Electrochemical deposition of niobium from fluoride solution and chloroaluminate melts on glassy carbon, platinum and gold

Cilj ovog rada bio je da se ustanovi da li dolazi do elektrohemijskog taloženja niobijuma i aluminijuma iz hloroaluminatnih rastopa obogaćenih niobijumom na podlogama od staklastog ugljenika, platine i zlata. Nadalje, ako dolazi do rečenog taloženja, da li pri tome dolazi i do formiranja legura niobijuma sa izabranim podlogama kao i da li dolazi do formiranja legura niobijuma sa zajednički taloženim aluminijumom. I na kraju, cilj je bio da se navedeni fenomeni ostvare na što nižim temperaturama. Nb i Al su elektrohemijski taloženi na staklastom ugljeniku, platini i zlatu pri 200 °C, pod atmosferom argona, iz rastopa napravljenog od ekvimolarne smeše AlCl3 + NaCl kome je dodat niobijum. U istraživanjima su korišćene: linearna i ciklička voltametrija, metoda potenciodinamičke polarizacione krive, metoda „otvorenog kola“, hronoamperometrija, SEM, EDS, AFM i XRD analiza. Elektrohemijsko taloženje Nb i Al iz primenjenih rastopa pri potpotencijalima uočeno je na podlozi od zlata. Taloženje niobijuma pri potpotencijalima na zlatu je novost, a taloženje Al na zlatu pri potpotencijalima poznato je od ranije. Elektrotaloženje Al i Nb iz primenjenih rastopa pri potpotencijalu na zlatu prethodi procesima elektrotaloženja niobijuma i aluminijuma pri natpotencijalima. Rezultat ovih procesa su Nb/Au i Al/Au legure nastale zajedničkim taloženjem i interdifuzijom istaloženog Nb, odnosno Al i podloge - zlata (AlAu, AlAu2 , AlAu4, AlNb2 , AlNb3 , Au2Nb, Au2Nb3 , AuNb3 , AlNb3). Elektrohemijsko taloženje Nb iz primenjenih rastopa pri potpotencijalima uočeno je na platini i prethodi procesima elektrotaloženja Nb i Al. Rezultat su formirane Nb/Pt legure nastale interdifuzijom istaloženog Nb i podloge - platine (Nb3Pt). Pri natpotencijalima aluminijuma na platini dolazi do taloženja metalnog niobijuma, metalnog aluminijuma i zajedničkog taloženja Nb i Al. Kao posledica ovih procesa dolazi i do formiranja legura (AlNb3, Al3Pt5 , Nb3Pt). Elektrohemijsko taloženje niobijuma iz primenjenih rastopa na izabranim podlogama odigrava se na potencijalima koji su pozitivniji od potencijala elektrotaloženja aluminijuma. Sve dobijene legure formirane su pri temperaturi od 200 °C što je nekoliko stotina stepeni niže od odgovarajućih temperatura potrebnih da se formiraju termičkim putem.The aim of this study was to establish electrodeposition of niobium and aluminium from chloroaluminate melt (AlCl3 + NaCl) enriched with niobium onto gold, platinum and glassy carbon substrates. Furthermore, if such deposition is shown to occur, to assess if it can lead to formation ofniobium alloys with chosen substrates or formation of Nb/Al alloys as a result of codeposition. And finally, if the deposition is indeed confirmed, to establish the lowest operational temperature at which it is possible. Niobium and aluminium were electrodeposited onto glassy carbon, gold and platinum at 200 °C, under an argon atmophere from the melt made of equimolar mixture AlCl3 + NaCl with niobium being added. Research methods used were: cyclic voltammetry, potentiodynamic polarization curves, "open circuit”, chronoamperometry, SEM, EDS, AFM and XRD analysis. Underpotential deposition of Nb and Al from the melt onto gold substrate was observed. Of the two, niobium deposition is a novelty, while alumininum deposition has been previously studied. Underpotential deposition of NB and Al onto gold from given melt precedes the overpotential deposition of aluminium and niobium onto gold. The result of these processes are Nb/Au and Al/Au alloys formed by codeposition of the two metals and interdiffusion between the Nb and Al deposits and the substrate -gold (AlAu, AlAu2, AlAu4, AlNb2, AlNb3, Au2Nb, Au2Nb3, AuNb3, AlNb3). Underpotential deposition of niobium onto platinum from used melts was recorded and it precedes the processes of overpotential deposition of niobium and aluminium. The result is formation of Nb/Pt alloys as a consequence of interdiffusion between the substrate and the deposited Nb (Nb3Pt). The potentials more negative than the aluminium deposition potential in the used system lead to deposition of niobium and aluminium individually and jointly. Thus, a number of alloys are formed (AlNb3, Al3Pt5, Nb3Pt). Niobium electrodeposition onto chosen substrates from the melt applied takes place at potentials which are more positive than the potential of electrodeposition of aluminium. Formation of the obtained alloys occurred at a temperature of 200 °C which is several hundred degrees lower than the temperatures needed for their formation by thermal methods

On Responsibility in University Teaching: Aspects Contributing to the Enhancement of Teaching Quality Provided at Universities

This paper will highlight the intrinsic link between university educators’ general responsibilities and the three domains of responsibilities. The text initially presents perspectives regarding responsibility and the act of teaching. It is then followed by an analysis of the concept of responsibility in teaching, which is examined across three distinct domains: the domain of encouraging students’ curiosity, the domain of keeping abreast of the prospective career requirements for students, and the domain of language usage. In brief, it is crucial to enhance teachers' sense of responsibility toward their students, as it can ultimately result in enhanced academic achievement and personal development for students

Tailoring of MgO/Mg(OH)2 structures by molten salt electrolysis

The magnesium oxide (MgO)/magnesium hydroxide (Mg(OH)2) nanostructures aside from showing high surface area, good thermal, electrical, optical and chemical characteristics, are also low-cost materials of benign nature with minimal environmental impact, which make them suitable for various application. Due to their specific properties magnesium oxide and magnesium hydroxide are used in medicine, sensors, solar cells, drinking and waste water treatments. Depending on the in advance planned application, considerable attention should be paid to the formation of appropriate magnesium oxide/hydroxide composition and surface morphology. Herein, a novel approach was used to the synthesis of MgO/Mg(OH)2 structures by electrochemical deposition from magnesium nitrate hexahydrate melt onto glassy carbon. Galvanostatic and potentiostaic regimes of electrolysis were employed for direct formation of magnesium oxide. Morphology of the composed structures were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). Analysis of the deposits made by both electrolysis regimes recognized formation of magnesium oxide as well as magnesium hydroxide. Comparative study of the deposits morphology showed that nano-sized needles and holes are produced by applied electrodepositions. Most of the needles formed participate in flower-like shapes. The holes observed in the deposit are a product of the hydrogen evolution and in the number, shape and size strongly depend on the deposition parameters applied. During controlled working potential or current density, the detached hydrogen bubbles produced different types of deposit structures, from dish-like to those of the honeycomb-like shape. Formation mechanism of the observed deposits is discussed.Invited lecture, [http://sitzam.org.rs/YUCORR/

LESSON STUDY MODEL APPLICATION IN THE FIELD OF TEACHING MUSIC AND STUDENT COMPETENCIES

These articles are a result of the bilateral cooperation project ”Assumptions and possibilities of developing innovative models of teaching for accomplishing transparency of university education and for raising competitiveness in national and international knowledge markets”, carried out and financied by the University of Kragujevac, Faculty of Education, Jagodina (Republic of Serbia) and the University of Primorska, Faculty of Education, Koper (Republic of Slovenia), in the period 2017–2019.This paper considers the possibilities of applying the Japanese Lesson Study Model in the process of teaching music to future kindergarten teachers. Given the artistic character of the subject and diverse music abilities of students, the aim of this paper is to explore the possibility of applying the Lesson Study with regard to students’ personal feelings toward competencies to prepare and perform activities during the music lesson. Research results show that student competencies acquired during formal education are sufficient for preparation and performance of activities, but that differences in experiencing competencies can be spotted within individual parameters. According to the attitudes of future teachers, the application of the Lesson Study in teaching music would yield positive results in the context of improving their social competences, self-assurance and confidence when performing music, their ability for collaborative work and some aspects of the teaching method.Publishe

Electrochemical deposition of niobium from fluoride solution and chloroaluminate melts on glassy carbon, platinum and gold

Cilj ovog rada bio je da se ustanovi da li dolazi do elektrohemijskog taloženja niobijuma i aluminijuma iz hloroaluminatnih rastopa obogaćenih niobijumom na podlogama od staklastog ugljenika, platine i zlata. Nadalje, ako dolazi do rečenog taloženja, da li pri tome dolazi i do formiranja legura niobijuma sa izabranim podlogama kao i da li dolazi do formiranja legura niobijuma sa zajednički taloženim aluminijumom. I na kraju, cilj je bio da se navedeni fenomeni ostvare na što nižim temperaturama. Nb i Al su elektrohemijski taloženi na staklastom ugljeniku, platini i zlatu pri 200 °C, pod atmosferom argona, iz rastopa napravljenog od ekvimolarne smeše AlCl3 + NaCl kome je dodat niobijum. U istraživanjima su korišćene: linearna i ciklička voltametrija, metoda potenciodinamičke polarizacione krive, metoda „otvorenog kola“, hronoamperometrija, SEM, EDS, AFM i XRD analiza. Elektrohemijsko taloženje Nb i Al iz primenjenih rastopa pri potpotencijalima uočeno je na podlozi od zlata. Taloženje niobijuma pri potpotencijalima na zlatu je novost, a taloženje Al na zlatu pri potpotencijalima poznato je od ranije. Elektrotaloženje Al i Nb iz primenjenih rastopa pri potpotencijalu na zlatu prethodi procesima elektrotaloženja niobijuma i aluminijuma pri natpotencijalima. Rezultat ovih procesa su Nb/Au i Al/Au legure nastale zajedničkim taloženjem i interdifuzijom istaloženog Nb, odnosno Al i podloge - zlata (AlAu, AlAu2 , AlAu4, AlNb2 , AlNb3 , Au2Nb, Au2Nb3 , AuNb3 , AlNb3). Elektrohemijsko taloženje Nb iz primenjenih rastopa pri potpotencijalima uočeno je na platini i prethodi procesima elektrotaloženja Nb i Al. Rezultat su formirane Nb/Pt legure nastale interdifuzijom istaloženog Nb i podloge - platine (Nb3Pt). Pri natpotencijalima aluminijuma na platini dolazi do taloženja metalnog niobijuma, metalnog aluminijuma i zajedničkog taloženja Nb i Al. Kao posledica ovih procesa dolazi i do formiranja legura (AlNb3, Al3Pt5 , Nb3Pt). Elektrohemijsko taloženje niobijuma iz primenjenih rastopa na izabranim podlogama odigrava se na potencijalima koji su pozitivniji od potencijala elektrotaloženja aluminijuma. Sve dobijene legure formirane su pri temperaturi od 200 °C što je nekoliko stotina stepeni niže od odgovarajućih temperatura potrebnih da se formiraju termičkim putem.The aim of this study was to establish electrodeposition of niobium and aluminium from chloroaluminate melt (AlCl3 + NaCl) enriched with niobium onto gold, platinum and glassy carbon substrates. Furthermore, if such deposition is shown to occur, to assess if it can lead to formation ofniobium alloys with chosen substrates or formation of Nb/Al alloys as a result of codeposition. And finally, if the deposition is indeed confirmed, to establish the lowest operational temperature at which it is possible. Niobium and aluminium were electrodeposited onto glassy carbon, gold and platinum at 200 °C, under an argon atmophere from the melt made of equimolar mixture AlCl3 + NaCl with niobium being added. Research methods used were: cyclic voltammetry, potentiodynamic polarization curves, "open circuit”, chronoamperometry, SEM, EDS, AFM and XRD analysis. Underpotential deposition of Nb and Al from the melt onto gold substrate was observed. Of the two, niobium deposition is a novelty, while alumininum deposition has been previously studied. Underpotential deposition of NB and Al onto gold from given melt precedes the overpotential deposition of aluminium and niobium onto gold. The result of these processes are Nb/Au and Al/Au alloys formed by codeposition of the two metals and interdiffusion between the Nb and Al deposits and the substrate -gold (AlAu, AlAu2, AlAu4, AlNb2, AlNb3, Au2Nb, Au2Nb3, AuNb3, AlNb3). Underpotential deposition of niobium onto platinum from used melts was recorded and it precedes the processes of overpotential deposition of niobium and aluminium. The result is formation of Nb/Pt alloys as a consequence of interdiffusion between the substrate and the deposited Nb (Nb3Pt). The potentials more negative than the aluminium deposition potential in the used system lead to deposition of niobium and aluminium individually and jointly. Thus, a number of alloys are formed (AlNb3, Al3Pt5, Nb3Pt). Niobium electrodeposition onto chosen substrates from the melt applied takes place at potentials which are more positive than the potential of electrodeposition of aluminium. Formation of the obtained alloys occurred at a temperature of 200 °C which is several hundred degrees lower than the temperatures needed for their formation by thermal methods

Aluminium electrodeposition onto glassy carbon from deep eutectic system made of AlCl3+urea

Electrochemical deposition of aluminium onto glassy carbon from deep eutectic solvent (DES), made of the AlCl3+urea, at 25-50°C have been investigated. The deposition was performed in potentiostatic mode. The morphology of the obtained deposits were characterized using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Critical overpotential of aluminium deposition decreased from around – 0.150 V at 25°C to around – 0.100 V at 50°C. All recorded currents were small but would substantially increase with increasing working temperature (from 0.01 mA cm-2 up to 0.25 mA cm-2). The deposits obtained showed variety of morphological shapes depending on the working temperature and potential applied. All the deposits were made of very small crystallites grouped randomly into more or less separate agglomerates. Density of the crystallites distribution over the substrate and complicity of the crystal forms increased with the potential applied. Electrodeposition/dissolution of aluminium in used electrolyte onto used substrate obviously promises positive results if research aiming at reversible systems of such composition working at temperatures very close to room temperature.Ispitivano je elektrohemijsko taloženje aluminijuma na staklastom ugljeniku iz eutektičke smeše (DES), AlCl3+urea, na temperaturama od 25-50°C. Elektrotaloženje je izvođeno potenciostatski. Morfologija dobijenih taloga je analizirana skenirajućom elektronskom mikroskopijom (SEM) i energetsko disperzivnom spektroskopijom (EDS). Kritične prenapetosti elektrotaloženja aluminijuma kretale su se od oko – 0.150 V pri 25°C do oko – 0.100 V pri 50°C. Zabeležene gustine struje bile su male, ali su njihove vrednosti značajno rasle sa povećanjem radne temperature (od 0.01 mA cm-2 do 0.25 mA cm-2 uz povećanje temperature od 25°C do 50°C). Dobijeni talozi pokazali su raznovrsne morfološke oblike što je zavisilo od primenjene temperature i potencijala. Svi talozi sastojali su se od veoma malih kristala objedinjenih u aglomerate koji su bili nasumično raspoređeni po površini radne electrode. Gustina rasporeda kristalita po površini elektrode i njihova pojedinačna raznovrsnost po obliku rasle su sa povećanjem primenjenog potencijala. Elektrohemijsko taloženje/rastvaranje aluminijuma u upotrebljenom elektrolitu i na upotrebljenoj podlozi obećava pozitivne rezultate u istraživanjima usmerenim na reverzibilne sisteme istog ili sličnog sastava koji bi trebalo da rade na temperaturama veoma bliskim sobnoj

Creative Ability of Students as a Precondition for the Successful Development of Children’s Musical Creativity in Teaching Music in Lower Grades of Primary School

The effectiveness of teaching music in lower grades of primary school depends on competences of pre-service and in-service teachers who have to teach the subject curriculum. During their formal education, student teachers at pedagogical faculties acquire elementary knowledge of the theory of music and didactic-methodical competencies, but the important factor of successful teaching has to be their musical-performing and creative abilities. In this paper we examine the musical and creative abilities of student teachers in the final year of their bachelor studies (N = 48), by analyzing their products within the course of the Methodological Practicum of Music Teaching. Descriptive method and procedure of qualitative analysis of obtained student teachers’ products in the field of music creation were used. The results show that student teachers’ musical and creative abilities and the quality of their creative products do not exceed the level of curriculum requirements for teaching music in the fourth grade of primary school. The aim of this paper is to determine the level of creativity aptitude of student teachers in order to improve it by adequate methodical procedures and training in order to achieve an optimal level sufficient for developing musical and creative activities in teaching young children in a regular school context. On the basis of the obtained results, it can be concluded that frequent neglect of work in the field of developing children’s musical creativity in music teaching practice is connected with teachers’ insecurity about their own creative abilities and competencies necessary for teaching music.Publishe

Aluminum/zirconium alloys obtained by Al underpotential deposition onto Zr from low temperature AlCl3+NaCl molten salts

Contrary to the widely accepted hypothesis that it is not possible, aluminum underpotential deposition (UPD) onto zirconium from a low temperature (200, 250 and 300 °C) equimolar chloroaluminate melt was recorded. Furthermore, it was shown that aluminum UPD facilitates alloy formation between the deposited aluminum monolayer and the zirconium substrate by interdiffusion. The aluminum/zirconium alloys formed at temperatures substantially lower than those needed for thermal preparation of the same alloys were Al3Zr2 and Al3Zr. The experimental techniques linear sweep voltammetry, potential step, scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction were used for the characterization of the obtained electrode surfaces

Alloy formation by mg under-potential deposition on al from nitrate melts

Magnesium was underpotentially deposited on aluminium electrodes from magnesium nitrate-ammonium nitrate melts at temperatures ranging from 390 to 500 K. The electrochemical techniques used were linear sweep voltammetry and potential step. Electrodes were studied by scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). It was found that reduction processes of nitrate, nitrite and water (when present), in the underpotential range studied, took part simultaneously with magnesium underpotential deposition. Consequently, magnesium UPD reduction and stripping voltammetry peaks were not pronounced and well defined. Nevertheless, EDS, EDX and XRD measurements showed evidence of Mg2Al3, MgAl2 and Al12Mg17 alloys formed by underpotential deposition of magnesium onto aluminium substrate

Aluminium electrodeposition onto glassy carbon from deep eutectic system made of AlCl3+urea

Electrochemical deposition of aluminium onto glassy carbon from deep eutectic solvent (DES), made of the AlCl3+urea, at 25-50°C have been investigated. The deposition was performed in potentiostatic mode. The morphology of the obtained deposits were characterized using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Critical overpotential of aluminium deposition decreased from around – 0.150 V at 25°C to around – 0.100 V at 50°C. All recorded currents were small but would substantially increase with increasing working temperature (from 0.01 mA cm-2 up to 0.25 mA cm-2). The deposits obtained showed variety of morphological shapes depending on the working temperature and potential applied. All the deposits were made of very small crystallites grouped randomly into more or less separate agglomerates. Density of the crystallites distribution over the substrate and complicity of the crystal forms increased with the potential applied. Electrodeposition/dissolution of aluminium in used electrolyte onto used substrate obviously promises positive results if research aiming at reversible systems of such composition working at temperatures very close to room temperature.Ispitivano je elektrohemijsko taloženje aluminijuma na staklastom ugljeniku iz eutektičke smeše (DES), AlCl3+urea, na temperaturama od 25-50°C. Elektrotaloženje je izvođeno potenciostatski. Morfologija dobijenih taloga je analizirana skenirajućom elektronskom mikroskopijom (SEM) i energetsko disperzivnom spektroskopijom (EDS). Kritične prenapetosti elektrotaloženja aluminijuma kretale su se od oko – 0.150 V pri 25°C do oko – 0.100 V pri 50°C. Zabeležene gustine struje bile su male, ali su njihove vrednosti značajno rasle sa povećanjem radne temperature (od 0.01 mA cm-2 do 0.25 mA cm-2 uz povećanje temperature od 25°C do 50°C). Dobijeni talozi pokazali su raznovrsne morfološke oblike što je zavisilo od primenjene temperature i potencijala. Svi talozi sastojali su se od veoma malih kristala objedinjenih u aglomerate koji su bili nasumično raspoređeni po površini radne electrode. Gustina rasporeda kristalita po površini elektrode i njihova pojedinačna raznovrsnost po obliku rasle su sa povećanjem primenjenog potencijala. Elektrohemijsko taloženje/rastvaranje aluminijuma u upotrebljenom elektrolitu i na upotrebljenoj podlozi obećava pozitivne rezultate u istraživanjima usmerenim na reverzibilne sisteme istog ili sličnog sastava koji bi trebalo da rade na temperaturama veoma bliskim sobnoj