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We have investigated the multiferroic and glassy behaviour of metal-organic framework (MOF) material (CH3)2NH2Co(CHOO)3. The compound has perovskite-like architecture in which the metal-formate forms a framework. The organic cation (CH3)2NH2+ occupies the cavities in the formate framework in the framework via N-H⋯O hydrogen bonds. At room temperature, the organic cation is disordered and occupies three crystallographically equivalent positions. Upon cooling, the organic cation is ordered which leads to a structural phase transition at 155 K. The structural phase transition is associated with a para-ferroelectric phase transition and is revealed by dielectric and pyroelectric measurements. Further, a PE hysteresis loop below 155 K confirms the ferroelectric behaviour of the material. Analysis of dielectric data reveal large frequency dispersion in the values of dielectric constant and tand which signifies the presence of glassy dielectric behaviour. The material displays a antiferromagnetic ordering below 15 K which is attributed to the super-exchange interaction between Co2+ ions mediated via formate linkers. Interestingly, another magnetic transition is also found around 11K. The peak of the transition shifts to lower temperature with increasing frequency, suggesting glassy magnetism in the sample. [ABSTRACT FROM AUTHOR]

The effect of x-ray irradiation on polarization switching properties of a glycine phosphite (GPI) single crystal is investigated using the Merz technique. GPI undergoes a paraelectric to ferroelectric phase transition at 224.7 K. Switching studies were performed in the temperature range of 173–221 K with the applied field varying from 1.1 to 4.9 kV/cm. X-ray irradiation causes an increase in the threshold field below which switching could not occur. The activation energy for the domain wall motion is found to increase with irradiation from 0.12 eV for a pristine sample to 0.34 eV after irradiating it for 20 min. The temperature dependence of domain wall mobility shows an unusual behavior with the radiation dosage. The calculated domain wall mobility increases with the exposure time, which is contrary to expectation. This apparent increase in mobility with exposure time is attributed to the creation of a large number of radiation induced defects, identified as PO32- radicals, resulting in the loss of effective switchable volume of the sample. [ABSTRACT FROM AUTHOR]

Single crystal (100) wafers of n-InSb were implanted with 50 MeV Li3+ ions at various influences ranging from 10 to 10 ions/cm at room temperature. Investigations of the optical, electrical, and structural properties of the as-grown, irradiated, annealed wafers were carried out by infrared and Raman spectroscopies, Hall measurements, and high resolution x-ray diffraction (HRXRD). In the case of samples irradiated with an ion fluence of 1.610 ions/cm, electrical measurements at 80 K reveal that there is a decrease in carrier concentration from 8.510 (for unirradiated) to 1.1 10/cm and an increase in mobility from 5.4104 to 1.6710 cm/V s. The change in carrier concentration is attributed to the creation of electron trap centers induced by ion beam irradiation and the increase in mobility to the formation of electrical inactive complexes. Nevertheless, even with the irradiation at 1.610 ions/cm fluence the crystalline quality remains largely unaffected, as is seen from HRXRD and Raman studies. c 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Deals with a study which determined the simulated emission cross section for the transition of neodymium in lead borate and bismuth borate glasses through fluorescence measurements. Theoretical framework; Experimental details; Results and discussion; Conclusions.

Presents a study that investigated the hole transport properties of gallium antimonide with various degrees of tellurium compensation in the temperature range of 4.2-300 K. Details of the single-crystal substrates of undoped and Te-compensated p-GaSb used; Illustration of the plots of the temperature dependence of hall coefficient; Conclusions.

Deals with a study which discussed the photoluminescence and cathodluminescence properties of a-Si:H treated undoped and tellurium-compensated p-GaSb. Background to the study; Experimental details; Results and discussion.

Presents a study which measured the thermal expansion, specific heat, dielectric constant, and resistivity of the novel organic nonlinear crystal, L-arginine phosphate monohydrate as a function of temperature. Information on the dielectric constant and resistivity of the crystal; Description of the specific heat data of solids; Electrical properties of the crystal.

Negative differential resistance (NDR) in current-voltage (I-V) characteristics and apparent colossal electroresistance were observed in Gd0.5Sr0.5MnO3 single crystals at low temperatures. The continuous dc I-V measurements showed a marked thermal drift. In addition, temperature of the sample surface was found to be significantly higher than that of the base at high applied currents. Two different strategies namely estimation and diminution of the Joule heating (pulsed I-V measurements) were employed to investigate its role in the electric transport properties. Our experiments reveal that the NDR in Gd0.5Sr0.5MnO3 is a consequence of Joule heating rather than the melting of charge order. [ABSTRACT FROM AUTHOR]

Potassium titanyl phosphate single crystals were irradiated with 48 MeV lithium ions at fluences varying from 5x10[sup 12] to 10[sup 16] ions/cm[sup 2]. The defects created in the crystal have been characterized using x-ray rocking curve measurements, optical transmittance, and photoluminescence spectroscopy. From x-ray rocking curve studies, the full width at half maximum for the irradiated samples was observed to increase, indicating lattice strain caused by the energetic ions. Optical transparency of these samples was found to decrease upon irradiation. The irradiated samples exhibited a broadband luminescence in the 700-900 nm region, for fluences above 5x10[sup 13] ions/cm[sup 2]. The results indicate that ion-beam-induced optical effects in KTiOPO[sub 4] single crystals are very similar to the ones obtained for crystals with "gray tracks," which are attributed to the electronic transitions in the Ti[sup 3+] levels. © 2001 American Institute of Physics. Potass! ium titanyl phosphate single crystals were irradiated with 48 MeV lithium ions at fluences varying from 5x10[sup 12] to 10[sup 16] ions/cm[sup 2]. The defects created in the crystal have been characterized using x-ray rocking curve measurements, optical transmittance, and photoluminescence spectroscopy. From x-ray rocking curve studies, the full width at half maximum for the irradiated samples was observed to increase, indicating lattice strain caused by the energetic ions. Optical transparency of these samples was found to decrease upon irradiation. The irradiated samples exhibited a broadband luminescence in the 700-900 nm region, for fluences above 5x10[sup 13] ions/cm[sup 2]. The results indicate that ion-beam-induced optical effects in KTiOPO[sub 4] single crystals are very similar to the ones obtained for crystals with "gray tracks," which are attributed to the electronic transitions in the Ti[sup 3+] levels. © 2001 American Institute of Physics. Potassium titanyl! phosphate sin... [ABSTRACT FROM AUTHOR]

Presents a study which reported laser induced damage threshold values for metal-organic complex crystals, zinc tris(thiourea) sulfate (ZTS), and bis(thiourea) cadmium chloride (BTCC). Approach used in carrying out laser damage threshold measurements; Observation on the number of pulses required to case damage; Results on the damage resistance of BTCC and ZTS.

Provides information on a study which observed improvements in the optical and electrical properties of gallium antimonide after ruthenium passivation. Effect of ruthenium passivation on gallium antimonide; Observation on the passivation and luminescence efficiency of ruthenium; Discussion of the boundary passivation of polycrystallines.

A foreword to "Bulletin of Materials Science" is presented.

The linear, second order, and third order nonlinear optical properties of glucuronic acid γ-lactone single crystals were investigated. The optic axes and principal dielectric axes were identified through optical conoscopy and the principal refractive indices were obtained using the Brewster's angle method. Conic sections were observed which is perceived to be due to spontaneous non-collinear phase matching. The direction of collinear phase matching was determined and the deff evaluated in this direction was 0.71 pm/V. Open and closed aperture Z-scan measurements with femtosecond pulses revealed high third order nonlinearity in the form of self-defocusing, two-photon absorption, as well as saturable absorption. [ABSTRACT FROM AUTHOR]

We investigate the structural, magnetic, and specific heat behavior of the hexagonal manganite Dy0.5Y0.5MnO3 in order to understand the effect of dilution of Dy magnetism with nonmagnetic yttrium. In this compound, the triangular Mn lattice orders antiferromagnetic at TNMn≈ 68 K observed experimentally in the derivative of magnetic susceptibility as well as in specific heat. In addition, a low-temperature peak at TNDy∼ 3 K is observed in specific heat which is attributed to rare earth order. The TNMn increases by 9 K compared to that of hexagonal (h)DyMnO3 while TNDy is unchanged. A change in slope of thermal evolution of lattice parameters is observed to occur at temperature close to TNMn. This hints at strong magnetoelastic coupling in this geometric multiferroic. In magnetization measurements, steplike features are observed when the magnetic field is applied along the c axis which shift to higher fields with temperature and vanish completely above 40 K. The presence of different magnetic phases at low temperature and strong magnetoelastic effects can lead to such field-induced transitions which resemble metamagnetictransitions. This indicates the possibility of strong field-induced effects in dielectric properties of this material, which is unexplored to date. [ABSTRACT FROM AUTHOR]

The design and fabrication of a state of the art high temperature top seeded solution growth (HTTSSG) unit with seed and crucible rotation options is discussed. Crystals from solid solutions of high viscosity could be grown using the setup. The fabricated setup is used to grow high optical quality single crystals of cesium lithium borate with dimensions 50×40×40 mm3 for frequency conversion of ir to UV laser through harmonic generation. [ABSTRACT FROM AUTHOR]

We report structural, magnetic, and dielectric properties of the perovskite compound Pr1-xYxMnO3 (0.1⩽x⩽0.4) studied using dc magnetization, ac susceptibility, neutron powder diffraction, and dielectric techniques. These compounds crystallize in orthorhombic space group (Pnma) in the temperature range 5-300 K. The Mn-O-Mn bond angle decreases with the Y substitution along with an increase in the Jahn-Teller distortion. The Jahn-Teller distortion for Pr0.9Y0.1MnO3 shows an anomalous change near 50 K, below which it falls sharply. Neutron powder diffraction patterns of all reported compositions at low temperature constitute additional magnetic Bragg peaks that suggest magnetic ordering. Magnetic reflections were indexed in the nuclear lattice with the propagation vector k=(0, 0, 0). Rietveld refinement of powder patterns conform to A type antiferromagnetic ordering where moments are aligned ferromagnetically in a-c plane and coupled nearly antiferromagnetically along b-axis resulting in a net ferromagnetic component along the b-direction. The antiferromagnetic transition temperature was deduced from dc magnetization and ac susceptibility data. The transition temperature decreases by nearly 22K (from 81K to 59K) as yttrium content (x) increases from 0.1 to 0.4. Measurements reveal strong frequency dispersion in dielectric constant and dielectric loss. Activation energy and relaxation time are estimated from the Arrhenius plot. It is further shown that relaxation behaviour is altered with yttrium doping concentration. [ABSTRACT FROM AUTHOR]

Large size single crystals of potassium L-ascorbate monohydrate, KC6H7O6.H2O (KLAM), are grown using solution growth technique by lowering the temperature at the rate of 0.24 °C/h, where water was used as a solvent. The structure of KLAM was solved by single-crystal XRD. KLAM crystallizes in P21 space group with unit cell parameters a = 7.030(5)Å, b = 8.811(5)Å, c = 7.638(5)Å and β = 114.891(5)°. The crystal grows with bulky morphology in all three directions having (100), ( 1 - 00), ( 1 - 10), (0 1 - 1 - ), (0 1 - 1), (001) and (00 1 - ) prominent faces. Thermo-gravimetric analysis and Differential scanning calorimetry measurements show that KLAM is stable up to 80 °C. The crystal offers good optical transparency with a lower cut off as low as 297 nm. Second harmonic conversion efficiency measured on powder sample is 3.5 times that of potassium dihydrogen phosphate. Phase matching (PM) is observed on the a-plate of the KLAM. Noncollinear phase matching rings are also observed near the PM directions, which help to identify the PM directions. The observation of noncollinear second-harmonic rings up to third-order indicates high magnitudes of nonlinear optical coefficients. Single-pulse laser damage threshold value of the crystal is 3.07 GW/cm2 at 1064 nm on the a-plate of the crystal. [ABSTRACT FROM AUTHOR]