Glycine Phosphite Research Articles

Dielectric Investigation of Glycine Phosphite Crystal

The complementary measurements of the dielectric dispersion in ferroelectric phase of glycine phosphite crystal at the frequency range of 200 Hz -1 MHz have been carried out. The analysis of the dielectric spectra of the low frequency relaxation process showed that it can be fitted by two Debye-type relaxators. The activation energy of the both processes has been calculated. The observed behaviour of the relaxators suggests that they are connected with a domain structure; one with the growth of the nuclei whereas the second with the domain wall movement.

Thermal properties of glycine phosphite across ferroelectric phase transition: a photopyroelectric study

A photopyroelectric measurement of the thermal parameters of glycine phosphite (GPI) single crystals across the ferroelectric phase transition temperature has been carried out. The thermal parameters—thermal diffusivity (α), thermal effusivity (e), thermal conductivity (K), and heat capacity (c p)—of GPI single crystals are reported. The para-ferroelectric phase transition is reflected in these thermal parameters as anomalies at the transition point. The anisotropy in thermal wave propagation is established by measuring thermal conductivity along the a, b, and c crystal axes. The anomalous variations in the thermal parameters across the phase transition temperature reveal an order-disorder type transition at 224 K in this crystal.

Acoustic and dielectric anomalies in the temperature range of a ferroelectric phase transition in glycine phosphite crystals

The acoustical and dielectric properties of glycine phosphite crystals are investigated in the temperature range of a ferroelectric phase transition. The acoustic anomalies for longitudinal waves along the X, Y, and Z crystallographic axes (where Y is the spontaneous polarization axis) are analyzed in the framework of the Landau theory. It is shown that pronounced acoustic anomalies of the velocity can be quantitatively described within the pseudoproper ferroelectric phase transition model with due regard for the long-range dipole-dipole interaction. For longitudinal acoustic waves propagating along the polar crystal axis, the striction anomaly of the velocity is only partly suppressed by the long-range dipole-dipole forces and an abrupt jump in the velocity is observed in the vicinity of the phase transition. The temperature coefficients of the velocity in the paraphase are determined. The striction contribution and the contributions biquadratic in the order parameter and in the strain to the velocity anomaly are separated.

Growth and characterization of ferroelectric glycine phosphite single crystals

Single crystals of a recent ferroelectric material, glycine phosphite were grown from aqueous solution employing the techniques of slow cooling and controlled evaporation. Powder X-ray diffraction studies as well as thermal analysis were carried out on the grown crystals. The morphology of the crystal has been determined using contact and optical goniometry. The mechanical hardness of the crystal was evaluated by Vickers indentation method. Thickness dependence of the dielectric properties has been investigated and the results can be interpreted in terms of a surface layer of lower dielectric constant.

Anomalous Larmour Frequency Dependence of Proton Spin-Lattice Relaxation Time (T1) in the Ferroelectric Glycine Phosphite

We report here the results of our $^{1}H$ NMR spin lattice relaxation time $(T_1)$ studies in glycine phosphite which is ferroelectric below 224 K. The experiments have been carried out in the temperature range from 200 to 419 K and at two Larmour frequencies of 11.40 and 23.56 MHz. We have noticed a Larmour frequency dependence of $T_1$ on the high-temperature side of the $T_1$ minimum. A model is proposed based on the BPP theory to explain the observation.

Interferences in light deflection by ferroelastic domain walls

Deflection of light is studied in a crystal of glycine phosphite containing two twin walls. When the crystal is rotated in the incident laser beam, interferences are observed in both the direct beam and in the main deflected beam (A or B) for both polarizations of the incident light. The contrast is especially high, because the mutual tilt angle of the principal axes is close to 45 degrees in this twinned crystal. On this principle, fundamental-harmonic beam splitters could be built from as-grown twin crystals. Furthermore, the electrical modulation of the light deflected by ferroelectric-ferroelastic crystals can be now explained in terms of interference effects.

Preparation of Ferroelectric Glycine Phosphite Single Crystals

An experimental procedure to prepare single crystals of ferroelectric glycine phosphite (GPI) is presented. Since the solubility of GPI in water increases with temperature, the single crystals are grown from fine seed crystals in a saturated aqueous solution by the gradually-decreasing-temperature method. Full faced, transparent, colorless crystals weighing about 10 g are obtained within 20–30 days. Crystallographic axes and the Miller indices for all faces of the obtained crystals are determined using the lattice parameters as a clue.

Twinning in GLY·H3PO3 crystals

Systematic polarized microscopic observation were done for glycine phosphite crystals along the b-axis. In some as grown crystals natural twinning was found in the (001) plane. Occasionally, appearance of twins in single domain crystals was observed during cracking or polishing of the samples and therefore the crystal can be regarded as at least potentially ferroelastic.

Ultrasonic investigation of elastic properties and a phase transition in ferroelectric glycine phosphiteNH3CH2COOH3PO3single crystals

A detailed ultrasonic study of the elastic properties of glycine phosphite single crystals has been carried out at room temperature as well as across the ferroelectric phase-transition temperature. All 13 elastic stiffness moduli of this monoclinic crystal at room temperature have been determined by measuring the velocities of ultrasonic waves of different polarizations, propagating along different symmetry directions using the pulse echo overlap technique. The anisotropy in elastic wave propagation is established employing polar plots of the phase velocity surfaces in the ab, ac, and bc planes. Variation of selected mode velocities with temperature establishes the reported ferroelectric phase transition in this crystal at 224 K.

Anomalous Larmour Frequency Dependence of Proton Spin–Lattice Relaxation Time (T1) in the Ferroelectric Glycine Phosphite

We report here the results of our 1 H NMR spin–lattice relaxation time (T1) studies in glycine phosphite which is ferroelectric below 224 K. The experiments have been carried out in the temperature range from 200 to 419 K and at two Larmour frequencies of 11.40 and 23.56 MHz. We have noticed a Larmour frequency dependence of T1 on the high-temperature side of the T1 minimum. A model is proposed based on the BPP theory to explain the observation.

Temperature study of the elastic properties of glycinium phosphite and deuterated glycinium phosphite crystals by brillouin scattering

Brillouin spectroscopy was used to study the elastic properties of glycinium phosphite (GPI) and deuterated glycinium phosphite (DGPI) crystals. The temperature measurements of the hypersonic velocity for acoustic modes propagating in various directions have been performed in the temperature range 170 K-300 K and 295 K-355 K for GPI and DGPI, respectively. Brillouin study has confirmed the existence of the order-disorder type ferroelectric phase transition (P21/a - P21) at 224 K for GPI and 322 K for DGPI. The obtained results are also discussed in terms of the reordering of the hydrogen bonds in the ferroelectric phase.

Peculiarities in Thermal Linear Expansion and Refractive Indices of (NH2CH2COOH) · H3PO3 Single Crystals in the Region of Phase Transition

Temperature dependences of thermal linear expansion and optical path difference determined by the refractive index (200 to 270 K) and spectral dependences of refractive indices and optical birefringence (475 to 700 nm) of glycine phosphite [GPI: (NH2CH2COOH) · H3PO3] single crystal have been measured. The characteristic indices 2β of power-like temperature dependence for the parameters measured have been determined to be temperature dependent. The coefficients of electrostriction and quadratic electrooptic effect of GPI crystal decrease at approaching the phase transition temperature Tcwhen going from the ferroelectric phase.

Peculiarities in Thermal Linear Expansion and Refractive Indices of (NH2CH2COOH) � H3PO3 Single Crystals in the Region of Phase Transition

Temperature dependences of thermal linear expansion and optical path difference determined by the refractive index (200 to 270 K) and spectral dependences of refractive indices and optical birefringence (475 to 700 nm) of glycine phosphite [GPI: (NH2CH2COOH) · H3PO3] single crystal have been measured. The characteristic indices 2β of power-like temperature dependence for the parameters measured have been determined to be temperature dependent. The coefficients of electrostriction and quadratic electrooptic effect of GPI crystal decrease at approaching the phase transition temperature Tcwhen going from the ferroelectric phase.

Linear birefringence in ferroelectric glycine phosphite and deuterated glycine phosphite

Linear birefringence changes were measured with the rotating analyzer method for the glycine phosphite crystal and its deuterated analogue in the vicinity of ferroelectric phase transition. Continuous character of the phase transition was assured. Power rule was found as fulfilled only in close vicinity of Tc. Evident isotope effect was denoted: deuteration changes Tc from 225 to 324K.

Ferroelectricity in partially deuterated glycine phosphite crystals

Crystals of Gly·H3PO3 with various degree of deuteration were grown and their physical properties were investigated. Anomalies of permittivity related to para- ferroelectric phase transition were observed in the whole range of deuterium content. Ferroelectric character of the observed phase transitions was confirmed from hysteresis loops observation and pyroelectric measurement. The dependence of Tc on deuterium content was found to be linear.

Crystal structure of glycinium arsenate, C2NH8O2+AsO4-

C2H8ASN06, monoclinic, Pl2i/cl (No. 14), a= 7.919(2) A, b= 4.744(1) A, c =17.59(1) A, s = 91.71(4)°, V= 660.5 A, Ζ = 4, Rst(F) = 0.021, wR(F) = 0.050, T= 293 K. Source of material The compound was synthesized by controlled evaporation of a water solution of arsenic acid and glycine in molar ratio 1:1. Large single crystals were obtained from which good quality specimens were selected for X-ray measurements. Discussion Glycine arsenate is a new glycine compound. Inspection of the carboxylic C 0 distances clearly shows that the glycine moiety is protonated. Whereas glycine phosphite is ferroelectric below 224 Κ [1], no pyroelectric current was detected either decreasing or increasing the temperature in the range 20 Κ 300 Κ [2]. Small anomalies in the dielectric constant as well as dielectric loss were found around 250 Κ in cooling runs from room temperature. Examination of the crystal structure shows layers of thAsCU tetrahedra alternating with glycine groups, parallel to the ab plane. This feature can be contrasted with that occurring in glycine phosphate where similar groups are found to be parallel to the be plane [3]. Each H2ASO4 group is connected by two hydrogen bonds (2.543(3) A, 2.687(3) A) to its neighbours forming helical chains along the i»-axis. The hydrogen atom of the carboxylic group is involved in an hydrogen bond with one of the bare Ο atoms of the H2ASC>4 ion, the distance O O being rather short (2.566(3) A). Two hydrogen atoms of the NH3 group establish hydrogen bonds with the two bare 0 3 and 0 4 atoms of neighbour H2 AsO^f tetrahedra; the third amino hydrogen atom is donated to atom 0 6 of the closest carboxylic group [4]. Table 1. Data collection and handling. Crystal: colourless, transparent, truncated pyramid, size 0.15 χ 0.20 x 0.25 mm Wavelength: Mo Ka radiation (0.71073 A) μ: 51.25 cm Diffractometer, scan mode: Enraf-Nonius CAD-4, ω/2θ 26max: 49.98° N 2a(/„bs), 974 N(param)KfiTxA' 94 Programs: PLATON [4], SDP [5], SHELXS-97 [6], SHELXL-97 [7], ORTEPII [8] Table 2. Atomic coordinates and displacement parameters (in A). Atom Site X y ζ Uiso H(l) 4e 0.9823 -0.1681 0.6833 0.057 H(2) 4e 0.6377 -0.3499 0.6940 0.050 H(0A) 4e 0.7043 -0.5223 0.8517 0.043 H(0B) 4e 0.5675 -0.3568 0.8822 0.043 H(0C) 4e 0.6388 -0.5910 0.9257 0.043 H(1A) 4e 0.8120 -0.1084 0.8955 0.046 H(1B) 4e 0.8891 -0.3616 0.9425 0.046 H(5) 4e 0.7521 0.1459 1.0642 0.054 * Correspondence author (e-mail: lourdes@pollux.fis.uc.pt) Unauthenticated Download Date | 12/28/16 9:07 PM 536 Glycin ium arsenate Table 3. Atomic coordinates and displacement parameters (in A). Atom Site X y ζ C/i 1 U22 U33 {/12 i/13 U23 As 4e 0.75626(3) 0.04960(6) 0.70741(2) 0.0235(2) 0.0217(2) 0.0193(2) 0.0002(1) 0.0022(1) 0.0023(1) O( l ) 4e 0.9150(3) -0.0838(5) 0.6552(1) 0.032(1) 0.055(2) 0.029(1) 0.016(1) 0.0103(9) 0.007(1) 0(2) 4e 0.6206(3) -0.2213(4) 0.7240(1) 0.042(1) 0.019(1) 0.039(2) -0.0060(9) 0.018(1) -0.0020(9) 0(3) 4e 0.6597(2) 0.2857(4) 0.6515(1) 0.033(1) 0.022(1) 0.025(1) 0.0049(8) 0.0025(9) 0.0045(9) 0(4) 4e 0.8207(3) 0.1752(5) 0.7910(1) 0.032(1) 0.044(1) 0.021(1) -0.006(1) -0.0025(8) -0.006(1) Ν 4e 0.6619(3) -0.4514(5) 0.8939(2) 0.033(1) 0.030(1) 0.024(2) -0.000(1) 0.003(1) -0.003(1) C( l ) 4e 0.7856(4) -0.2599(7) 0.9303(2) 0.032(2) 0.034(2) 0.026(2) -0.005(1) 0.008(1) -0.006(1) C(2) 4e 0.7149(3) -0.1389(6) 1.0019(2) 0.029(1) 0.026(1) 0.020(2) 0.001(1) 0.003(1) -0.001(1) 0(6) 4e 0.6021(3) -0.2517(5) 1.0346(1) 0.043(1) 0.041(1) 0.028(1) -0.014(1) 0.013(1) -0.006(1) 0(5) 4e 0.7879(3) 0.0966(5) 1.0230(1) 0.044(1) 0.035(1) 0.030(1) -0.012(1) 0.012(1) -0.010(1) Acknowledgments. We thank gratefully Dr. J. Albers for his collaboration in the study of betaine compounds. We are indebted to the Cultural Service of the German Federal Republic Embassy, the Deutscher Akademischer Austauschdienst (DAAD) and the German Agency for Technical Cooperation (GTZ) for the offer of a CAD-4 automatic diffractometer which enabled the experimental work to be carried out. This work was supported by the project PRAXIS/2/2. l/FIS/26/94. J. Agostinho Moreira thanks Project PRAXIS XXI for his grant (DB/3192/94).

Study of the elastic properties of glycine phosphite crystals (Gly·h3PO3) by Brillouin scattering

The results concerning the elastic properties of glycinium phosphite (GPI) crystals obtained by Brillouin scattering method are reported. The temperature measurements of the relative change AVN of the phase velocity for acoustic modes propagating in q = [100], q = [010], q = [110] and q = [011] directions have been performed in the temperature range 300 K - 170 K. Obtained results confirm the existence of the ferroelectric phase transition (P21/a - P21) at 224 K.

Dynamics of a glycine molecule in a new ferroelectric glycine phosphite studied by proton NMR

The second moments of the proton magnetic resonance lines and relaxation times in the laboratory frame T 1, in polycrystalline glycinum phosphite (NH + 3CH 2COOH)(H 2PO − 3) were measured. The proton spin-lattice relaxation measurements reveal one minimum due to the C 3 reorientations of the amino groups of glycinum cations. Analysis of the relaxation data yields the activation energy barrier of 28.7 kJ mol −1. Second moment measurements confirm the phase transition at T c =224 K known from different studies. The molecular mechanism of the order–disorder phase transition is discussed.

Characterization of Ferroelectric Phase Transition in GPI Crystal

The dielectric behaviour of a glycine phosphite [GPI: Gly.H 3 PO 3 ] crystal is investigated around its ferroelectric phase transition. The temperature dependence of the dielectric constant is measured for dc bias fields up to 200 kV/m. The dielectric constant is also measured in the paralectric phase as a function of electric field at constant temperatures. The results are discussed on the basis of the classical state equation and the equation coefficients are estimated. The obtained results lead to the conclusion that the ferroelectric phase transition in GPI has an intermediate character between critical and tricritical one.

Characterization of Ferroelectric Phase Transition in GPI Crystal

The dielectric behaviour of a glycine phosphite [GPI: Gly · H3PO3] crystal is investigated around its ferroelectric phase transition. The temperature dependence of the dielectric constant is measured for dc bias fields up to 200 kV/m. The dielectric constant is also measured in the paralectric phase as a function of electric field at constant temperatures. The results are discussed on the basis of the classical state equation and the equation coefficients are estimated. The obtained results lead to the conclusion that the ferroelectric phase transition in GPI has an intermediate character between critical and tricritical one.