The mixed zirconium, titanium, hafnium and first-row transition metal oxides (containing phosphorous oxide) were prepared
using ion exchange method followed by calcinations at 1020 K during 12 h. The resulted mixed oxides were identified by XRPD
method and studied their thermal behaviour by TG-DTA analysis. As a result of thermal analysis there were found one exothermic
(with a peak at about 950 K), and one endothermic (with a peak at about 1300 K) processes, both without mass loss. The observation
was valid for all investigated samples.
The analysis of XRPD patterns of the investigated samples showed well-defined crystal phases characteristic of each oxide.
The XRPD analysis also verified the phase transition of tetravalent metal oxides from orthorhombic to tetragonal, observed
by DTA analysis.
The prepared amorphous
γ-ZrP\SiO2 composite had a complicated composition,
since a part of γ-ZrP is converted to α-form during the exfoliation
of it. The γ-ZrP\SiO2 composite have specific surface
area of 421 m2g–1.
The acidic P–OH groups of the lamellae species placed on the surface
(it is ≈1.0 meq g–1), do not destroy until
the temperature of 1030 K. During the thermal treatment the total mass loss
of 7.79% was found. This value corresponds to 0.42 mole of H2O
per molecule unit. The water loss process was found very slow, because of
the placing of bilamellar species in the composite.
The thermal behavior of tin containing oxalate, EDTA, and inositol-hexaphosphate were investigated. The end products of synthesis were identified by Mössbauer-, XRD analyses, and FTIR studies. The thermal decompose of the samples was studied by DTA-TG analysis. The simultaneously obtained DTA and TG data makes it possible to follow the thermal decomposition of the investigated samples. The tin oxalate decomposed in the temperature range of 520–625 K through tin carbonate formation and finally yielded CO2 and SnO. The tin EDTA complex first lost its hydrate bound water till 520 K. The followed thermal events related to the pyrolysis of anhydrous salt. The intense exothermic process that exists in the temperature range of 820–915 K is due to the formation of SnO2. The tin sodium inositol-hexaposphate lost its hydrate bound water (∼10%), up to 460 K. The following sharp exothermic process, in the temperature range of 680–750 K is due to the decomposition and parallel oxidation of organic part of the molecule. At the end of this process, a mixture of phosphorous pentaoxide, sodium carbonate, and tin dioxide is obtained.
Tin(II/IV) phosphate was prepared by various synthetic methods. The different methods resulted in tin phosphate with different properties, i.e., different crystalline form and behaviour during thermal treatment. The prepared materials have 3 mol water of crystallisation, which they lose in different ways. Total mass loss was between 20 and 30%. This could be connected with water loss, going generally in two steps in parallel with endothermic processes. At the end of thermal treatment, tin pyrophosphate is obtained, irrespective of the method of preparation used.
Authors:L. Szirtes, J. Megyeri, L. Riess, and E. Kuzmann
The thermal decomposition of hafnium phosphate (both in amorphous and crystalline forms), molybdate and tungstate was investigated.
Hafnium phosphate has a layered structure, that of molybdate and of tungstate are tetragonal one. On investigating these materials
two main endothermic processes with mass loss were observed in the temperature range of 298–1023 K. These processes were identified
as crystal and structural water loss of the materials. The total mass loss of hafnium phosphate, molybdate and tungstate was
11,35 and 6.0%, respectively. In the case of mixed hafnium-titanium salts various crystal water quantities were found, depending
on the titanium content of the sample.
Authors:L. Szirtes, J. Megyeri, L. Riess, and E. Kuzmann
The thermal decomposition of zirconium molybdate, tungstate and arsenate were investigated. The total mass losses of the investigated materials were 12.5, 11 and 8.5%, respectively. Despite having different crystal dimensions and structure the thermal decomposition of the samples takes place in a similar way. During heating two main endothermic processes with mass loss were observed. At the end of the thermal decomposition, oxides of the original materials were observed. The mentioned mass losses originate partly from the crystal water loss of the materials. The calculated crystal water content in the original molecule was 1.3 and 1 mole/molecule unit, respectively. Furthermore, for zirconium arsenate, a sublimation process was recorded above 960 K.
Authors:O. Pozdnyakova, J. Megyeri, E. Kuzmann, and L. Szirtes
Hydrated microcrystalline compound, V1-xCrxOy·nH2O, where x<0.063 and 4.4<n<8 and hydrated amorphous phases, CrVO4·H2O and Cr2V4O13·4H2O have been prepared using peroxo-polyacids of vanadium and chromium. The transformations of these hydrated phases upon heating were studied by TG-DTA and XRD techniques and led to three crystalline anhydrous compounds: (i) phase V1-xCrxOy, which is closely related to the orthorhombic V2O5, (ii) Cr2V4O13 and (iii) monoclinic CrVO4-M. The ranges of coexistence of phases in equilibrium were also determined.
Authors:C. Kuti, L. Láng, M. Megyeri, J. Bányai, and Z. Bedő
Genebanks are storage facilities designed to maintain the plant genetic resources of crop varieties (and their wild relatives) and to ensure that they are made available and distributed for use by plant breeders, researchers and farmers. The Martonvásár Cereal Genebank (MV-CGB) collection evolved from the working collections of local breeders and consists predominantly of local and regional materials. Established in 1992 by the Agricultural Research Institute of the Hungarian Academy of Sciences (Bedő, 2009), MVCGB with its over 10,000 accessions of the major species (Triticum, Aegilops, Agropyron, Elymus, Thinopyrum, Pseudoroegneria, Secale, Hordeum, Avena, Zea mays), became one of the approx. 80 cereal germplasm collections that exist globally. In Martonvásár breeding is underway on a number of cereal species, and large numbers of genotypes are tested each year in the field and under laboratory conditions. The increasing size of the research programmes assisted by a modern genebank background involve an enormous increase in the quantity of data that must be handled during research activities such as traditional breeding, pre-breeding and organic breeding. A computerized system is of primary importance to synchronize breeding and genebank activities, to monitor the quality and quantity of seed accessions in cold storage, to assist the registration of samples, and to facilitate characterization, regeneration and germplasm distribution.