J. Huang

Physicochemical behavior of nonlinear optical crystal CdHg(SCN)4

Abstract The preparation and purification of cadmium mercury thiocyanate, CdHg(SCN)4 (CMTC) are described. The identity of the synthesized compound was characterized by Raman, infrared and X-ray powder diffraction spectra. The thermal stability and thermal decomposition of CMTC crystals were investigated by means of thermogravimetric analysis and differential scanning calorimetry. The impurities in the growth solutions and their effects are discussed.

Spectroscopic and thermal behavior of ZnHg(SCN)4

Abstract The synthesis and purification of zinc mercury thiocyanate, ZnHg(SCN)4 (ZMTC), are described. The identity of the synthesized compound was characterized by elemental analysis, X-ray powder diffraction, infrared, Raman, and UV/Vis/NIR transmission spectra. The thermal stability and thermal decomposition of ZMTC crystal were investigated by means of thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) measurements. The intermediates and final products of the thermal decomposition were identified by X-ray powder diffraction (XRPD).

A systematic spectroscopic study of four bimetallic thiocyanates of chemical formula AB(SCN)4: ZnCd(SCN)4 and AHg(SCN)4 (A=Zn, Cd, Mn) as UV nonlinear optical crystal materials

Abstract Bimetallic thiocyanate complexes of chemical formula AB(SCN)4(ABTC): ZnCd(SCN)4 and MHg(SCN)4 (M=Zn, Cd, Mn) were discovered as potentially useful crystal materials in ultraviolet second-harmonic generation. The structures of these compounds were derived from powder X-ray diffraction data, and unit-cell parameters were calculated by the TREOR program. Their vibrational spectra were studied by Raman spectroscopy, which show that the characteristic vibrational modes of AB(SCN)4 crystals arise mainly from the internal vibrations of the SCN, A(NCS)4, and B(SCN)4 clusters. The reason of the high optical nonlinearities of ABTC crystals has been studied by the use of the Raman spectra and the molecular orbital theory: the distorted A(NCS)4 and B(SCN)4 tetrahedra and the conjugated charge-transfer (–A–NCS–B–) bridges that connect all the distorted tetrahedra together.

Investigation on growth and macro-defects of a UV nonlinear optical crystal: ZnCd(SCN)4

Abstract Large single crystals of the coordination complex nonlinear optical material zinc cadmium thiocyanate, ZnCd(SCN) 4 (abbreviated as ZCTC), were grown from aqueous solutions by the solvent evaporation method. The morphology of the crystals was indexed. The grown crystals were characterized by the powder X-ray diffraction analysis allowing to identify the diffraction planes. Six kinds of macro-defects were found in ZCTC large crystals. These defects include cracks, inclusions, negative crystals, growth striations, sector boundaries and straight pipes. The morphologies and distribution regularities of these defects were observed and analyzed using optical microscopy. Their formation mechanisms and the methods of eliminating these defects are discussed.

Growth morphology and thermal properties of the organometallic nonlinear optical crystal: MnHg(SCN)4(C2H6OS)2

Abstract Manganese mercury thiocyanate-bis(dimethyl sulfoxide) MnHg(SCN) 4 (C 2 H 6 OS) 2 (MMTD) single crystals of optical quality have been grown from solution by the slow temperature-lowering method. The X-ray powder diffraction (XRPD) spectroscopy of MMTD crystal was performed at room temperature. The morphology of the crystal was indexed. The thermal decomposition process is characterized by differential scanning calorimetry (DSC). The specific heat of the crystal is 699.5 J mol −1 K −1 at 300 K. The thermal expansion coefficient (TEC) along the a -, b - and c -axis is α 1 =5.33×10 −5 , α 2 =4.51×10 −5 and α 3 =3.10×10 −5 /K, respectively. All the TECs are positive and interpreted on the basis of crystal structure.

Preparation and properties of a novel nonlinear optical crystal: MnHg(SCN)4(H2O)2.2(C3H6CONCH3)

In this article, diaquatetrakis (thiocyanato) manganese(II) mercury(II)-N-methyl-2-pyrrolidone, MnHg(SCN) 4 (H 2 O) 2 .2(C 3 H 6 CONCH 3 ), (abbreviated as MMTWMP), a new organometallic nonlinear optical crystal material is reported. The structure, optical and thermal characterizations were determined by elemental analysis, infrared and Raman spectroscopy, X-ray powder diffraction, thermogravimetric analysis, differential scanning calorimetry, special heat, SHG measurements and UV/Vis/NIR optical transmission spectra. It belongs to the tetragonal crystallographic system, with cell parameters: a = 12.1294, c = 8.2238A, V = 1211.27 A 3 . Single crystals with dimensions up to 8 x 7 x 5 mm 3 have been obtained. The morphology of the crystals was indexed. The MMTWMP crystal exhibits good physicochemical stability at normal temperature and pressure. Its UV transparency cutoff is 360 nm, which is shifted to the violet by 13 nm, as compared with MnHg(SCN) 4 (MMTC); the optical transmission is 44. 82% at 404 nm, which is by 17.46% higher than that of MMTC.

Dielectric Properties of Bi2Ti2O7 Thin Films With (111) Orientation

Bismuth titanate thin films have been prepared on silicon by metalorganic decompositionMOD) technique with bismuth nitrate and titanium butoxide as source materials. The growth procedure of the Bi 2 Ti 2 O 7 thin films is discussed in this paper. The surface morphology of the Bi 2 Ti 2 O 7 film was investigated by using Electric Force Microscope (EFM), and the crystallization of the films was studied by x-ray diffraction (XRD). Bismuth titanate thin film prepared on (100) silicon substrate showed strong (111) orientation. Its dielectric properties and the current-voltage (I-V) characteristics were measured. The dielectric constant of the Bi 2 Ti 2 O 7 thin films vs. frequency, in the temperature range of 100-800 °C, were studied. The dielectric constant and the dielectric loss for Bi 2 Ti 2 O 7 are 118 and 0.07 respectively at 100KHz. For the Bi 2 Ti 2 O 7 films with 0.4µm in thickness annealed at 580 °C for 40 minutes, their leakage current density is 4.06×10 −7 A/cm 2 at an applied voltage of 15V. The ferroelectric phase transition has been observed distinctly and the Curie temperature was determined for the Bi 2 Ti 2 O 7 ceramic films. Capacitance vs. temperature was measured from 27-800 at 1KHz, 100KHz, 100KHz and 1MHz.

Dielectric and ferroelectric properties of Bi2Ti2O7 thin films with (111) orientation

Abstract Transparent and crack-free Bi2Ti2O7 thin films with strong (111) orientation were successfully prepared on n-Si(100) by chemical solution deposition (CSD) using bismuth nitrate and titanium butoxide as starting materials. The growth procedure of the Bi2Ti2O7 thin films is discussed in this paper. The surface morphology of the Bi2Ti2O7 film was investigated by using Electric Force Microscope (EFM), and the crystallization of the films was studied by x-ray diffraction (XRD). Bismuth titanate thin film prepared on (100) silicon substrate showed strong (111) orientation. Its dielectric properties and the current-voltage (I-V) characteristics were measured. The dielectric constant of the Bi2Ti2O7 thin films vs. frequency in the temperature range of 100–800°C were studied. The dielectric constant and the dielectric loss for Bi2Ti2O7 are 118 and 0.07 respectively at 100 KHz. For the Bi2Ti2O7 films with 0.4 μrn in thickness annealed at 580°C for 40 minutes, their leakage current density is 4.06×10−7 A/cm2 at an voltage of 15 V. The ferroelectric phase transition has been observed distinctly and the Curie temperature was determined for the Bi7Ti2O7 ceramic films. Capacitance vs. temperature was measured from 27°800°C at 1KHz. 10KHz, 100KHz and 1MHz.