Microwave ceramics for resonators and filters

Wersing, W.

doi:10.1016/s1359-0286(96)80056-8

Cited by 423 publications

(246 citation statements)

References 77 publications

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“…Though high dielectric constant materials can give better miniaturization, the applications requiring narrow bandwidth and extremely low insertion loss (0.3 dB) enables the use of ceramics having even ⑀ r ‫ס‬ 38. 1 Dielectric materials with ⑀ r > 40 and Q × f > 45,000 GHz can allow for further miniaturization of the devices without much compromise in quality. Materials with ⑀ r in the range 40 to 65 suitable for such applications are few, and the search for such materials is one of the current areas of research in microwave dielectrics.…”

Section: Introductionmentioning

confidence: 99%

Microwave dielectric properties of MO–La₂O₃–TiO₂ (M = Ca, Sr, Ba) ceramics

et al. 2002

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9 O 31 , were prepared through the solid-state ceramic route. The phases and structure of the ceramics were analyzed through x-ray diffraction and scanning electron microscopy. The microwave dielectric properties of the ceramics were studied using a network analyzer. The investigated ceramics show high ⑀ r in the range 42 to 54, high quality factors with Q × f in the range 16,222 to 50,215 GHz, and low f in the range −25 to +6 ppm/°C. These high dielectric constant materials with high Q × f up to 50,215 GHz are suitable for applications where narrow bandwidth and extremely low insertion loss is necessary, especially at frequencies around 1.9 GHz.

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Section: Introductionmentioning

confidence: 99%

Microwave dielectric properties of MO–La₂O₃–TiO₂ (M = Ca, Sr, Ba) ceramics

et al. 2002

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“…11,15) The Q Â f value of microwave dielectric ceramic could be affected by many factors, such as vacancies, grain boundaries, second phases and density. 1) The Q Â f value of x ¼ 0:1 was higher than that of x ¼ 0:3 although the second phase La 2 Ti 2 O 7 content of x ¼ 0:1 was higher than that of x ¼ 0:3. So the second phase was not the major factor that affected Q Â f value.…”

Section: Resultsmentioning

confidence: 86%

“…Requirements of microwave dielectric ceramics used as dielectric resonators and filters are combined with high dielectric constant (" r ), high quality factor (Q) and near-zero temperature coefficient of resonant frequency ( f ). 1,2) These three parameters are correlated to the size, frequency selectivity and temperature stability of the microwave electronic component.…”

Section: Instructionmentioning

confidence: 99%

Microwave Dielectric Properties of the (1−x)La2&frasl;3TiO3–xLa(Ti1&frasl;2Mg1&frasl;2)O3 System

et al. 2006

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(1 À x)La 2=3 TiO 3 -xLa(Mg 1=2 Ti 1=2 )O 3 ceramics with x ranging from 0.1 to 0.9 were prepared by conventional solid-state reaction. La 2=3 TiO 3 and La(Mg 1=2 Ti 1=2 )O 3 were found to form a solid solution over the whole compositional range. However, the second phase La 2 Ti 2 O 7 existed for x ¼ 0:1 and 0.3. As the x value increased from 0.1 to 0.9, the dielectric constant " r decreased from 65.1 to 28.4. The oxygen vacancies were the main factor affecting the Q Â f values of the (1 À x)La 2=3 TiO 3 -xLa(Mg 1=2 Ti 1=2 )O 3 ceramics. A f value of À5 ppm/ C can be obtained at x ¼ 0:3. Keywords: microwave ceramic, dielectric properties, La 2=3 TiO 3 , La(Mg 1=2 Ti 1=2 )O 3 InstructionRecently, the development of microwave applications, including mobile telephones and satellite communication systems, makes rapid progress due to the improved performance of dielectric resonators and filters. Requirements of microwave dielectric ceramics used as dielectric resonators and filters are combined with high dielectric constant (" r ), high quality factor (Q) and near-zero temperature coefficient of resonant frequency ( f ).1,2) These three parameters are correlated to the size, frequency selectivity and temperature stability of the microwave electronic component.La 2=3 TiO 3 is a perovskite compound with general formula ABO 3 . It is unstable in its pure form due to the high content of vacancies in the A cationic sublattice.3) La 2=3 TiO 3 has become an interesting dielectric material after it was stabilized by Ni, 4) Pb, 5) Al, [6][7][8] or Nb 9) et al. For example, La 2=3 TiO 3 doped with 4% LaAlO 3 has attractive microwave properties: " r ¼ 61:9, Q Â f ¼ 23900 GHz and f ¼ 123 ppm/ C. 7) The value of f of such materials can be adjusted to zero by preparation of solid solution with compounds having negative temperature coefficient of resonant frequency. 10,11) As it has reported, La(Mg 0:5 Ti 0:5 )O 3 ceramics was a promising microwave material for application of dielectric resonators and filters.12,13) It exhibits dielectric constant of 28, Q Â f of 631000 GHz and negative f of À79 ppm/ C. The purpose of the present work thus is to stabilize La 2=3 TiO 3 and adjust the f of La 2=3 TiO 3 by introducing La(Mg 0:5 -Ti 0:5 )O 3 . The sintering and microwave dielectric properties of (1 À x)La 2=3 TiO 3 -xLa(Mg 1=2 Ti 1=2 )O 3 were also investigated. ExperimentIn this work, the La 2 O 3 , TiO 2 and MgO powders were mixed according to the compositions (1 À x)La 2=3 TiO 3 -xLa(Mg 1=2 Ti 1=2 )O 3 (x ¼ 0:1; 0:3; 0:5; 0:7; 0:9) and milled with ZrO 2 balls for 24 h in ethanol and then dried at 120 C for 10 h. The dried powders were calcined at 1250 C for 3 h. A small mount of Al 2 O 3 was added as sintering aid. The calcined powders were milled again for 24 h and dried at 120 C for 10 h. After the dried powders doped with 7 mass% polyvinyl alcohol (PVA) were preformed using cylindrical mold of 16 mm diameter, they were pressed at 2000 kg/cm 2 with cold-isostatic pressing. The pellets were sintered at 1400-1600 C for 3 h in air w...

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“…Bismuth niobate (BiNbO 4 ) has been reported to be a promising microwave dielectric ceramics [1,2] To improve the microwave dielectric properties of BiNbO 4 various attempts have been undertaken. Among them one can mention e.g.…”

Section: Introductionmentioning

confidence: 99%

Influence of Bismuth Content on Complex Immittance Characteristics of Pressureless Sintered BiNbO4 Ceramics

Czekaj¹,

Lisińska-Czekaj²,

Adamczyk³

2014

Archives of Metallurgy and Materials

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Goal of the present research was to study immittance properties of BiNbO 4 ceramics fabricated by the solid state reaction route followed by pressureless sintering. Four sets of samples were examined, namely the one fabricated from the stoichiometric mixture of oxides, viz. Bi 2 O 3 and Nb 2 O 5 as well as the ones with an excess of 3%, 5% and 10% by mole of Bi 2 O 3 . The immittance properties were studied by impedance spectroscopy. Measurements were carried out within the frequency range ν =20Hz-1MHz and temperature range T =RT-550• C. The Kramers-Kronig data validation test was employed in the impedance data analysis. It was found that complex impedance first increases with an increase in Bi 2 O 3 content and decreases for 10mol% excess of Bi 2 O 3 . Two relaxation phenomena manifested themselves at elevated temperature (T >267• C) within the measuring frequency range. The conductivity relaxation phenomenon (M (ν) spectra) took place at higher frequency than the phenomenon with dominant resistive component (Z (ν) spectra).Keywords: BiNbO 4 ceramics, impedance spectroscopy, impedance and modulus analysis Celem niniejszej pracy było zbadanie właściwości immitancyjnych ceramiki BiNbO 4 wytworzonej metodą reakcji w fazie stałej i spiekania swobodnego. Badaniom poddano cztery zestawy próbek wytworzonych ze stechiometrycznej mieszaniny tlenków Bi 2 O 3 i Nb 2 O 5 oraz mieszaniny zawierającej nadmiar Bi 2 O 3 w ilości 3, 5 i 10% molowych. Badania przeprowadzono z zastosowaniem spektroskopii impedancyjnej. Pomiary dokonano w zakresie częstotliwości ν =20Hz-1MHz i temperatury T =RT-550• C. Do analizy zgodności danych pomiarowych zastosowano test Kramersa-Kroniga. Stwierdzono, że ze wzrostem zawartości Bi 2 O 3 w mieszaninie do 5% molowych wzrasta impedancja próbek, która dla 10% molowych maleje poniżej wartości zarejestrowanej dla BiNbO 4 bez nadmiaru Bi 2 O 3 . Zaobserwowano obecność dwóch procesów relaksacyjnych w temperaturze T >267• C. Stwierdzono, że zjawisko relaksacji przewodnictwa (widma M (ν)) zachodzi w wyższej częstotliwości niż zjawisko z dominującą składową rezystywną (widma Z (ν)).

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Microwave ceramics for resonators and filters

Cited by 423 publications

References 77 publications

Microwave dielectric properties of MO–La₂O₃–TiO₂ (M = Ca, Sr, Ba) ceramics

Microwave dielectric properties of MO–La₂O₃–TiO₂ (M = Ca, Sr, Ba) ceramics

Microwave Dielectric Properties of the (1−<I>x</I>)La<SUB>2&frasl;3</SUB>TiO<SUB>3</SUB>–<I>x</I>La(Ti<SUB>1&frasl;2</SUB>Mg<SUB>1&frasl;2</SUB>)O<SUB>3</SUB> System

Influence of Bismuth Content on Complex Immittance Characteristics of Pressureless Sintered BiNbO4 Ceramics

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Microwave ceramics for resonators and filters

Cited by 423 publications

References 77 publications

Microwave dielectric properties of MO–La2O3–TiO2 (M = Ca, Sr, Ba) ceramics

Microwave dielectric properties of MO–La2O3–TiO2 (M = Ca, Sr, Ba) ceramics

Microwave Dielectric Properties of the (1&minus;<I>x</I>)La<SUB>2&frasl;3</SUB>TiO<SUB>3</SUB>&ndash;<I>x</I>La(Ti<SUB>1&frasl;2</SUB>Mg<SUB>1&frasl;2</SUB>)O<SUB>3</SUB> System

Influence of Bismuth Content on Complex Immittance Characteristics of Pressureless Sintered BiNbO4 Ceramics

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Microwave dielectric properties of MO–La₂O₃–TiO₂ (M = Ca, Sr, Ba) ceramics

Microwave dielectric properties of MO–La₂O₃–TiO₂ (M = Ca, Sr, Ba) ceramics

Microwave Dielectric Properties of the (1−<I>x</I>)La<SUB>2&frasl;3</SUB>TiO<SUB>3</SUB>–<I>x</I>La(Ti<SUB>1&frasl;2</SUB>Mg<SUB>1&frasl;2</SUB>)O<SUB>3</SUB> System