الفهرس 
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Abstract
The growing interest in studying the physical properties of double sulfate crystals is due to the fact that they show anomalies behaviour at transition temperatures (T^) as well as they undergo an interesting sequence of structural phase transitions.
At atmospheric pressure, Lithium ammonium sulfate, LiNH4S04/ has the following sequence of structural phase transitions :
Orthorhombic
[mmm (z=4)]
Paraelectric
460K Orthorhombic ——————> [mm2 (z=4)] Ferroelectric
285K Monoclinic
——————> [2/ra (2=8)]
Ferroelastic
In this work, the effect of changing the stoichiometric ratios of the initial salts, Li2S04 and (NH4)2S04, in the growth solutions as well as structural defects due to doping and irradiations were studied.
Single crystals of LiNH4S04 were grown by slow evaporation method from aqueous solution containing the initial salts at stoichiometric ratios. Samples in the form of rods (1x1x0.2 cm) were cut from the prepared crystals using a wet thread saw with edges parallel to the crystallographic axes.