Doped ADP Crystals Research Articles

Tailoring the low dielectric constant in glutamic acid doped ammonium dihydrogen phosphate single crystal by virtue of MPa shock waves for microelectronic applications: the complex impedance and modulus formulation studies

Ammonium Dihydrogen Phosphate, ADP, (NH4H2PO4) crystal has a wide range of applications in integrated and nonlinear optics. The amino acid-like l-glutamic acid (C5H9O4N) causes the defect in the framework of ADP crystal. The 0.6wt% l-glutamic acid doped ADP crystal is grown using the slow evaporation technique. The grown crystal is subjected under the shockwave of Mach number 1.7 and shock number 2, 4 and 6. The Powder XRD study shows the lattice strain introduced in the structure of grown crystals due to impose of the shockwave. The Photoluminescence confirmed the presence of D-defect and Self Trapped Excitons. The influence of shockwave on dielectric, impedance and modulus properties of glutamic acid doped ADP crystal is well studied in the frequency range of 100 Hz to 10 MHz and the temperature range of 323 K to 373 K. The shockwave is reduced the dielectric constant, A.C. Conductivity, strength of polarizibility and the grain capacitance. The Correlation Barrier Hopping (CBH) conduction mechanism is well studied for pristine and shocked glutamic acid doped ADP crystals over the temperature range considered. The presence of grain over the frequency range considered is identified and confirmed using the complex impedance and the complex modulus spectroscopy. The pristine and shocked glutamic acid doped ADP crystals have possessed the temperature-independent, Non-Debye type relaxation process. The results are discussed here.

Optical and SHG Measurements of Aminoacids doped ADP NLO crystals

L-Arginine and L-Alanine aminoacids doped ADP crystals were grown from aqueous solution by slow evaporation technique at constant temperature. The crystalline nature of the grown crystals was confirmed using powder X-ray diffraction technique. The vibrational frequencies of the grown crystals were identified using FTIR spectral analysis. Optical absorption study was carried out and a good transparency in the entire visible region was observed with the lower cutoff wavelength of 308 nm and 318 nm for the L-Alanine & L-Arginine doped crystals respectively. The transmission data has been used to evaluate the optical band gap of L-Alanine and L-Arginine doped ADP crystals and is found tobe 5.023 eV. Second harmonic generation (SHG) studies were performed by the classical Kurtz powder technique using a Nd: YAG laser operating at 1064 nm. The SHG efficiency of doped ADP is found to be higher compared to Pure ADP crystals.

Exploring remarkable impact of thiourea in enhancing the performance of NH4H2PO4 single crystal for photonic device applications

The present investigation is primarily aimed to investigate the impact of thiourea on characteristic properties of ammonium dihydrogen phosphate (NH4H2PO4, ADP) crystal to emphasize its utmost liability for designing nonlinear optical device applications. The most commercial slow solvent evaporation method has been opted to grow the undoped and thiourea doped ADP single crystals. The single crystal X-ray diffraction study has been employed to determine the structural parameters of undoped and thiourea doped ADP crystal. The elemental analysis has been performed to confirm the presence of thiourea in ADP crystal. The UV–visible studies have been carried out within 200–1100 nm to examine the constructive impact of thiourea on optical transparency and vital linear optical parameters (extinction coefficient, refractive index and reflectance) of ADP crystal. The Kurtz-Perry test has been employed to ascertain the enhancement in SHG efficiency of ADP crystal due to presence of thiourea. The third order nonlinear optical nature and properties such as nonlinear absorption (β), refraction (n2) and susceptibility (χ3) of T-ADP crystal has been examined at 632.8 nm by imposing the Z-scan studies. The color centered photoluminescence emission behavior of pure and thiourea doped ADP crystal has been investigated within 320–650 nm. Vickers microhardness study has been imposed to evaluate the role of thiourea in uplifting the hardness parameters of ADP crystal. The dielectric parameters (dielectric constant and dielectric loss) of undoped and thiourea doped ADP crystal has been comparatively investigated within the temperature range of 25–100 °C. The surface growth habitat of thiourea doped ADP crystal has been investigated by means of chemical etching technique.

Crystal growth, A.C. electrical and nonlinear optical studies of pure and dl-methionine doped ammonium dihydrogen phosphate single crystals

The pure and 0.1 wt% dl-methionine doped ADP crystals are grown using slow solvent evaporation technique at room temperature. The powder XRD study shows single phase nature of both grown crystals with tetragonal structural symmetry. The UV–Vis transmittance spectroscopy shows improvement in optical transmittance, energy band, and low refractive index of doped ADP crystal compare to pure ADP crystal. The Wemple–DiDomenico single oscillator model is found to be appropriate for the refractive index dispersion below the energy band edge of ADP crystal. The Nyquist plots of pure and doped ADP crystals represent presence of grain and grain boundary. The Jonscher’s powder law is successfully applied to the conductivity phenomena in pure and doped ADP crystals. The complex modulus spectroscopy helps to discriminate the grain and grain boundary in grown crystals clearly. The Non-Debye type relaxation is observed in both crystals. The nonlinear optical properties such as second harmonic generation efficiency and third order susceptibility are improved on doping the dl-methionine in ADP crystal.

Systematic analysis on linear and nonlinear optical traits of citrulline doped NH4H2PO4 (ADP) crystal

The current investigation is aimed to explore the optical properties of citrulline doped ammonium dihydrogen phosphate (NH4H2PO4,ADP) crystal by employing crystal growth, structural, UV–vis, Kurtz-Perry test and Z-scan characterization techniques. The growth of citrulline doped ADP single crystal has been achieved by slow solvent evaporation technique at ambient temperature. The pure and citrulline doped ADP crystals have been characterized by single crystal X-ray diffraction technique for structural analysis. The functional groups of grown crystal have been qualitatively identified by means of Fourier transform infrared analysis. The influence of citrulline on optical transmittance of ADP crystal has been evaluated within 200–900nm by means of UV–vis spectral analysis. The enhanced second harmonic generation (SHG) efficiency of citrulline doped ADP crystal has been determined using the Q-switched mode Nd:YAG laser and it is found to be 2.18 times higher than standard KDP crystal. The third order nonlinear optical (TONLO) behavior of citrulline doped ADP crystal has been investigated using He-Ne laser operating at 632.8nm. The close and open aperture Z-scan configuration has been used to evaluate the nature of TONLO refraction and absorption. The magnitude of TONLO parameters of citrulline doped ADP crystal has been determined using the Z-scan transmittance data. The potential liability of citrulline doped ADP crystal for optical applications has been discussed.

Growth, optical and dielectric studies of glycine doped ammonium dihydrogen phosphate NLO crystal: potential material for optoelectronics applications

A 3 mole% glycine doped ADP crystal was grown by slow evaporation technique at ambient temperature. The incorporation of glycine was analyzed qualitatively by FT-IR analysis. The grown crystal exhibits high transmittance in the entire visible region and lower cut-off wavelength has been found to be 306 nm. The optical band gap is found to be 5 eV. The high optical quality of the grown crystal was ascertained by lower values of extinction coefficient (k) and refractive index (n). The dielectric constant and the dielectric loss decreases with the increasing frequency. Thermal studies of the grown crystal confirmed its stability up to 205 °C. The relative SHG efficiency for 3 mole% glycine doped ADP was measured using Nd:YAG laser and the value observed to be 1.88 times that of pure ADP.

Investigation on the Linear and Nonlinear Optical Properties of L-Lysine Doped Ammonium Dihydrogen Phosphate Crystal for NLO Applications

In present investigation L-lysine doped ADP crystal has been grown by slow evaporation technique. The crystalline nature of the grown crystal was confirmed using powder X-ray diffraction technique. The optical studies were carried to examine optical transparency and determine the optical constants of the grown crystal quenching the optoelectronics applications. The optical band gap of grown crystal is found to be 4.7eV. The third order nonlinear behaviour has been investigated using Z-scan technique at 632.8 nm. The nonlinear third order susceptibility of grown crystal is found to be 1 .578 x 10 -5 esu. The nonlinear index of refraction and absorption coefficient were determined to explore the optical limiting applications of the grown NLO crystal. The kurtz powder test confirmed the second harmonic generations by the grown crystal.

Structural, spectroscopic, and nonlinear optical investigations on a novel nonlinear optical crystal: Hippuric acid doped ammonium di hydrogen phosphate (HAADP)

Transparent single crystals of pure and 1mol% hippuric acid doped ammonium di hydrogen phosphate (HAADP) were grown from aqueous solution by employing slow evaporation technique. Crystallinity of the grown crystals was studied by powder X-ray diffraction analysis. Both pure ADP and HAADP crystals exhibit tetragonal crystal structure. The bonding structure and molecular associations due to chemical reactions were analyzed by FTIR spectroscopy. It also confirms the functional groups present in the grown crystals. UV–Vis–NIR spectral analysis was carried out to study the optical characteristics of the crystals which reveal that the cutoff wavelength for both pure and hippuric acid doped ADP crystal is around 300nm. From these spectra it can be clearly inferred that there is an absence of characteristic absorption in the region between 340 and 1200nm, which is a most desirable property of a material for both SHG and other NLO applications. Second harmonic generation (SHG) test adopting the Kurtz Perry technique revealed that the second harmonic generation efficiency of HAADP is 1.5 times that of pure ADP crystal.

Dielectric and Optical Characterization of Boron Doped Ammonium Dihydrogen Phosphate

Single crystals of pure and boron doped ammonium dihydrogen phosphate were grown from aqueous solution by slow solvent evaporation process. ICP studies were done to confirm the presence of the dopant boron in the parent crystal. The values of the lattice parameters were determined by single crystal X-ray diffraction. The pure and doped ADP crystals were found to have tetragonal structure. Complete optical characterizations of the crystals were done using the FTIR, UV-Vis and NLO studies. The presences of the various functional groups in the crystals were identified by FTIR spectrum. The band gap energies of the pure and doped crystals have been calculated at their cut off frequencies using the UV-Vis spectrum. The second harmonic generation efficiency of the crystals was determined. The electric properties of the grown crystal have been analyzed by studying the variation of dielectric constant and dielectric loss with frequency.

Effects of Triglycine Sulphate on Ferroelectric Behavior of Ammonium Dihydrogen Phosphate Crystals

Pure ADP and TGS doped ADP crystals were grown successfully in aqueous solution using the conventional slow evaporation technique. The structural characteristics of the grown crystals were examined by power X-ray diffraction spectroscopy. The results confirm that the samples were single crystalline with some additional planes when adding TGS dopant in the solution. Also, the results from the FT-IR show the presence of TGS in the grown ADP crystal. However, the addition of TGS did not show a strong influence on the dielectric nor the ferroelectric properties of the TGS doped ADP. Higher concentrations of TGS may be needed to improve both the dielectricity and ferroelectricity properties of ADP single crystals.

Investigations on the solubility, growth, structural, optical, mechanical, dielectric and SHG behaviour of ammonium acetate doped ammonium dihydrogen phosphate crystals

Ammonium acetate doped ammonium dihydrogen phosphate single crystals have been grown by slow cooling along with bidirectional seed rotation method. Effects of ammonium acetate on the solubility, growth rate, structural, optical, mechanical, dielectric properties, crystalline perfection and second harmonic generation efficiency of the crystals have been investigated. The high-resolution X-ray diffraction study shows that the crystalline perfection of the doped crystal is good. Fourier transform infrared studies confirm the functional groups of the crystals. It is seen from UV–vis studies that the optical transparency is increased much by the dopant. Vickers hardness measurements reveal the mechanical stability of the crystals. Low dielectric losses were observed from the dielectric measurements for the doped ADP crystals at higher frequencies. The relative SHG efficiency measurements revealed that the dopant has enhanced the efficiency.

Effect of ammonium malate on growth rate, crystalline perfection, structural, optical, thermal, mechanical, dielectric and NLO behaviour of ammonium dihydrogen phosphate crystals

The effect of ammonium malate on the growth rate, structural, optical, thermal, mechanical, dielectric properties, crystalline perfection and second harmonic generation (SHG) efficiency of ammonium dihydrogen phosphate single crystals grown by the slow cooling method has been investigated. The lattice parameters of the grown crystals were obtained by the single-crystal X-ray diffraction analysis. Fourier transform infrared studies confirm the functional groups of the crystals. UV–vis study shows that the transparency is increased much by the dopant. Thermal analysis was performed to study the thermal stability of the grown crystals. Vickers hardness measurements reveal the higher hardness of the doped crystals. Low dielectric losses were observed from the dielectric measurements for the doped ADP crystals. The high-resolution X-ray diffraction studies show that the crystalline perfection of the crystals is good. The relative SHG efficiency measurements revealed that the dopant has enhanced the efficiency.

Effect of Heavy Ion Irradiation on Dielectric Properties of ADP and Doped ADP Crystals

Effect of Heavy Ion Irradiation on Dielectric Properties of ADP and Doped ADP Crystals

EPR studies of MoO 43- centres in ADP crystals

Paramagnetic centre MoO 3 3- is produced by γ-irradiation of MoO 4 2- doped ADP crystals. The g values of MoO 4 3- centre suggest that its ground state is d z 2. From 142 to 260 K the EPR spectra of MoO 4 3- showed a triplet super-hyperfine structure. The triplet to quintet transition has not been detected in this case.

Electrical conductivity and dielectric loss studies of MoO 4 2- -doped KH2PO4 single crystals

KH2PO 4 (KDP) and NH4H2PO 4 (ADP) crystals are protonic conductors. Murphy [1] considered the presence of L and D defects in the H2PO4 sublattice to explain the conduction mechanism in ADP. However, Harris and Vella [2], in analogy with the Har r ing tonStavelley [3] model for NH4C1 , considered that the proton migration in ADP crystal occurs in the NH4 + sublattice (A defect) in addition to the H2PO 2 sublattice. Our earlier studies on the electrical conductivity and dielectric loss of MoO I -doped KDP crystals [4] were explained in terms of L defect mechanism. ADP being isomorphous to KDP, the above mechanism should also hold here. In the present study the electrical conductivity and dielectric loss studies of MoO ] -doped ADP crystals were undertaken to verify whether proton migration in the NH2 sublattice also contributes to the conduction in the ADP crystal, in addition to the migration in the H2PO4 sublattice. Because crystals of MoO] -doped ADP were grown by the slow evaporation of the saturated solution. K2MoO 4 was used as dopant. The presence of the impurity MOO4:in the crystal was detected by studying its optical absorption. A Cary-14 spectrophotometer was used to record the optical absorption. The crystal faces were polished and coated with silver paint to give good electrical contact between the crystal and the electrodes for the transport studies. The resistance of the sample was measured using a Keithley electrometer model 610C. The temperature of the crystal could be controlled to within 4-0.5 K. For dielectric loss measurements, a GR1615 Impedance Bridge was used. The connections between the electrode and the bridge were made through lowloss cables. The optical absorption of the doped crystals showed two bands at 230 and 210 nm. The band positions agree very well with the earlier reported spectrum of MoO42 in solution [5]. The above study confirmed the presence of MoO] in the ADP crystal. Fig. 1 shows the plot of log (aT) against l IT for undoped and MoO]-doped ADP crystals. The conductivity plot shows the following characteristics: (i) there is a knee around 94 ° in case of the pure ADP crystal in agreement with the reports by Murphy [1] and Perino and Wentreck [6]; (ii) the conductivity of