M.K. Lu

Investigation of Bimetallic Thiocyanates belonging to ABTC Structure Type: ZnCd(SCN)4 and AHg(SCN)4 (A = Zn, Cd, Mn ) as Nonlinear Optical Crystal Materials

Bimetallic thiocyanate complexes crystal materials belonging to ABTC structure type: ZnCd(SCN) 4 and AHg(SCN) 4 (A = Zn, Cd, Mn) which are potentially useful in second harmonic generation (SHG) have been prepared. Their structural, optical and physicochemical properties are characterized by infrared spectroscopy, X-ray powder diffraction, vis/UV/NIR spectroscopy, SHG measurements and thermal analysis. The states of crystal growth solutions are discussed in this article. The crystals belong to tetragonal system with the space group I4 and exhibit SHG efficiencies over one order of magnitude higher than that of urea. Their transparency cutoffs lie in the UV region, and they possess good physicochemical stabilities.

Thermal and laser properties of Nd:YVO4 crystal

Nd:YVO 4 crystal has been grown by Czochralski method. The data of thermal expansion and specific heat have been measured. The thermal expansion coefficients along a- and c-axis are α 1 = 2.2 × 10 -6 /K, and α 3 = 8.4 × 10 -6 /K respectively. The specific heat is 24.6 cal/mol K at 330 K. The large anisotropy along c- and a-axis of thermal expansion coefficients is explained by the structure of YVO 4 crystal. 921 mW output laser at 1.06 μm has been obtained with a 3 mm × 3 mm × 1 mm crystal sample when pumped by 1840 mW cw laser diode, and the slope efficiency is 55.5%.

Crystal growth and characterization of the organometallic nonlinear optical crystal : manganese mercury thiocyanate (MMTC)

Manganese mercury thiocyanate (MMTC) has been discovered to be a novel organometallic nonlinear optical crystal. In this article, preparation and crystal growth of MMTC have been investigated. The crystal grown is characterized by infrared spectroscopy, differential thermal analysis, thermogravimetric analysis and transmission spectrum. The cutoff wavelength is 373 nm, which is nearly the same as that of cadmium mercury thiocyanate (CMTC). The thermoanalysis shows that it possesses better physicochemical stability than that of CMTC.

Growth, spectra and influence of annealing effect on laser properties of Nd:YVO4 crystal

Abstract Nd:YVO 4 single crystal has been grown by the Czochralski method. The effective segregation coefficients k eff of Nd, Y and V elements have been measured for crystals with different neodymium-doped concentrations. The absorption and fluorescence spectra of Nd:YVO 4 crystal have been measured. The lasers at 1.06 μm have been demonstrated when the crystal samples of annealed and non-annealed Nd:YVO 4 are pumped by laser diode (LD). The influence of annealing effect on laser properties is discussed.

The effect of Co2+ and Co3+ on photoluminescence characteristics of ZnS nanocrystallines

Abstract Free-standing powder of doped ZnS nanoparticles has been synthesized by using a chemical co-precipitation of Zn 2+ , Co 2+ , Co 3+ with sulfur ions in aqueous solution. X-ray diffraction analysis shows that the diameter of the particles is ∼2.6±0.2xa0nm. Unique luminescent properties have been observed from ZnS nanoparticles doped with Co 2+ and Co 3+ . The effect of Co 3+ on emission spectra of doped samples is remarkably different from that of Co 2+ . Very strong and stable visible-light emission have been observed from ZnS nanoparticles doped with Co 2+ . However, the fluorescence intensity of Co 3+ -doped ZnS nanoparticles is much weaker than that of ZnS nanoparticles. Nanoparticles can be doped with cobalt during the synthesis without altering the X-ray diffraction pattern and emission wavelength. However, doping makes the fluorescence intensity vary. The fluorescence intensity of doped sample is about five times of that of pure ZnS nanocrystallines when the doped mole ratio of Co 2+ is 0.5%. The fluorescence efficiencies of samples decreases as doped mole ratio of Co 2+ and Co 3+ increases. When Co 3+ is doped in ZnS nanoparticles, the fluorescence efficiencies of doped ZnS nanoparticles almost died away. Therefore, Co 3+ leads to fluorescence decay of ZnS nanocrystallites.

Growth, morphology and laser performance of Nd : YVO4 crystal

Abstract Ndxa0:xa0YVO 4 single crystal with good optical quality and large dimension has been grown by Czochralski method. The synthesizing of Ndxa0:xa0YVO 4 polycrystalline material and some problems of single crystal growth have been studied. We have developed the equilibrium shape of Ndxa0:xa0YVO 4 single crystal which is composed of {1xa00xa00} and {1xa00xa01} simple forms. The effective segregation coefficients k eff of elements have been measured and k eff of Nd element is about 0.63. The lasing at 1.06xa0μm has been demonstrated pumped by a 3xa0W laser diode (LD), and the light–light conversion efficiency is up to 50%.

Preparation and Characterization of Nonlinear Optical Crystal Materials: Cadmium Mercury Thiocyanate and its Lewis Base Adducts

Cadmium mercury thiocyanate (CdHg(SCN) 4 , CMTC) and its two lewis base adducts: cadmium mercury thiocyanate dimethyl-sulphoxide (CdHg(SCN) 4 (H 6 C 2 OS) 2 , CMTD) and cadmium mercury thiocyanate glycol monomethyl ether (CdHg(SCN) 4 (C 3 H 8 O 2 ), CMTG) have been discovered as nonlinear optical (NLO) crystal materials. Their structural, optical and physicochemical properties were characterized by X-ray powder diffraction (XRPD), infrared spectroscopy, vis/UV/NIR spectra and thermal analysis. It is discovered that their transparency cutoffs lie in the UV region and CMTD crystals possess the shortest cutoff wavelength among the three crystal materials.

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.

Growth and thermal properties of tri-allylthiourea cadmium chloride (ATCC) crystal

Abstract The tri-allylthiourea cadmium chloride crystal grown was characterized by recording the powder X-ray diffraction pattern and indexing the diffracting planes. The thermal expansion coefficients along a - and c -axes are 2.19×10 −5 and 6.15×10 −5 xa0K −1 , respectively. The specific heat of the crystal was measured to be 590.43xa0J/molxa0K at 293.15xa0K. The thermal decomposition process was analyzed according to the result of differential thermal analysis and PXRD patterns of residues at different temperatures.

Crystal growth and characterization of a novel organometallic nonlinear-optical crystal:: MnHg(SCN)4(C2H6OS)2

Abstract A potentially useful second harmonic generation (SHG) organometallic nonlinear-optical crystal, MnHg(SCN) 4 (C 2 H 6 OS) 2 (MMTD), has been prepared, and high optical quality single crystals up to 25×18×18xa0mm 3 in size have been successfully grown by the slow temperature-lowering technique. Its structural, physicochemical and optical properties have been characterized using elemental analyses, infrared spectroscopy, thermal analysis, SHG measurements and VIS/UV/NIR spectroscopy. The material possesses a good physicochemical stability up to 145°C and exhibits powder SHG efficiencies about 23 times that of urea. The UV transparency cutoff is 375xa0nm, and the transmission is 44.81% at 404xa0nm, which is 17.45% higher than that of MnHg(SCN) 4 (MMTC).