The aim of the optimization of the technological process was to coat the surface of the pigment in a controlled manner and to supress photoactivity in the titanium dioxide (TiO2) pigment. As part of this research, a systematic approach to TiO2 pigment surface treatment with alumina was conducted. Surface treatment with alumina plays a significant role in the improvement of TiO2 properties (e.g. weather resistance and photostability). This research encompasses a raw material analysis and process conditions study. Sodium aluminate and aluminium sulphate were used as a source of alumina hydroxide. The effectiveness of surface treatment was determined using scanning-transmission (STEM) and transmission (TEM) electron microscopy. The photoactivity of pigmentary TiO2 was determined before and after surface treatment. A controlled surface treatment process resulted in pigmentary TiO2 particles with uniform amorphous layers, which supressed the photoactivity of the pigment.
Nanocrystalline rutile TiO2 doped with various amounts of manganese (Mn) atoms was prepared using a hydrothermal synthesis route and a polycrystalline TiO2 precursor. The diffuse reflectance spectra of the highly doped rutile nanocrystallites display a notable red shift in the band-gap transition. The absorbing band edge moved to the visible range when the Mn content in the rutile nanocrystallite exceeded 0.4 %. The doped rutile nanocrystallites were analysed using X-ray powder diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and UV-Vis spectroscopy. The Kubelka-Munk band-gap approximation was used to examine the narrowing of the band gap in comparison with the pure rutile TiO2 nanocrystallites. The doped rutile nanocrystallites displayed a remarkable decrease in the photocatalytic activity due to the formation of recombination sites induced by Mn ions incorporated into the crystal structure of the TiO2. Keywords: suspension, TiO2, rutile, doped with inorganic metal elements, UV absorber Z uporabo hidrotermalne sinteze in polikristalinini~ne rutilne oblike nanodelcev TiO2, smo pripravili nanokristalini~ne rutilne delce, dopirane z Mn. S pomo~jo UV-VIS difuzivno refleksijske spektroskopije smo zaznali izrazit premik absorpcijskega roba k valovnim dol`inam vidne svetlobe. Energijska vrzel z Mn dopiranega TiO2 se je z nara{~anjem koncentracije dopanta o`ala. Za analizo dopiranih rutilnih TiO2 nanodelcev smo uporabili rentgensko pra{kovno difrakcijo (XRD), elektronsko mikroskopijo (TEM, HRTEM), UV-Vis spektroskopijo, kalkulacijo energijskih vrzeli s Kubelka Munk pribli`kom. Pri merjenju fotokatalitske aktivnosti, z metodo degradacije izopropanola v alkohol, smo ugotovili, da dopiranje rutilne oblike TiO2 z Mn povzro~i inhibicijo fotokatalitske aktivnosti, kar smo pripisali tvorbi rekombinacijskih centrov, ki nastanejo pri dopiranju z Mn ioni v kristalno re{etko TiO2.
Dobra opremljenost in ergonomska pravilnost učilnice za Tehniko in tehnologijo sta osnovna dejavnika pri izvajanju praktičnega dela pouka, zato je pomembno, da je učitelj s predpisi o opremi učilnice dobro seznanjen. V teoretičnem delu so predstavljeni zakoni in dokumenti, ki zadevajo opremljenost učilnic za Tehniko in tehnologijo ter analiza dokumentov, ki predpisujejo potrebna orodja, stroje in pripomočke v delavnicah. V empiričnem delu je bila izvedena raziskava o prostorskih pogojih v učilnicah za Tehniko in tehnologijo, njihovi opremljenosti ter zadovoljstvu učiteljev Tehnike in tehnologije s trenutnim stanjem v učilnicah. Podatki so bili pridobljeni s pomočjo spletnega vprašalnika, na katerega vprašanja je odgovarjalo 128 učiteljev iz vse Slovenije. Analiza pridobljenih podatkov je pokazala, da obstajajo velike razlike med normativi za prostorske pogoje in priporočili o opremljenosti učilnic ter dejanskim stanjem učilnic. Na podlagi teoretičnih izhodišč in raziskave v empiričnem delu lahko za učinkovito izboljšanje stanja predlagamo, da se veljavni dokumenti posodobijo in poenotijo. V njih je potrebno jasno določiti minimalne zahteve za orodja, stroje, opreme, učil in pripomočkov, ki se morajo nahajati v vseh učilnicah.
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