminum content. Al95Nb5, Al90Nb10 and Al20Nb80 films were nanocrystalline. For the purpose of examination of thermal stability the samples were deposited onto glass and alumina ceramics. Thermal stability and phase transformation of the Al-Nb amorphous and nanocrystalline films under isochronal conditions were examined by continuous in situ electrical resistance measurements in vacuum. Estimated values of ρ and α are in accordance with the Mooij correlation, and reflect typical properties of the amorphous alloys containing early transition metals. As determined by the XRD method, the first dominant component after phase transformation is the AlNb3 intermetallic compound for Nb-rich alloys and the Al3Nb intermetallic compound for Al-rich alloys. The rate of extraction of intermetallic phase is dependent on composition. Amorphous Al-Nb films with composition closer to stoichiometric ratio of intermetallic compounds exhibit lower crystallization temperatures.

Karbidi prijelaznih metala, među njima i volframski karbid, odlikuju se nizom osobina koji ih čine tehnološki zanimljivim - visoko talište, ekstremna tvrdoća, mali koeficijent trenja, kemijska postojanost, otpornost na oksidaciju, i dobra električna vodljivost. Stanje površine takvih materijala je kritično u nekim primjenama, te se postupci pripravljanja optimiziraju u tom smislu. Površinske karakteristike (topografija, pripovršinski sloj) niza tankih filmova volfram-ugljik slitina, pripravljenih reaktivnom magnetronskom depozicijom (argon + benzen) na podlogama od monokristalnog silicija, ispitane su metodama GISAXS, AFM i SEM. Uvjeti pripravljanja varirani su u širokom rasponu vrijednosti parametara depozicije: parcijalni tlak benzena u rasponu 1-10% sa ciljem dobivanja W-C filmova sa različitim udjelom nevezanog ugljika. Temperaturom podloge (RT, 200°C, i 400°C) i polarizacijom (-70V) utjecalo se na strukturu filmova: dominantni karbid WC1-x formira se sukcesivno u mikrokristalnoj, nanokristalnoj i amorfnoj fazi kako raste udio ugrađenog ugljika, sa finom disperzijom DLC-čestica između zrna.GISAXS analiza daje 3 nm za veličinu nanozrna. Ista metoda pokazuje da je površina filmova vrlo glatka - hrapavost od 0, 5 nm - sa vrlo kratkom korelacijskom dužinom na površini. AFM rezultati potvrđuju visoku glatkost površine, koja ipak ovisi o uvjetima pripravljanja. Iz AFM rezultata određena je i prosječna veličina zrna na površini - 10-20 nm u promjeru - što površinu daje "ljuskastu" morfologiju. Rezultati pretražne elektronske mikroskopije potvrđuju površinsku topografiju filma, ali otkrivaju i strukturu filma po dubini: postoji pripovršinski sloj debljine 10-20 nm koji se po strukturi jasno razlikuje od osnovnog sloja debljine 200 nm. Osnovni sloj sastoji se od zrna-kolumni promjera 50-100 nm, na kojima je završni/ segregirani sloj finije građe. Ovaj strukturni diskontinuitet neposredno ispod površine nesumnjivo utječe na osobine filmova i otpornost na habanje u mehaničkoj primjeni.

Tanki filmovi AlxNb1-x (95  x  20) dobiveni su magnetronskom depozicijom na sobnoj temperaturi korištenjem uređaja za depoziciju CMS 18. Struktura tek deponiranih filmova ispitana je rentgentskim zračenjem, i ustanovljeno je da su filmovi AlNb amorfni u području od 30% do 85% udjela aluminija, dok izvan tog područja dobivamo nanokristalne strukture. Termička stabilnost i fazne transformacije ispitvane su kontinuiranim in situ mjerenjem električnog otpora pod ne-izotermnim (izokronim) uvjetima pri brzini grijanja od 2 K/min. Svaka promjena u ponašanju otpora koja može značiti i faznu transformaciju sukcesivno je ispitana rendgentskim zračenjem. Analize rentgenograma pokazuju da se kao konačni produkti transformacija amorfnih Al-Nb filmova javljaju intermetalni spojevi Al3Nb odnosno AlNb3, ovisno o sastavu amorfne faze. Brzina izlučivanja intermetalne faze ovisna je o blizini stehiometrijskog omjera aluminija i niobija u sastavu amorfne faze. Promjena otpornosti s temperaturom kod Al-Nb amorfnih tankih filmova pokazuje analogno ponašanje sa sistemima Al-Ta i Al-Mo osobito u kombinacijama sa velikim udjelom aluminija.

The surface features of tungsten-carbon thin films, deposited onto monocrystalline silicon substrates by reactive magnetron sputtering (argon + benzene) has been investigated by GISAXS, AFM and SEM. Benzene partial pressure was varied from 1% to 10% of the total working gas pressure in order to produce W-C films with variable fraction of incorporated unbound carbon. A series of samples were prepared, with the substrate temperature held at RT, 200°C, and 400°C, and the substrate potential held at floating potential or biased -70 V with respect to discharge plasma. Structure of the films is found to be nanocrystalline to amorphous WC1-x as the carbon content increase, with a fine dispersion of DLC-clusters imbedded between nanograins. The GISAXS analysis revealed the particle size of about 3 nm within the films. The same results indicate that the surface of the examined films is rather smooth - surface roughness is about 0, 5 nm, with a very short inplane height-height correlation length. The AFM measurements and SEM results are employed to characterize the surface and subsurface layer of the films, in order to examine a degree of bulk structure propagation to the surface.

Transition metals carbides, and tungsten carbides in particular, exhibit many properties of interest to technology - high metling point, extreme hardness, low friction coefficient, chemical inertness, oxidation resistance, and good electric conductivity. The surface conditions of these materials are critical for some applications, and preparation processes are optimized to meet such requirements. Surface layer of W-C thin films prepared by reactive magnetron sputtering (argon + benzene) on monosilicon substrates has been examined by GISAXS, AFM and SEM methods. Preparation conditions have been varied in a wide range of deposition parameter values: benzene partial pressure in the 1-10% range, substrate temperature in steps RT, 200°C, and 400°C, and beside deposition onto substrates at floating potential a substrate bias of -70 V has been applied . It was found that WC1-x is a dominant carbide in all prepared films, with (111) preferential orientation in films deposited at room temperature. The surplus/unreacted carbon forms a fine dispersion of graphitic nanoparticles imbedded in the intergranular space. The W-C grainsize is determined at about 3 nm by the GISAXS method, with a very smooth surface - roughness about 0, 5 nm - and a very short height-height correlation length at the surface. The AFM examination show roughness depending upon the preparation conditions - from about 0, 5 nm on films prepared at low benzene partial pressure increasing towards a few nanometers when high benzene partial pressure was used. A corresponding average lateral grainsize has been estimated at 10-20 nm, revealing a scale-like morphology of the film surface. The SEM results corroborate the surface morphology, but reveal the subsurface film structure: at the top of the film there is a 10-20 nm thick layer which clearly differs from the main body of the film beneath. The "bulk" of the W-C films (about 200 nm thick) consist of columns 50-100 nm in diameter, atop of which there is a continuous segregated fine-structured layer. The observed structural discontinuity in the prepared W-C films inevitably influence their mechanical properties.

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Relaksacija Al-(Nb, Mo, Ta, W) amorfnih tankih filmova

The extraction of structural parameters of nanocrystalline materials prepared under different conditions is a necessary prerequisite in understanding their properties and possible application in technology. Therefore, their structural features are a widespread subject of research nowadays. However, there are special types of nanocrystalline materials, where the extraction of their structural parameters using conventional diffraction techniques like XRD fails. They are very often thin films, embedded nanosized crystals in glass host, or implanted ions in matrix. In such cases, the selected area electron diffraction (SAED) is the only tool in structural characterization [1]. Here, we present the investigation of commercially available Schott filter glasses with different concentration of CdSxSe1-x quantum dots having different sizes, embedded in a glass host. The samples OG515, OG530, OG550, OG570, OG590, were investigated by transmission electron microscopy and SAED (JEOL 2010 200kV microscope with point resolution 0.19 nm). The numbers next to the letters point out the cut-off wavelength of the glass. The grains of CdSxSe1-x are crystallized in the hexagonal structure of wurtzite type, space group P63mc. The analysis of corresponding SAED pattern (Figure 1(c)), using the formula for hexagonal structure, leads to the lattice parameter values of CdSxSe1-x, a=0.4196 nm and c=0.6857nm.The TEM micrographs indicate the presence of nanocrystallites in the glass matrix, whose sizes are from 2.6 nm (OG515) to 6.7 nm (OG590). The grains are mostly spherical in shape. The size distribution of TiO2 [2] and CdSxSe1-x nanocrystallites obtained by TEM showed a good agreement with the Raman scattering results [3]. In Fig 2, we give the distributions for CdSxSe1-x nanoparticles in an amorphous host A. We used Fourier filtering of HRTEM image (Fig 1(a)) in order to reveal lattice fringes (110) and (102) of CdSxSe1-x, nanocrystallites.

Nanokristalini\v{; ; c}; ; ni materijali dimenzija 1 do 10 nm imaju povoljna svojstva za primjenu u optoelektroni\v{; ; c}; ; kim uredjajima. Nanokristalini\v{; ; c}; ; ni CdS, CdSe i CdS$_x$Se$_{; ; 1-x}; ; $, kada su ugradjeni u amorfnu matricu, nadma\v{; ; s}; ; uju ostale materijale svojom visokom opti\v{; ; c}; ; kom kvalitetom i velikom stabilno\v{; ; s}; ; \'{; ; c}; ; u. Prou\v{; ; c}; ; avali smo komercijalna Schott filter stakla sa nanokristalima CdS$_x$Se$_{; ; 1-x}; ; $ u raznim koncentracijama. Ispitivana je struktura i mikrostruktura ($D= 2.6$ do 6.7 nm) metodama transmisijske elektronske mikroskopije, pogotovo elektronskom difrakcijom. Naime, kod ovih materijala rentgensku difrakciju nije mogu\'{; ; c}; ; e primijeniti tako da je elektronska difrakcija jedina mogu\'{; ; c}; ; a metoda za strukturnu analizu. Rezultati su usporedjeni sa rezultatima dobivenih Raman spektroskopijom. Rezultati pokazuju vrlo dobro slaganje distribucija i srednjih veli\v{; ; c}; ; ina kristalita/\v{; ; c}; ; estica. Time je pokazano, kao \v{; ; s}; ; to smo ve\'{; ; c}; ; prije objavili za druge sisteme, te za slobodne nanokristalne \v{; ; c}; ; estice dobivene ``sol-gel'' metodom [1, 2], da je Raman spektroskopija metoda koja daje izvrsne rezultate pri mikrostrukturnim istra\v{; ; z}; ; ivanjima nanokristalini\v{; ; c}; ; nih materijala.

Tanki filmovi AlxNb1-x (95  x  20), AlxMo1-x (90  x  20), AlxTa1-x (95  x  20), AlxW1-x (50 x  80), dobiveni su magnetronskom depozicijom na sobnoj temperaturi korištenjem uređaja za depoziciju CMS 18. Struktura filmova ispitana je rentgentskim zračenjem, i ustanovljeno je da su filmovi AlNb amorfni u području od 30% do 85% udjela aluminija, dok su potpuno kristalni filmovi Al95Nb5 i Al20Nb80. Filmovi AlMo amorfni u području od 45% do 85% udjela aluminija, a potpuno kristalni filmovi su Al90Mo10 i Al40Mo60. Za AlTa amorfno je područje od 40% do 85% udjela aluminija, a kristalno Al95Ta5 i Al40Ta60. AlW filmovi amorfni su u području od 65% do 80% udjela aluminija, a kristalni su uzorci Al60W40 i Al50W50. Kod svih kombinacija između granica potpuno amorfnih i kristalnih filmova nalazi se područje u kojem su kristalna i amorfna faza mješane. Debljine filmova i naprezanja mjerena su na instrumentu Rank Taylor Hobson Form Talysurf. Debljine uzoraka kreću se prosječno od 325 do 400 nm, ovisno o sastavu. Naprezanja u AlMo i AlNb uzorcima su dominantno vlačnog tipa dok u AlTa naprezanja su dominantno tlačna. Mikrotvrdoća (opterećenje 2mN) mjerena je uređajem Mitutoyo MVK-H2. Mikrotvrdoće AlW i AlTa filmova, u amorfnom području, više su od virjednosti tvrđeg elementa u kombinaciji (W, Ta). Kod AlNb i AlMo filmova tvrdoća je dominantno pod utjecajem tvrđeg elementa i kontinuirano opada sa povećanjem udijela aluminija. Udio elastične energije u tvrdoći kreće se od približno 20% kod AlMo do 60% kod AlTa filmova.

Tanki filmovi AlXTM100-X (TM = Mo, W, Nb i Ta) slitina pripravljeni su kodepozicijom čistog aluminija i čistih prijelaznih metala iz dva nezavisno kontrolirana magnetronska izvora. Filmovi su deponirani na različite podloge (staklo, korund, safir) a debljina ispitanih filmova iznosi oko 400 nm, izuzev AlW filmova čija debljina iznosi oko 2  m. Struktura pripravljenih slitina ispitana je difrakcijom X-zraka. Intervali sastava za koje su dobiveni filmovi amorfni iznose 63≤ x≤ 88 za AlXW100-X slitine, 45≤ x≤ 85 za AlXMo100-X, te 30≤ x≤ 90 za AlXNb100-X i AlXTa100-X slitine. Temperaturna stabilnost amorfnih filmova ispitana je mjerenjem električne otpornosti,   pri izokronom grijanju (dT/dt=2 K/min) na osnovu čega su određene dinamičke temperature kristalizacije, TC. Najstabilnije su amorfne AlW slitine sa temperaturama kristalizacije iznad 500OC, zatim slijede AlMo slitine sa 450OC≤ TC≤ 520OC te AlNb i AlTa slitine sa 300OC≤ TC≤ 400OC. Iz ovoga vidimo da temperature kristalizacija nije moguće direktno korelirati sa širinom intervala sastava u kojem je moguće dobiti amorfne slitine. Električna otpornost amorfnih AlMo i AlW filmova pokazuje izraziti maksimum (1200 odnosno 500   cm) na koncentracijama koje odgovaraju intermetalnim Al3Mo i Al4W spojevima. Nadalje, bez obzira na odsustvo izrazitog maksimuma u otpornosti AlNb i AlTa (

Different methods of X-ray diffraction line profile analysis (XRDLPA) are used to study microstructural parameters such as crystallite size (diffracted domain size), microstrain and texture in tungsten thin films deposited on glass by DC magnetron sputtering at different substrate temperatures and at different working-gas pressures. The whole-pattern analysis within the Rietveld method, the "single-line" method and "double Voigt" method (equivalent to the Warren-Averbach method) are applied and mutually compared. In addition, the results obtained by the Scherrer method are also discussed. The line broadening has been found to be isotropic, supporting the reliability of usage of the Rietveld method in the size-microstrain extraction., Primijenili smo različite metode za analizu profila linija rendgenske difrakcije radi proučavanja mikrostrukturnih parametara, kao što su veličina kristalita (veličina difrakcijskih domena), mikronaprezanja i struktura u tankim slojevima volframa naparenim na staklo magnetronskim DC rasprašivanjem pri različitim temperaturama podloge i radnim tlakovima plina. Primijenili smo cjelovitu analizu spektara Rietveldovom metodom, metodom “jedne linije” i metodom “dvo-Voigta” (jednakovaljanog metodi Warrena-Averbacha) i usporedili ih. Nadalje, raspravljamo i rezultate dobivene Scherrerovom metodom. Nalazimo da je širenje linija izotropno, što potvrđuje pouzdanost primjene Rietveldove metode za izvođenje veličine i mikronaprezanja.

Metastabilne slitine Ag-W se odnedavno ispituju kao podesan materijal za metalizaciju u sub-100 nm integriranim poluvodičima. Zbog potpune nemješljivosti svojih komponenata, takve slitine se moraju pripravljati termodinamički neravnotežnim postupcima. Izložićemo rezultate ispitivanja strukture tankih filmova Ag-W pripravljenih postupkom magnetronskog rasprašenja u širokom rasponu sastava slitine. Tanki filmovi Ag-W slitina pripravljeni su kodepozicijom čistog srebra i čistog volframa iz dva nezavisno kontrolirana magnetronska izvora. Brzina depozicije na podloge (staklo, korund, safir, mono-Si) na sobnoj temperaturi bile je oko 0, 33 nm/s, a konačna debljina filma oko 0, 5 μ m. Ispitan je i utjecaj tlaka radnog plina, te dodatka kisika odnosno aluminija na strukturu slitine odabranog sastava. Kemijski sastav pripravljenih filmova određen je RBS metodom: Ustanovljeno je da stvarni sastav odstupa od nominalnog u korist volframa, i to sve više kako udio volframa u slitini raste. Struktura pripravljenih slitina ispitana je difrakcijom X-zraka: Potpuno amorfni film nije dobiven u ispitanom rasponu sastava Ag94W6-Ag12W88. Prezasićena čvrsta otopina Al(W) sa fcc strukturom formira se pri udjelu volframa

Korozijska otpornost aluminija se znatno povećava legiranjem sa prijelaznim metalima, a molibden je jedan od najučinkovitijih metala u tom pogledu. U ovom radu prikazati ćemo postupak pripravljanja Al-Mo (10-90 at.%) tankih filmova, strukturnu i električnu karakterizaciju, te termičku stabilnost amorfnih Al-Mo slitina. Tanki filmovi Al-Mo slitina pripravljeni su kodepozicijom čistog aluminija i čistog molibdena iz dva nezavisno kontrolirana magnetronska izvora, pri tlaku argona od 5 mtorr. Nominalni kemijski sastav pripravljenih slitina bio je u rasponu od Al90Mo10 do Al10Mo90. Brzina depozicije na različite podloge (staklo, korund, safir, monokristalni silicij) bila je (ovisno o sastavu) 0, 17-0, 35 nm/s, a konačna debljina filmova oko 370-400 nm. Sastav pripravljenih slitina ispitan je RBS metodom, a struktura određena rentgenskom difrakcijom. Električne osobine ispitane su u ovisnosti o sastavu slitine, a termička stabilnost amorfnih slojeva u režimu izokronog grijanja u vakuumu. Naprezanja u filmovima određena su analizom profilometrijskim mjerenja. Potpuno XRD-amorfni filmovi dobiveni su u rasponu sastava Al85Mo15-Al45Mo55 na podlogama držanim na lebdećem potencijalu i sobnoj temperturi. Amorfnost ovih slitina potvrđena je visokim negativnim vrijednostima termičkog koeficijenta električne otpornost (do -13ˇ10-4 K-1) na sobnoj temperaturi, koja se u pojedinim slučajevima i povećava nakon termičke kristalizacije. Amorfne Al-Mo slitine su termički stabilne do oko 460 oC za slitine sa velikim udjelom aluminija pa do oko 530 oC za amorfne slitine sa podjednakim udjelom oba elementa. Mjerenja korozijske otpornosti Al-Mo slitina prije i nakon kristalizacije su u tijeku.

Binary Ni-W (5-25 at % W) alloy coatings (250-310 nm) with good adhesion to alumina ceramic have been prepared by dc magnetron sputtering codeposition method. The obtained films exhibit microcrystalline structure in the examined composition range. Their catalytic properties for the hydrogen evolution reaction (HER) have been investigated in an alkaline electrolyte solution. The kinetic parameters deduced from linear polarization and electrochemical impedance spectroscopy measurements indicated outstandingly high electrocatalytic activity of Ni-W films. The main factor influencing the performance of the Ni-W electrodes as a cathode material in terms of hydrogen evolution in an alkaline solution has been discussed on the basis of intrisic activity of materials as well as the synergistic electronic effects.

The phase transformation and crystallization kinetics of amorphous Al78W22 thin films under isothermal and isochronal conditions was examined by continuous in situ electrical resistance measurments. The results indicate that the crystallization mechanism is a diffusion-controlled process with a quenched-in nuclei during non-isothermal heating, whereas it is a diffusion-controlled process with a steady-state nucleation during isothermal heating.

Nanokristalni nikal (nc-Ni) je vrlo zanimljiv materijal zbog svojih odličnih mehaničkih i korozijskih osobina. S druge strane, ova faza nikla je metastabilna i zagrijavanjem se transformira u uobičajeni krupnozrnati nikal. U ovom radu ispitali smo strukturu i termičku stabilnost nc-nikla pripravljenog postupkom magnetronskog rasprašenja. Tanki filmovi nikla pripravljeni su istosmjernim magnetronskim rasprašenjem na različite dilelektrične podloge (staklo, taljeni kvarc, korund i safir). Rezidualni tlak u radnoj komori bio je u rasponu 10-6 - 10-5 Pa, a radni plin je bio argon u protočnom režimu. Brzina depozicije bila je 7-8 nm/min, a konačna debljina filmova nikla oko 400 nm. Ispitan je utjecaj tlaka argona (0, 33-1, 33 Pa) i temperature podloge (sobna temperatura - 700°C) na strukturu pripravljenih filmova. Struktura pripravljenih i termički tretiranih filmova ispitana je metodom rentgenske difrakcije, dok je površinska topografija ispitana na nanoskopu (AFM). Filmovi nikla deponirani na podloge na sobnoj temperaturi imaju nanokristalnu strukturu: prosječna veličina zrna je u rasponu od 12 nm (pri 1, 3 Pa argona) do 16 nm (pri 0, 35 Pa Ar). Osjetljivost strukture nikla na temperaturu podloge pri depoziciji vidljiva je iz porasta prosječne veličine zrna na oko 75 nm na 150°C, odnosno na 150 nm pri depoziciji na 700°C. Termička stabilnost nc-Ni faze ispitana je izokronim grijanjem uzoraka do 700 °C u vakuumu reda 10-4 Pa kontinuiranim mjerenjem električnog otpora filma. Promjena električnog otpora tijekom prvog grijanja ukazuje na faznu transformaciju oko 170-200 °C - temperaturi koja okvirno odgovara nastupanju abnormalnog rasta zrna u nc-Ni slojevima pripravljenim elektrodepozicijom. Dramatična transformacija odvija se na temperaturama iznad oko 600 °C, pri čemu vrijednost električnog otpora naglo pada, nakon čega temperaturna ovisnost električnog otpora u slijedećim ciklusima grijanje-hlađenje odgovara ponašanju masivnog krupnozrnatog nikla. Rentgenska (Rietveld) analiza potvrđuje da je veličina kristalnih zrna u uzorcima zagrijavanim do 700°C narasla na 75-105 nm.

Different phases of tungsten are produced by magnetron sputtering under different preparation conditions: stable alpha-W phase (b.c.c. structure) is obtained at low working gas pressure, metastable beta-W phase (A15 struc-ture) is obtained at increased working gas pressure, and amorphous-like tung-sten (a-W) is obtained at even higher pressure. The occurence of various phases is related to the oxygen content and built-in stresses in the prepared thin films. We employed these facts to produce tungsten films composed of stacked layers of different tungsten phases. Tungsten multilayers were prepared by sequential deposition of tungsten sputtered under different con-ditions in a cylindrical magnetron device. Working gas pressure was varied in the range of 0, 7 - 3, 5 Pa, and circular substrates (monocrystalline silicon, borosilicate glass) were cooled in contact with the LN2 container. The aver-age current density at the target was kept constant for all depositions, and the particular/single layer thickness was determined by the deposition time. Various combinations of alpha-W layer with beta-W phase or amorphous-like tungsten layer were prepared: simple bilayers, several times repeated bilayers, and inversely-sequenced multilayers. The thickness of single-phase layers was varied, as well. The deposition rate was about 0, 17 nm/s, and the total film thickness range was 50-200 nm. Phase composition of the films was examined by the XRD: The prepared films generally contain stable alpha-W phase layers prepared at low argon pressure, alternating with the layers of metastable beta-W phase or amorphous-like tungsten prepared at 3.5 Pa argon pressure. From the results on single-phased films it is expected that the stress of the layers prepared at 0, 7 Pa is strongly compressive, while the alternating layer is in tensile stress. The stratification of the films was examined by the X-ray re ectancy and GISAXS measurements, using the X-ray beam energy of 8 keV. From the results both total thickness of the prepared films and the thicknesses of the separate layers in a periodic multi-layers were determined. It was found that the tungsten deposition rate at 3, 5 Pa argon pressure is about 15The overall stress in prepared tungsten films results from the opposite stresses of individual layers. However, the effective stress cannot be simply derived from data for single-phase films, probably due to the variation of stress with the layer thickness and the contribution of the interfaces. Profilometric measurements show that by combining several

The properties of dc-magnetron sputtered thin tungsten films depend very strongly on deposition conditions. Depending on Ar gas pressure, substrate material, substrate temperature and deposition duration, there is a different relative amount of beta- and alpha-W phase deposit. In this work tungsten thin films prepared under different conditions of working-gas pressure and deposition temperature were investigated by means of X-ray diffraction (XRD) on a Philips powder diffractometer (PW 1820) and subsequently refined by the Rietveld method. The goal of this work was to investigate the dependence of microstructure and phase composition on deposition condition. Moreover, the microstructure, size and microstrain were extracted by different methods: Rietveld method, single-line method and Warren-Averbach method. The structures were refined in the space group of  -W, Im-3m and  -W, Pm-3n. The quantitative phase composition was estimated from refined values of scale factors according to the procedure of Hill and Howard. It was found that at the deposition temperature of 293 K, on increasing the working-gas pressure, the amount of  -W phase increases. However, at low (77 K) and high (523 K) deposition temperature, on increasing the working-gas pressure, there is a sudden decrease in the amount of  -W phase at 1.4 Pa, then a further increase of working-gas pressure yields to the increase in the amount of  -W phase. The lattice parameters of alpha and beta tungsten film decrease with the increasing of working-gas pressure. The results of size-strain analysis, volume averaged grain size and r.m.s. microstrain obtained by different methods used in this work are in good agreement.

Aluminum-tungsten amorphous alloys seem to be promising materials according to the specific properties of their respective components. However, their thermal stability is essential for any application at sustained elevated temperatures. We have investigated Al-W amorphous alloys thermal stability and variation of mechanical, electrical and corrosion properties up to the crystallization temperature. The Al-W thin films were prepared by simultaneous d.c. sputtering of both pure Al and pure W in a two source sputtering apparatus. The films with composition in the range from Al82W18 to Al62W38 were completely amorphous. Thermal stability of amorphous films was investigated by the continuous in situ electric resistance measurements in a vacuum better than 10-5 mbar. The initial and final structure of the film submitted to the up/down temperature cycle were determined by the XRD method. The Al-W amorphous alloys exhibit high crystallization temperatures (520oC-620oC) within a whole compositional range of amorphicity. A dominant crystallization product is always Al4W. The Al-W films are also rather stable against prolonged annealing at temperatures slightly below crystallization temperature. However, the amorphous films exhibit a pronounced structural relaxation upon first heating at temperatures between about 100oC to 500oC. The relaxation was more pronounced in aluminum-rich alloys, which might be due to specific electronic structure of aluminum. Hall effect measurements support the importance of the sp-d electronic bands hybridization in the examined films. Attempt to minimize relaxation by the increase of substrate temperature during deposition yielded a two-phase films, and the SEM examination revealed a dense population of whiskers at the surface of samples. Microhardness of the as-deposited Al-W amorphous films is about 11 GPa and only slightly depends upon composition. It only marginally increases upon annealing in vacuum up to the crystallization temperatures, while rise of about 20-30% is observed after crystallization. Corrosion resistance of amorphous Al-W alloys was investigated in chloride acid solution and artificial saliva solution. The Al-W thin films are inherently passive materials, and the increase of tungsten content in the alloy increases the resistance against pitting corrosion and lowers the overall rate of corrosion. Thermally crystallized Al-W films exhibit somewhat lower corrosion resistance in comparison with amorphous films. In conclusion, Al-W amorphous thin films are rather thermally stable and exhibit physical properties which make them suitable for certain applications.

The Hall coefficient, RH, electrical resistivity, r, and temperature coefficient of resistivity, a, of AlXW100-X (61 Ł x Ł 88) thin films and amorphous-like tungsten films are reported. The AlXW100-X films have been prepared by magnetron codeposition of pure metals onto glass substrate. Films are X-ray amorphous for 63 Ł x Ł 86. Amorphous-like tungsten films (x = 0) were obtained at different sputtering conditions than those applied for preparation of Al-W alloys. The RH value is strongly dependent upon the alloy composition: it changes sign from positive to negative value at x ť 78, and exhibits a maximum for x ť 68 at%. With the decrease of Al content, r steeply increases and exhibits a maximum at x ť 80 at%. Temperature coefficient of resistivity exhibits large negative values, with a well defined minimum at x ť 80. The Hall coefficient of films with 67 Ł x Ł 80 has also been determined at liquid nitrogen temperature, and the values obtained were the same as the room temperature values. Since the value of electrical resistivity of examined alloys in the temperature interval from 77 to 300 K noticeably changes (10%), a significant anomalous contribution to the Hall effect is thus excluded.

High-energy dry ball-mill and post-anneal processing were applied to synthesize MgTiO3 and Mg2TiO4 single crystalline phases from the predetermined compositions of MgO-TiO2 powder mixtures. Also, the experiments were performed to show that it is possible to prepare MgAl2O4 single crystalline phase from the predetermined composition of MgO-Al2O3 powder mixture only by employing high-energy dry ball milling, i.e. without the post-annealing the milled samples. In contrast, fully developed single crystalline powders of MgTiO3 and Mg2TiO4 were obtained after post-annealing the milled samples for one hour at 900 oC and 1200 oC, respectively.

Phase transformation and crystallization kinetics of the amorphous Al78W22 thin films under isothermal conditions was examined by continuous in situ electrical resistance measurements. The sample preparation was performed by magnetron codeposition. The resistivity of the samples was monitored during isothermal annealing at 803, 813 and 823 K, respectively, i.e. at the temperatures where the crystalline phase starts to develop. The temperature dependence of the resistivity ˆ(T) was estimated from isochronal measure-ments while the volume fraction of crystalline phase ˆ(x, t) was established using a general two phase resistivity model for this system and estimated from isothermal measurements. Combinations of these two approaches were used for modeling of the resistivity variation during cooling cycles. The activation energy for crystallization and the reaction order were determined within the framework of the JMA theory. The results indicated that the crystalliza-tion mechanism in isothermal heating was diffusion–controlled process with steady–state nucleation.

Kinetika kristalizacije i fazna transformacija amorfnog Al78W22 tankog filma promatrana je kontinuiranim in situ mjerenjemm električnog otpora pod izotermnim i neizotermnim (izokronim) uvjetima....

Recently, thin films of amorphous-like tungsten were prepared by the CVD process. We present a preliminary characterization of the amorphous-like tungsten thin films prepared by magnetron sputtering. Thin tungsten films (approx. 0, 2 ? ; m) were prepared by magnetron sputtering of pure tungsten in a cylindrical magnetron device. Working gas pressure was varied in the range of 0, 7 � 3, 5 Pa, and substrates were cooled to LN2. Structure of the films was examined by the XRD and SAXS methods: films prepared at low argon pressure consist predominantly of stable ? ; -W phase, while the metastable ? ; -W prevails in films prepared at 2, 8 Pa argon pressure. The XRD-patterns of tungsten films deposited at 3, 5 Pa argon pressure regularly exhibit only a very broad signal centered at 2? ; ? ; 40? ; - a distinctive mark of amorphous metals and alloys. The grain size of such tungsten material was estimated from the width of this peak to be about 2 nm, which was confirmed by SAXS measurement. Thermal coefficient of the electric resistivity was negative � a characteristic feature of amorphous metals and alloys. Thus, thin tungsten films sputter-deposited onto cooled substrates at 3, 5 Pa argon pressure exhibit the amorphous-like structure. Thermal stability of the amorphous-like tungsten films was investigated by isochronal heating up to 720? ; C in vacuum, with continuous monitoring of electric resistivity. The electric resistivity drops sharply at about 300? ; C, and the XRD-analysis of the samples after a completed thermal cycle confirms a full transformation to the stable ? ; -W phase. The obtained results indicate that considerably thick films of amorphous-like tungsten can be prepared by magnetron sputtering, and that such material exhibits a considerable thermal stability.

Rapid solidification by melt spinning is widely spread method in producing metallic glasses. By varying the quenching rate during melt spinning it is also possible to produce partially crystalline and nanocrystalline alloys. Recently, the alloys that consist of a nanocrystalline phase embedded in the amorphous matrix have attracted a lot of attention because of their potential applications. Also, Zr-based metallic glasses are good candidates for hydrogen storage application. In this work we will give some preliminary results about quench-in structures in Zr76Ni24 alloy depending on quenching rate during melt spinning and the influence of hydrogen storage on the structure. As quenched ribbons (about 0.05 mm thick) prepared by rapid melt solidification on a single-roll spinning copper wheel in an argon atmosphere and heated with the heating rates of 10 K/min and 60 K/min up to temperatures between 563 K and 823 K were investigated by XRD using a PHILIPS PW 1820 diffractometer with Cu Ka radiation. It was found that two sides of the quenched ribbons (in contact with the wheel-the dark side of the ribbon or DSR ; in contact with the inert atmosphere-shiny side of the ribbon or SSR) showed different structures. The diffraction pattern of the DSR shows a broad maximum centred at 2a = 36.1o of dw = 4.2o corresponding to an amorphous phase. A diffraction peak was found to be superimposed on the amorphous pattern and it was found to belong to the (002) peak of a-Zr (hexagonal close packed structure). On the other hand, the XRD pattern of the SSR showed to consist of a set of sharp lines. We were able to fit the peaks to the orthorhombic metastable Zr3Ni phase. The derived lattice constants are as follows: a= (1.098 +- 0.002) nm, b= (0.880 +- 0.001) nm and c= (0.333 +- 0.002) nm. We found that the SSR crystalline layer was relatively thin. After the SSR was abraded for about 0.005 mm and examined with XRD only a broad maximum was present on diffraction pattern, which means that the thickness of the crystalline layer was about 0.005 mm of thickness. We conclude that the existence of the Zr3Ni crystalline phase on the SSR is a consequence of lower quench rate achieved in rapid solidification on this side of ribbon. Some preliminary results about the influence of the absorbed hydrogen up to 4.4 wt. % H on the structure of the ribbons will be also presented.

Izvrsne osobine volframa čine ga podesnim za primjene u obliku tankih filmova. ....

Tanki filmovi volframa se zbog dobrih osobina široko primjenjuju u tehnologiji, a pojava metastabilne beta -W faze čini ih zanimljivim i za znanstvena istraživanja. U ovom radu prikazaćemo rezultate ispitivanja udjela kisika na pojavu beta -W faze u tankim volframskim filmovima pripravljenim magnetronskom depozicijom. Tanki filmovi volframa pripravljeni su na podlogama od stakla i monokristalnog silicija na sobnoj temperaturi. Ispitan je utjecaj tlaka argona (0.7-3.5 Pa), i parcijalnog tlaka kisika u radnom plinu (do 8%) na fazni sastav filmova. Fazni sastav i mikrostruktura ispitani su metodom rentgenske difrakcije. Rezidualno mikronaprezanje i veličina zrna određeni su analizom oblika difrakcijskih linija, a makronaprezanje je određeno iz deformacije podloge uzrokovane nanešenim filmom. Udio kisika određen je mjerenjem produkcije protona u nuklearnoj reakciji 16O (D, p) 17O. U ispitanom rasponu parametara depozicije, pripravljeni filmovi općenito sadrže i stabilnu ? -W fazu (bcc) i metastabilnu A15 ? -W fazu (W3W), a pri 3, 5 Pa dobiva se amorfična a-W faza. Niži tlak radnog plina povećava udio ? -W faze, dok s porastom tlaka raste udio ? -W faze. Pri tome se makroskopsko naprezanje mijenja od jakog tlačnog (- 2 GPa), prolazi kroz ravnotežno pri 2, 5 Pa, i dosiže 0, 5 GPa vlačnog naprezanja pri 2, 8 Pa tlaka radnog plina. Udio kisika raste približno proporcionalno sa radnim tlakom. Da bi razlučili utjecaj kisika na pojavu ? -W faze, kontrolirano je dodavan kisik u radni plin na ukupnom tlaku od 1, 4 Pa. Do oko 14 at.% ugrađenog kisika dobiveni su ? -W filmovi, a iznad 16 at.% svi su filmovi imali amorfičnu strukturu. U uskom rasponu 14-16 at% ugrađenog kisika filmovi sadrže sve tri faze volframa, pri čemu je udio ? -W faze redovito mali. Zaključujemo da je za pojavu ? -W faze osim dovoljne količine ugrađenog kisika (za stabilizaciju) važna i energija deponiranih volframskih atoma koja određuje način rasta filma.

TiO2 is used in many applications such as photovoltaic devices, integrated wave guides, gas and humidity sensors, inorganic membranes, catalyst supports and electrochemical displays. Due to the grain-size dependence of structural parameters of nanocrystalline TiO2 such as: lattice parameters, Debye-Waller factors, microstrain, etc..., it seems obvious to explore this dependence and find smooth function which matches to experimental data. In this work we examined different (undoped and iron-doped) TiO2 samples prepared by the sol-gel route. They were characterised by means of X-ray diffraction measurements (XRD) on a Philips powder diffractometer (PW 1820) and selected area electron diffraction (SAED) by using JEOL JEM 2010 200 kV microscope, Cs=0.5 mm, point resolution of 0.19 nm. The Rietveld refinement of XRD and SAED data was applied in order to extract structural parameters such as unit cell parameters, bond lengths and angles. The obtained XRD patterns were analyzed by the Rietveld method using program FULLPROF [J. Rodriguez-Carvajal, FULLPROF- A program for Rietveld Refinement, Laboratoire Leon Brillouin, CEA-Saclay, France]. The values of refined unit cell parameters a and c of anatase are above/below ICDD values (a0=0.37852 nm, c0=0.95139 nm) within our grain size range (5-12 nm). By the increase of average grain size, the anatase unit cell parameters are approaching to ICDD values obtained from conventional polycrystalline materials. Fitting the relative deviations from ICDD values  a,  c ( a=(a-a0)/a0) to the inverse average grain size 1/D, asumming potential scaling law  a,  c 1/D , we obtained almost linear dependence for parameter c ( =0.9 0.2) and almost squared dependence for parameter a ( =2.0 0.6). Similarly, the fitting of r.m.s. microstrain   2 0.5 to the inverse average grain size yielded to exponent value  =0.7 0.2. The relative deviations from ICDD values  a,  c and r.m.s. microstrain   2 0.5 could be identified as a measure of defects, or more precisely defect concentration cd in nanocrystalline material. A model in which defects are uniformly distributed throughout individual grains, but present in larger concentration with smaller grain-sizes, such that cd 1/D, could be the model which gave the best description of observed grain-sized behaviour of TiO2 prepared by the sol-gel method [Eastman  Fitzsimmons, J. Appl. Phys. 77 (2), (1995) 522-527]. Significant changes of lattice parameters were found between undoped and iron doped samples in parameter a for 0.08 % and c 0.69 % (XRD) and a 1.6 %, c 0.5 % (SAED). The changes are observed in bond lengths and angles.

Nanocrystalline (NC) titania (TiO2) has enhanced mechanical, magnetic and transport properties in comparison to coarse-grained one. For such properties, the deviation from conventional behaviour is a sensitive function of the average grain size and its distribution [1]. Therefore, it is important to measure the average grain size and grain size distribution and correlate them with physical properties of nanocrystalline materials. Two kinds of nanocrystalline TiO2 samples were prepared by the sol-gel method: a) iron doped TiO2 (TiO2 anatase + Fe solid solution and poly(ethylene)glycol) ; b) undoped TiO2 containing anatase and a small amount of brookite [2]. The samples were annealed which gave the average grain size ranging from 3 to 12 nm. TEM and high-resolution transmission electron microscopy (HRTEM) investigations were carried out by using JEOL JEM 2010 200 kV microscope, Cs=0.5 mm, point resolution of 0.19 nm with a beryllium window energy-dispersive (EDS) detector. For each sample the dark-field (DF) image, bright-field (BF) and HRTEM image were recorded and the average grain size was determined by measuring individual grains from captured micrographs. The X-ray diffraction (XRD) measurements of the samples were carried out at room temperature on a Philips powder diffractometer (PW 1820) with monochromatized CuK radiation. The corrections due to the instrumental broadening of diffraction lines were done using XRD pattern of NIST LaB6 crystalline standard. The average grain size and its distribution were determined by means of the direct method using dark-field TEM images taken from (101) nanocrystalline ring of anatase (Figure 1a) by measuring grain diameters in one fixed direction [3]. The corresponding selected area electron diffraction pattern (SAED) consists of characteristic rings for NC materials (Figure 1b). The same analysis was done from complementary bright-field image (Figure 1c), while the average grain size from HRTEM images was determined by measuring grain diameters in a direction perpendicular to the direction of nanocrystalline planes. To calculate the average grain size from broadening of XRD peaks of TiO2 anatase, we applied Rietveld refinement of XRD pattern. The basic assumption for this size-strain analysis is representation of size broadening profile by Lorentzian function and microstrain broadening profile by Gaussian function. The obtained results for hkl dependence of average grain sizes and microstrains show isotropic character of line broadening. The goodnes of fitting was tested by means of values of Rwp, whose values were below 10 %, indicating satisfied fit, which is shown in Figure 1d. Good agreement between the average grain sizes determined by the Rietveld method and TEM (HRTEM) indicates the complementarity of direct and indirect method that we performed in the grain size analysis.