Zinc Tris-Thiourea Sulfate Lab Report

Zinc Tris-thiourea Sulfate (ZTS) is a Semi Organic Nonlinear Optical (NLO) material which finds applications in the area of laser technology, optical communication, data storage technology, and optical computing etc. The author has successfully grown ZTS crystal by gel method. Gel technique has been adopted at ambient temperature to attain better result. The grown crystals were transparent and colourless. The crystal size has been obtained the range about 5mm X 3mm X 2mm. Thermal study of ZTS crystal from Thermo-Gravimetric Analysis (TGA) and calculate activation energy and other Thermal parameters.
Key Words
ZTS Crystal, TGA Analysis, Activation Energy Introduction
Zinc Tris-thiourea Sulfate (ZTS) is a Semi Organic Nonlinear Optical (NLO)
For experiment silica gel or Sodium Meta Silicate is used to prepare gel. Sodium Meta Silicate (SMS) solution was prepared by Distilled Water. The solution was filtered by the filter paper about 4 to 5 times. For different pH, the Acitic Acid was poured in to the solution. Pour different test tubes for different pH. To avoid porous gel and decomposition, 3N Thiourea using stirrer at 42o C temperature were prepared. These thiourea as a feed solution was poured in the different pH test tubes which is filled with the SMS solution. Zinc Sulfate Heptahydrate (AR Grade) and Thiourea (AR Grade) were taken in 1:3 ratios. Then, gel solution was allowed to set at ambient temperature. After completing reaction between Zinc Sulphate Heptahydrate and Thiourea, by following reaction ZTS crystal was synthesised within 4-6
Thermogram of the pure ZTS crystal
Activation Energy:
Broido relation was used to calculate the activation energy “E” and the frequency factor “z”.When a pure solid substance is heated in vacuum, it undergoes pyrolysis in which at least some of the pyrolysis products are volatile. Wt , the weight at any time t, is related to the fraction of the number of initial molecules not yet decomposed, y, by the equation, y=N/N0 =(Wt-W∞)/(Wo-W∞) = fraction of the number of initial molecules not yet decomposed.
Where Wt = Weight of active material at absolute temperature, W0 = Weight of the material taken initial, W∞ = Weight of active material at the end of the reaction. According to Arrhenius equation, the activation energy is calculated by lnln 1/y = E/RT + constant ……………(1)
Thus the slope of the plot of lnln(1/y) 1/T (fig. 3,4 and 5) yields the required energy of activation (see table:1). The plot gives a good linear fit for