Ammonium Dihydrogen Phosphate Single Crystals Research Articles

Effect of Ni2+ doping on structural, optical, mechanical and dielectric properties of ammonium dihydrogen phosphate (ADP) single crystals: A novel NLO material

Owing to its exceptional applications in nonlinear optical devices, ammonium dihydrogen phosphate (ADP) is considered as potential candidate in modern era of hi-tech applications. Therefore, in the present work we have grown good quality single crystals of pure and Ni2+ doped (1, 2.5% and 5%), ADP using slow evaporation technique. X-ray study has been carried out in order to see the effect of dopant on the structural parameter of ADP. The UV–vis–NIR studies confirmed that 1.0mol%, 2.5mol% doped crystals have high transmittance compare to 5.0mol% Ni2+ doped ADP crystals. Surface studies have been carried out on pure and doped crystals. Typical striations are observed on the (100) faces of pure and doped crystals, suggest that the growth occurs by 2D nucleation. The microhardness studies of pure and doped crystals carried out at different loads. The hardness of 5.0mol% Ni2+ doped crystals shows higher hardness value compare to 1.0mol%, 2.5mol% doped crystals. The mechanical properties such as fracture toughness (Kc), brittleness index (Bi) and yield strength (σy) are presented. The dielectric studies were carried out in the high frequency range (1–6MHz) and all the results indicate that the grown crystals are of good quality.

Characterization of a potential nonlinear optical material: Sodium fluoride additive on ammonium dihydrogen orthophosphate single crystals

Effects of the additions of sodium fluoride (NaF) on the growth, structural and various optical properties of ammonium dihydrogen orthophosphate (ADP) single crystals grown by a slow evaporation solution growth technique from aqueous solution has been investigated. Crystallinity of the grown crystals was studied by powder X-ray diffraction analysis. Both pure and NaF doped ADP crystals exhibit tetragonal crystal structure. 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 NaF doped ADP crystal is around 300nm. From the spectra it can be clearly inferred that the transmittance percentage is increased in the NaF doped crystals. Also 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. The bonding structure and molecular associations due to chemical reactions were analyzed by FTIR analysis. It also confirms the functional groups present in the grown crystals. Second harmonic generation (SHG) test adopting Kurtz-Perry technique revealed that the second harmonic generation efficiency of NaF doped ADP is 1.3 times that of pure ADP crystal.

Effects of 1,2-dichloroethane on the optical, thermal, mechanical and NLO behaviors of ADP crystals

The effects of 1,2-Dichloroethane (DCE) over a concentration range from 1 to 5mol% on the optical absorption, hardness, thermal, microhardness behaviors and SHG efficiency of ammonium dihydrogen phosphate (ADP) single crystals grown by slow evaporation solution growth technique have been investigated. The powder X-ray diffraction and FT-IR analyses indicate that the crystals undergo considerable stress as a result of doping and these also confirm the slight distortion of the structure of the crystal in the presence of a high concentration of dopant (5mol%). UV–vis studies reveal that the absorption of the DCE doped crystals is less than that of pure ADP. Thermal studies (TG/DTG) disclose that the decomposition temperature of doped ADP is more than that of pure ADP. Vicker's microhardness study reveals that the addition of DCE increases the hardness of the ADP. SHG efficiency of DCE doped ADP is higher than that of pure ADP. Presence of dopant was confirmed by energy-dispersive spectrometry.

Growth, SXRD, optical and dielectric studies on inorganic ammonium sulphate doped ammonium dihydrogen phosphate (ASADP) single crystals

Growth, SXRD, optical and dielectric studies on inorganic ammonium sulphate doped ammonium dihydrogen phosphate (ASADP) single crystals

Indentation studies on 〈1 0 0〉, 〈0 0 1〉 and 〈1 0 1〉 face of ammonium dihydrogen phosphate (ADP) single crystals: A novel nonlinear optical material

In the present work, Vickers microhardness measurements were carried out on different faces i.e. (100), (001) and (101) of ammonium dihydrogen phosphate (ADP) single crystals grown by slow evaporation solution technique at room temperature in the load ranging from 0.2 to 2N. The obtained results show that the load independent hardness values are 0.8, 0.7 and 0.66GPa, respectively at different faces of ADP crystal. From the crack length measurements, the fracture toughness values (Kc) was estimated using Evans and Anstis model and the present studies suggest that Evans model is more relevant when compared to Anstis model. The load variation of some mechanical properties viz. brittle index number (Bi) and yield strength (σy) for ADP have also been calculated for the first time.

Dynamical diffraction of X-rays in ADP single crystal under influence of temperature gradient

The dependence of the integrated intensity of X-ray beams diffracted from a single crystal of ammonium dihydrogen phosphate (ADP) in the Laue geometry on the applied temperature gradient has been investigated. It is found that the integrated intensity of the X-ray beam reflected from a single crystal depends almost linearly on the magnitude of the temperature gradient, applied perpendicular to the reflecting atomic planes, up to saturation. For small values of the temperature gradient, in case of antiparallel vectors of diffraction and temperature gradient, integrated intensity of the reflected X-rays is initially reduced by about 10% and then increases monotonically with increasing value of the temperature gradient. Based on the theoretical analysis, an explanation of the observed phenomena is given.

Study of pure and l-tartaric acid doped ammonium dihydrogen phosphate single crystals: A novel nonlinear optical non-centrosymmetric crystal

Single crystals of pure and l-tartaric acid (LTA) C4H6O6 doped ammonium dihydrogen phosphate (ADP) (NH4) H2PO4 were grown by slow evaporation solution technique (SEST) at ambient conditions. Powder X-ray diffraction (PXRD) analysis was carried out to confirm the crystal structure and no additional phase was observed due to doping except a systematic variation in peak intensities. Fourier transform infrared spectral analysis was done to examine the presence of various functional groups in the grown crystals. UV–VIS–NIR spectroscopic analysis was carried out to see the change in optical transparency of pure ADP and crystals due to LTA with different doping concentrations. Second harmonic generation (SHG) efficiency measurement was done to examine the enhancement in the nonlinear optical characteristics of the grown crystals. The effect of LTA dopant on crystal morphology, thermal and mechanical properties of ADP have also been presented in this paper. The above studies reveal the effect of incorporation of LTA into the lattice of ADP crystals.

Structural, spectroscopic, optical, dielectric and mechanical study of pure and l-Proline doped ammonium dihydrogen phosphate single crystals

Single crystals of pure and l-Proline (LP) C5H9NO2 doped ammonium dihydrogen phosphate (ADP) (NH4) H2PO4 were grown by slow evaporation solution technique (SEST) at ambient conditions. Powder X-ray diffraction (PXRD) analysis was carried out to confirm the crystal structure and no additional phase was observed due to doping except a systematic variation in peak intensities. FT-Raman analysis also confirms that there is no additional phase formation due to doping. Fourier transform infrared spectral analysis was done to examine the presence of various functional groups in the grown crystals. UV–VIS–NIR spectroscopic analysis was carried out to see the change in optical transparency of pure ADP and crystals due to LP with different doping concentrations. The high-resolution X-ray diffraction (HRXRD) analysis was carried out to examine the crystalline perfection and observed reasonable changes with LP doping. Second harmonic generation (SHG) efficiency measurement was done to examine the enhancement in the nonlinear optical characteristics of the grown crystals. The dielectric behavior of the samples shows that the dielectric constant decreased with increase the value of frequency. The effect of LP dopant on crystal morphology, mechanical properties of ADP has also been presented in this paper. The above studies reveal the effect of incorporation of LP into the lattice of ADP crystals.

Effect of Hippuric Acid on the Growth, Structural and Optical Properties of Non Linear Optical Crystals

Non-linear optical potassium dihydrogen phosphate (KDP) and ammonium dihydrogen phosphate (ADP) single crystals with 1 mol% of hippuric acid dopant were grown from aqueous solution by employing slow evaporation technique. With appropriate dopants, the KDP and ADP crystals exhibit several desirable properties. Crystallinity of the grown crystals was studied by powder XRD analysis. The bonding structure and molecular associations 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 hippuric acid doped KDP and ADP crystals is around 300 nm. Second harmonic generation (SHG) test adopting the Kurtz Perry technique revealed that the SHG efficiency has increased due to doping when compared with pure KDP and ADP crystals.

Growth and spectroscopy studies of ADP single crystals with l-glutamine and l-cysteine amino acids

Ammonium dihydrogen orthophosphate (ADP) crystals were grown with l-glutamine C5H10N2O3 (gln) and l-cysteine C3H7NO2S (cys) amino acids, with polar side-chains, as additives at 4% molar concentrations. X-ray diffractograms, vibrational FT-IR, and Raman and NMR MAS of 31P, 1H and of pure and treated compounds were recorded at room temperature and interpreted. A lift of degeneracies of the ν4 asymmetric bending modes of both PO4 and NH4 tetrahedron species, as well as a shift of the wavenumbers of some of their internal modes was observed. At the same time, some characteristic vibrational modes of the organic molecules appeared. However, NMR results show a little shift of the resonance of the phosphorus and hydrogen nucleus, associated with some shoulders for this latter. The presence of the organic molecules was also revealed by 13C MAS NMR. These observations indicate that the host-additives interactions were achieved.

Growth and Characterization of ADP Single Crystal

Ammonium dihydrogen phosphate (ADP) (NH<SUB>4</SUB>H<SUB>2</SUB>PO<SUB>4</SUB>) single crystals were grown by gel method using sodium metasilicate (SMS). The X-ray diffraction analysis of the as–grown ADP crystals showed that it possess tetragonal structure having lattice parameters a = 7.502 °A and c = 7.554 °A. The Fourier transform infrared spectroscopy (FTIR) of as-grown ADP crystal taken between wave-number 400 to 4000 cm<SUP>-1</SUP> showed peaks due to vibration and stretching of functional group O-N=P and –ONO<SUB>2</SUB> in 485 to 902 cm<SUP>-1</SUP>, P=O and O-H in 1076 to 1544 cm<SUP>-1</SUP> and O-H and N-H in 2400 to 3371 cm<SUP>-1</SUP> range. The UV-Vis-NIR spectroscopy of ADP crystal showed direct optical bandgap of 4.99eV and indirect optical bandgap of 4.12eV. The optical microscopy employed to study the surface microstructure showed hillocks on the as-grown surfaces arising due to local increased supersaturation. The thermal properties of the as-grown ADP crystals were studied by thermogravimetric analysis (TGA). The thermal activation energy determined from the TGA curve using Broido, Piloyan-Novikova (PN) and Coats Redfern (CR) relations were in good agreement with each other. The obtained results are discussed in details.

EPR and optical studies of Cu 2+ doped ammonium dihydrogen phosphate single crystals

Electron paramagnetic resonance (EPR) spectra of Cu 2+ ion in ammonium dihydrogen phosphate are studied at liquid nitrogen temperature (77 K). Four magnetically inequivalent Cu 2+ sites in the lattice are identified. The angular variation spectra of the crystal in the three orthogonal planes indicate that the paramagnetic impurity, Cu 2+ enters the lattice substitutionally in place of NH 4 + ions. The spin Hamiltonian parameters are determined with the fitting of spectra to rhombic symmetry crystalline field. The ground state wave function of Cu 2+ ion is constructed and found to be predominantly | x 2– y 2〉. The cubic field parameter ( Dq) and tetragonal parameters ( Ds and Dt) are determined from optical spectra at room temperature. By correlating EPR and optical absorption spectra, the bonding coefficients are calculated and nature of bonding of metal ion with different ligands in the crystal is discussed.

Growth and spectroscopy studies of ADP single crystals with l-proline and l-arginine amino acids

Ammonium dihydrogen orthophosphate (ADP) single crystals were grown with l-proline and l-arginine amino acids as additives at 4% molar concentrations. X-ray diffractograms, vibrational FT-IR, and Raman and NMR MAS of 31P and 1H spectra of pure and treated compounds were recorded at room temperature and interpreted. A shift of the wavenumbers of some internal modes of both PO 4 and NH 4 tetrahedrons species was observed. At the same time, some characteristic vibrational modes of N–H and C–H bonds of the organic molecules appeared in IR spectra. However, NMR results show a little shift of the resonance of the phosphorus and hydrogen nucleus, associated with some shoulders for this latter. These observations indicate that the host-additives interactions were achieved.

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.

A comparative study on pure, l-arginine and glycine doped ammonium dihydrogen orthophosphate single crystals grown by slow solvent evaporation and temperature-gradient method

Single crystals of pure, l-arginine and glycine doped ammonium dihydrogen orthophosphate (ADP) were grown by both the slow solvent evaporation method and the temperature-gradient method of Sankaranarayanan–Ramasamy (SR). The metastable zone width for different saturation temperatures of pure glycine and l-arginine added solutions were carried out. The grown crystals were characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), powder X-ray diffraction (XRD), optical transmission, dielectric constant, dielectric loss, and Vickers microhardness. The DSC and TG curves of the grown crystals indicated that they were stable up to 200 °C. The XRD study confirmed the structure of the grown crystal. The optical transmission analysis revealed that the pure and doped ADP crystals had very high percentage of transmission in the entire visible region. The important optical parameters such as reflectance and extinction coefficients of the grown crystals were calculated. l-arginine and glycine were used as dopants to reduce dielectric constant of ADP. The a.c. resistivity and a.c. conductivity were calculated. Dielectric loss of the doped ADP crystals grown by the SR method is lower than the doped ADP crystals grown by the conventional method. Larger hardness value for the SR method grown crystals confirmed greater crystalline perfection.

Single crystal EPR, optical absorption and superposition model study of Cr 3+ doped ammonium dihydrogen phosphate

The electron paramagnetic resonance (EPR) studies are carried out on Cr 3+ ion doped ammonium dihydrogen phosphate (ADP) single crystals at room temperature. Four magnetically inequivalent sites for chromium are observed. No hyperfine structure is obtained. The crystal-field and spin Hamiltonian parameters are calculated from the resonance lines obtained at different angular rotations. The zero field and spin Hamiltonian parameters of Cr 3+ ion in ADP are calculated as: | D| = (257 ± 2) × 10 −4 cm −1, | E| = (79 ± 2) × 10 −4 cm −1, g = 1.9724 ± 0.0002 for site I; | D| = (257 ± 2) × 10 −4 cm −1, | E| = (77 ± 2) × 10 −4 cm −1, g = 1.9727 ± 0.0002 for site II; | D| = (259 ± 2) × 10 −4 cm −1, | E| = (78 ± 2) × 10 −4 cm −1, g = 1.9733 ± 0.0002 for site III; | D| = (259 ± 2) × 10 −4 cm −1, | E| = (77 ± 2) × 10 −4 cm −1, g = 1.973 ± 0.0002 for site IV, respectively. The site symmetry of Cr 3+ doped single crystal is discussed on the basis of EPR data. The Cr 3+ ion enters the lattice substitutionally replacing the NH 4 + sites. The optical absorption spectra are recorded in 195–925 nm wavelength range at room temperature. The energy values of different orbital levels are determined. On the basis of EPR and optical data, the nature of bonding in the crystal is discussed. The calculated values of Racah interelectronic repulsion parameters ( B and C), cubic crystal-field splitting parameter ( D q) and nephelauxetic parameters ( h and k) are: B = 640, C = 3070, D q = 2067 cm −1, h = 1.44 and k = 0.21, respectively. ZFS parameters are also determined using B kq parameters from superposition model.

Effect of cobalt and dl-malic acid on the growth rate, crystalline perfection, optical, mechanical, dielectric, piezoelectric properties and SHG efficiency of ADP single crystals

Effects of the additions of cobalt (II) acetate hexahydrate and dl-malic acid on the growth and various properties of ammonium dihydrogen orthophosphate single crystals grown by slow evaporation method have been studied. The grown crystals were subjected to UV–vis, microhardness, dielectric, piezoelectric, high resolution X-ray diffraction and SHG studies. UV spectra show good transparency in the entire visible region which is an essential requirement for a nonlinear optical crystal. Vickers hardness study carried out on (1 0 0) face at room temperature shows increased hardness of the crystals added with dl-malic acid compared to the pure and cobalt (II) acetate hexahydrate added crystals. Dielectric constant and dielectric loss were measured for the grown crystals for different frequencies and temperatures. It reveals that the dl-malic acid added ADP crystals have low dielectric loss. Crystalline perfection of the grown crystals was analyzed using HRXRD. Good piezoelectric behaviour was observed for all the crystals. Preliminary measurements indicate that the second harmonic generation efficiency of the dl-malic acid doped crystals is greater than pure and cobalt (II) acetate hexahydrate added ADP.

Growth of 〈1 0 0〉 directed ADP crystal with slotted ampoule

Good quality ammonium dihydrogen phosphate single crystals have been grown by: (i) Sankaranarayanan–Ramasamy (SR) method and (ii) SR method with slotted ampoule. The grown crystals were subjected to UV–Vis spectroscopy, high-resolution X-ray diffractometer, dielectric, piezoelectric and laser damage threshold studies. Compared to the (1 0 0) plane of the conventional method grown ADP crystal and 〈1 0 0〉 directed SR method grown ADP crystal, the crystal grown by SR method with slotted ampoule has higher growth rate, higher optical transparency, high crystalline perfection, low dielectric loss, high piezoelectric charge coefficient and high laser damage threshold due to diffusion of segregated impurities away from the growing crystal in the slotted ampoule growth.

Effect of Ni2+ on the structural, optical, thermal and dielectric properties of ADP single crystals

The effects of the addition of Ni2+ on the growth and various properties of ammonium dihydrogen phosphate single crystals grown from aqueous solution by the slow evaporation method have been studied. The grown crystals were subjected to HRXRD, UV–Vis, TG/DTA and dielectric studies. The structural perfection of the grown crystal has been analyzed by high resolution X-ray diffraction rocking curve measurements. UV–Vis studies show that the grown crystal has good transparency in the entire visible region which is an essential requirement for a nonlinear crystal. Higher decomposition temperature was observed from TG/DTA. Dielectric constant and dielectric loss were measured for the grown crystal for different frequencies and temperatures.

Comparative study on l-asparagine monohydrate doped ADP crystals

Good quality ammonium dihydrogen phosphate single crystals added with 1 mol% of l-asparagine monohydrate in the mother solution were grown from solutions by slow evaporation, slow evaporation along with seed rotation and Sankaranarayanan–Ramasamy method with the vision to improve the properties of the crystals. The growth rate of Sankaranarayanan–Ramasamy method grown crystal was four times higher than the slow evaporation grown crystal. The grown crystals were found to be transparent in the entire visible region. Thermal stability is higher for l-asparagine monohydrate-added ammonium dihydrogen phosphate crystals. Higher hardness has been obtained for the Sankaranarayanan–Ramasamy method grown unidirectional crystal. Slow evaporation along with seed rotation method and Sankaranarayanan–Ramasamy method grown single crystals have low dielectric loss compared to slow evaporation method grown crystal. The second harmonic efficiency was measured for all the crystals and there was no measurable difference obtained between them.