Wyniki wyszukiwania - Biblioteka Nauki

1

The development of lec technology for GaAs single crystal growth from laboratory scale to mass production

100%

Jurisch M. , Eichler S.

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tom T. 31, nr 1-2

7-17

EN

Mass production of SI GaAs single crystals based on an advanced LEC growth process has been established during the last decade of the last century. Two key issues had to be solved : Scaling up of the growth equipment and carbon control. The progress in modelling of thermal heat transfer (radiation, conduction and turbulent convection) due to high computer power and advanced codes has made it possible to optizme the equipment and the processes in rather short time and at lower costs.

2

Crystal growth of the oxide fiber single crystal for optical applications

100%

Yoon D. H.

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tom Vol. 12, No. 2

199-212

EN

Recently, certain materials have attracted attention for a new generation of high speed, efficient, multi-functional optical devices. Among these materials, small-diameter and long-length bulk crystals are of considerable interest for miniaturization and high efficiency. In particular, rod or fiber-like micro-single crystals have already received attention as attractive materials for a variety of electro-optical application, such as second harmonic generation (SHG), micro-laser sources or optical memory arrangements because of their extended interaction length and high optical intensity.

3

Growth and optical properties of Nd:YVO₄ laser crystals

100%

Kaczmarek S. M. , Łukasiewicz T. , Giersz W. , Jabłoński R. , Jabczyński J. K. , Świrkowicz M. , Gałązka Z. , Drozdowski W. , Kwaśny M.

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1999

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tom Vol. 7, No. 2

149-152

EN

Growth conditions for Nd:YVO₄ crystals and some optical properties are presented. The obtained Nd:YVO₄ crystal shows lower content of point defects and consequently, lower susceptibility to ionising radiation. ESR measurements show the presence of V ions in intersitial sites with another than 5t valency. Obtained by Czochralski method crystals reveal very good optical properties, some of which are better than for Nd:YAG.

4

YAG:V³⁺ : new passive Q-switch for lasers generating radiation within near infrared range

100%

Mierczyk Z. , Frukacz Z.

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2000

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tom Vol. 8, No. 1

67-74

EN

The paper presents results of investigations on growth conditions of yttrium-aluminium garnet doped with trivalent vanadium YAG:V³⁺ ions and investigations of these crystals for their application in passive Q-switches of laser resonators generating radiation within near infrared range. Absorption spectra of the crystals were examined. It was sated that within a spectral range of 720-1500 nm there are three absorption bands with their maxima for the wavelengths of 822 nm, 1098 nm, and 1282 nm. For these maxima the crystal absorption is nonlinearly dependent on intensity of incident radiation, i.e., crystal is a saturable absorber. The process of reduction of V⁵⁺ and V⁴⁺ ions to V³⁺ ones was carried out by means of crystals heating what significantly increases concentration of V³⁺ ions that are responsible for nonlinear absorption. Saturation characteristics have been determined and modulation properties in the systerm of YAG:Nd laser, generating giant-pulses of wavelengths of 1064 nm and 1318 nm have been investigated. Detailed review of the literature and the results of hitherto carried out investigations have been also performed.

5

Investigation on Nucleation Kinetics, Growth and Nonlinear Optical Properties of L-Cystine Hydrochloride Crystal

100%

Manivannan D. , Kirubavathi K. , Selvaraju K.

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tom 133

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nr 1

63-67

EN

The semiorganic nonlinear optical crystal of amino-carboxyl acid family, L-cystine hydrochloride (LCHCl) was successfully grown from its aqueous solution by the slow evaporation solution growth method. The solubility, metastable zone width and induction period were determined for the first time experimentally and there by the possibility of growing bulk crystals of LCHCl using deionized water as solvent. The induction period was recorded for the different supersaturation ratios (S=1.2, 1.3, 1.4, and 1.5), which reveals that the induction period of LCHCl decreases with increase in supersaturation. The nucleation kinetic parameters such as critical free energy, change of volume free energy, critical radius, number of molecules in the critical nucleus and nucleation rate have been evaluated for LCHCl crystals. The interfacial energy values of LCHCl were determined for different supersaturation ratio by means of varying temperatures. The single crystal X-ray diffraction gives the lattice parameters value of the grown crystals. The second harmonic generation efficiency was confirmed by the Kurtz-Perry powder method. The laser damage threshold energy of the grown crystal indicates that grown crystal has excellent resistance to laser radiation also compared with known other nonlinear optical crystals.

6

Crystal growth and characterisation of In-rich phases in Cu-In-Ga-Se system

100%

Filipowicz J. I. , Bacewicz R. , Wolska A.

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2000

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tom Vol. 8, No. 4

372-374

EN

Technological parameters of crystal growth using Bridgman-Stockbarger method for some materials of Cu-In-Se and Cu-In-Ga-Se systems are presented. Single crystals as large as 1 cm³ have been grown. The composition variation along crystal ingots was determined by the microprobe analysis. A strong segregation effect is observed. Crystals with composition close to the compounds with nominal compositions Cu₂In₄Se₇, CuIn₃Se₅, CuIn₅Se₈, CuGa₃Se₅ and Cu(In₀.₈Ga₀.₂)₃Se₅ were identified. Photolumiscence spectra of the crystals from the Cu-In-Se system were measured and analysed in terms of quasi-donor-acceptor transitions.

7

Synthesis of claw-like CuO and its catalytic activity in the thermal decomposition of ammonium perchlorate

100%

Wang J. , He S. , Li Z. , Jing X. , Zhang M.

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tom Vol. 27, No. 2

501--507

EN

Claw-like CuO was prepared by solution process at 100 °C simply by using copper nitrate and hexamethylenetetramine for 3 h. The structure and morphology of resulting CuO powders were characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. CuO nanocrystals were studied as an additive for promoting the thermal decomposition of ammonium perchlorate. With the addition of the claw-like CuO nanocrystals, thermal decomposition temperature of ammonium perchlorate decreased. CuO nanocrystals showed catalytic activity on the decomposition of ammonium perchlorate.

8

Growth and characterization of an NLO material - crystal of triglycine acetate

100%

Hussaini S. S. , Dhumane N. R. , Dongre V. G. , Shirsat M. D.

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tom Vol. 27, No. 2

365--372

EN

Triglycine acetate (TGAc), a nonlinear optical material, has been synthesized. The second harmonic generation efficiency has been determined by Kurtz's powder test and it was found to be 1.55 times more than potassium dihydrogen phosphate. The solubility studies were carried out in the temperature range 30-55 °C. Single crystals of TGAc have been grown by slow evaporation of solution at 30 °C. The cell parameters were determined by the X-ray diffraction analysis. The UV-visible absorption spectra have been recorded to study the optical transmittance in the range from 200 nm to 800 nm. The Fourier transform infrared analysis identified various functional groups present in the material. The mass spectral analysis was carried out to measure the total molecular weight of the grown crystal. Using thermogravimetric analysis the thermal behaviour was studied.

9

Growth of large SbSI crystals

100%

Szperlich P. , Toron B. , Nowak M. , Jesionek M. , Kepinska M. , Bogdanowicz W.

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tom Vol. 32, No. 4

669--675

EN

In this paper a novel method of SbSI single crystals fabrication is presented. In this method a sonochemically prepared SbSI gel is used as an intermediate product in a vapour growth process. The main advantages of the presented technique are as follows. First, the SbSI gel source material has lower temperature of sublimation and allows to avoid explosions during SbSI synthesis (the sonochemical synthesis is free of any explosion hazard). Second, but not least, the grown SbSI single crystals have smaller ratio of longitudinal and lateral dimensions. The cross sections of the presented crystals are relatively large (they are up to 9 mm2 ). The crystals have been characterized by X-ray diffraction, angle-resolved optical spectroscopy, and diffusive reflectivity.

10

Morphology and the kinetics of the crystal growth

100%

Jakubczyk M. , Kopyciak G.

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2005

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tom Vol. 10

59--63

11

The birefringence spectroscopic studies on ferroelectric glycine phosphite (GPI) single crystals

88%

Bhoopathi G. , Jayaramakrishnan V. , Ravikumar K. , Prasanyaa T. , Karthikeyan S.

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tom Vol. 31, No. 1

1-5

EN

The ferroelectric glycine phosphite single crystals have been grown from aqueous solution by both conventional and Sankaranarayanan-Ramasamy methods. The modified channelled spectrum method has been adopted for spectral dependence of optical birefringence studies over the wavelength range of 480-620 nm, which show that both the crystals exhibit relatively high birefringence values. The photoluminescence excitation studies were carried out for the grown crystals in a wide wavelength range between 300 nm and 600 nm at 224 K. The crystals were also subjected to scanning electron microscopy analysis in order to determine the ferroelectric domain pattern configuration.

12

A comparative study on the performance of radiation detectors from the HgI2 crystals grown by different techniques

88%

Martins J. F. T. , Costa F. E. , dos Santos R. A. , de Mesquita C. H. , Hamada M. M.

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tom Vol. 57, No. 4

555-562

EN

In this work, the establishment of a technology for HgI2 purification and crystal growth is described, aiming at a future application of this crystal as a room temperature radiation semiconductor detector. Two methods of crystal growth were studied in the development of this work: (1) physical vapor transport (PVT) and (2) saturated solution from dimethylsulphoxide (DMSO) complexes. In order to evaluate the crystals obtained using each of these methods, systematic measurements were carried out for determining the stoichiometry, structure, orientation, surface morphology and impurity of the crystal. The influence of these physicochemical properties of the crystals developed was evaluated in terms of their performance as a radiation detector. The best response to radiation was found for the crystals grown by the PVT technique. Significant improvement in the performance of HgI2 radiation detector was found, purifying the crystal by means of two successive growths by the PVT technique.

13

Investigation on optical, electrical and etching properties of 2-aminopyridinium 4-aminobenzoate: A phase matchable organic single crystal for optoelectronic device applications

88%

Chandra L. , Chandrasekaran J. , Perumal K. , Babu B. , Jayaramakrishnan V.

Materials Science Poland

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2017

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tom Vol. 35, No. 1

126--134

EN

NLO active 2-aminopyridinium 4-aminobenzoate (APAB) single crystals were successfully grown by the standard slow evaporation technique. The crystallinity of the grown crystals was analyzed through X-ray diffraction (XRD) measurements. Fourier transform infrared (FT-IR) spectroscopic studies were also performed for the identification of different modes present in the compound. The UV-Vis absorption and transmittance spectra were recorded for the grown crystal and the optical band gap was calculated. Birefringence and etching studies were also carried out. The dielectric study showed that the dielectric constant decreased with an increase in frequency. The photoconductivity study revealed its positive photoconducting nature. Theoretical HOMO LUMO investigations were also made for the crystal. The relative SHG efficiency of the material was investigated by the Kurtz and Perry powder technique. The phase matching property of the crystal was studied through the SHG dependence of average particle sizes.

14

Synthesis, growth and studies of pristine and nickel doped L-valinium picrate crystals for organic light emitting diodes applications

88%

Ragunathan A. S. , Selvapandiyan M.

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tom Vol. 38, No. 2

374--380

EN

Single crystals of L-Valinium Picrate (LVP), 0.1 mol% Ni2+ doped L-Valinium Picrate, and 0.2 mol% Ni 2+ doped L-Valinium Picrate were grown by low temperature solution growth method, especially by solvent evaporation technique at ambient temperature. Function groups and modes of vibration were identified by FT-IR studies. The grown crystals belong to monoclinic system which has been revealed by powder XRD. The estimated band gaps were found to be 3.86 eV for LVP, 3.72 eV for 0.1 mol% Ni2+ doped LVP, and 3.70 eV for 0.2 mol% Ni2+ doped LVP crystals, respectively. The PL excitation wavelength of the grown materials is 370 nm. All the elements (C, N, O, Ni, and Cl) as per molecular formula were present in the EDAX spectrum of the grown materials. The 0.2 mol% Ni2+ ion doped LVP materials had higher thermal stability (208 °C) than LVP and 0.1 mol% Ni2+ doped LVP.

15

Synthesis, surface tension, optical and dielectric properties of bismuth oxide thin film

88%

Tezel F. M. , Kariper A. I.

Materials Science Poland

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2017

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tom Vol. 35, No. 1

87--93

EN

Bismuth oxide thin film was deposited by chemical bath deposition (CBD) technique onto a glass substrate. The grain size (D), dislocation density (δ) and number of crystallites per unit area (N), i.e. structural properties of the thin film were determined as 16 nm, 39.06 x 10-4 line/nm2, 31.25 x 10-3 1/nm2, respectively. Optical transmittance properties of the thin film were investigated by using a UV-Vis spectrophotometer. The optical band gap (Eg) for direct transitions, optical transmission (T %), reflectivity (R %), absorption, refractive index (nr), extinction coefficient (k), dielectric constant (ϵ) of the thin film were found to be 3.77 eV, 25.23 %, 32.25 %, 0.59, 3.62, 0.04 and 2.80, respectively. The thickness of the film was measured by AFM, and was found to be 128 nm. Contact angles of various liquids on the oxide thin film were determined by Zisman method, and surface tension was calculated to be 31.95 mN/m.

16

Growth, optical and EPR properties of Li1.72Na0.28Ge4O9 single crystals pure and slightly doped with Cr

88%

Jasik A. , Berkowski M. , Kaczmarek S. , Suchocki A. , Kaminska A. , Leniec G. , Nowakowski P. , Domukhovski V.

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tom 10

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nr 2

506-513

EN

Single crystals of lithium-sodium-tetragermanate, a member of the solid solution series Li2−xNaxGe4O9 with x=0.28, pure and slightly doped with Cr3+ ions (0.03 mol.% and 0.1 mol.%), were grown in ambient atmosphere by the Czochralski technique from stoichiometric melt. The crystals with dimensions up to 20 mm in diameter and 50 mm in length were obtained. The crystal structure has been determined by means of X-ray diffraction. Phase analysis and structural refinement of the Li1.72Na0.28Ge4O9 crystals were performed by X-ray powder diffraction using Ni-filtered Cu Kα radiation with a Siemens D5000 diffractometer. The absorption, excitation and photoluminescence spectra of the crystals were measured in the UV-VIS and IR range at low temperatures. EPR investigations were performed using a conventional X-band Bruker ELEXSYS E 500 CW-spectrometer operating at 9.5 GHz with 100 kHz magnetic field modulation. Temperature and angular dependences of the EPR spectra of the crystal samples were recorded in the 3–300 K temperature range.

17

Growth and characterization of Cr:SrGdGa₃O₇ and Cr:SrLaGa₃O₇ single crystals

88%

Kaczmarek S. M. , Berkowski M. , Jabłoński R. , Pracka I. , Kwaśny M. , Świrkowicz M.

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tom Vol. 47, nr 7-8

141-151

EN

Growth and recharging processes of chromium ions in SrGdGa₃O₇ and SrLaGa₃O₇ single crystals incorporated during growth or doping by diffusion (only for SrLaGa₃O₇ crystal) were analyzed. The annealing at 1000°C in air and ionizing with gamma rays (doses from 10³ to 10⁵ Gy) and protons (10¹⁴ cm⁻² only for SrGdGa₃O₇ crystal) were performed. Different kinds of chromium ions valency, from two to four, were found. Electron spin resonance measurements in the temperature range 5-300 K with the use of Brucker spectrometer were also done.

PL

Analizowano proces wzrostu i procesy zmiany walecyjności jonów chromu w monokryształach SrGdGa₃O₇ i SrLaGa₃O₇. Chrom wprowadzono podczas procsu wzrostu oraz w wyniku procesu dyfuzji (tylko dla kryształu SrLaGa₃O₇). Przeprowadzono wygrzwanie w temperaturze 1000°C w powietrzu oraz naświetlania kwantami gamma (dawki 10³ - 10⁵ Gy) i protonami (10¹⁴ cm⁻² tylko dla kryształu SrGdGa₃O₇). Stwierdzono występowanie jonów chromu o walencyjności od 2 do 4. Przeprowadzono również pomiary elektronowego rezonansu spinowego w zakresie temperatur 5-300 K z wykorzystaniem spektrometru firmy

18

Kryształy V3+ : YAG do pasywnej modulacji doborci rezonatorów laserów generujących w obszarze bliskiej podczerwieni

75%

Mierczyk Z. , Frukacz Z.

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1998

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tom T. 26, nr 3-4

28-46

PL

W pracy przedstawiono wstępne wyniki badań warunków wzrostu kryształów granatu itrowo-glinowego domieszkowanych trójwartościowymi jonami wanadu V3+:YAG oraz wyniki badań tych kryształów w aspekcie przydatności do wytwarzania pasywnych modulatorów dobroci rezonatorów laserowych (Q-switch, mode locking) generujących w obszarze bliskiej podczerwieni. Zbadano widma absorpcji otrzymanych kryształów i stwierdzono, ze w obszarze spektralnym od 720 nm do 1500 nm występują trzy pasma absorpcji z maksimum dla dlugości fal 822 nm, 1098 nm i 1282 nm, w których kryształ ten wykazuje nieliniowa. zależność absorpcji od intensywności padającego promieniowania, czyli jest absorberem nasycalnym. Metoda wygrzewania kryształów przeprowadzono proces redukcji jonów V5+ i V4+ do V3+, co znakomicie zwiększa koncentracje. jonów V3+ odpowiedzialnych za nieliniową absorpcje. Wyznaczono charakterystyki nasycalności oraz zbadano własności modulacyjne w układzie lasera NdrYAG, generującego monoimpulsy o dlugości fali 1064 nm i 1318 nm. Dokonano także szczegółowego przeglądu literatury i wyników dotychczasowych badań.

EN

In this work we present results on YAG:V3+ single crystal growth and examination for the purposes of Q-switching of laser resonator in the near IR band. A numbers of YAG single crystals doped with different concentrations of V3+ ions were obtained by the Czochralski method. The absorption and emission spectra measurements on those crystals are presented. After crystal growth only a small part of vanadium atoms is introduced into a crystal structure as V3+ ions in tetrahedral positions, the other ones are at different positions or at higher charge states V4+ and V5+ Receiving of vanadium ions of V3+ valency in the desired points of YAG structure can be possible as a result of complex reactions in solid-state phase. Such reactions proceed during the process of a multi-stage crystal annealing in reducing atmosphere and in vacuum.The as grown crystals have not non-linear absorption bands of V3+ ions in tetrahedral positions (822 nm, 1098 nm and 1282 nm). After annealing of the crystals in reducing atmosphere the absorption bands, described above, arise. The investigations of changes in transmission properties of YAG crystals with different concentrations of V3+ ions have been carried out as a function of power density of transmitted radiation at 822 nm (Ti:Sapphire laser) and 1064 nm (YAG:Nd laser).

19

Problemy wzrostu monokryształów fosforku galu (GaP) o średnicy 4" i orientacji < 100 > oraz < 111 >

75%

Orłowski W. , Mirowska A. , Hruban A. , Strzelecka S.

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tom T. 38, nr 2

9-19

PL

Opracowano warunki otrzymywania monokryształów fosforku galu (GaP) o średnicy 4" i orientacji < 100 > oraz < 111 >. Skonstruowano układy termiczne dla urządzenia MarkIV, w których można otrzymywać metodą Czochralskiego z herme-tyzacją cieczową (LEC - Liąuid Encapsulated Czochralski) duże monokryształy GaP. Zbadano termiczne warunki wzrostu kryształów. Doświadczalnie określono wpływ niektórych elementów układu termicznego na kształt pola temperatur w obszarze wzrostu kryształów. Otrzymano monokryształy GaP o średnicy 4" i orientacji < 100 > oraz < 111 >. Zbadano ich własności elektryczne i strukturalne.

EN

Technological parameters for growing 4"(GaP) single crystals in < 100 > and < 111 > direction were investigated. Thermal systems were constructed for MarklV puller, which allow growing GaP single crystals with big diameter by Liquid Encapsulated Czochralski method. The influence of some of the thermal system elements on the temperature field near the growing crystal was experimentally assessed. GaP crystals of 4" in diameter were obtained in < 100 > and < 111 > direction. Electrical and structural parameters were assessed.

20

Photoluminescence and structural properties of selected wide-gap II-VI solid solutions.

75%

Firszt F. , Łęgowski S. , Męczyńska H. , Sekulska B. , Szatkowski J. , Paszkowicz W. , Marczak M.

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1999

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tom Vol. 7, No. 2

87-92

EN

This work presents results of investigations of photoluminescence and structural properties of ternary Zn₁-xBexSe, Cd₁-xMgxSe, Zn₁-xMgxSe and quaternary Cd₁-x-yMgxZnySe, Zn₁-x-yBexMgySe, Zn₁-xMgxSe₁-ySy mixed crystals. These crystals were grown from the melt by the high-pressure Bridgman method. Zn₁-xMgxSe and Zn₁-xSrxSe were also obtained by annealing of ZnSe crystals in evacuated quartz ampoules containing Mg or Sr metal. It has been found that admixing of Mg into ZnSe favours the formation of wurtzite Zn₁-xMgxSe while Besphalerite Zn₁-xBexSe structures. Low temperature (40 K) photoluminescence spectra consist of exciton, edge and deep levels emission bands. For most of investigated crystals the emission corresponding to the highest photon energy line in luminescence spectrum is observed up to room temperature.