?, ? and ? phases in the vanadium ? Oxygen system

Gel’d, P. V.; Alyamovskii, S.I.; Matveenke, I. I.

doi:10.1007/bf01141791

Cited by 4 publications

(2 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Attempts at varying the conditions of the wet H2 treatment to obtain a crystalline phase intermediate to V203-V205 , specifically VO2, were not successful. This is consistent with the work of Gel'd et al (15) who found that, although VO2 and VoOl~ were detected during the reduction of powders of V205 in H2, single phases of these compositions could not be formed. I In order to obtain VO2 films the water vapor treatment was used to provide a slightly oxidizing atmosphere for the sputtered V-O films.…”

Section: Apparatus and Proceduressupporting

confidence: 93%

Preparation of Thin Films of Vanadium (Di-, Sesqui-, and Pent-) Oxide

Rozgonyi¹,

Polito²

1968

J. Electrochem. Soc.

View full text Add to dashboard Cite

Polycrystalline thin films of V20~, VO2, and V205 have been prepared in the thickness range from 500 to 4000A. The films are obtained by a postdeposition heat-treatment of sputtered V or V-O films. The quality of the films has been studied by x-ray diffraction techniques and by measuring resistivity as a function of inverse temperature to check the magnitude of the metal to semiconductor transition. Electrically the films compare favorably with bulk crystals, and in addition the films are extremely stable during repeated cycling through the transition temperature.Since Morin (1) reported on the metal to semiconductor transition in certain oxides there has been considerable interest in the preparation and properties of single crystals of the oxides of vanadium. Vanadium dioxide, VO2, which gives rise to a conductivity change of up to 104 at 338~ has received the most attention (2-7) due to the very convenient transition temperature. However, for fundamental studies and some more restricted device applications vanadium sesquioxide, V208, with a conductivity change of greater than 106 at 168~ is also of great interest (8-10). A serious problem encountered with both V20~ and VO2 is a tendency for bulk crystals to fracture. This fracture, plus the need for material in configurations compatible with modern device technology, has stimulated our effort to deposit thin films of the above oxides.Previous work on thin films has been restricted to the deposition of VO2 films. The films were obtained either by vapor deposition techniques (11, 12) using VOCI~ or by reactive sputtering of vanadium in argon and oxygen mixtures (13). Since difficulties have been encountered in obtaining consistently reproducible results on these films simple postdeposition annealing of films was attempted. Considerable success was achieved in obtaining uniform large area films of V,~O5 and V203, as well as VO2, by choosing a suitable oxidizing or reducing atmosphere while treating sputtered V or V-O films. Apparatus and ProceduresExperimentally the vacuum system is identical to that used previously for the sputtering of ZnO (14) with the ZnO cathode replaced by V205. However, due to the complexity of the oxidation states of vanadium it was not possible to deposit crystalline films reproducibly and directly, as was accomplished with ZnO. Therefore, postdeposition treatments were devised which recrystallized the films such that their properties were comparable to bulk single crystals. Vanadium films sputtered in conventional bell jar systems were also studied. Substrate materials included single crystal sapphire and amorphous Pyrex glass slides with the best results obtained on the sapphire.Depending on the oxide desired the films were annealed in the presence of three different flowing gases in three separate open tube furnaces. The gases were water vapor, a mixture of 90% N2-10% 02, and H2 which had been bubbled through water. The optimum conditions for obtaining the V-O composition of interest are presented in Table I. No attempt has be...

show abstract

Section: Apparatus and Proceduressupporting

confidence: 93%

Preparation of Thin Films of Vanadium (Di-, Sesqui-, and Pent-) Oxide

Rozgonyi¹,

Polito²

1968

J. Electrochem. Soc.

View full text Add to dashboard Cite

show abstract

“…Most authors have investigated the decomposition in air or in carbon dioxide at one atmosphere pressure. Only Gel'd &Esin (1949) andNo11 (1950) have used some other partial pressures of carbon dioxide. No11 heated the samples in streaming gas mixtures of nitrogen and carbon dioxide at a constant total pressure of one atmosphere ; Gel'd & Esin used carbon dioxide at different pressures, as was done in the present investigation.…”

Section: Experimental Methodsmentioning

confidence: 99%

On the thermal decomposition of dolomite. IV.thermogravimetric investigation of the dolomite decomposition

Haul

Markus

1952

J. Appl. Chem.

View full text Add to dashboard Cite

The thermal decomposition of dolomite at various constant temperatures and carbon dioxide pressures has been investigated by the ‘loss‐of‐weight method.’ Depending on these conditions, dolomite can be decomposed either stepwise to magnesium oxide and calcium carbonate (‘half‐burnt dolomite’) with subsequent dissociation of calcium carbonate, or in a single stage to both magnesium oxide and calcium oxide. It is most significant that partial decomposition is independent of the carbon dioxide pressure occurring within the same narrow temperature range, about 680°. If the ambient carbon dioxide pressure is lowered below the dissociation pressure of calcite corresponding to this temperature, then decomposition curves are shifted to lower temperatures. The second stage of the step‐wise decomposition occurs at increasingly higher temperatures with increased carbon dioxide pressure. However, complete decomposition becomes progressively more difficult owing to remaining calcium carbonate. A reaction mechanism of the thermal decomposition of dolomite is propounded based on these thermogravimetric results in conjunction with thermodynamic calculations and X‐ray studies.

show abstract

The V-VO phase system

Alexander

Carlson

1971

Metall Trans

View full text Add to dashboard Cite

?, ? and ? phases in the vanadium ? Oxygen system

Cited by 4 publications

References 4 publications

Preparation of Thin Films of Vanadium (Di-, Sesqui-, and Pent-) Oxide

Preparation of Thin Films of Vanadium (Di-, Sesqui-, and Pent-) Oxide

On the thermal decomposition of dolomite. IV.thermogravimetric investigation of the dolomite decomposition

The V-VO phase system

Contact Info

Product

Resources

About