scholarly journals Dilatometric and dielectric studies on phase transition of potassium dihydrogen phosphate-boric acid binary system

1997 ◽  
Vol 20 (5) ◽  
pp. 637-642 ◽  
Author(s):  
M L N Madhu Mohan ◽  
C Haranadh
Keyword(s):  
Phase Transition ◽  
Binary System ◽  
Boric Acid ◽  
Potassium Dihydrogen Phosphate ◽  
Dihydrogen Phosphate ◽  
Dielectric Studies ◽  
Potassium Dihydrogen

THERMAL, DIELECTRIC STUDIES ON PURE AND AMINO ACID (L-GLUTAMIC ACID, L-HISTIDINE, L-VALINE) DOPED POTASSIUM DIHYDROGEN PHOSPHATE SINGLE CRYSTALS

2007 ◽  
Vol 16 (02) ◽  
pp. 255-268 ◽  
Author(s):  
P. KUMARESAN ◽  
S. MOORTHY BABU ◽  
P. M. ANBARASAN
Keyword(s):  
Amino Acids ◽  
Glutamic Acid ◽  
Potassium Dihydrogen Phosphate ◽  
Lattice Parameter ◽  
Dihydrogen Phosphate ◽  
Dielectric Studies ◽  
Slow Cooling ◽  
Spectral Parameters ◽  
Potassium Dihydrogen ◽  
Good Thermal Stability

Amino acids (L-Glutamic acid, L-Histidine, L-Valine) doped potassium dihydrogen phosphate crystals were grown by the solution growth technique. Slow cooling as well as slow evaporation methods were employed to grow these crystals. The concentration of dopants in the mother solution was varied from 0.1 mole % to 10 mole %. The solubility data for all dopant concentrations were determined. The variation in pH and the corresponding habit modification of the grown crystals were characterized with UV - VIS, FT-IR and SHG trace elements, and dielectric studies reveal slight distortion of lattice parameter for the heavily doped KDP crystals. TGA-DTA studies reveal good thermal stability. The dopants increase the hardness value of the material, which also depends on the concentration of the dopants. Amino acids doping improved the NLO properties. The detailed results on the spectral parameters, habit modifications and constant values will be presented.

On the ferroelectric behaviour of potassium dihydrogen phosphate

1959 ◽  
Vol 250 (1261) ◽  
pp. 266-285 ◽  
Keyword(s):  
Phase Transition ◽  
Ferroelectric Properties ◽  
Potassium Dihydrogen Phosphate ◽  
Energy Parameter ◽  
Dihydrogen Phosphate ◽  
Hydrogen Ions ◽  
Ionic Model ◽  
Potassium Dihydrogen ◽  
Configurational Energy ◽  
The Difference

In this paper we consider the properties of potassium dihydrogen phosphate (K D P). In the introduction we compare the behaviour of K D P with that of some isomorphous crystals. From this comparison we conclude that the hydrogen bonds play a deciding part in the phase transition, although the magnitude of the polarization seems to be determined by the heavy ions. As a first theoretical approach we apply the first Bethe approximation to an Ising model, based on the hydrogen lattice of K D P. This model contains an additional configurational energy U as compared to Slater’s work. His results are obtained in the limit as U → ∞. We find a phase transition for all positive values of U , but according to whether U is larger than or smaller than a certain value, which is about 3/2 times Slater’s energy parameter, the transition is a first-or a second-order one. After that we consider an ionic model of K D P which we treat as a polar hydrogen lattice with interpenetrating ionic potassium, phosphorus, and oxygen lattices. As far as possible the detailed behaviour of the constituent atoms is taken into account. The rigidity of the hydrogen bond, the effect of the configurational energy of the hydrogen ions about the phosphate tetrahedra, and the displacements of the K, P and O ions from their lattic sites all appear explicitly in the calculations. It is not found possible to choose our parameters in such a way that we can fit the complete temperature dependence of the susceptibility. The combination of a hydrogen triggering mechanism and the neutron diffraction data imply effective changes of opposite sign for the K and P ions, in disagreement with the expected properties of electro-positive atoms. On the other hand, however, our model gives not only a qualitative account of the similarity of the ferroelectric properties of K D P and its isomorphs, but also of the difference in the temperature independent part of the susceptibility in the ferroelectric and paraelectric phases of K D P, respectively.

scholarly journals Optical Absorption Spectra of Vanadyl Ion (Impurities) in Three Host Crystal Compounds

1985 ◽  
Vol 40 (11) ◽  
pp. 1164-1166
Author(s):  
O. P. Agarwal ◽  
Prem Chand
Keyword(s):  
Optical Absorption ◽  
Potassium Dihydrogen Phosphate ◽  
Optical Data ◽  
Dihydrogen Phosphate ◽  
Host Crystal ◽  
Optical Absorption Study ◽  
Potassium Dihydrogen ◽  
Vanadyl Complexes ◽  
Vanadyl Ion ◽  
Magnesium Ammonium

Results of the optical absorption study of vanadyl ion doped in magnesium ammonium sulphate hexahydrate, rubidium sulphate and potassium dihydrogen phosphate single crystals at RT are reported. The nature of optical bands suggests a C4v symmetry of the Vanadyl complexes in conformity with the EPR results. Powder EPR data and optical data are correlated to obtain the MO coefficients.

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