Synthesis,growth, morphology and characterization of ferroelectric glycine phosphite single crystals

Glycine phosphite (NH₃CH₂COO.H₃PO₃), a potential ferroelectric material, was grown as single crystals from aqueous solutions by slow evaporation and slow cooling methods. Laboratory synthesized title compound was purified by recrystallization method and confirmed by Fourier transform infrared and Laser Raman studies. Temperature dependent solubility in double distilled water in the range between 288 and 328 K was determined by gravimetric method. Morphological importance of various growth faces were studied by optical goniometry. Powder x‐ray diffraction study performed on the grown crystals confirms the crystal system and lattice parameters of the unit cell. Optical transparency of the grown crystals in the ultraviolet–visible ‐near infrared region was studied by spectroscopic method. Thermal stability of the grown crystals in the temperature region above ambient until melting was studied using differential scanning calorimetry. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Crystallization and characterization of nonlinear optical l‐histidinium dihydrogen orthophosphate orthophosporic acid single crystal

L‐histidinium dihydrogen orthophosphate orthophosporic acid (abbreviated as LHP) with molecular formula C₆H₁₀N₃O₂⁺·H₂PO₄^‐·H₃PO₄ was successfully grown by slow evaporation technique from aqueous solution. The crystal was characterized by X‐ray diffractometry (XRD), UV‐Vis‐NIR, TGA, DTA, microhardness and solubility studies. The dielectric constant and dielectric loss of the crystal were studied as function of frequency. Photoconductivity studies were also carried out on the sample. The SHG efficiency of the crystal is studied using the Kurtz and Perry technique. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Growth and characterization of ferroelectric‐ferroelastic Tb2(MoO4)3 crystals

Transparent and nearly colorless ferroelectric‐ferroelastic β′‐Tb₂(MoO₄)₃ (TMO) single crystals have been grown by the Czochralski (CZ) method. The single crystal structure was investigated by X‐ray powder diffraction and was shown to be a single phase with the structure similar as the β′‐Gd₂(MoO₄)₃ crystal. The optical transparency of the TMO crystal has been measured and the crystal is almost transparent in the visible and near infrared regions. The defects of TMO crystal were evaluated by etching technique and the ferroelectric domain structures were observed by an optical microscope. A high‐resolution X‐ray diffraction analysis demonstrates that the as‐grown TMO crystal possesses relatively high optical quality. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis and characterization of a new nonlinear optical single crystal: L‐Lysinium trifluoroacetate

Single crystals of a new L‐Lysine salt: L‐Lysinium trifluoroacetate {abbreviated as LLyTFA; [(NH₂)‐(CH₂)₄‐CH‐(NH₃)‐(COOH)]⁺ CF₃COO^‐} were grown by slow evaporation of an aqueous solution at room temperature. The grown crystals were subjected to single crystal X‐ray diffraction, FTIR and UV‐Vis‐NIR spectrum analyses. The UV‐Vis‐NIR spectrum shows that the absorption is very less in the whole of the region from ultraviolet to near IR. The Kurtz‐Perry powder SHG measurement using a Nd:YAG laser of wavelength 1064nm confirms the frequency doubling of the crystal and its powder SHG efficiency was measured as d_eff = 0.96 d_eff (KDP). (© 2007 WILEY ‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Induced growth of Pb0.97La0.02(Zr0.66Sn0.27Ti0.07)O3 antiferroelectric single crystals with a platinum wire

Relaxor antiferroelectric (Pb,La)(Zr,Sn,Ti)O₃ (PLZST) with the composition near the morphotropic phase boundary shows excellent electrical properties. However, the crystal growth of PLZST is limited by the incongruent melting of the materials. Crystal growth of PLZST was induced by a platinum wire in the flux solution with 50 wt% PbO‐PbF₂‐B₂O₃ as a solvent. The obtained PLZST single crystals are optical transparent with light yellow color. The size of the crystals in regular rectangular shape varies from 0.5 mm to 1 mm. The PLZST single crystals exhibit tetragonal phase structure. The element contents of the crystals were measured by inductively coupled plasma atomic emission spectrometry. The results show that the composition of as‐grown crystals is a little bit deviated from the starting composition. The single crystals show two dielectric peaks at 115 °C and 182 °C, corresponding to antiferroelectric‐ferroelectric and ferroelectric‐paraelectric phase transitions. The dielectric data of as‐grown crystals indicate there is typical relaxor behavior near 182 °C. The value of relaxor factor n is 1.49642.     

Growth and characterization of the nonlinear optical crystal: L‐arginine trifluoroacetate

Single crystal growth of the organic nonlinear optical crystal, L‐arginine trifluoroacetate (L‐Arg·CF₃COOH, abbreviated as LATF) is reported. Low temperature solution growth method is employed for the growth of bulk single crystals. The cell parameters are verified by single crystal diffraction. Fourier transform infrared (FT‐IR) and Fourier transform Raman analysis are used to confirm the presence of various functional groups in the grown crystal. The thermal properties of the grown crystals are studied by thermogravimetric analysis and differential scanning calorinetry analysis (TGA/DSC). Second harmonic generation (SHG) measurement confirms the NLO properties of the grown crystal. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Growth and properties of ferroelectric potassium ferrocyanide trihydrate single crystals

Single crystals of potassium ferrocyanide trihydrate, K₄[Fe(CN)₆·3H₂O (KFCT), a ferroelectric material with Curie temperature 251K were grown in silica gel at room temperature for the first time by the solubility reduction method. Resorcinol and ethyl alcohol were used for the purpose of gel setting and supernatant liquid respectively. Optical and mechanical properties were studied for the grown crystal. The structure of the grown crystal was confirmed by X‐ray diffraction analysis. Fourier Transform Infrared (FTIR) and FT Raman spectral analysis of the crystalline samples reveal that the crystalline sample consist consists of all functional groups. Thermal analysis of the crystalline sample was performed by TGA and DTA methods. The Vicker's micro hardness value was measured for KFCT crystals. The square etch pits with a hopper‐like structure is an indicative of 2D nucleation mechanism. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Optical and dielectric studies on succinic acid single crystals

Single crystals of ferroelectric succinic acid (SA) with very high degree of transparency were grown from aqueous solution by slow evaporation technique. Single crystal X‐ray diffraction analysis reveals that the crystal belongs to monoclinic system with the space group P2₁/c. Some physical parameters have been determined for grown crystal. The optical absorption study reveals the transparency of the crystal in the entire visible region and the cut off wave length was found to be 240 nm. The optical band gap is found to be 3.75 eV. The dependence of extinction coefficient (k) and refractive index (n) on the wavelength have also been reported. The presence of functional groups was determined qualitatively by using Fourier transform infrared spectrum (FTIR) from which force constant has been calculated. The dielectric constant was also studied as a function of frequency at room temperature and electrical conductivity has been calculated from the Cole‐Cole plot. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Growth and characterization of magneto‐optical YFeO3 crystals

The floating zone growth of magneto‐optical crystal YFeO₃ has been investigated. The polycrystalline feed rod was prepared by a pressure of 250MPa and sintering at about 1500°C. A crack‐ free YFeO₃ single crystal has been successfully grown. The crystal preferred to crystallize along <100> direction with about 10° deviation. The X‐ray rocking curve of the crystal has a FWHM of 24 arcsec, confirming the high crystal quality of the sample. The (100) plane was etched by hot phosphoric acid and the dislocation density was about 10⁴/cm². A thin outer layer with Y₂O₃‐rich composition was found at the periphery of as‐grown crystals, which was attributed to the Fe₂O₃ evaporation during growth. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Solution growth and morphology of CH3NH3PbBr3 single crystals in different solvents

In this work, large‐sized CH₃NH₃PbBr₃ single crystals were successful grown using solution evaporation method with hydrohalic acid and N, N‐Dimethylformamide (DMF) as solvent respectively. The lattice parameters of cubic CH₃NH₃PbBr₃ were estimated using XRD method. The solubility of CH₃NH₃PbBr₃ in hydrobromic acid was determined at the temperature range between 20 °C–90 °C. A special micro‐solution crystallizer was designed to in‐situ study the morphology of CH₃NH₃PbBr₃ crystal. The largest crystal face was indexed by the XRD patterns and it would be {110} for CH₃NH₃PbBr₃ grown from HBr solution and {100} from DMF solution. The results show that solvent would affect the morphology and crystal habit greatly during crystal growth from solution.     

Study of crystalline perfection and thermal analysis of zinc cadmium thiocyanate single crystals grown in silica gel

Zinc cadmium thiocyanate ZnCd(SCN)₄ abbreviated as ZCTC is a bimetallic thiocyanate complex that exhibits excellent nonlinear optical property. Single crystals of ZCTC have been grown in silica gel by the process of diffusion. Colorless transparent crystals of size 12 mm x 2 mm x 1.3 mm have been obtained. High resolution X‐ray diffraction study was carried out to investigate the crystalline perfection of the grown crystal and the quality of the crystal was found to be quite good. Thermal stability of the grown crystal was investigated by thermogravimetric and differential thermal analyses. Fourier Transform Infrared spectrum was recorded to confirm the functional groups. Microhardness of the crystal is also studied. Being a nonlinear optical material, a comparative study of its second harmonic generation efficiency with urea has been made. (© 2007 WILEY ‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Effect of different metal ions on structural,thermal, spectroscopic and optical properties of ATCC and ATMC single crystals

A novel metal‐organic coordination complex nonlinear optical crystals, tri‐allylthiourea cadmium chloride [(CdCl₂(AT)₃] and tri‐allylthiourea mercury chloride [(HgCl₂(AT)₃] abbreviated as ATCC, ATMC (AT is Allylthiourea i.e.,CH₂=CHCH₂NHCSNH₂) has been synthesized and grown as single crystals. It was synthesized in deionised water and further recrystallized to improve its purity. Single crystals of the allylthiourea co‐ordination complex nonlinear optical crystals tri allylthiourea cadmium chloride (ATCC) with dimensions of 14x14x10 mm³ and tri allylthiourea mercury chloride (ATMC) with dimensions of 15x15x12 mm³ were grown successfully from aqueous solution by solvent evaporation as well as by temperature lowering method. It exhibits powder SHG efficiencies higher than that of a well known organic NLO crystal Urea. The solubility of the as grown crystals was estimated from the aqueous solution and the effect of different metal ions on the grown crystals, structural, thermal, spectral and optical properties were analyzed. XRD studies the reveals the same structure of both materials. Influence of the different central metal (Cd and Hg) atoms, changing the thermal properties of the materials when NLO complexes formed with the common ligand allylthiourea. The metal co‐ordination was confirmed form the spectroscopic analysis. From the UV transmittance studies, red shift was from the transparency cut‐off wavelengths. The value is 285nm for ATCC is and is 335nm ATMC, Non‐linear an optical study confirms the suitabilities of the as grown crystals for the non linear optical applications. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

An effective growth method to improve the homogeneity of relaxor ferroelectric single crystal Pb(In1/2Nb1/2)O3‐ Pb(Mg1/3Nb2/3)O3‐PbTiO3

Compositional segregation usually has negative effects on the growth of solid solution ferroelectric single crystals of Pb(In_1/2Nb_1/2)O₃‐Pb(Mg_1/3Nb_2/3)O₃‐PbTiO₃ (abbr. PIN‐PMN‐PT or PIMNT). A modified Bridgman method was adopted in this work to control the segregation and improve the compositional homogeneity significantly. The characteristic of this work is to use multiround growths and gradient composition raw materials in order to keep the PbTiO₃ concentration constant during the crystal growth. As an example, the two‐round growth of ternary PIN‐PMN‐PT single crystal is conducted in the same Pt crucible with gradient raw materials, where the first‐round boule was used as the seed crystal for the second‐round growth. Our results show that the as‐grown (Ф80 mm × 270 mm) PIN‐PMN‐PT crystals exhibit higher phase transition temperatures (T_c∼180 °C, T_r/t∼110 °C) and larger coercive field (E_c∼5–5.5 kV/cm), which are much better than the performances of Pb(Mg_1/3Nb_2/3)O₃‐PbTiO₃ crystals, and similar dielectric and piezoelectric performances (ε∼5000, tanδ∼1.25%, d₃₃∼1500 pC/N, k_t∼60%). And about 85 percent of the crystal boule grown by the two‐round growth technique could maintain its compositions around the morphotropic phase boundary.     

Czochralski Growth of Potassium Lithium Niobate Single Crystals with Low Li Content and Their Characterization

Single crystalline and crack free potassium lithium niobate (KLN) single crystals with low Li content were grown by the Czochralski method. The crystal composition can be written as K_2.60Li_1.17Nb_5.44O₁₅ (=K_2.95Li_1.33Nb_6.17O₁₇) which contain relatively fewer Li ions than ferroelectric K₃Li₂Nb₅O₁₅ crystals. All experimental results show that the deficiency of the Li ions in the KLN crystals strongly influences their physical properties. Especially, the as‐grown crystals do not indicate any signature for a ferroelectric phase transition in contrast to the ferroelectric K₃Li₂Nb₅O₁₅ crystals. However, due to ionic conduction, the temperature dependence of the dielectric constant of such KLN‐2 crystals show a broad anomaly near 300°C. In addition, the existence of proton defects can be revealed by infrared absorption spectroscopy near 3500 cm^‐1 in as‐grown crystals.     

Crystal growth and electric‐property change by rubidium or cesium doping on potassium‐sodium‐niobate

Alkali metals (Na, Rb or Cs) co‐doped with fiber‐ and bulk‐shaped KNbO₃ single crystals were grown using two original methods by means of doping together of small ionic Na and large ionic Rb or Cs into KNbO₃. Single‐phase crystals could be grown with an orthorhombic system at room temperature as well as pure KNbO₃. Piezoelectric and ferroelectric property changes by the co‐doping of Rb or Cs with Na were estimated using d₃₃ values and a polarization‐electric field hysteresis curve in fiber‐ and bulk‐shaped crystals. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

High‐quality LaCoO3 single crystal grown by optical floating zone method and its electromagnetic properties

A LaCoO₃ single crystal with 4 mm in diameter and 30 mm in length has been grown by optical floating zone method. The as‐grown crystal is highly crystalline with the rhombohedral perovskite structure (R3c) and grows parallel to the (121) direction. The room temperature resistivity of the as‐grown crystal is 0.12 Ω·cm and the insulator‐metal transition occurs around 500 K. The coercivity and the remanence of the as‐grown crystal are 5 Oe and 6.61×10^–5 μ_B/f.u. at 5 K, respectively. In 1000 Oe under zero‐field cooling, the magnetic susceptibility of the as‐grown crystal shows an upturn in a Curie tail fashion below 35 K, and appears a wave crest over the interval 55 K≤T≤90 K. In addition, a slope change of 1/χ(T) at about 12 K is observed in 50000 Oe under zero‐field cooling. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Growth and characterization of borono phenylalanine

Borono phenylalanine abbreviated as BPA is a biologically important compound which is obtained from L‐Phenylalanine (C₉H₁₁NO₂) in which a boron atom is bonded. BPA is an amino acid analogue, helpful in the treatment of glioblastoma multiforme, a highly malignant form of brain tumor is crystallized in silica gel under pH 6.0 by single diffusion method in a period of 30 minutes. The grown crystals were characterized by x‐ray powder diffraction, Fourier Transform infrared spectroscopy and visible ultraviolet spectroscopy. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Growth defects in a PZNT93/7 crystal prepared by directional solidification

Novel relaxor ferroelectric crystal 0.93Pb(Zn_1/3Nb_2/3)O₃‐0.07PbTiO₃ (PZNT93/7) with dimensions about Ø40× 70 mm³ was obtained by directional solidification technique. The growth defects of the crystal were investigated. Rocking curve analysis revealed the crystalline quality of PZNT93/7 crystal was not perfect and the FWHM value was measured to be about 0.7°. Some pits and oxide particles in micro‐size were formed in the crystal due to the growth conditions. A series of growth steps parallel to (001) face were observed which were attributed to the growth behavior. Moreover, it was found the average chemical composition of the crystal was deviated slightly to the stoichiometric value of PZNT93/7. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Investigation on growth defects in Pb(Zn1/3Nb2/3)O3‐PbTiO3 crystals

Relaxor ferroelectric crystal (1‐x)Pb(Zn_1/3Nb_2/3)O₃‐xPbTiO₃ (PZNT) with x=0.07 (PZNT93/7) has been grown by the vertical Bridgman method from the high temperature solution of PZNT‐PbO system. The growth defects, such as nucleation core, inclusions, boundaries and particles, were investigated by optical microscope and scanning electron microscope. Sub‐structures were found in the flux inclusions and the lack of ZnO component in PZNT crystals was attributed to the existence of ZnO particles in the inclusions. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis,growth and characterization of L‐histidinium acetate dihydrate single crystals

L‐histidinium acetate dihydrate {abbreviated as LHAc; [C₆H₁₀ N₃O₂⁺ C₂H₃O₂^‐ 2H₂O], a new nonlinear optical (NLO) material has been grown from aqueous solution. The grown crystals were subjected to X‐ray diffraction, Fourier transform infrared (FTIR) and FT‐Raman analyses. Thermal studies have been carried out for its thermal stability. Optical behaviour such as UV‐Vis‐NIR spectrum and second harmonic generation (SHG) were also investigated. Its SHG efficiency was found as d_eff = 2.2 d_eff (KDP). (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)