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).
There are wide uses of tin oxide thin films, especially in the field of
transparent conductors, solar cells, gas sensors and piezoelectric materials.
Laser deposition is considered one of the most important techniques followed to
obtain these film
s. In this research, we develop a technique to obtain
homogeneous thin films of tin oxide depending on vaporization of pile targets of
this oxide by continuous CO2 laser in the atmosphere, with a fan which
guarantees obtaining homogenous films. Some of these films were annealed in
different conditions. The optical microscope images revealed the presence of
high degree of homogeneity, while the X-Ray study showed different
crystallization grain orientations which depend on the preparation conditions.
The preferred direction is (110). The optical absorption gives information
about the value of the effective band gal for the samples before and after
thermal annealing. We have found that some films have Eg = 3.2 ev. before
annealing, and after long annealing they have Eg=1.3ev. In addition, the hard
annealed thin films reveal anisotropy in the optical and electrical.
Characteristics, they have different absorption coefficients in two
perpendicular directions, also there is an electrical resistance anisotropy along
these two directions especially after hard annealing. The Eb was 0.73 ev before
annealing, it became 0.37 ev for one direction and 0.32 ev for the other
direction.
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).
