TRIVEDI, R. Studium povrchů tenkovrstvých materiálů [online]. Brno: Vysoké učení technické v Brně. Fakulta chemická. 2011.
Rutul Trivedi nastoupil do doktorského studijního programu v září 2006. V oblasti rastrovací sondové mikroskopie (SPM) do té doby nepracoval. Do problematiky SPM a nanoindentace byl proškolen v rámci týdenního kursu profesionálními pracovníky. Pod vedením zkušenějšího kolegy se postupně propracovával k samostatné činnosti. V průběhu studia zvládl využití techniky AFM, částečně Kelvinovu sondu (KPM), AFAM, nanoindentaci a vrypovou zkoušku. V rámci měsíční stáže v USA pracoval na jiném typu nanoindentačního zařízení. Podílel se na řešení řady odborných projektů: " Projekt evropské spolupráce (COST P12, 1P05OC087, MŠMT) Vytváření struktur plazmových polymerů " Rozvoj plazmochemických procesů pro vývoj inteligentních polymerních nanostruktur (GAČR 104/06/0437) " Nanokompozitní vrstvy a nanočástice vytvářené v nízkotlakém plazmatu pro povrchové modifikace (Nanotechnologie pro společnost, KAN101120701, AVČR) Rutul Trivedi při své práci prokázal přiměřený stupeň samostatnosti při zvládání experimentálních technik a vyhodnocení naměřených dat. Jeho práce je přínosem k rozvoji oboru a přinesla nové a zásadní poznatky prezentované na konferencích a v časopisech. Podílel se na publikacích prezentovaných ve 4 impaktovaných časopisech a 6 konferenčních sbornících. R. Trivedi splnil své studijní povinnosti stanovené studijním plánem. Práce splňuje kritéria kladená na disertační práci a doporučuji ji přijmout k obhajobě.
The thesis is devoted to a field of plasma polymerized coatings which find important applications in a number of industrial areas. The author aimed at an ambitious goal of relating the depositions and resulting film properties to the nanostructure and nanomechanical properties. The author has selected a class of organosilicon precursors and used them to deposit plasma polymerized samples which he then measured by an impressive range of experimental tools (ranging from various AFM modes to nanoindentation and scratch testing). In addition, he used the sectioning for profiling the layers in order to probe different parts of multilayers. The author had to overcome a number of difficulties which have to be expected. Plasma polymerized films exhibit a wide variety of structures and the advanced mesurement methods also present a number of challenges (temperature drifts, creep, artefacts etc.). In the chapter 2 the thesis reviews current state of research on about 30 pages. The review is adequate for the purpose, including references to 89 papers or books. The chapter 3 describes the preparation of the samples and measurement procedures. I appreciate the care which was taken to stabilize the plasma in the helical system before the start of the actual deposition - this step surely improves the reproducibility of the sample preparation and allows for easier interpretation of the results. I would expect that the transition of the plasma conditions would also occur for the capacitive system, but it seems that here it was not possible to use the same procedure. The chapter 4 describes the results of the various experiments. However, I found this chapter difficult to follow. I missed a table of the all samples which are discussed (in this way it is difficult for the reader to judge the number of samples, compare the range of deposition parameters etc.). Instead there is paragraph about thin film preparation on p. 57, 59 and again on p. 70. I also did not like that even in the chapter 4 author repeats again introductory sentences about the instruments (e.g. p. 59 the Hysitron Triboscope). Finally, the chapter 5 (Conclusion) should in my opinion be divided into two parts: discussion and proper conclusions. Some of the results presented are indeed interesting, e.g. the procedure for reducing the drift for the nanoindentation using the prolonged tip-sample contact prior to measurement. The comparison between the cyclic and conventional nanoindentation and their agreement (Fig. 38) allows for much more rapid testing of the films. The formation of the circular grains on the surfaces seen for example in the Figs. 43, 44 and described on page 73 is surprising. The thesis is written in reasonably good English, although at some places the text is quite awkward. There is a quite large number of typing and/or grammatical errors in the text and figures (e.g. Fig. 3). In some cases I was not even sure what is meant: for example the word "demesnes of chemical composition" on p. 16. Other important mistakes would be for example: " p. 10: "Temperature more than a few thousand centigrade ... " the centigrade temperature scale is not in use anymore. " p. 17 The name of principal inventor of STM was Binnig, not Binning, " p. 17 Nobel price (not Noble price) " p. 17 Electrically conducting (not Eclectically conducting) " The results of the polynomial fit on the page 35 are given with precision which is not physically possible, with no estimate of the expected errors. " p. 40 Helical = inductive coupling (not capacitive) " p. 51 patented technology (not pattern technology) I have noticed that the language of the text in the chapter 4 and in the conclusions seemed to be a lot better than in the introductory chapters (perhaps because the author concentrated to this part more). The general assessment of the thesis is that the author has performed number of advanced experiments, obtained new experimental facts and thus fulfilled the goals for the thesis. Part of the results have been published in an international journal [Cech V, Cechalova B, Trivedi R, et al: Single layer and multilayered films of plasma polymers analyzed by nanoindentation and spectroscopic ellipsometry, THIN SOLID FILMS Vol. 517 Issue: 21 Pages: 6034-6037, Published: SEP 1 2009]. It should be pointed out that this already is an achievement which makes the thesis stand above the average. On the other hand the work which aspires to the truly international level has to be judged correspondingly. In this respect, I was left with an impression that with a little more care the thesis could be a lot better, especially as concerns the presentation of the results. Finally, I would like to state that in spite of the questions and reservations expressed above I consider the thesis to fulfil the requirements for the Ph.D. thesis and recommed it for the defence.
Práce se zabývá problematikou studia morfologie a povrchových vlastností tenkých vrstev a vrstevnatých systémů, se zvláštním zřetelem na mechanické vlastnosti, studované metodou nanoindnentace a vrypové zkoušky. Pro studium byly využity systémy připravené plazmovou depozicí přímo na pracovišti FCh VUT, práce je tedy začleněna do šíře řešené problematiky plazmové modifikace povrchů, depozice vrstev a jejich charakterizace, což jistě ovlivnilo jak formulaci tématu práce, tak výběr studovaných vzorků. Práce je přehledně členěna, a to následujícím způsobem: v úvodní teoretické kapitole (kapitola 2, 29 stran) jsou zmíněny základní principy použitých experimentálních metod (PECVD, AFM, nanoindentace), a to velmi přehledně, nicméně v rozsahu nepřekračujícím úroveň přehledových článků či manuálů k jednotlivým experimentálním zařízením. V kapitole popisující experiment (kapitola 3, 18 stran), je popsána experimentální aparatura použitá pro vytváření vrstev, následovaná podrobným popisem zařízení pro měření pomocí AFM a nanoindentaci, včetně podrobného pracovního postupu. Vlastní experimentální výsledky autora jsou popsány v nejrozsáhlejší kapitole 4 (53 stran), jsou rozčleněny podle studovaných systémů a představují hlavní přínos autora k problematice. Obsah práce je přes uvedené výhrady nepochybně přínosem pro pracoviště FCh VUT a výsledky si zasluhují publikaci v mezinárodních časopisech (některé již byly zřejmě publikovány). Autor také beze zbytku splnil přiložené zadání práce a tím prokázal svou schopnost samostatně provést a vyhodnotit poměrně složité experimenty. Navrhuji proto práci doporučit k obhajobě a po zodpovězení výše uvedených otázek k udělení akademického titulu doktor.
The thesis is aimed at the study of surface properties of single layers and multilayers deposited from monomers in a plasma environment. The main goal of the work was to become acquaint with deposition techniques and their optimization in order to prepare films of required properties. To deposit the films a plasma enhanced chemical vapour deposition technique (PE CVD) utilizing vinyltriethoxysilane and tetravinylsilane monomers were applied. The thin film properties as their surface morphology and mechanical properties were studied by various methods of scanning probe microscopy, nanointendation techniques and nanoscratch tests. In this way the optimization of the prepared thin films has been achieved. The topic of the thesis is complex and reflects the world-wide activities in materials science of these perspective plasma-polymerized organosilicon films. It is in the line of contemporary methods and approaches. The technique used in the work meets high-level international standards. The student also has brought novel approaches into the studied subject, for instance investigation of depth profiles of multilayered films by sectioning methods. The student had to study various technological and characterization methods, carried out a lot of time demanding experiments and to analyze and interpret their results. The thesis is well structured and clearly formulating and explaining the problems and achievements. However, English is not on a proper level - there are many grammar errors, imperfections, incorrect formulations/citations, and typos, which are often disturbing. For instance: - "phase shit" (p. 26), - "vibration dumping" (p. 50), - "protect instrument and experiment from error", - "Binning" - correct is Binnig (p. 17, 113), - "2nd experimental setup was carried out" (p.110), - "..load was almost remained…" (p.111), - the wrong or ambiguous application or omission of articles (e.g. figure captions in Fig. 8 and 9), - and many others. To improve the presentation quality of the work performed, careful re-reading and corresponding detailed corrections are highly recommended. Also, if possible, the title of the thesis could be changed to "Study of Thin Film Surfaces" or to "Study of Surfaces of Thin Film Materials". The student has met all proposed objectives of the thesis, acquired solid knowledge and experience in the relevant fields of interest, and proved to be capable of carrying out research at a proper level. The results, he achieved, were published in peer-review journals. Provided the defense of the thesis will be successful and all the proposed queries properly answered I recommend to award Mr. Rutul Rajenda Trivedi the degree "PhD". The short version of the thesis covers all significant parts of the full version and is written in agreement with the regulations of BUT.
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