The importance of diagram system MnO2─NaVO3 is in obtaining a crystal phase
(chemical compounds or solid solutions). Acknowledging the fact that these compounds
have grade properties in the field of technology, it was important to study the possibi
lity of
obtaining new phases with different mole ratios, and to draw phase diagram for it,
especially the used compounds in this study have different crystal structures.
The samples were made beginning from powders of reagent grade MnO2 and NaVO3 of
5gr for each of them at following percentage mole ratios of MnO2: (10, 20, 25, 30, 33.33,
50, 66.66, 70, 71, 75, 80, 90). The mixing and grinding process was made for these
samples. Then, it made pills ellipsoidal using manually hydraulic press, and it burned into
oven at different degrees. The study was made using powder X─Rays diffraction PXRD
and different thermal analysis TG─ DTA. The results are compared with X─rays
spectrums of grade compounds and parameters of it. Then, the formation phase changes
degrees were determined. New compound was formed at ratio (MnO2)10(NaVO3)90
mole%, and crystal solid solution was formed to ratio (MnO2)25(NaVO3)75 mole%. As well
solid solution (amorphous+ new compound) was formed until mole ratio
(MnO2)75(NaVO3)25 mole%, and amorphous solid solution was formed beginning mole
ratio (MnO2)80(NaVO3)20 mole%, then the phase diagram for the studied system was
drawing.
Due to the importance of Strontium Titanate in modern
technological industries, optical devices, solar cells and other
utilization; in this research we study the synthesis of ST from
SrCO3:TiO2 (1:1).
This study was achieved to identify some characteristics of clay minerals of
soils in the southern of region (provinces of Daraa, Sweida). Several soils
profiles were selected, forming a toposequence, including the western slope of
Jabal Al Arab a
nd part of Huran plateau which rise about 500-1200m a.s.L.
and rainfall between 250-350mm. These soils usually are planted with rainfed
crops and some trees. Three samples were collected from each profile at depth
0-25 cm, 25-50cm and 50-100cm in order to determine some physical and
chemical of soli characteristics and x-ray and Differential Thermal Analysis
(DTA) were applied to determine the mineralogical composition of clay
minerals. Results indicated that the soils had an clayey texture (37.9 % in Tafas
Dr2 to 67.5% in Tal al Haded SW2), rather high CEC (35-49.4) meq /100g soil,
neutral pH in Sahwa blata SW1 soil (7.1) to slightly alkaline pH (8) in other
soils, low content of organic matter (1)%. CaCO3 ranged of (3.16)% in Sahwa
blata SW1 soil to (25.35)% in Tafas Dr2. Cacium was the dominant cation on
the exchange complex (33.11mq/100g) in TafasDr2, and followed by magnesium
(13.99 mq/100g) in Tal al Haded SW2. Mineralogical analsis by x-ray and DTA
showed the presence of three main clay minerals, Smectites (montmurillonite),
Kaolinite and Mica (probablly illite).
errite (x=0.5) was prepared by a well-known conventional ceramic double sintering method (CCDS). Force constant K was calculated for tetrahedral and octahedral sites. The elastic constant C11, bulk modulus B , longitudinal and shear wave velocities w
ere calculated. Threshold frequency for electronic transition was determined using IR spectra. In addition, the drift mobility for tetrahedral and octahedral sites, as well as magnetic dipole moment changes for bond were determined. The area beneath endothermic peaks was correlated to the weight change TG%. On the other hand, the heat capacity under constant pressure CP was correlated to sample treatment temperature. It has been noticed that the CP has a critical value at 175.
