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, (NH3CH2COOH3PO 3), with load was studied. Vickers hardness, Hv and Knoop hardness numbers, Hk 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 'Kc', determined from measurements of crack lengths, were estimated to be 0.1266 MN/m3/2, The brittleness indices 'Bi' were estimated as 4270.7 m -1/2. Elastic stiffness coefficient, C11 and Young's modulus were calculated from the hardness. © 2010 Taylor &amp; Francis Group, LLC.

Ezhil Vizhi R

Department of Physics

School of Advanced Sciences

Vellore Campus

Rajan Babu D

Sathiyanarayanan K

Department of Chemistry

Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

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

Ferroelectrics Letters Section

A nonlinear optical material γ-glycine single crystal was grown for the first time in the presence of sodium bromide by slow cooling method. The solubility of the material was analyzed gravimetrically. Metastable zonewidth was studied by the polythermal method. The form of crystallization was confirmed by powder X-ray diffraction analysis. The crystal of γ-glycine were found to crystallize in hexagonal crystal system. The presence of all the functional groups of the γ-glycine was confirmed by FT-IR and FT-Raman spectral analysis. Thermal properties of the grown crystal were determined by thermo-gravimetric analysis (TGA) and differential thermal analysis (DTA), which indicated the thermal stability (up to 210 °C) and the melting point (257 °C). The grown crystal was subjected to Vickers microhardness test. The dielectric response of the sample is studied as a function of frequency and temperature. The optical transparency and lower cut-off value of UV transmission (223 nm) were ascertained by recording a UV–visible spectrum of γ-glycine crystal. The second-order nonlinear optical property was confirmed by Q-switched Nd:YAG laser. © 2016 Elsevier B.V.

Journal of Crystal Growth

Investigations on the growth and characterization of γ-glycine single crystal in the presence of sodium bromide

A single crystal of urea oxalic acid was grown by slow evaporation method. The lattice parameters are a=5.13 Å, b=12.48 Å, c=7.07 Å, β=98.13° with V=448.5 Å3 which belongs to monoclinic system with space group P21/c obtained from single crystal X-ray diffraction analysis. UV–visible spectrum was recorded from the wavelength region of 200–800 nm and its cutoff wavelength was found to be 270 nm. Optical energy band gap of 4.57 eV was determined using Tau's plot relation. Fourier transform infrared vibrational spectrum confirmed the presence of N–H asymmetric stretching which occurs at 3444 cm−1 and 1853 cm−1 arising due to the amide C=O symmetric stretching. The emission was observed at 364 nm from the photoluminescence spectrum. The mechanical stability of the grown crystal was estimated by Vickers microhardness studies and it is evident that the grown crystal belongs to soft material category. Hardness related parameters such as elastic stiffness constant, fracture mechanics, brittleness index and yield strength were also evaluated. The dielectric constant and dielectric loss of the grown crystal were carried out as a function of frequency for different temperatures. © 2016 Elsevier B.V.

Synthesis, growth, optical and mechanical studies of ferroelectric urea-oxalic acid single crystals

The new organic nonlinear optical material piperazinium (bis) hydrogen succinate single crystal (PPHS) was synthesized by the slow evaporation method. The solubility of PPHS was determined by gravimetric analysis and the metastable zonewidth was assessed by polythermal method. The induction period was measured by isothermal method. The experimentally calculated values of the interfacial energies are in agreement with the theoretical values. As an outcome of studying the nucleation parameters, a bulk single crystal of PPHS was grown by slow cooling method. The structure of PPHS was estimated from single crystal X-ray diffraction analysis. FT NMR spectrum was analyzed. The cut - off wavelength and energy band gap values were found to be 254 nm and 4.85 eV respectively from the UV–vis–NIR spectrum analysis. The thermal stability of the grown crystal was studied. The mechanical strength and third order nonlinear optical susceptibility of the grown crystal were measured by Vicker's microhardness test and Z-scan technique respectively. © 2016 Elsevier B.V.

Bulk growth and characterization of novel organic piperazinium (bis) hydrogen succinate single crystals

The semiorganic crystals of potassium boro-succinate (KBS) were grown by slow evaporation method. KBS crystallizes in monoclinic system which was confirmed by powder XRD analysis. Vickers microhardness study has been carried out over a load range of 25-100 g. The Vickers hardness numbers (Hv) of the material increases as the load increases so the material is suitable for device fabrication. The Meyer index 'n' is estimated to be greater than 1.6, the crystal system belongs to the soft material category. The elastic stiffness coefficient, c11, has also been calculated using Wooster's empirical relation from the hardness data. The fracture toughness values 'Kc', determined from measurements of crack lengths, were estimated to be 0.15166 MN/m3/2. The brittleness indices 'Bi' were estimated as 276 m-1/2. © Published under licence by IOP Publishing Ltd.

Fulltext

IOP Conference Series: Materials Science and Engineering

Vickers microhardness studies on solution-grown single crystals of potassium boro-succinate

Single crystals of ferroelectric material tri-glycine barium nitrate (TGBN) were grown from aqueous solution employing the techniques of slow cooling under controlled evaporation. Highly transparent seed crystals were harvested after repeated recrystallization process. Optical quality seed crystal has been used for the bulk growth. The solubility of the synthesized material was determined by using water as solvent. The solubility of TGBN was determined for various temperatures between 20°C and 50°C. It is found that this material has a positive temperature coefficient of solubility. Single crystal X-ray diffraction analysis confirms the crystal structure. The FTIR analysis confirms the presence of functional groups in the complex. The Vicker's microhardness of the samples were found using Mitutoyo MH 120 microhardness tester. The measurements were done at room temperature for different forces. © 2013 Taylor &amp; Francis Group, LLC.

A Study on Structural, Optical, Mechanical and Ferroelectric Properties of Tri-Glycine Barium Nitrate Single Crystals

Ferroelectric 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 &amp; Co. KGaA.

Crystal Research and Technology

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

An experimental procedure adopted to prepare the recent Ferroelectric Glycine Phosphite (GPI) single crystal is presented. As the crystal solubility in water depends on temperature, single crystals were grown from fine seed crystals in a saturated solution by employing the slow cooling technique. Transparent, colourless crystals with habit morphology weighing about 8 gm were obtained with in a month. The same procedure was used to grow single crystals with Thiourea doped GPI (TUGPI). Powder X-ray diffraction studies as well as FTIR studies were carried out on both the crystals. The results are discussed in detail.

Journal	Ferroelectrics Letters Section
Publisher	Informa UK Limited
ISSN	0731-5171
Open Access	No