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  1. 12 Archives of Materials Science and Engineering
  2. 8 Archives of Metallurgy and Materials
  3. 2 Ceramic Materials
  4. 2 Inżynieria Materiałowa
  5. 2 Materials Engineering
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  1. 39 Bąk W.
  2. 16 Kajtoch C.
  3. 10 Starzyk F.
  4. 9 Garbarz-Glos B.
  5. 8 Czekaj D.
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  1. 4 2020
  2. 1 2017
  3. 4 2016
  4. 1 2014
  5. 2 2013
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1
Content available X-Ray Diffraction Study of Bismuth Layer-Structured Multiferroic Ceramics
Lisińska-Czekaj A., Czekaj D., Garbarz-Glos B., Bąk W., Kuźniarska-Biernacka I.
Archives of Metallurgy and Materials
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2020
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Vol. 65, iss. 2
811--815
EN
Goal of the present research was to apply a solid state reaction route to fabricate bismuth layer-structured multiferroic ceramics described with the formula Bi5FeTi3O15 and reveal the influence of processing conditions on its crystal structure and phase composition. Simple oxide powders Bi2O3, TiO2 and Fe2O3 were used to fabricate Aurivillius-type bismuth layer-structured ferroelectrics. Pressureless sintering in ambient air was employed and the sintering temperature was TS = 900°C, TS = 1000°C and TS = 1040°C. The phase composition as well as crystal structure of ceramics sintered at various processing conditions was examined with powder X-ray diffraction method at room temperature. The Rietveld refinement method was applied for analysis of X-ray diffraction data. It was found that ceramics adopted orthorhombic structure Cmc21. The unit cell parameters of bismuth layer-structured multiferroic ceramics increased slightly with an increase in sintering temperature.
2
Content available The Application of the Mechanochemical Synthesis for the Preparation of Advanced Ceramics Based on Barium Titanate
Garbarz-Glos B., Bąk W., Budziak A., Dulian P., Lisińska-Czekaj A., Czekaj D.
Archives of Metallurgy and Materials
|
2020
|
Vol. 65, iss. 4
1391--1396
EN
In the present study, the lead-free BaTi1-x Zrx O3 (for x = 0, 0.05 and 0.15) ceramics were prepared by High-Energy Ball Milling and heat treatments. The performed X-ray, SEM and EDS measurements confirmed high purity, good quality and the expected quantitative composition of the obtained samples. The study of dielectric properties was performed by means of broadband dielectric spectroscopy at the frequency ranging from 0.1 Hz to 10 MHz. The obtained measurement data, analyzed in accordance with the Arrhenius formalism demonstrated the presence of relaxation type dielectric mechanisms. The impedance answer of studied ceramic materials indicated the presence of two relaxation processes: one with a dominant resistive component and the other with a small capacitive component. The observed dielectric relaxation process is temperature dependent and has a “non-Debye” character.
3
Content available Modelling of Dielectric Properties of BiNbO4-Based Microwave Ceramics
Czekaj D., Lisińska-Czekaj A., Garbarz-Glos B., Bąk W.
Archives of Metallurgy and Materials
|
2020
|
Vol. 65, iss. 3
1177--1181
EN
In the present paper results of the studies devoted to computer simulations of dielectric response of electroceramics in a frequency domain as well as analysis of the experimental data are given. As an object of investigations BiNbO4-based microwave ceramics was taken. Simulations of the hypothetical impedance response of the ceramic system were performed under assumption of the brick-layer model. A strategy for analysis and modelling of the impedance data for microwave electroceramics was discussed. On the base of the discussed strategy modelling of the dielectric response of BiNbO4 ceramics was performed with the electric equivalent circuit method. The Voigt’s and Maxwell’s circuits were taken as electric models. Parameters of the electric components of the circuits were determined and related to parameters of the ceramic object under study. It was found that fitting quality was good and changed within the range χ2 = 6.78 × 10-4 – 6.77 × 10-5 depending on the model.
4
Content available Alternative, Direct Synthesis Method of the Ceramic Solid Solutions Based on BaTiO3 Through a High Energy Ball Milling
Bąk W., Dulian P., Garbarz-Glos B., Czekaj D., Lisińska-Czekaj A.
Archives of Metallurgy and Materials
|
2020
|
Vol. 65, iss. 2
805--810
EN
Polycrystalline samples BaTiO3 and the solid solutions Ba0.9 Sr0.1 TiO3, 0.9 Sr0.1 Ti0.9 Sn0.1 O3, Ba0.9 Sr0.1 Ti0.8 Sn0.2 O3 were obtained by means of a mechanochemical treatment based on the high-energy ball milling technique and next a high temperature solid state reaction method. The influence of synthesis condition on microstructural, dielectric and ferroelectric properties of obtained solid solutions were investigated. The structure and morphology of the investigated samples were characterized by an X-ray diffraction (XRD) and scanning electron microscopy (SEM). The characterization of electrical properties of the ceramics within the temperature range from –130°C to 250°C were performed by means of a dielectric spectroscopy method at the frequency ranging from 0.1 Hz to10 MHz. The diffusion of the paraelectric – ferroelectric phase transition and dielectric relaxation for ceramic samples are described.
5
Content available remote Właściwości dielektryczne materiałów ceramicznych otrzymanych na bazie TiO2
Bąk W., Dulian P., Garbarz-Glos B., Żukowski W., Kajtoch C.
Materiały Ceramiczne
|
2017
|
T. 69, nr 4
370--373
PL
Domieszkowane jonami donorowymi (Nb5+, V5+) i akceptorowymi (In3+) próbki TiO2 (rutyl) otrzymano konwencjonalną metodą reakcji w stanie stałym. Strukturę badanych próbek scharakteryzowano przy pomocy analizy XRD. Właściwości dielektryczne próbek zbadano w zakresie temperatur od -100 stopni C do 200 stopni C przy pomocy szerokopasmowej spektroskopii dielektrycznej w zakresie częstotliwości pola elektrycznego od 0,1 Hz do 10 MHz. Analiza zależności temperaturowych przenikalności dielektrycznej, przewodnictwa i modułu elektrycznego dostarczyła nowych informacji na temat właściwości fizycznych badanych materiałów ceramicznych.
EN
Doped with donor (Nb5+, V5+) and acceptor (In3+) ions TiO2 (rutile) was obtained by the conventional solid state reaction method. The structure of the investigated samples was characterised by X-ray diffraction (XRD). The dielectric properties of the samples at the temperature ranging from -100 C to 200 C was studied by means of the broadband dielectric spectroscopy method at the frequency ranging from 0,1 Hz to 10 MHz. An analysis of the temperature dependences of dielectric permittivity, electric modulus and conductivity provided new details about the physical properties of the ceramic samples.
6
Content available Low temperature broad band dielectric spectroscopy of multiferroic Bi6Fe2Ti3O18 ceramics
Lisińska-Czekaj A., Rerak M., Czekaj D., Lubina M., Garbarz-Glos B., Bąk W.
Archives of Metallurgy and Materials
|
2016
|
Vol. 61, iss. 3
1447--1452
EN
In the present research the tool of broadband dielectric spectroscopy was utilized to characterize dielectric behavior of Bi6Fe2Ti3O18is (BFTO) Aurivillius-type multiferroic ceramics. Dielectric response of BFTO ceramics was studied in the frequency domain (Δν=0.1Hz - 10MHz) within the temperature range ΔΤ=-100°C - 200°C. The Kramers-Kronig data validation test was employed to validate the impedance data measurements and it was found that the measured impedance data exhibited good quality justifying further analysis. The residuals were found to be less than 1%, whereas the "chi-square" parameter was within the range χ2~-10-7 -10-5. Experimental data were analyzed using the circle fit of simple impedance arc plotted in the complex Z”-Z` plane (Nyquist plot). The total ac conductivity of the grain boundaries was thus revealed and the activation energy of ac conductivity for the grain boundaries was calculated. It was found that activation energy of ac conductivity of grain boundaries changes from ΕA=0.20eV to ΕA=0.55eV while temperature rises from Τ=-100°C up to Τ=200°C. On the base of maxima of the impedance semicircles (ωmτm=l) the relaxation phenomena were characterized in terms of the temperature dependence of relaxation times and relevant activation energy was calculated (ΕA=0.55eV).
7
Content available Influence of Sn and Pb Ions Substitutions on Dielectric Properties of Barium Titanate
Bąk W., Kajtoch C., Ptaszek S., Lisińska-Czekaj A., Czekaj D., Ziętek D., Glos T., Garbarz-Glos B.
Archives of Metallurgy and Materials
|
2016
|
Vol. 61, iss. 2A
905--908
EN
The results of the microstructural and dielectric measurements of (Ba1-xPbx)(Ti1-xSnx)O3 (BPTSx) (x = 0, 0.05, 0.10, 0.30) polycrystalline samples are presented. The samples were obtained by means of a high temperature synthesis and their expected stoichiometry was confirmed by energy dispersive spectroscopy (EDS) measurements. The dielectric properties of BPTSx were studied with the use of broadband dielectric spectroscopy. The measurements over a wide range of temperature (from 140 K to 600 K) and frequency (from 0.1 Hz to 10 MHz) were performed. The experimental results indicate an influence of Pb ions in a sublattice A and Sn ions in a sublattice B substitution on paraelectric - ferroelectric phase transition parameters. Diffused phase transitions from a paraelectric to ferroelectric state (for x = 0.10 and x = 0.30) were observed. From the electric modulus measurements in the frequency domain the relaxation times and the activation energy were determined.
8
Content available Influence of Processing Conditions on Crystal Structure of Bi6Fe2Ti3O18 Ceramics
Lisińska-Czekaj A., Lubina M., Czekaj D., Rerak M., Garbarz-Glos B., Bąk W.
Archives of Metallurgy and Materials
|
2016
|
Vol. 61, iss. 2A
881--886
EN
Aim of the present research was to apply a solid state reaction route to fabricate Aurivillius-type ceramics described with the formula Bi6Fe2Ti3O18 (BFTO) and reveal the influence of processing conditions on its crystal structure. Pressureless sintering in ambient air was employed and the sintering temperatures were 850 and 1080 °C. It was found that the fabricated BFTO ceramics were multiphase ones. They consisted of two Bim+1Fem-3Ti3O3m+3 phases, namely the phase with m=5 (i.e. the stoichiometric phase) and m=4 (i.e. the phase with a reduced number of layers in the slab). Detailed X-ray diffraction patterns analysis showed that both phases adopted the same orthorhombic structure described with Fmm2 (42) space group. The ratio of weight fractions of the constituent phases (m=5): (m=4) was ~30:70.
9
Content available Effect of Semiconductor Element Substitution on the Electric Properties of Barium Titanate Ceramics
Garbarz-Glos B., Lisińska-Czekaj A., Czekaj D., Bąk W.
Archives of Metallurgy and Materials
|
2016
|
Vol. 61, iss. 2A
887--890
EN
The investigated ceramics were prepared by a solid-state reaction from simple oxides and carbonates with the use of a mixed oxide method (MOM). The morphology of BaTi0.96Si0.04O3 (BTSi04) ceramics was characterised by means of a scanning electron microscopy (SEM). It was found that Si+4 ion substitution supported the grain growth process in BT-based ceramics. The EDS results confirmed the high purity and expected quantitative composition of the synthesized material. The dielectric properties of the ceramics were also determined within the temperature range (ΔT=130-500K). It was found that the substitution of Si+4 ions had a significant influence on temperature behavior of the real (ε’) and imaginary (ε”) parts of electric permittivity as well as the temperature dependence of a.c. conductivity. Temperature regions of PTCR effect (positive temperature coefficient of resistivity) were determined for BTSi04 ceramics in the vicinity of structural phase transitions typical for barium titanate. No distinct maximum indicating a low-temperature structural transition to a rhombohedral phase in BTSi04 was found. The activation energy of conductivity was determined from the Arrhenius plots. It was found that substitution of Si ions in amount of 4wt.% caused almost 50% decrease in an activation energy value.
10
Content available remote Dielectric properties of vanadium doped barium titanate synthesized via high-energy ball milling
Dulian P., Bąk W., Wieczorek-Ciurowa K., Kajtoch C.
Materials Science Poland
|
2014
|
Vol. 32, No. 2
257--263
EN
The study shows the advisability of using a mechanochemical synthesis method, based on a high-energy planetary ball milling, to a modification of barium titanate by a vanadium doping. This method improves useful properties of BaTi0:95V0:05O3 as a capacitor material. It has a high value of electric permittivity e' in the wide range of temperature and low dielectric losses e" as well as a low electrical conductivity.
11
Corrosivity of the intake manifold engine powered by fuel and superheated steam mixture
Bąk W., Sajkiewicz M., Fogt M., Bąkowski H.
Zeszyty Naukowe Instytutu Pojazdów / Politechnika Warszawska
|
2013
|
z. 4/95
5--10
EN
The main aim of this work was determine the corrosion resistance of the selected materials used in the produce of intake manifold of the combustion engine. Another aspect of the research was to carry out the preliminary test of the Diesel engine, powered by alternative fuels (water-fuel). The results allowed to inspire the great optimism due to the low level of technical elements used. The application of simple methods and equipment allowed to reduction of the fuel consumption. In this way, reduce the toxic emission. In other side we observed decrease hardness and resistance of wear.
PL
Celem pracy było określenie odporności na korozję wybranych materiałów wykorzystywanych do wytwarzania poszczególnych części silnika spalinowego. Drugim aspektem było przeprowadzenie wstępnych badań eksploatacyjnych silnika spalinowego o zapłonie samoczynnym, zasilanego paliwami alternatywnymi (woda, alkohol). Wyniki badań napawają dużym optymizmem z uwagi na niski poziom techniczny użytych elementów, chociaż z drugiej strony zmniejszenie twardości spowoduje spadek odporności na zużycie.
12
Content available remote Controlled mechanochemical synthesis and properties of a selected perovskite-type electroceramics
Dulian P., Bąk W., Wieczorek-Ciurowa K., Kajtoch C.
Materials Science Poland
|
2013
|
Vol. 31, No. 3
462--470
EN
This paper presents mechanochemical synthesis as an alternative to the traditional high-temperature synthesis of advanced electrotechnical ceramic materials with a perovskite-type structure. The reaction conditions for high-energy ball milling, e.g. reaction environment, energy of milling and additives to BaTiO3 such as metallic iron or zirconia from the exfoliation of the milling vessel and grinding media are discussed.
13
Content available remote Możliwości wytwarzania zaawansowanej elektroceramiki na bazie tytanianu baru metodą mechanochemiczną
Dulian P., Wieczorek-Ciurowa K., Bąk W., Kajtoch C.
Czasopismo Techniczne. Mechanika
|
2012
|
R. 109, z. 9-M
57--65
PL
W artykule przedstawiono mechanochemiczną syntezę jako alternatywną w stosunku do tradycyjnych, wysokotemperaturowych metod wytwarzania zaawansowanych ceramicznych materiałów elektrotechnicznych o strukturze perowskitu. Wykazano, iż mechanochemiczna synteza jest również skuteczną metodą modyfikacji właściwości BaTiO3 poprzez substytucyjne podstawienie obcych jonów. Określono również właściwości otrzymanych roztworów stałych.
EN
This paper considers mechanochemical synthesis as an alternative to the conventional, hightemperature method of manufacturing advanced electrical ceramic materials with a perovskite structure. Mechanochemical synthesis is also presented as an effective method for modifying the properties of BaTiO3 by substitution of foreign ions, and the effect of such substitution on the properties of the solid solutions is also discussed.
14
Content available remote Modyfikacja właściwości elektrycznych CaTiO₃ metodą wysokoenergetycznego mielenia jako przykład zielonej chemii
Wieczorek-Ciurowa K., Dulian P., Bąk W., Kajtoch C.
Przemysł Chemiczny
|
2011
|
T. 90, nr 7
1400-1403
15
Content available remote Diffuse phase transition of polycrystalline (Ba0.9Sr0.1)TiO3
Kajtoch C., Gabryś M., Bąk W., Starzyk F.
Materiały Ceramiczne
|
2010
|
T. 62, nr 3
400-402
PL
Przedstawiono wyniki pomiarów rentgenowskich (XRD) i dielektrycznych dla polikrystalicznego (Ba0,9Sr0,1)TiO3 (BS10T). Wyniki pomiarów pokazują obecność, w temperaturze 373 K, rozmytej przemiany fazowej (DPT) pomiędzy strukturą regularną i tetragonalną. Temperatura maksimum rzeczywistej składowej przenikalności elektrycznej (ε') nie zależy od częstotliwości elektrycznego pola pomiarowego. Kąt fazowy, Φ ≈-90°, między prądem a przyłożonym napięciem elektrycznym sugeruje występowanie obszarów polarnych (klasterów) poniżej 400 K, tj. w obszarze temperaturowym DPT i w fazie paraelektrycznej.
EN
The results of X-ray diffraction (XRD) and dielectric measurements performed for polycrystalline (Ba0.9Sr0.1)TiO3 (BS10T) are presented. Data from these measurements show a presence of diffuse phase transition (DPT) between cubic and tetragonal structure at a temperature of 373 K. The temperature Tm of the maximum of real part permittivity (ε') does not depend on the frequency of the applied electric field. A phase angle, Φ ≈ -90° between current and applied voltage, suggests an occurrence of polar regions (clusters) below 400 K i.e. in the DPT temperature range of and in the paraelectric phase.
16
Synergiczne układy warstwowe: azotek krzemu - warstwa przejściowa na multikrystalicznym krzemie
Bąk W., Jurzecka-Szymacha M., Jonas S., Tkacz-Śmiech K.
Inżynieria Materiałowa
|
2010
|
Vol. 31, nr 4
864-868
PL
Sprawność ogniw fotowoltaicznych opartych o multikrystaliczny krzem może być skutecznie poprawiona przez stosowanie warstw a-SiNx:H. War- stwy takie mają dobre właściwości antyrefleksyjne, a zawarty w nich wodór bierze udział w pasywacji defektów podłoża. W pracy zaprezentowano wyniki badań warstwowych układów kompozytowych, w których pomiędzy podłożem i właściwą warstwą azotku krzemu zastosowano warstwę przejściową, wytworzoną w plazmie NH3 lub warstwę a-Si:H. Warstwy osadzono na multikrystalicznych podłożach krzemowych (mc- Si, BAYSIX) z zastosowaniem metody RFCVD. Część próbek (z warstwą) dodatkowo wygrzano w temperaturze 800°C. Takie postępowanie zapewnia warunki odpowiednie dla dyfuzji wodoru z warstwy do podłoża, poprawiając tym samym efekty pasywacji. W ocenie pasywacji defektów podłoża wykorzystano wyniki z pomiarów temperaturowej zależności przewodnictwa elektrycznego próbek z warstwami, przed i po wygrzewaniu.
EN
An efficiency of solar cells based on multicrystalline silicon may be effectively improved with application of a-SiNx:H layers. They have good antireflective properties and take part in defect passivation of the substrate. It is shown, in this work, that good results may be expected when composed layer systems are used. We propose application of a transition layer between the substrate and the antireflective a-SiNx:H. This can be either an a-Si:H layer or a layer formed in NH3 plasma. The layers studied in this work were deposited on multicrystalline silicon (mc-Si, BAYSIX) with application of RFCVD. Some of the samples were additionally heated at 800°C to enhance the hydrogen diffusion from the layer to the substrate. Such treatment improves defect passivation. An evaluation of defect passivation was based on the results of measurements of temperature dependence of electrical conductivity performed for the samples with various layers, both before and after heating.
17
Dielectric properties of polycrystalline Ba0.36Na0.64Ti0.36Nb0.64O3
Bąk W.
Inżynieria Materiałowa
|
2010
|
Vol. 31, nr 6
1415-1417
EN
Polycrystalline samples of Ba0,36Na0,64Ti0,36Nb0,64O3 (BNTN64) solid solution were obtained with conventional method and subjected to dielectric properties studies. The measurements were made with application of dielectric spectroscopy technique at the frequencies ranging from 20 Hz to 1 MHz and the temperature above 123 K and below 473 K. The temperature and frequency dependencies of real (??) and imaginary (??) parts of the dielectric permittivity confirm a presence of ferroelectric diffuse phase transition in BNTN64. The parameters describing the phase transition and occurring in the Curie-Weiss law were calculated. It has been also shown that thermal activation energy of AC electric conductivity (at 20 Hz) assumes a value typical for semiconductors.
PL
Polikrystaliczne próbki roztworu stałego Ba0,36Na0,64Ti0,36Nb0,64O3 (BNTN64) otrzymano metodą kalcynacji/konwencjonalną. Badania właściwości dielektrycznych wykonano metodą spektroskopii dielektrycznej w zakresie temperatury od 153 K do 473 K oraz w zakresie częstotliwości 20 Hz÷1 MHz. Analiza temperaturowych i częstotliwościowych zależności rzeczywistej (??) i urojonej (??) części przenikalności dielektrycznej wskazuje na rozmytą przemianę fazową. Parametry przejścia fazowego materiału opisano za pomocą uogólnionego prawa Curie-Weissa, uwzględniającego stopień rozmycia przemiany. Wartość cieplnej energii aktywacji przewodnictwa przemiennoprądowego (dla 20 Hz) jest typowa dla półprzewodników.
18
Content available remote Study of the relaxor behaviour in Ba0.68Na0.32Ti0.68Nb0.32O3 ceramic
Bąk W.
Journal of Achievements in Materials and Manufacturing Engineering
|
2009
|
Vol. 37, nr 1
24-27
EN
Purpose: The purpose of this work was to synthesize a new ceramic solid solution Ba0.68Na0.32Ti0.68Nb0.32O3 (BNTN32), as well as to measure and analyse its dielectric properties within the temperature range 123 K-473 K, where dielectrically active phase transition was supposed to occur. Design/methodology/approach: The new ceramic composition was prepared by means of conventional method. Dependence of phase transition features on temperature and frequency of measuring field were measured using dielectric spectroscopy method within the frequency range from 20 Hz to 1 MHz. Findings: The electric susceptibility along with temperature decrease generally rises up and has transient dispersion vanishing at about 230 K. At higher and low temperatures, frequency dependence of dispersion differs in character: at temperatures at ~400 K, low frequency values dominate. Dielectric energy losses are very high at ~high temperature, they decline down while temperature decrease, and at about 200 K range its frequency dependence is reversed and less scattered with maximum at ~150 K. The whole transition of ferroelectric - paraelectric (FE - PE) type can be described by means of Curie-Weiss law and it gets diffused character. Research limitations/implications: For modelling purposes the structure parameters of BNTN32 have to be measured by X-ray diffraction in order to establish the dielectric/structural activities of transitions taking place within used the temperature range. Additionally, dielectric measurements within broader frequency range up to 1.8 GHz will be performed. Originality/value: The new type of ceramic material was prepared with interesting dielectric properties. Dispersion reverse of energy losses activated thermally and low frequency memory of barium titanate (BT) transition effect visible at ~400 K is to be a subject of modelling further work.
19
Content available remote The dielectric behaviour of polycrystalline Ba0.96Na0.04Ti0.96Nb0.04O3 solid solution
Bąk W., Gabryś M., Kajtoch C., Tejchman W., Starzyk F.
Archives of Materials Science and Engineering
|
2009
|
Vol. 40, nr 1
13-16
EN
Purpose: The purpose of this work was to measure and investigate dielectric properties of new material, polycrystalline solid solution Ba0.96Na0.04Ti0.96Nb0.04O3 (BNTN4) within the temperature range 153 K-473 K. Design/methodology/approach: The dielectric spectroscopy method has been applied to measure dielectric and electric parameters within the frequencies from 20 Hz to 1 MHz. Findings: The dielectric permittivity (&epsilon') dependence on temperature (T) within the range of 473 K-225 K consist of two components: the reversly proportional one and the second one in the form of small local, transient peak at about 400 K. The global maximum is frequency dependent and above &sim 400 K along the T decrease, the dispersion of &epsilon' is initiated and low frequency dispersion of &epsilon' prevails below 250 K. Energy losses measure (&epsilon"), correlated with &epsilon'(T), is generally shifted towards lower T values. Its frequency dependence undergoes inversion which develops with T decrease and is initiated at about 370 K. The whole temperature induced phase transition turned out to be of relaxor kind and diffused process. The detailed analysis of this transition and its features was performed. Research limitations/implications: In order to determine the details of polycrystalline structure of BNTN4 new material for modelling of ferroelectric properties the precise X-ray diffraction measurements should be performed as function of T. The nature of ferroelectric - paraelectric (FE - PE) transition diffusive character will be studied by means of dielectric measurements within frequency range 1 MHz-1.8 GHz. Originality/value: The new kind of ferroelectric solid solution (BNTN4) was synthesized. The specific features of this material at low T range involves among others, the T-dependent dispersion of dielectric properties on low T side of broad &epsilon'(T) peak.
20
Content available remote 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
|
2009
|
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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