Search results

1

Influence of Temperature on Refractive Indices of BaLaGa_{3}O_{7} and SrLaGa_{3}O_{7}

100%

Ryba-Romanowski W., Gołąb S., Berkowski M.

Acta Physica Polonica A

|

1993

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vol. 83

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issue 2

167-172

EN

A simple theoretical approach based on Kramers-Krönig relations predicts well the dispersion and birefringence of BaLaGa_{3}O_{7} and SrLaGa_{3}O_{7}. In the whole transparency region the birefringence of both compounds is too low to offset dispersion in the process of a second harmonic generation, thus the crystals cannot be made phase matchable. Birefringence of BaLaGa_{3}O_{7} and SrLaGa_{3}O_{7} is stable with respect to the temperature region of 300-550 K. The refractive indices increase linearly at a rate of 2 × 10^{-5} K^{-1} with increasing temperature.

2

Material Parameters Characterizing the Performance of Flashlamp Pumped BaLa_{1-x}Nd_{x}Ga_{3}O_{7} Laser

100%

Ryba-Romanowski W., Gołąb S., Berkowski M.

Acta Physica Polonica A

|

1991

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vol. 79

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issue 4

501-506

EN

Physical properties of optically uniaxial BaLa_{1-x}Nd_{x}Ga_{3}O_{7} crystals have been investigated. Specific heat, thermal expansion coefficients, thermal diffusivity, Young modules and Poisson ratios of the crystal have been determined. Basing upon these parameters and the available spectral data the operating conditions for lasers employing rods made of BaLa_{1-x}Nd_{x}Ga_{3}O_{7} have been defined.

3

Doping Effects of Co, Ni, and Cu in FeTe_{0.65}Se_{0.35} Single Crystals

100%

Bezusyy V., Gawryluk D., Berkowski M., Cieplak M.

Acta Physica Polonica A

|

2012

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vol. 121

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issue 4

816-819

EN

The resistivity, magnetoresistance, and magnetic susceptibility are measured in single crystals of FeTe_{0.65}Se_{0.35} with Cu, Ni, and Co substitutions for Fe. The crystals are grown by Bridgman's method. The resistivity measurements show that superconductivity disappears with the rate which correlates with the nominal valence of the impurity. From magnetoresistance we evaluate doping effect on the basic superconducting parameters, such as upper critical field and coherence length. We find indications that doping leads to two component superconducting behavior, possibly because of local charge depression around impurities.

4

Identification of the Domain Walls Configuration in the Ferroelastic Nanosize Material La_{0.95}Sr_{0.05}Ga_{0.9}Mg_{0.1}O_{3-x}

100%

Savytskii D., Paulmann C., Bismayer U., Berkowski M.

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issue 1

62-73

EN

This paper deals with the identification of multidomain configuration in ferroelastic phases of La_{0.95}Sr_{0.05}Ga_{0.9}Mg_{0.1}O_{3-x} using polychromatic synchrotron X-ray radiation (Laue method). A nondestructive approach for the determination of domain misorientations, orientation of domain walls and their configuration in the nanosize ferroelastic domain structure was developed. The proposed approach can be used to study the nanosize ferroelastic domain structure in small crystals of submillimeter sizes at different external fields, including temperature. The ferroelastic domain structure in the orthorhombic as well as in the rhombohedral phases of La_{0.95}Sr_{0.05}Ga_{0.9}Mg_{0.1}O_{3-x} crystals has been identified. The intersection of walls leads to the formation of a chevron-like pattern. The observed reversibility of domain patterns during temperature cycles is probably caused by the interaction of domain boundaries with point defects, most likely oxygen vacancies.

5

High Quality (100) and (001) Oriented Substrates Prepared from Czochralski Grown SrLaGaO_{4} and SrLaAlO_{4} Single Crystals

100%

Berkowski M., Fink-Finowicki J., Sass J., Mazur K.

Acta Physica Polonica A

|

1997

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vol. 92

|

issue 1

201-204

EN

The growth of SrLaGaO_{4} and SrLaAlO_{4} crystals on ⟨100⟩ and ⟨001⟩ oriented seeds was investigated. Various defects, which appeared in crystals grown on these two orientations, were observed in polarized light and by X-ray diffraction topography. It was found that to obtain a substrate of the best quality, the crystal should be cut along the growth directions. Therefore, crystals pulled along ⟨100⟩ direction are utilized for preparation of (001) substrates, whereas (100) substrates are better to cut from crystals grown on ⟨001⟩ seed. The quality of the prepared substrates was determined by high resolution X-ray diffraction study in terms of rocking curve and mean mosaic angle.

6

Defects in Detwinned LaGaO_{3} Substrates

100%

Mazur K., Fink-Finowicki J., Berkowski M., Schell N.

Acta Physica Polonica A

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1997

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vol. 92

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issue 1

205-208

EN

Single crystals of lanthanum gallate would be the suitable substrate for YBaCuO films except for the phase transition and the tendency to twinning existing in this material. However, by appropriate choice of growth conditions in the Czochralski method, it is possible to grow single crystal of LaGaO_{3} with low density of twin boundaries. Special stress and temperature treatment can then be applied to such materials to remove majority of existing twins. The substrates were examined by X-ray topography before and after detwinning and the surface was scanned with a profilometer.

7

Role of Crystal-Melt Interface and Surface Tension on Czochralski Growth of Substrate Materials with K_{2}NiF_{4} Structure

100%

Berkowski M., Fink-Finowicki J., Gutowski M.

Acta Physica Polonica A

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1997

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vol. 92

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issue 1

197-200

EN

Crystal-melt interface was investigated during Czochralski growth of SrLaGaO_{4} and SrLaAlO_{4} crystals on ⟨001⟩ oriented seeds. Relations between the ratio of the core diameter, grown on (001) plane, and the crystal diameter, as a function of seed rotation speed were determined. It was confirmed that it is possible to control the core diameter during the crystal growth. A new module was introduced into the crystal growth controlling program. It enables to estimate the surface tension coefficient between crystal and melt at the beginning of crystallization. This value is then used to compute proper corrections for automatic weighting system.

8

SrLaGaO_{4}-SrLaAlO_{4} Solid Solutions - Substrate Materials with Tuneable Lattice Parameter for Various HTSC Compounds

100%

Berkowski M., Fink-Finowicki J., Mojaiskaia E.

Acta Physica Polonica A

|

1997

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vol. 92

|

issue 1

182-186

EN

The increase in Τ_{c} for high temperature superconductors can be realized, among others, by appropriate substrate/film combinations. SrLaGaO_{4}-SrLaΑlO_{4} solid solutions were grown by the Czochralski method. The already achieved results allow to obtain single crystals of SrLaΑl_{1-x}Ga_{x}O_{4} with lattice constant a in the range from 0.3754 to 0.3775 nm, and SrLaGa_{1-x}Αl_{x}O_{4} crystals with lattice constant a in the range from 0.3843 to 0.3826 nm. Electron-probe microanalysis along obtained single crystals was used for determination of segregation coefficient between aluminum and gallium ions.

9

Effect of Annealing and Irradiation on the Optical Properties of Oxide Crystals

100%

Kaczmarek S., Berkowski M., Moroz Z., Warchoł S.

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vol. 96

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issue 3-4

417-427

EN

We described results of the effect of annealing and irradiation treatments on the optical properties of Y_{3}Al_{5}O_{12}, YAlO_{3}, SrLaGa_{3}O_{7}, LiNbO_{3}, Gd_{3}Ga_{5}O_{12}, LaGaO_{3}, ZnSe, and LiF single crystals. Changes in absorption and luminescence are presented. Recharging processes of uncontrolled impurities (e.g. Fe^{3+}, Fe^{2+}, and Mn^{2+}), and active ions (e.g. Nd^{3+}, Dy^{3+}, Cr^{4+}, Cr^{3+}, and Ce^{3+}), as well as types of color centers produced in the crystals after a particular irradiation or annealing treatment are presented.

10

Negative Magnetoresistance in the Variable-Range-Hopping Transport of Strongly Underdoped La_{2-x}Sr_xCuO_4

100%

Malinowski A., Cieplak M., Berkowski M., Guha S.

Acta Physica Polonica A

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2006

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vol. 109

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issue 4-5

611-615

EN

The in-plane transport of strongly underdoped La_{2-x}Sr_xCuO_4 films was examined in the magnetic fields up to 14 T and in temperatures down to 1.6 K. While at high temperatures the samples display metallic-like resistivity, the low-T transport is governed by variable-range-hopping mechanism. Careful analysis shows that the temperature dependence of pre-exponential factor in Mott's variable-range-hopping law may not be neglected and that the density of states at the Fermi level can be effectively expressed as g(E-E_F)=N_0 (E-E_F)^p, with a small exponent p of the order of 0.1. In the magnetic field parallel to CuO_2 planes one of the variable-range-hopping parameter,ρ_0, increases by about 20-25%, while the other one, T_0, decreases by about 10-15%, resulting in the decrease in total resistivity. This effect may be related to the decrease of the tunneling barrier between different antiferromagnetic clusters in the presence of magnetic field.

11

Effect of Manganese Concentration on Thermoluminescent Properties of YAlO_{3}:Mn Crystals

100%

Zhydachevskii Y., Suchocki A., Berkowski M., Warchol S.

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issue 1

177-180

EN

This work is devoted to experimental study of the effect of manganese concentration on thermoluminescent properties of YAlO_{3}:Mn crystals grown by the Czochralski method. A new type of emitting centers beside of Mn^{4+} and Mn^{2+} ions was revealed at low concentration of manganese ions in the crystal. These centers are responsible for the high-temperature thermoluminescent peak at 570 K. A potential of this thermoluminescent peak for thermoluminescence dosimetry application is discussed.

12

Impact of Strain on the Superconducting Properties of Strongly Underdoped La_{2-x}Sr_xCuO_4 Thin Films

88%

Zaytseva I., Cieplak M., Paszkowicz W., Abal'oshev A., Berkowski M.

Acta Physica Polonica A

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2012

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vol. 121

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issue 4

858-865

EN

Using pulsed laser deposition we have grown films of La_{2-x}Sr_xCuO_4 with x in close vicinity of the superconductor-insulator transition, x=0.051 and x=0.048, on SrLaAlO_4 substrates, and of different thickness d (from 25 nm to 250 nm). The X-ray diffraction shows that for each d the films grow with variable degree of compressive in-plane strain, with the largest strain achieved in thinnest films. The resistivity measurements show strong enhancement of superconductivity with increasing strain, so that the onset of superconductivity at temperature as high as 27 K is observed. With increasing strain the character of resistivity changes from the insulating to metallic.

13

Magnetic Properties of La₃Ga_{5.5}Ta_{0.5}O₁₄ Single Crystals Doped with Sm³⁺ and Er³⁺ Ions

88%

Kaczmarek S., Leniec G., Berkowski M., Kazan S., Acikgoz M.

Acta Physica Polonica A

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2017

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vol. 131

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issue 3

366-369

EN

Electron paramagnetic resonance and magnetic susceptibility measurements were performed for two La₃Ga_{5.5}Ta_{0.5}O₁₄ single crystals doped with 1.96 at.% of Sm³⁺ ions and 3.8 at.% of Er³⁺ ions. Two magnetically inequivalent sites were found to be responsible for the electron paramagnetic resonance spectra of Sm³⁺ ions. Both sites reveal a low (at least C₂) symmetry with g_{x}~0.46, g_{y}~0.46 and g_{z}~0.52. The symmetry of isolated erbium ions is higher than C₂. From electron paramagnetic resonance and magnetic susceptibility experiments it results that the ground state of Er³⁺ ions is Γ⁶ or Γ⁷. Below 51 K electronic transitions within Γ⁶ doublets take place. Between 51 and 60 K, Γ⁶ to Γ⁷ transitions dominate, while above 60 K mainly transitions within Γ⁷ doublet are active.

14

Growth and Optical Properties of Li_2B_4O_7 Single Crystals Pure and Doped with Yb, Co and Mn Ions for Nonlinear Applications

88%

Podgórska D., Kaczmarek S., Drozdowski W., Berkowski M., Worsztynowicz A.

Acta Physica Polonica A

|

2005

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vol. 107

|

issue 3

507-518

EN

The paper reports on the growth conditions of Li_2B_4O_7 single crystals in both pure and Yb, Co, Mn doped systems. The crystals were grown by the Czochralski method using an intentional concentration of the above-mentioned ions at a level of 0.5 mol.%. The pure and Mn-doped crystals were found to be highly transparent and clear. The crystals doped with Yb_2O_3 had a lot of precipitations making them opaque. The Co-doped crystals were purple-blue in colour and highly transparent. The growth of Yb and Co doped Li_2B_4O_7 crystals was reported for the first time in this paper. Absorption was measured in the range of 200 to 3200 nm, moreover analysis of changes in the absorption spectrum ofγ-irradiated pure and doped Li_2B_4O_7 crystals was performed. Some thermoluminescence properties were measured, e.g. energies and lifetimes of the traps of different charge carriers occurring in the crystals at low temperatures.

15

Influence of Iron Substitutions on the Transport Properties of FeTe_{0.65}Se_{0.35} Single Crystals

88%

Bezusyy V., Gawryluk D., Malinowski A., Berkowski M., Cieplak M.

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vol. 126

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issue 4a

A-76-A-80

EN

We study the ab-plane resistivity and Hall effect in the single crystals of Fe_{1-y}M_yTe_{0.65}Se_{0.35}, where M = Co or Ni (0 ≤ y ≤ 0.21). In case of each dopant two types of crystals, with different crystalline quality, are prepared by Bridgman's method using different cooling rates, fast or slow. The impurities suppress the superconducting transition temperature, T_c, with different rates. T_c reaches zero at markedly different impurity content: only 3 at.% of Ni, and about 14 at.% of Co. In addition, the suppression is somewhat dependent on the crystal cooling rate. The resistivity at the onset of superconductivity rises only weakly with the Co doping, while it increases 10 times faster for Ni. The Hall coefficient R_{H} is positive for Co doping indicating that hole carriers dominate the transport. For Ni R_{H} changes sign into negative at low temperatures for crystals with the Ni content exceeding 6 at.%. The implications of these results are discussed.

16

Metal-Insulator Transition in Zinc-Doped LaSrCuO

88%

Malinowski A., Cieplak M., Berkowski M., Plesiewicz W., Skośkiewicz T.

Acta Physica Polonica A

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2006

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vol. 109

|

issue 4-5

617-621

EN

The magnetotransport in the vicinity of the metal-insulator transition in La_{1.85}Sr_{0.15}Cu_xZn_{1-x}O_4 is studied in the mK temperature range. Both longitudinal and transverse magnetoresistance are negative indicating the importance of spin effects. The magnitude of transverse magnetoresistance is larger than the magnitude of longitudinal magnetoresistance, indicating the absence of positive orbital magnetoresistance, in sharp contrast to strongly underdoped La_{2-x}Sr_xCuO_4. Both transverse and longitudinal magnetoresistance are proportional to the relative change of zero-field conductivity. This suggests that low-temperature localization of carriers may originate in the spin-disorder scattering on the spin droplets around Zn-impurities.

17

Solid Solutions of Oxide Crystals as Substrates for Epitaxial Layer Depositions

76%

Berkowski M., Fink-Finowicki J., Aleksijko R., Diduszko R., Byszewski P., Kikalejshvili-Domukhovska R.

Acta Physica Polonica A

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2006

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vol. 109

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issue 4-5

457-463

EN

We present results of investigation on growth of solid solution crystals with perovskites and K_2NiF_4 structures used as substrates for epitaxy. Perovskite single crystals with no twins and crystals with K_2NiF_4 structure with the lattice parameter in the range 3.876-3.819Å and 3.754 to 3.688Å, respectively, can be grown. Here preliminary results on investigation on growth of other solid solution crystals with the lattice constant from 3.946 to 3.688Å are also presented thus covering the whole interesting range for depositing oxide materials. These crystals can be grown by the Czochralski method that secures their high structural quality. Discussed crystals are resistant to reaction with the deposited oxide layers.

18

Effect of Lutetium Co-Doping on the Main Dosimetric Peak of YAP:Mn²⁺ Thermoluminescent Detectors

76%

Zhydachevskyy Y., Glowacki M., Martynyuk N., Ubizskii S., Berkowski M., Suchocki A.

Acta Physica Polonica A

|

2018

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vol. 133

|

issue 4

973-976

EN

An effect of lutetium co-doping on photoluminescent and thermoluminescent properties of the Mn²⁺-doped (Lu-Y)AP crystals (with Lu content from 0 to 20% with respect to Y) grown by the Czochralski technique has been studied. It was found that the maximum of the thermoluminescent peak at 200°C is shifted towards higher temperatures at Lu content more than 5%. At the same time the position of the second thermoluminescent peak near 350°C remains unchanged. The observed changes in the thermoluminescent peak position are discussed in terms of the point defects of the material.

19

Strain Relaxation in Thin Films of La_{1.85}Sr_{0.15}CuO_4 Grown by Pulsed Laser Deposition

76%

Zaytseva I., Cieplak M., Abal'oshev A., Berkowski M., Domukhovski V., Paszkowicz W., Shalimov A.

Acta Physica Polonica A

|

2007

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vol. 111

|

issue 1

185-188

EN

X-ray diffraction, resistivity, and susceptibility measurements are used to examine the effects of film thickness d (from 17 to 250 nm) on the structural and superconducting properties of La_{1.85}Sr_{0.15}CuO_4 films grown by pulsed laser deposition on SrLaAlO_4 substrates. For each d the film sgrow with a variable strain, ranging from a large compressive strain in the thinnest films to a negligible or tensile strain in thick films. Our results indicate that the tensile strain is not caused by the off-stoichiometric layer at the substrate-film interface. Instead, it may be caused by the extreme oxygen deficiency in some of the films.

20

Effect of the In-Plane Epitaxial Mismatch between the Substrate and the Film on the Properties of YBa_2Cu_3O_{7-δ} Films

76%

Abal'osheva I., Cieplak M., Adamus Z., Berkowski M., Domukhovski V., Aleszkiewicz M.

Acta Physica Polonica A

|

2006

|

vol. 109

|

issue 4-5

549-554

EN

We study the effect of the in-plane epitaxial mismatch between the substrate and the film on the crystallographic structure and the transport properties of YBa_2Cu_3O_{7-δ} superconducting films of thicknesses ranging between 600 and 3000Å. The films are grown by pulsed laser deposition on the new type of single-crystalline substrates prepared by Czochralski method, with the chemical formula (SrAl_{0.5}Ta_{0.5}O_3)_{0.7}(CaAl_{0.5}Ta_{0.5}O_3)_{0 .1}(LaAlO_3)_{0.2}. We find that superconducting properties of the samples are excellent, and generally they improve with increasing of the film thickness as a result of improved structural ordering. We also investigate the influence of the film thickness on the behavior of the critical current densities.

Refine search results

Influence of Temperature on Refractive Indices of BaLaGa_{3}O_{7} and SrLaGa_{3}O_{7}

Material Parameters Characterizing the Performance of Flashlamp Pumped BaLa_{1-x}Nd_{x}Ga_{3}O_{7} Laser

Doping Effects of Co, Ni, and Cu in FeTe_{0.65}Se_{0.35} Single Crystals

Identification of the Domain Walls Configuration in the Ferroelastic Nanosize Material La_{0.95}Sr_{0.05}Ga_{0.9}Mg_{0.1}O_{3-x}

High Quality (100) and (001) Oriented Substrates Prepared from Czochralski Grown SrLaGaO_{4} and SrLaAlO_{4} Single Crystals

Defects in Detwinned LaGaO_{3} Substrates

Role of Crystal-Melt Interface and Surface Tension on Czochralski Growth of Substrate Materials with K_{2}NiF_{4} Structure

SrLaGaO_{4}-SrLaAlO_{4} Solid Solutions - Substrate Materials with Tuneable Lattice Parameter for Various HTSC Compounds

Effect of Annealing and Irradiation on the Optical Properties of Oxide Crystals

Negative Magnetoresistance in the Variable-Range-Hopping Transport of Strongly Underdoped La_{2-x}Sr_xCuO_4

Effect of Manganese Concentration on Thermoluminescent Properties of YAlO_{3}:Mn Crystals

Impact of Strain on the Superconducting Properties of Strongly Underdoped La_{2-x}Sr_xCuO_4 Thin Films

Magnetic Properties of La₃Ga_{5.5}Ta_{0.5}O₁₄ Single Crystals Doped with Sm³⁺ and Er³⁺ Ions

Growth and Optical Properties of Li_2B_4O_7 Single Crystals Pure and Doped with Yb, Co and Mn Ions for Nonlinear Applications

Influence of Iron Substitutions on the Transport Properties of FeTe_{0.65}Se_{0.35} Single Crystals

Metal-Insulator Transition in Zinc-Doped LaSrCuO

Solid Solutions of Oxide Crystals as Substrates for Epitaxial Layer Depositions

Effect of Lutetium Co-Doping on the Main Dosimetric Peak of YAP:Mn²⁺ Thermoluminescent Detectors

Strain Relaxation in Thin Films of La_{1.85}Sr_{0.15}CuO_4 Grown by Pulsed Laser Deposition

Effect of the In-Plane Epitaxial Mismatch between the Substrate and the Film on the Properties of YBa_2Cu_3O_{7-δ} Films