A solvothermal route to crystalline lithium niobate

A solvothermal route for the preparation of crystalline state lithium niobate using Li2 CO3 and Nb2 O5 is developed. Oxalic acid is employed as solvent, which coordinates with niobium oxide to stimulate the main reaction. Scanning electron microscopy images show that the as-prepared sample displays a cubic morphology. X-ray diffraction and IR spectrum of the as-prepared sample indicate that the sample is well crystalline.

Solvothermal Synthesis of InP Quantum Dots

We report an efficient and fast solvothermal route to prepare highly crystalline monodispersed InP quantum dots. This solvothermal route, not only ensures inert atmosphere, which is strictly required for the synthesis of phase pure InP quantum dots but also allows a reaction temperature as high as 430 degrees C, which is otherwise impossible to achieve using a typical solution chemistry; the higher reaction temperature makes the reaction more facile. This method also has a judicious control over the size of the quantum dots and thus in tuning the bandgap.

Delamination of Surfactant-Intercalated Brucite-Like Hydroxy Salts of Cobalt and Copper and Solvothermal Decomposition of the Resultant Colloidal Dispersions

Surfactant anion intercalated hydroxy salts of copper and cobalt of the formula M(OH)(2-x)(surf)(x)center dot mH(2)O [M = Cu, Co; surf = dodecyl sulfate. dodecyl benzene sulfonate. and x = 0.5 for Cu and 0.67 for Co] delaminate readily in 1-butanol to give translucent colloidal dispersions that are stable for months. The extent of delamination and the colloidal dispersion observed in these solids is higher than what had been observed for layered double hydroxides. The dispersions yield the corresponding nanoparticulate oxides on solvothermal decomposition. While the copper hydroxy salt forms similar to 300 nm dendrimer-like CuO nanostructures comprising nanorods of similar to 10 nm diameter, the cobalt analogue forms similar to 20 nm superparamagnetic particles of Co3O4.

Delamination and solvothermal decomposition of layered zinc hydroxysalt: Formation of bimodal zinc oxide nanostructures

Dodecylsulphate-intercalated zinc hydroxysalt, Zn-5(OH)(8)(DS)(2)center dot mH(2)O delaminates to give monolayer colloidal dispersions in alcohols such as 1-butanol and ethylene glycol. The extent of delamination and the stability of the colloidal dispersion are comparable to those of layered double hydroxides. The solvothermal decomposition of the colloidal dispersion of the hydroxysalt in ethylene glycol yields a bimodal ZnO having a nanotubular structure decorated with nanosheets. (C) 2010 Elsevier Masson SAS. All rights reserved.

Defect related luminescence in Hg0.2Cd0.8Te nano- and micro-crystals grown by the solvothermal method

The photoluminescence (PL) properties of nano- and micro-crystalline Hg1-xCdxTe (x approximate to 0.8) grown by the solvothermal method have been studied over the temperature range 10-300 K. The emission spectra of the samples excited with 514.5 nm Ar+ laser consist of five prominent bands around 0.56, 0.60, 0.69, 0.78 and 0.92 eV. The entire PL band in this NIR region is attributed to the luminescence from defect centers. The features like temperature independent peak energy and quite sensitive PL intensity, which has a maximum around 50 K is illustrated by the configuration coordinate model. After 50 K, the luminescence shows a thermal quenching behavior that is usually exhibited by amorphous semiconductors, indicating that the defects are related to the compositional disorder. (C) 2010 Elsevier B.V. All rights reserved.

Solvothermal synthesis of Hg1-xCdxTe nanostructures-Their structural and optical properties

This article describes a facile, low-cost, solution-phase approach to the large-scale preparation of Hg1-xCdxTe nanostructures of different shapes such as nanorods, quantum dots, hexagonal cubes of different sizes and different compositions at a growth temperature of 180 degrees C using an air stable Te source by solvothermal technique. The XRD spectrum shows that the crystals are cubic in their basic structure and reveals the variation in lattice constant as a function of composition. The size and morphology of the products were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The formation of irregular shaped particles and few nano-rods in the present synthesis is attributed to the cetyl trimethylammonium bromide (CTAB). The room temperature FTIR absorption and PL studies for a compositon of x = 0.8 gives a band gap of 1.1 eV and a broad emission in NIR region (0.5-0.9 eV) with all bands attributed to surface defects.

Solvothermal routes to capped oxide and chalcogenide nanoparticles

We review our recent contributions to the use of solvothermal methods for the preparation of different oxide and chalcogenide nanoparticles. We have prepared sub 10-nm,gamma-Fe2O3 ZnFe2O4, and CoFe2O4 particles by the decomposition of the corresponding cupferron complexes in the presence of n-octylamine or n-dodecylamine in solvothermal toluene. Similarly, dodecanethiol-capped chalcogenide nanoparticles of CdSe have been prepared by reacting cadmium stearates with H2Se under solvothermal conditions. The H2Se is generated in situ by the reduction of Se by tetralin. Using this latter technique, we have also been able to prepare PbSe and PbI2 in toluene under solvothermal conditions, albeit in bulk (rather than nanocrystalline) form. In the preparation of PbI2, HI is prepared by the in situ reduction of I-2 by tetralin.

Temperature Dependent Photoluminescence Studies in Hg0.2Cd0.8Te Nanorods Synthesized by Solvothermal Method

Hg0.2Cd0.8Te nanorods were synthesized via solvothermal route using an air-stable Na2Te-O-3. The structural and morphological studies were done by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The diameters of the nanorods were found to be 20-50 nm. The growth of the nanorods were facilitated due to the use of CTAB as surfactant. The temperature dependent photoluminescence (PL) studies between 10-300 K show three prominent PL bands in 0.5-0.7 eV and are attributed to defect centers. The features like temperature independent peak energy and quite sensitive PL intensity which shows a thermal quenching behavior indicate that the defects are related to the compositional disorder.