Glycine Phosphite Crystals Research Articles

Rapid enhancement of optical transparency on glycine phosphite crystals by shock waves

Rapid enhancement of optical transparency on glycine phosphite crystals by shock waves

Structural, conductivity and DFT studies of L-Histidinium phosphite – Ferroelectric phosphite single crystal

L-Histidinium phosphite [C6N3O2H10]+. [HPO3H]- abbreviated as HPI, is a semi-organic nonlinear optical material. In the present work HPI crystals were grown from the aqueous solution of HPI by slow evaporation technique. Single crystal XRD (SXRD) reveals that the resulting crystals predominantly exhibit monoclinic structure with space group P21. Sharp and well-defined peaks of the powder XRD pattern attested the good crystallinity of HPI and the pattern is in agreement with SXRD results. The different modes of vibrations of molecular groups and functional groups present in the HPI crystal was investigated using IR spectra. It is evident from the UV–Vis spectrum that HPI is transparent in the examined frequency regime. The TG-DTA studies ascertain that the crystal is thermal stable till 230 ​°C. A.C. and D.C. conduction mechanism in the grown crystals were studied from 119 ​K to 380 ​K for 1 ​kHz to 1 ​MHz frequency range. The pattern suggests that there is ferroelectric to paraelectric transition at 270 ​K. This transition temperature is higher than the glycine phosphite crystals. Detailed insight about the conduction mechanism in HPI crystals was analyzed by complex impedance and modulus studies. Density functional theory was applied to know in detail about the structure and non-linear optical characteristics of the grown crystal and it attested that HPI is NLO active at room temperature.

Impact of shock waves on vibrational and structural properties of glycine phosphite

This article carries the findings of the effect of shock waves on glycine phosphite (GPI) powder samples which have been investigated under pre and post shock loaded conditions with the shock pulses of 50 and 100 at the Mach number of 2.2. Molecular structural stability and crystal structural stabilities have been established by Fourier transform infrared spectroscopy (FTIR) and powder X-ray diffractometry (XRD). From XRD studies, it has been observed that there is change in crystalline peak intensity, peak distortion and formation of new peaks in shock wave loaded samples whereas no alteration in the original crystal system. There is no change observed in FTIR profiles at shock loaded conditions. The obtained crystallographic studies prove with substantial evidence that the crystal has molecular stability and stable crystallographic structure against the impact of applied shock waves. On the other hand, many of the crystalline planes have disappeared and re-appeared with respect to number of shock waves but maintaining the same crystallographic phase. From the shock wave impact study; the authors suggest that GPI crystal, particularly (21-1) orientation, is suitable for devices used in harsh environment and high power laser application due to the relative stability of the crystalline properties.

Growth, structural, dielectric and optical characteristics of glycine phosphite single crystals

Interesting compounds are formed when glycine reacts with inorganic materials. These compounds exhibit phase transitions with exciting dielectric and elastic properties. In this aspect, glycine with orthophosphorus acid forms glycine phosphite (GPI) single crystals. Good quality, optical transparent glycine phosphite (GPI) single crystals are grown from aqueous solution. GPI crystals have a wide range of nonlinear optical applications. The present work focuses on the growth of GPI from its aqueous solution by slow evaporation method. The PXRD (powder XRD) pattern recorded at ambient temperature shows the single phase nature of the grown GPI crystals and it exists in the monoclinic system with space group P21/a. Etching studies were carried out to know more about the growth morphology and FTIR spectra shows the presence of a variety of normal mode vibration of GPI crystals. Dielectric studies were carried out from 100 K to 383 K. the ferroelectric to para electric transition was observed at 201 K. The dielectric relaxation of the grown crystals was studied using Debye fitting. The activation energy associated with the transition was also calculated. As the GPI crystals are paraelectric at room temperature, no second order non linearity was observed.

Thermal, dielectric, and surface analysis of NaDP doped glycine phosphite single crystals

Transparent, unidirectional single crystals of sodium dihydrogen phosphate-doped glycine phosphite (NaDP–GPI) are grown by the Sankaranarayanan-Ramasamy method. The good quality crystal is obtained under controlled thermal conditions. The functional groups and melting temperature of NaDP–GPI single crystals are analysed. The phase transition temperature of NaDP–GPI is calculated from the dielectric studies. The mound-like patterns are observed on the surface of the crystal. The growth process under the controlled thermal condition was observed by optical studies. The obtained results are discussed in detail.

Improvement in Structural, Dielectric, Ferroelectric and Mechanical Properties in Metal Ions Doped Glycine Phosphite Single Crystals

The single crystals of metal ions (Zn2+, Mg2+ and Cd2+) doped Glycine Phosphite (GPI) were grown from aqueous solution by employing the solvent evaporation and slow cooling techniques. Incorporation of dopants with GPI was confirmed by X-ray fluorescence spectroscopic analysis. Single crystal X-ray diffraction analysis was carried out to determine the lattice parameters and to analyze the structural morphology of GPI with dopants. Ferroelectric transition temperature was identified by dielectric measurements for pure and doped GPI crystals. Transition temperature of doped crystal increases significantly. Piezoelectric charge coefficient d33 was measured for pure and doped GPI crystals. Hysteresis (P-E) loop was traced for pure and doped GPI crystals with different biasing field. Crystalline perfection of doped GPI crystals was determined by HRXRD analysis. Microhardness measurements were carried out for understanding the mechanical stability of the crystals, the mechanical parameters such as elastic stiffness constant ‘C11’, yield strength ‘σy’ were calculated from hardness value. Meyer's index number was in the range of 1.6 to 2 for all the crystals. This indicates that the grown crystals are relatively soft materials.

Effect of rare earth ions on the properties of glycine phosphite single crystals

Optically transparent glycine phosphite (GPI) single crystals doped with rare earth metal ions (Ce, Nd and La) were grown from aqueous solution by employing the solvent evaporation and slow cooling methods. Co-ordination of dopants with GPI was confirmed by X-ray fluorescence spectroscopic analysis. Single crystal X-ray diffraction analysis was carried out to determine the lattice parameters and to analyze the structural morphology of GPI with dopants, which indicates that cell parameters of doped crystals were significantly varied with pure GPI. Crystalline perfection of doped GPI crystals was determined by high resolution X-ray diffraction analysis by means of full width at half maximum values. Influence of the dopants on the optical properties of the material was determined. Paraelectric to ferroelectric transition temperature (Tc) of doped GPI crystals were identified using differential scanning calorimetric measurements. Piezoelectric charge coefficient d33 was measured for pure and doped GPI crystals. Hysteresis (P–E) loop was traced for ferroelectric b-axis and (100) plane of pure and doped GPI crystals with different biasing field and ferroelectric parameters were calculated. Mechanical stability of crystals was determined by Vickers microhardness measurements; elastic stiffness constant ‘C11’ and yield strength ‘σy’ were calculated from hardness values. Mechanical and ferroelectric properties of doped crystals were improved with doping of rare earth metals.

Study of the influence of dopants on the crystalline perfection of ferroelectric glycine phosphite single crystals using high-resolution X-ray diffraction analysis

Good quality and optically transparent single crystals of pure and doped glycine phosphite (GPI) were grown by both solvent-evaporation and temperature-cooling techniques. Dopants were chosen in different categories, namely transition metals (Cr, Mn, Co, Ni, Zn, Mg, Cd), rare-earth metals (Ce, Nd, La), dyes (rhodamine B, malachite green, fluorescein) and an amino acid (L-proline). The concentration of dopants was chosen depending on the category of dopants and the quality of crystallization during the growth process. The crystalline perfection of the as-grown pure and doped GPI crystals was investigated by high-resolution X-ray diffraction at room temperature. A multicrystal X-ray diffractometer employing a well collimated and highly monochromated Mo Kα1beam and set in the (+, −, −, +) configuration was employed. Most of the crystal specimens show excellent crystalline perfection. However, grain boundaries, low-angle tilt boundaries, and vacancy and interstitial point defects were observed in some crystal specimens.

Synthesis, Crystal Growth, Structural, Dielectric and Ferroelectric Properties of N-Acetyl Glycine Phosphite (AGPI) Single Crystals

Single crystals of N-Acetyl Glycine Phosphite (AGPI) were grown from aqueous solution by low temperature solution growth technique. Formation of the new crystal has been confirmed by single crystal XRD studies. AGPI belongs to monoclinic system with cell parameters a = 7.419 Å, b = 8.487 Å, c = 9.791 Å. Crystalline quality was found using rocking curve. The presence of functional groups were estimated qualitatively by FTIR analysis. The dielectric studies were carried out to identify the phase transition temperature and to find the dielectric constant. Hysteresis studies were carried out to identify the ferroelectric nature of the material. AFM studies were carried out to understand the ferroelectric surface and the domain structure.

Studies on conventional and Sankaranarayanan–Ramasamy (SR) method grown ferroelectric glycine phosphite (GPI) single crystals

Transparent single crystals of glycine phosphite were grown by Sankaranarayanan–Ramasamy (SR) method and conventional slow evaporation solution technique (SEST) which had the sizes of 100 mm in length, 30 mm diameter and 10×11×8 mm 3. The conventional slow evaporation and Sankaranarayanan–Ramasamy method grown glycine phosphite single crystals were characterized using laser damage threshold, chemical etching, Vickers microhardness, UV–vis–NIR and dielectric analysis. The laser damage threshold value was higher in SR method grown GPI crystal as against conventional method grown crystal. The SR method grown GPI has higher hardness and also higher transmittance compared to conventional method grown crystal. The chemical etching and dielectric loss measurements indicate that the crystal grown by SR method has low density of defects and low value of dielectric loss compared to conventional method grown GPI crystal.

Study of Microhardness and Its Related Physical Constants of Ferroelectric Glycine Phosphite (GPI) Single Crystals

The ferroelectric crystals of Glycine Phosphite were grown by low temperature solution growth technique. The variation of hardness on (010) plane of monoclinic GPI crystals, (NH3CH2COOH3PO3), with load was studied. Vickers hardness, H v and Knoop hardness numbers, H k were found to decrease with an increase in load. Meyer's index ‘n’ was found to be less than 2 showing soft-material characteristics. The fracture toughness values ‘K c’, determined from measurements of crack lengths, were estimated to be 0.1266 MN/m3/2, The brittleness indices ‘B i’ were estimated as 4270.7 m−1/2. Elastic stiffness coefficient, C 11 and Young's modulus were calculated from the hardness.

Structural and microhardness studies of pure and thiourea doped glycine phosphite single crystal

AbstractFerroelectric Glycine Phosphite (GPI) crystal have been grown from aqueous solution employing the slow cooling technique. As the crystal solubility in water depends on temperature, single crystals were grown. Transparent, colourless crystals with habit morphology weighing about 8g were obtained with in a month. The same procedure was used to grow single crystals of 10 wt% of Thiourea doped GPI (TUGPI). Formation of a new crystal was confirmed by Powder X‐ray diffraction studies as well as FTIR studies. Crystalline quality were found using rocking curve for both the crystals. Due to the presence of Thiourea in TUGPI, it improves the crystalline perfection and also enhances the growth rate. The variation of hardness on (010) faces of monoclinic GPI and TUGPI crystals, with load were studied.Vickers hardness numbers, Hv were found to decrease with the increase in load. The value of Mayer's index, ‘n ’ was found to be greater than 1.6 for GPI and TUGPI showing soft‐material category. The results are discussed in detail. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Dielectric properties of glycine phosphite crystals in the model of a phase transition with inclusion of high-order invariants

Dielectric anomalies in the vicinity of the ferroelectric phase transition in nominally pure glycine phosphite (GPI) crystals and glycine phosphite crystals containing 2 mol % glycine phosphate (GP) are studied. It is revealed that the impurity-induced internal macroscopic polarization observed for GPI-GP crystals brings about smearing of the dielectric anomalies in directions both parallel and perpendicular to the axis of spontaneous polarization. The ferroelectric phase of the GPI and GPI-GP crystals is characterized by an unusual variation in the inverse permittivity in the Z direction perpendicular to the Y axis of spontaneous polarization. The temperature dependence of the inverse permittivity is described by a power expression (Tc − T)n with an exponent n larger than unity. The experimental data are analyzed in terms of the proposed thermodynamic model with two order parameters, namely, the displacement parameter η and the order-disorder parameter P, which have different physical natures but the same symmetry and allow for coupling invariants of the ηP and η3P types, as well as for the built-in polarization in the case of GPI-GP crystals. The experimental and theoretical dependences are in good agreement. The coefficients of bilinear and nonlinear coupling between the order parameters are determined. It is shown that the phase transition in the crystals occurs in the vicinity of the tricritical point and that the unusual behavior of the permittivity with a variation in the temperature is explained by the contribution from high-order invariants of coupling.

Ferroelectric Phase Transition Character of Glycine Phosphite

The phase transition of glycine phosphite (GPI) and partially deuterated glycine phosphite (DGPI) single crystals has been characterized by applying the effective mean field theory. Temperature dependence of the spontaneous polarization P s(T) has been analyzed from hysteresis loops for these crystals. With the increment of deuteration ratio, saturated spontaneous polarization P s 0 is also increased. As a result, the quantitative phase transition indicator g according to the mean field theory is being increased but the maximum increment is underlying the decisive tricritical point g = 1/3. The phase transition character of GPI crystal is proved to be second order but very near to the tricritical point.

Defect Dipoles and Internal Bias Field in Glycine Phosphate-Doped Glycine Phosphite Crystals

Temperature dependences of pyroelectric, piezoelectric and dielectric responses of glycine phosphite crystals doped with glycine phosphate, in temperature interval 120–320 K, have been investigated. It was established that, unlike the undoped crystals, glycine phosphite crystals grown from the solution containing 25% of glycine phosphate reveal strongly asymmetric hysteresis loops below ferroelectric phase transition temperature T C , and considerable pyroelectric and piezoelectric activity was observed both below and above T C . Analysis of the shape of the hysteresis loops and temperature dependences of dielectric permittivity with and without external biasing points to the existence of internal bias field ∼ 5 kV/cm along the twofold symmetry axis. Possible origin of the internal bias field is discussed.

Acoustic Properties of Glycine Phosphite Crystals with an Admixture of Glycine Phosphate

Acoustic and dielectric anomalies in the region of the ferroelectric phase transition in crystals of glycine phosphite (GPI) with a 2 mol % admixture of glycine phosphate (GP) are studied. The acoustic anomalies were found to differ strongly from those observed in nominally pure glycine phosphite crystals. A theoretical analysis of the acoustic and dielectric properties of the crystals was carried out within the model of a pseudoproper ferroelectric phase transition. It is shown that the acoustic anomalies, as well as the temperature dependences of the dielectric constant (for various external electric fields) and pyroelectric current observed in the vicinity of the phase transition in GPI-GP crystals, can be adequately described when the macroscopic polarization present in these crystals above the phase transition temperature is taken into account. The thermodynamic-potential parameters describing electrostriction and the biquadratic relation between the polarization and strain turned out to be close to those characterizing a nominally pure GPI crystal. An irreversible phase transition was observed to occur in GPI-GP crystals at T = 240 K, i.e., above the ferroelectric phase transition temperature.

Deflection of Light on a Single Domain Wall in GPI Crystal

Deflection of light on a single domain wall in glycine phosphite crystal (GPI) was studied. The angular positions for all crossing the sample beams were measured as a function of the incidence angle ranged in 0 ± 40°. The angles of α o = α cri = 24.7° have been measured. The angular positions of all beams are in agreement with those calculated using the coordinate free method. Angular dependences of all output beam intensities were observed for two polarizations: the polarization along the high-index direction: (beams D B , R B ,A, and A′) and the polarization along the low-index direction: (beams D A , R A ,B, and B′). The experimental data show clearly the exchange of the intensities of the output beams appearing after crossing the sample containing one domain wall. Communicated by Prof. Bozena Hilczer et al.

Pyroelectric, piezoelectric, and polarization responses of glycine phosphite crystals with an admixture of glycine phosphate

Temperature dependences of the pyroelectric, piezoelectric, and polarization responses of glycine phosphite crystals containing different amounts of glycine phosphate were studied in the range 120–320 K. The experimental data obtained suggest the presence of a built-in bias field oriented along the twofold symmetry axis in these crystals. This field was found to be 5 kV/cm. It is suggested that the built-in bias plays a decisive role in the formation of the pyroelectric and piezoelectric crystal responses in the temperature interval 225–280 K, which is significantly higher than the ferroelectric phase transition point in nominally pure glycine phosphite crystals (224 K).

Theory of Electric Field Influence on Phase Transition in Glycine Phosphite*

The microscopic model based on the consideration of the proton ordering is proposed for theoretical study of glycine phosphite (GPI) crystals with a complex structure of the hydrogen bond network. The phase transition into the ferroelectric state is described and changes of the dielectric susceptibility of the crystal are investigated in the presence of the transverse external electric field acting along the c-axis. *Paper originally presented at 10th European Meeting on Ferroelectricity, Cambridge, U.K., August 3–8, 2003.

Effect of Internal Bias Field on 180° Domain Switching in Deuterated Glycine Phosphite

The switching process in deuterated glycine phosphite crystal (DGPI) has been investigated by microscopic observation of domain structure using nematic liquid crystal (NLC) decoration technique and by switching current registration in high electric fields. The stabilization mechanism of 180° domains appears to have a correlation to a defect—induced internal bias field in the crystal.