Results of dielectric and thermal studies on strontium tartrate pentahydrate crystals are described. The value of dielectric constant is shown to be independent of temperature till 360 K at all the frequencies (110-700 kHz) of the applied a.c. field. It increases abruptly achieving a peak value of 25⋅5 at 100 kHz; the peak value being strongly dependent on frequency. In the temperature range, 87 < T < 117°C, the value of ε′ falls suggesting a transition at around 100°C or so. The dielectric constant, ε′, of the material is shown to be frequency dependent but temperature independent in the pre-or post-T c range 87 < T < 117°C, suggesting that the contribution towards polarization may be due to ionic or space charge polarization which gets eliminated at higher frequencies. The ferroelectric transition is supported by the results of thermoanalytical studies. It is explained that crystallographic change due to polymorphic phase transition may be occurring in the material, besides the change due to loss of water molecules, which leads to the dielectric anomaly at around 100°C. Coats-Redfern approximation method is applied for obtaining non-isothermal kinetic parameters leading to calculation of activation energies corresponding to three decomposition stages of material in the temperature ranging from 379-1113 K.

Growth of pure-, sodium-and lithium-doped potassium hydrogen tartrate single crystals by gel technique is reported. Growth conditions conducive for the growth of single crystals are worked out. The crystals are characterized by using powder XRD, SEM, FTIR, AES, EDAX, CH analysis and thermoanalytical techniques. The stoichiometric composition for the grown crystals are established asDoping of sodium and lithium in the pure potassium hydrogen tartrate single crystals is found to influence the size, perfection, morphology, crystal structure and the thermal stability of crystals.

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The optical and electrical characteristics of pure, sodium- and lithium-doped potassium hydrogen tartrate crystals grown by the gel technique are reported. An optical absorption study conducted in the UV–Vis range of 200–800 nm reveals the transparency of these crystals in the entire visible range but not in the ultraviolet range. The optical band gap of pure potassium hydrogen tartrate crystals is found to be dependent on doping by Na or Li ions. The non-linear optical behaviour of these crystals is reported and explained. The electrical properties of pure and doped potassium hydrogen tartrate crystals are studied by measuring electrical resistivity from 80 to 300 K. It is shown that while pure potassium hydrogen tartrate crystal is an insulator at room temperature (300 K), doping by Na or Li ions makes it a semiconductor. The results have been explained in terms of the variable range hopping model.

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, 68.37.Hk Silica gel impregnated with L-tartaric acid and using strontium nitrate as the second reactant leads to the growth of well faceted strontium tartrate pentahydrate single crystals.The morphological developmen and internal cell dimensions are observed to be different from the ones reported in the literature for strontium tartrate trihydrate crystals. The crystals are characterized using XRD, CH analysis, SEM, FTIR spectroscopy and thermoanalytical techniques.The crystals are observed to be thermally stable upto about 105°C but thereafter start decomposing and ejecting water of hydration at various stages, finally reducing to strontium oxide.

Micromechanical characteristics of (001) and (111) planes of gel grown pure, sodium‐ and lithium‐doped potassium hydrogen tartrate single crystals as revealed by indentation induced technique are described. The indentation size effect (ISE) exhibited by the crystals is explained on application of proportional specimen resistance (PSR) model and the analytical law of Hays and Kendall. The load independent values of Vickers hardness of (001) and (111) planes of these crystals as indicated by indentation experiments and computed on the basis of PSR model and the analytical law are shown to be in good agreement. The doping by sodium or lithium results in the increase in hardness of potassium hydrogen tartrate crystals. The crystals exhibit hardness anisotropy. The values of yield strength of each plane of both pure and sodium and lithium doped potassium hydrogen tartrate single crystals are estimated using appropriate equations.