KDP single crystal growth via three‐dimensional motion growth method

A novel system for rapid crystal growth, namely three‐dimensional motion growth method (“3D MGM”) was proposed. Using this system, a potassium dihydrogen phosphate (KDP) seed was grown to a single crystal with a final size of 50×55×85 mm³. The KDP crystal was characterized by Raman spectroscopy, UV‐vis‐NIR spectroscopy, extinction ratio, laser damage threshold, and etching studies. Raman spectrum shows KDP crystal grown by “3D MGM” maintains good crystallinity as that grown by rotating‐crystal method (“RCM”). The “3D MGM” grown KDP crystal has much better transmittance, higher extinction ratio, higher damage threshold and less dislocation density, compared to “RCM” grown crystal.     

Study on rapid growth of KH2PO4 and its characterization

Large size crystals of KH₂PO₄ (KDP) were grown by adopting rapid growth technique from point seeds in a 1500‐liter crystallizer which is used to grow KDP crystals by conventional method. The grown KDP crystal size can reach to 310 × 310 × 320 mm³ and the average growth rate was 8mm/day. The optic properties of the rapidly grown KDP crystals were characterized comparing with the KDP crystals grown by the traditional temperature reduction method. We found it that the optical quality of the KDP crystals we grown rapidly are not significantly different from those of KDP crystals grown by traditional method. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Rapid Z-plate seed regeneration of large size KDP crystal from solution

Regeneration process of a 330×330×20 mm³ Z-plate seed is carried out in a 1.5 metric tonnage volume crystallizer that placed in a water bath of temperature fluctuation less than ±0.02 °C within 10 days. The surface of the whole crystal was restored by the formation of a box-like structure filled with growth solution, and then the transparent layer of perfect tetragonal KDP crystal without inclusions, crack and milky regions just like those produced by traditional slow cooling technique can be grown from solution. After the regeneration, the height of KDP crystal is merely 0.5 times the side of plate seed. We found it that the optical transmission and laser damage threshold of the KDP crystals we grown are not significantly different from those of KDP crystals grown by traditional method.     

Single crystal growth,structural, optical,mechanical, dielectric and thermal studies of formic acid doped potassium dihydrogen phosphate crystal for NLO applications

Optically transparent formic acid (FA) doped potassium dihydrogen phosphate (KDP) crystal of dimension 21×15×9 mm³ has been grown by slow evaporation solution technique (SEST). The X‐ray diffraction (XRD) technique was used to confirm the cell parameters and the shifts in peak positions of identified reflecting planes. The incorporation of FA in KDP has been qualitatively analyzed by fourier transform infrared analysis. The UV‐visible absorption spectrum of crystals has been recorded in the range of 200 to 900 nm and the doped KDP crystal is found to have improved optical parameters than pure KDP. The color centered photoluminescence emission spectrum of grown crystal has been illustrated in visible region. The mechanical behavior of pure and doped KDP crystal has been investigated using the Vicker's microhardness analyzer and hardness parameters have been calculated. The effect of FA on thermal stability of KDP crystal was examined by means of thermogravimetric and differential thermal analysis. The temperature dependent dielectric behavior of crystals was studied.     

Enhancement of stability of growth,structural and NLO properties of KDP crystals due to additive along with seed rotation

Potassium Acetate (CH₃COOK) and Potassium Citrate (K₃C₆H₅O₇) as new additives were added into the potassium dihydrogen phosphate (KDP) solutions in different molar ratios. The metastable zone width and induction period with and without these additives were determined and compared. Dielectric measurements on pure and doped KDP crystals at various temperatures ranging from 313 to 423 K were carried out by the conventional parallel plate capacitor method which results low dielectric constant value dielectrics in doped crystals. The high resolution XRD studies show that CH₃COOK doped KDP crystal and K₃C₆H₅O₇ doped KDP crystal do not contain any internal structural grain boundaries and indicates that the crystalline perfection is very good. Moreover, the addition of these potassium additives improves the quality of the crystal and yields highly transparent crystals with well defined features. The effect of additives on the growth, nucleation kinetics, structural, NLO and optical properties has been investigated. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Influence of La3+ ions on growth and NLO properties of KDP single crystals

Single crystals of pure and Lanthanum added KDP crystals were grown from aqueous solution. The influence of La³⁺ ions in KDP crystals is studied. Isolated centers are formed by La³⁺ ions in KDP structure along (100) plane. La³⁺ ions incorporated into superficial crystal growth layer and slightly affect the growth process as they generate weak lattice stresses. The creation of these weak lattice stress is confirmed by Vickers's micro hardness test. The HRXRD analysis showed reduced structural defects in the La added KDP in the (100) plane than pure KDP. The incorporation of La in the crystal was confirmed by EDAX analysis. The Kurtz's powder SHG efficiency was found to be 1.5 times that of pure KDP. The UV‐Vis transmission spectra of La added KDP showed excellent transmittance from 1100 nm to 340 nm and did not show any change in lower cutoff wavelength with respect to pure KDP. Laser damage threshold value has been determined using Q‐switched Nd:YAG laser operating at 1064 nm and with 65 ns pulses in single shot mode. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Influence of lithium ions on the NLO properties of KDP single crystals

Potassium Dihydrogen Phosphate (KDP) and its isomorphous deuterated form are popular due to their applications in frequency converters and electro‐optic modulation. Different attempts have been made to dope KDP with inorganic additives, organic materials and amino acids. Since many of the metal ions possess more electro negativity which increases the non centrosymmetry, it is of interest to dope them in KDP. The influence of lithium ion (Li⁺) on NLO properties of KDP crystal has been studied in the present investigation. Single crystal of Lithium ion doped Potassium Dihydrogen Phosphate (KDP) was grown by slow evaporation technique. The enhancement in SHG efficiency after addition of ion Lithium (Li⁺) was observed by Kurtz Powder SHG test. It was found that the SHG efficiency of KDP after addition of Lithium ion is 1.33 times more than pure KDP. The crystal structure and cell parameters of grown crystal were determined by X‐ray diffraction. The Energy Dispersive X‐ray analysis (EDAX) gives the chemical composition of grown crystal. The functional groups were identified by FT‐IR spectral analysis. The presence of Lithium in the material of grown crystal was detected by Atomic absorption spectroscopy (AAS). The optical absorption and transmission studies were done by UV‐Visible spectral analysis. The grown crystal was subjected to thermogravimetric analysis (TGA) and Differential Scanning Calorimetry (DSC). (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

An Investigation on the Lattice Distortion in Urea and KCl Doped KDP Single Crystals by X‐ray Diffraction Studies

Potassium dihydrogen phosphate (KDP) doped with different mole concentrations of Urea and KCl were grown using low temperature solution growth technique. X‐ray diffraction studies were carried out on the grown crystals using a Shimadzu X‐ray diffractometer with CuKD radiation. X‐ray study revealed that the structures of the doped crystals are slightly distorted compared to the pure KDP crystal. This may be attributed to strains on the lattice by the adsorption of urea and KCl.     

Growth and high frequency dielectric study of pure and thiourea doped KDP crystals

Non linear optical (NLO) materials have acquired new significance with the advent of a large number of devices utilizing solid‐state laser sources. Several NLO materials have been used for this kind of technological applications. The Potassium di‐hydrogen phosphate (KDP) one of NLO material having superior non linear optical properties has been exploited for variety of applications. In the present investigation we have grown KDP crystals from aqous solution with thiourea, an organic non linear optical material. We could enhance the SHG efficiency of thiourea doped KDP crystal. It was 1.99 times more that of pure KDP. We observed more enhancements in nonlinearity for low concentration of thiourea.The crystal structure and cell parameters of grown crystal were determined from Powder XRD.The incorporation of thiourea in the grown crystals was qualitatively analyzed from FT‐IR study. The absorption spectra of pure and thiourea doped KDP crystal reveal that thiourea doped KDP crystals would be a better nonlinear optical (NLO) material for second harmonic generation (SHG) than pure KDP. The thermal decomposition and weight loss of pure and thiourea doped KDP crystal was observed by thermogravimetric (TGA) analysis and Differential Scanning Calorimetry (DSC). The high frequency dielectric study of pure KDP crystal, thiourea doped KDP crystals and organic additive thiourea was carried out using X‐band at frequency 8GHZ and 12GHZ by transmission line wave guide method. We observed low dielectric constant of thiourea doped KDP crystal when it is doped with 2mole% of thiourea. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Growth and characterization of a novel NLO crystal bis-glycine hydrogen chloride (BGHC)

Single crystals of bis-glycine hydrogen chloride (BGHC), a semiorganic nonlinear optical (NLO) material, have been grown by slow solvent evaporation technique. Good optical quality single crystals with dimensions up to 33×5×5 mm³ are obtained. The crystals are characterized by optical transmission spectrum, FTIR and X-ray diffraction studies. The thermal stability of the crystal is studied by thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The second harmonic generation (SHG) efficiency of BGHC was found to be 5.6 times that of KDP. The laser damage threshold values studied in single shot mode indicates that BGHC crystal possesses a fairly high value of 9.8 GW/cm² and thus the NLO studies confirmed the superiority of BGHC over KDP and urea crystals. The dielectric constant of the crystal was studied as a function of frequency and the results are discussed.     

Growth and properties of dyed KDP crystals

Potassium dihydrogen phosphate (KDP) crystals doped with xylenol orange (XO) and methylthymol blue (MTB) are grown from aqueous solutions by the method of solvent evaporation at room temperature under the conditions of natural convection and by the method of temperature lowering. Studied is the influence of the mother solution acidity on the character of the crystal coloration. The color and coloration intensity of the grown crystals are shown to strongly depend on the solution's pH. It is revealed that the crystal habit changes in the presence of organic dyes. The optical transmission spectra and the luminescence spectra of KDP:XO solutions and of the grown crystals are measured. The effect of thermal treatment and UV‐irradiation on the coloration stability of the crystals is studied. It is found that the laser damage threshold in the prismatic impurity rich colored sectors of KDP:XO is the same as that in the prismatic sectors of pure KDP crystals. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Growth and characterization of bis-glycine sodium nitrate (BGSN), a novel semi-organic nonlinear optical crystal

Single crystals of bis-glycine sodium nitrate (BGSN), a semi-organic nonlinear optical (NLO) material, have been grown by slow cooling method. Good optical quality single crystals with dimensions up to 1.6×1.6×1.0 cm³ are obtained. Using a single-crystal diffractometer, the morphology of BGSN crystal was identified. Powder X-ray diffraction confirms the crystalline nature of BGSN. The grown crystals were characterized by optical transmission spectrum (UV) and FTIR studies. The NLO property of the crystal was confirmed by Kurtz second harmonic generation (SHG) test, and the output power generated by the crystal was compared with that of KDP. The thermal stability of the crystal was studied by thermo-gravimetric analysis (TGA), differential thermal analysis (DTA) and differential scanning calorimetry (DSC). Micro hardness study was carried out for different planes, and the anisotropy behavior of the crystal was observed.     

Single crystal growth and properties of semiorganic nonlinear optical L‐arginine hydrochloride monohydrate crystals

L‐arginine hydrochloride monohydrate (LAHCl.H₂O) has been synthesized and single crystals have been grown from its aqueous solution by slow evaporation and slow cooling methods. The solubility of the material was measured at various temperatures and bulk crystals of size 26×13×11 mm³ have been grown by optimizing the growth parameters. The grown crystals have been subjected to single crystal XRD studies to confirm the structure and to estimate the lattice parameters. FTIR analysis indicate the mode of vibrations of different molecular groups present in LAHCl and confirm the protonation of guanidyl, amino groups and deprotonation of COO^‐ groups. UV‐Vis transmission spectrum revealed the linear optical properties of the grown crystals with a transparency of 65% over the entire visible range upto 300 nm. Thermal behavior of the grown crystal was investigated from DTA and TGA measurements. Dielectric studies have been carried out on the grown crystals. Kurtz and Perry powder SHG technique confirms the NLO property of the grown crystal. The SHG efficiency of LAHCl was found to be 0.38 with respect to KDP. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Distribution of metallic ions in a single KDP crystal grown from aqueous solution

A single KDP (potassium dihydrogen phosphate) crystal was grown in a supersaturated solution containing a metallic ion (Al³⁺, Fe³⁺, or Cr³⁺). The growth rate, morphology, and distribution of the metallic ions into the KDP crystal were measured as the ionic concentration and supersaturation in the solution changed. It was found that in the KDP crystal, Al³⁺ and Fe³⁺ were greatly concentrated, but Cr³⁺ was diluted. Complete expressions for the effect of metallic ions on all aspects of the growth of KDP crystal were suggested. The growth rates of (100) and (101) faces were well correlated by the empirical equation and resulted in good estimation of morphology. The distribution of metallic ions into KDP crystal was also correlated by the distribution model. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Characterization of KDP crystal grown from solution with low pH value

Solubility curves of KDP (KH₂PO₄) in solutions with different pH values were measured. It was found that the solubility of KDP crystal increased with the reduction pH value of solution. Transparent KDP crystal was grown from solution with 1.5 pH by point seed. Chemical etching experiments revealed that pyramid sector of the crystal displayed more growth defects. Growth defects, such as growth striation and inclusion, were analyzed by white‐beam synchrotron radiation X‐ray topography. The reasons for the formation of these growth defects were discussed. Transmittance spectra test of both prismatic sector and pyramidal sector was performed. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Investigation on growth,optical, thermal,mechanical and dielectric studies of Benzimidazolium L-aspartate NLO crystal

The organic salt of Benzimidazolium L-aspartate (BLA) has been synthesised and single crystals were grown by slow evaporation solution growth technique at room temperature using water as the solvent. The grown crystal was subjected to single crystal X-ray diffraction analysis and confirmed it belongs to monoclinic crystal system with space group P2₁/c. The crystalline perfection was studied using High resolution X-ray diffraction (HRXRD). The functional groups were analysed by FT-IR analysis. The optical transmittance and the lower cut-off wavelength of the BLA crystal have been identified by UV-Vis study. The thermal stability of the title crystal was investigated by TGA/DTA analyses. The Vickers microhardness analysis was carried out to study the mechanical strength of the crystal. The dielectric response of the crystal was studied in the frequency range 100 to 5 MHz at different temperatures. The surface morphology of the grown BLA crystal was studied by scanning electron microscopy (SEM). The second harmonic generation efficiency was measured in comparison with KDP by employing Kurtz Perry Powder method.     

Synergy of organic dyes for KDP crystal growth

Single potassium dihydrogen phosphate (KDP) crystals were grown in a supersaturated solution containing an organic dye (sunset yellow FCF, brilliant blue FCF, and sky blue). The growth rate, morphology, and impurity dye distribution of faces, (100) and (101) in a KDP crystal were measured as dye concentration and the supersatutation of KDP were changed. Complete expressions for the effect of dye on all aspects of the growth of KDP crystals were discussed. The growth rates of (100) and (101) faces were well correlated by the empirical equation, and resulted in good estimation of the morphology. The distribution of dye in a KDP crystal was represented by the distribution model containing the minimum growth rate for coloring. The growth rate equation and distribution equation were expressed by functions of the supersaturation and dye concentration, and they could effectively provide the operational conditions with coloring the KDP crystal. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Crystal growth,structure and spectroscopic studies of a novel organic single crystal: L‐lysine p‐nitrophenolate monohydrate (LLNP)

A novel organic crystal, L‐lysine p‐nitrophenolate monohydrate (LLNP) has been grown successfully from an aqueous solution by the slow cooling method. Transparent single crystal of dimensions 22 × 12 × 12 mm³ has been obtained. The single crystal X‐ray diffraction has shown that LLNP belongs to the orthorhombic crystallographic system with space group P2₁2₁2₁. The functional groups and vibrational frequencies of the crystal have been identified using IR and Raman spectra. The proton and carbon configurations have been confirmed through ¹H‐NMR and ¹³C‐NMR spectra analyses. The UV‐Vis‐NIR transmittance spectrum for LLNP crystal has been recorded in the range from 200 to 2500 nm. The second harmonic generation (SHG) intensity of LLNP has been measured by powder SHG method and found to be as 4.2 times as that of KDP. The thermal properties have been studied by using thermo gravimetric (TG) and differential thermal analysis (DTA).     

Crystallization of benzimidazole by solution growth method and its characterization

The potential organic NLO crystal of benzimidazole (BMZ) has been successfully grown by slow evaporation solution growth technique at room temperature. The crystalline perfection has been verified by High resolution X‐ray diffraction (HRXRD) analysis. The very low angle boundary obtained for this solution‐grown specimen may be attributed to the segregation of solvent molecules (methanol), which were entrapped within the crystal during growth. The laser damage threshold has been measured by using high intensity Q‐switched Nd:YAG laser. The observed value is greater than that of KDP and lesser than that of melt grown benzimidazole. The NLO efficiency has been determined and it is compared with the KDP crystal. The thermal behaviour has been assessed by TG/DTA analysis. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Chemical bond analysis of the crystal growth of KDP and ADP

The bond valence model is employed to calculate the bond strength of constituent chemical bonds formed between growth units in both potassium dihydrogen phosphate (KDP) and ammonium dihydrogen phosphate (ADP) crystals, with the aim to predict and control the crystal shape. After calculating and comparing the relative growth rates of all selected planes, which are related to the crystallographic structure and chemical bond strength, the natural morphology of both KDP and ADP can be conveniently deduced. To check the calculated results, the crystallites of KDP and ADP are grown under different growth conditions; their morphologies accord well with our theoretical calculations. Meanwhile, the influence of ethanol anti-solvent on crystal morphology is microscopically interpreted, which alters the crystal morphology by changing the supersaturation of the growing solution and influencing the bonding process. When ethanol is added into the growing solution, the crystal shape becomes slender.