Crystal

We have developed a modified physical vapor transport (M-PVT) growth technique for the preparation of SiC single crystals which makes use of an additional gas pipe in order to control the gas phase composition of the conventional physical vapor transport (PVT) configuration. We discuss ...

India's population is achieved 1.2 billion and the population rate is increasing day by day then following 25-30 years there will be not kidding issue of sustenance, so the improvement of farming is essential. Today, the agriculturists are experiencing the absence of rains and lack of water .In earlier system human participation were used in such condition lack of accuracy and even time consumption was also more so to overcome this system, The fundamental goal of this paper is to give a programmed watering system framework in this way sparing time, cash and force of the former and also implemented the TCP/IP client android application to know the sensor values and automaticall1the system will be on and off. At whatever point there is an adjustment in temperature and dampness of the surroundings these sensors detects the adjustment in temperature and moistness and gives an sign to the microcontroller, with the help of microcontroller the GSM module send a IP address to the mobile number of the owner after that with the help of IP address the android application shows the sensors values. The constant expanding interest of the food requires the fast change in sustenance generation innovation. In a nation like India, where the economy is for the most part taking into account agriculture and the climatic conditions are isotropic, still we are not ready to make full utilization of rural assets. The fundamental reason is the absence of rains and lack of area supply water. Another imperative reason of this is because of spontaneous utilization of water because of which a lot of water goes waste. In the advanced dribble watering system frameworks, the most critical point of interest is that water is supplied close to the root zone of the plants drop by drop because of which an extensive amount of water is spared. The innovation of this watering system will reduce the man power required.

N-implantation to GaSe single crystals was carried out perpendicular to c-axis with ion beam of 6 × 1015 ions/cm2 dose having energy values 30 keV and 60 keV. Temperature dependent electrical conductivities and Hall mobilities of implanted samples were measured along the layer in the temperature range of 100-320 K. It was observed that N-implantation decreases the resistivity values down to 103 Ω-cm depending on the annealing temperature, from the room temperature resistivity values of as-grown samples lying in the range 106-107 Ω-cm. The temperature dependent conductivities exhibits two regions (100-190 and 200-320 K) with the activation energies of 234-267 meV and 26-74 meV, for the annealing temperatures of 500 and 700 °C, respectively. The temperature dependence of Hall mobility for the sample annealed at 500 °C shows abrupt increase and decrease as the ambient temperature increases. The analysis of the mobility-temperature dependence in the studied temperature range showed that impurity scattering and lattice scattering mechanisms are effective at different temperature regions with high temperature exponent. Annealing of the samples at 700 °C shifted impurity scattering mechanism toward higher temperature regions. In order to obtain the information about the defect produced by N-implantation, the carrier density was analyzed by using single donor-single acceptor model. We found acceptor ionization energy as Ea = 450 meV, and acceptor and donor concentration as 1.3 × 1013 and Nd = 3.5 × 1010 cm−3, respectively. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

A uniaxial sulphamic acid single crystal having dimensions of 35 mm diameter and 150 mm length was grown. Employing slow evaporation technique sulphamic acid crystals of size 10×10×5 mm3 were grown. Etching, microhardness, high-resolution X-ray diffraction, laser damage threshold, UV–visible, Thermogravimetric and differential thermal analysis were made on conventional and the Sankaranarayanan–Ramasamy method grown sulphamic acid crystals. Etching behaviour of the (1 0 0) plane of conventional and the Sankaranarayanan–Ramasamy method grown sulphamic acid crystals was investigated with different etchants. Vicker's microhardness test on the (1 0 0) plane confirmed the mechanical stability of the conventional and the Sankaranarayanan–Ramasamy method grown sulphamic acid crystals. High-resolution X-ray diffraction results show that the crystalline perfection of sulphamic acid single crystals grown by the Sankaranarayanan–Ramasamy method is extremely good compared to the conventional slow evaporation method grown sulphamic acid crystal. Thermogravimetric and differential thermal analysis was carried out to determine the thermal properties of the grown crystal.

Cadmium sulfide (CdS) one dimensional (1D) nanocrystals were prepared using a polyethylene glycol (PEG) assisted hydrothermal synthesis. X-ray diffraction result confirms that the nanorods are of hexagonal structure and the selected area electron diffraction (SAED) identifies the single crystalline nature of the sample. The sample was systematically characterized by UV-vis absorption, photoluminescence (PL) spectrum, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermal analysis. The UV-vis absorption spectrum indicates the narrow size distribution of the CdS nanorods. The absorption band edge is seen shifted to 505 nm than the bulk material and the corresponding band gap is found to be 2.45 eV. The PL emission peak is detected around 550 nm. From SEM and EDX analysis, the morphology of the aggregates and the composition of the obtained product are identified. The TEM micrographs indicate that the CdS nanorods exhibit well defined morphology and high crystalline quality with narrow size distribution of lengths and widths. The TG/DTA traces of the nanopowder show four major stages of weight loss.

Single crystals of ferroelectric succinic acid were grown from aqueous solution by low temperature solution growth technique. The cell parameters and space group are found using powder X-ray diffraction analysis. The presence of the functional groups has been estimated qualitatively by FTIR analysis. The UV-Visible spectrum shows the cut-off wavelength at 240 nm. The thermal stability of the crystal was studied by TG/DTA. The dielectric constant of the crystal studied as a function of frequency shows the pyroelectric property. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)