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Diffused phase transition of polycrystalline (Ba0.80Sr0.20)TiO3

Kajtoch C., Bąk W., Gabryś M., Handke B., Starzyk F.

Archives of Materials Science and Engineering

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2009

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Vol. 39, nr 2

88-91

EN

Purpose: The purpose of this work was to determinate the influence of the 20% Sr substitutions (in sublattice A) on changes of the character of phase transition (PT) in comparison with pure barium titanate BaTiO3 (BT). Design/methodology/approach: Polycrystalline samples of (Ba0.80Sr0.20)TiO3 (BS20T) were prepared by calcinations method at temperature 1620 K. X-ray measurements were executed from 10 deg to 120 deg with the 0.008 deg step. Images of the morphology of the samples were taken by means of electron microscope Philips SEM 525M at room temperature. Dielectric measurements were performed with application of Quatro Cryosystem 4.0 Agilent Precision LRC meter HP4824A equipped with WinDETA 5.62 software Novocontrol. Measurements were taken under cooling with 2 K/min speed. Measuring electric field frequency was from the range 20 Hz - 1 MHz. Findings: The difference between the value of temperature of structural transition (cubic-tetragonal) equal 310K and the temperature Tm (the temperature of maximum of real part electric permittivity) equal 340 K was affirmed. It was affirmed, that 20% substitution of Sr ions changed the type of phase transition. The transition was strongly diffused (DPT). The polar character of this solid solution was also observed in a broad temperature range (in the paraelectric phase too). It is connected with the occurrence of polar regions (clusters). Research limitations/implications: The results can be used to describe changes of PT in the DPT solid solutions with ferroactive substitutions in sublattice A. Originality/value: Value of this work relies on the experimental examination of the dielectric properties of (Ba0.80Sr0.20)TiO3 (BS20T) solid solution. The temperature of the DPT was calculated. The low value of phase angle is connected with the existence of the polar regions.

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Structural and dielectric properties of polycrystalline (Ba0.9Sr0.1)TiO3

Kajtoch C., Gabryś M., Tejchman W., Handke B.

Archives of Materials Science and Engineering

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2008

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Vol. 33, nr 2

89-92

EN

Purpose: This work is aimed to determination of the influence of Sr - ferroactive substitution on physical properties and character of phase transitions (PT) in barium titanate BaTiO3 (BT). Design/methodology/approach: Polycrystalline samples of BST-10 were prepared by means of calcination method at the 1600 K. Roentgenogram of BST-10 was made within the angles from 10 deg to 110 deg with the 0.008 deg step. Images of the morphology of the samples were taken by means of electron microscope Philips SEM 525M at room temperature. Dielectric measurements were performed with application of Quatro Cryosystem 4.0 and Agilent Precision LCR meter HP4284A equipped with WinDETA 5.62 software Novocontrol. Measurement were taken under cooling with 2 K/min speed. Measuring electric field frequency was from the range 20 Hz-1 MHz. Findings: Dielectric spectroscopy in the frequency domain was applied to measure complex dielectric permittivity and other dielectric functions of ferroelectric polycrystalline (Ba0.9Sr0.1)TiO3 (BST-10). It was established that 10% substitution of Sr in BST-10 solid solution did not change the character of the phase transitions. The temperatures of the phase transitions were correlated with low temperature of PT in SrTiO3 (ST). Similar properties of Ba and Sr ions were taken into consideration. The dipolar character of solid solution was also observed in paraelectric phase. Practical implications: Obtained results can be used to model the effects of ferroactive and nonferroactive substitutions in the A and B subnets of perovskite ferroelectrics. Originality/value: An attempt to correlate low phase angle values observed in the paraelectric phase of BTS-10 with high dielectric permittivity and the occurrence of polar regions.

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Wpływ grubości na optyczne, strukturalne i elektryczne własności cienkich warstw CdS otrzymywanych metodą CBD

Schabowska-Osiowska E., Pisarkiewicz T., Kenig T., Handke B., Porada Z.

Elektronika : konstrukcje, technologie, zastosowania

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2005

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Vol. 46, nr 2-3

60-61

PL

Cienkie warstwy siarczku kadmu o różnych grubościach nakładane były w kąpieli chemicznej (CBD). Warstwy wykazywały strukturę regularną. Ze wzrostem grubości przepuszczalność warstw w badanym zakresie widma silnie malała, zwiększała się natomiast wielkość ziarn CdS, występowała poprawa ciągłości warstwy i zmniejszały się nierówności powierzchni.

EN

Cadmium sulphide thin films with various thickness were deposited using CBD method. The films have shown a cubric structure. With the increase of the film thickness the transmission in examined spectral range strongly decreased, while CdS grain size increased, the continuity of the film improved and the roughness of the surface decreased.