scholarly journals The Structural and Dielectric Properties of Bi3−xNdxTi1.5W0.5O9 (x = 0.25, 0.5, 0.75, 1.0)

Electronics ◽  
2022 ◽  
Vol 11 (2) ◽  
pp. 277
Author(s):  
Sergei V. Zubkov ◽  
Ivan A. Parinov ◽  
Yulia A. Kuprina
Keyword(s):  
High Temperature ◽  
Dielectric Properties ◽  
Single Phase ◽  
Partial Substitution ◽  
Layered Perovskite ◽  
Structural Studies ◽  
Perovskite Layer ◽  
Aurivillius Phases ◽  
X Ray ◽  
Unit Cells

A new series of layered perovskite-like oxides Bi3−xNdxTi1.5W0.5O9 (x = 0.25, 0.5, 0.75, 1.0) was synthesized by the method of high-temperature solid-state reaction, in which partial substitution of bismuth (Bi) atoms in the dodecahedra of the perovskite layer (A-positions) by Nd atoms takes place. X-ray structural studies have shown that all compounds are single-phase and have the structure of Aurivillius phases (APs), with close parameters of orthorhombic unit cells corresponding to space group A21am. The dependences of the relative permittivity ε/ε0 and the tangent of loss tgσ at different frequencies on temperature were measured. The piezoelectric constant d33 was measured for Bi3−xNdxTi1.5W0.5O9 (x = 0.25, 0.5, 0.75) compounds of the synthesized series.

scholarly journals Sintering behaviour and microwave dielectric properties of MgO-2B2O3-xwt%BaCu(B2O5)-ywt%H3BO3 ceramics

2021 ◽  
Author(s):  
Haiquan Wang ◽  
Shixuan Li ◽  
Kangguo Wang ◽  
Xiuli Chen ◽  
Huanfu Zhou
Keyword(s):  
Dielectric Properties ◽  
Bulk Density ◽  
Single Phase ◽  
Sintering Temperature ◽  
Microwave Dielectric Properties ◽  
X Ray Diffraction ◽  
Microwave Dielectrics ◽  
X Ray ◽  
Microwave Dielectric ◽  
Sintering Behaviour

AbstractThis study investigates the bulk density, sintering behaviour, and microwave dielectric properties of the MgO-2B2O3 series ceramics synthesised by solid-state reaction. According to the X-ray diffraction and microstructural analyses, the as-prepared MgO-2B2O3 ceramics possess a single-phase structure with a rod-like morphology. The effects of different quantities of H3BO3 and BaCu(B2O5) (BCB) on the bulk density, sintering behaviour, and microwave dielectric properties of the MgO-2B2O3 ceramics were investigated. Accordingly, the optimal sintering temperature was obtained by adding 30 wt% H3BO3 and 8 wt% BCB. We also reduced the sintering temperature to 825 °C. Furthermore, the addition of 40 wt% H3BO3 and 4 wt% BCB increased the quality factor, permittivity, and temperature coefficient of resonance frequency of MgO-2B2O3 to 44,306 GHz (at 15 GHz), 5.1, and −32 ppm/°C, respectively. These properties make MgO-2B2O3 a viable low-temperature co-fired ceramic with broad applications in microwave dielectrics.

Probing Octahedral Tilting in Dion-Jacobson Layered Perovskites With Neutron Powder Diffraction and Raman Spectroscopy

2006 ◽  
Vol 988 ◽  
Author(s):  
Joshu A. Kurzman ◽  
Margret J. Geselbracht
Keyword(s):  
Raman Spectroscopy ◽  
Powder Diffraction ◽  
Neutron Powder Diffraction ◽  
Layered Perovskite ◽  
Strontium Content ◽  
Solid Solution Formation ◽  
X Ray ◽  
Unit Cells ◽  
Octahedral Tilting ◽  
Average Size

AbstractTwo new Dion-Jacobson type layered perovskite solid solutions, RbCa2-xSrxM3O10 (M = Nb, Ta; 0 ≤ x ≤ 2), were prepared and studied by X-ray powder diffraction, neutron powder diffraction, and Raman spectroscopy. X-ray powder diffraction confirmed single-phase solid solution formation with continuous expansion of the idealized primitive tetragonal unit cell with increasing strontium content. Neutron powder diffraction studies of selected samples revealed lower symmetries and larger unit cells, as necessitated by octahedral tilting within the perovskite slabs, compared to the idealized primitive cell. As the average size of the A-cation in the perovskite slab is varied from Sr2+ to Ca2+, more extensive octahedral tilting is introduced. Vibrational modes of the perovskite slab observed using Raman spectroscopy show subtle changes as a function of calcium/strontium content and more intriguing differences between the isostructural niobates and tantalates.

Electrochemical Performance of La0.7Sr0.3Cu1-xFexO3-δ as Cathode Material in IT-SOFCs

2010 ◽  
Vol 160-162 ◽  
pp. 666-670
Author(s):  
Min Zhang Zheng ◽  
Xiao Mei Liu
Keyword(s):  
Electrical Conductivity ◽  
High Temperature ◽  
Cathode Material ◽  
Single Phase ◽  
Cathodic Polarization ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cathodic Overpotential ◽  
A Current

To obtain more detail information about the cathode of La0.7Sr0.3Cu1-xFexO3-δ（x= 0.1,0.3,0.5,0.7,0.9）in IT-SOFCs, the cathode material La0.7Sr0.3Cu1-xFexO3-δ（x=0.1, 0.3, 0.5, 0.7, 0.9）was synthesized by a sol-gel method. X-ray diffraction revealed it to be form a single phase of perovskite. The high temperature electrical conductivity was measured by using the four-point dc technique, and cathodic overpotential with SDC（Sm0.15Ce0.85O1.925） electrolyte support was measured by using a current-interruption technique. The investigation of electrocheimical properties suggested that La0.7Sr0.3Cu0.7Fe0.3O3-δ has the highest electrical conductivity and the lowest cathodic polarization. Using La0.7Sr0.3Cu0.7Fe0.3O3-δ as cathode and 65%NiO/SDC as anode based on SDC electrolyte one can obtain higher current density and power density at intermediate temperatures, La0.7Sr0.3Cu0.7Fe0.3O3-δ is considered to be a possible cathode adapted to IT-SOFCs.

Synthesis, Structure and Dielectric Properties of Na2SnTeO6

1998 ◽  
Vol 547 ◽  
Author(s):  
J.-H. Park ◽  
P.M. Woodward ◽  
J.B. Parise ◽  
I. Lubomirsky ◽  
O. Stafsudd
Keyword(s):  
Dielectric Constant ◽  
High Pressure ◽  
High Temperature ◽  
Dielectric Properties ◽  
Temperature Treatment ◽  
High Temperature Treatment ◽  
Powder Diffraction Data ◽  
Ambient Conditions ◽  
X Ray ◽  
High Pressure High Temperature

AbstractA new perovskite was recovered from the high pressure-high temperature treatment of the α-TlSbO3 form of Na2SnTeO6 at 7 GPa and 950 °C for 30 minutes. Synchrotron x-ray powder diffraction data show the space group is P21/n with a=5.40361 (5), b=5.46152(5), c=7.69288(7) Å and ß=90.034(3)°. Using disk samples of both polymorphs, the dielectric properties were measured as a function of temperature. At ambient conditions, the perovskite form has a more than 1.5 fold enhancement in dielectric constant compared to the α-TlSbO3 form while the molar volume and the molecular polarizability decrease.

Investigation on the Thermal Stability of the Compounds Y3Fe29-xCrx

2013 ◽  
Vol 820 ◽  
pp. 71-74
Author(s):  
Xiao Hua Wang ◽  
Wei He ◽  
Ling Min Zeng
Keyword(s):  
Thermal Stability ◽  
High Temperature ◽  
Single Phase ◽  
Binary Compound ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
Transition Elements ◽  
X Ray Diffraction ◽  
X Ray ◽  
Thermal Stability Of

Binary compound Y3Fe29cannot be directly formed by rare earth Y and Fe and the third element M (non-iron transition elements) must be introduced to form ternary compound Y3(Fe,M)29. In this work, six alloys with compositions of the Y3Fe29-xCrx(x=1,2,3,4,5,6) were prepared and investigated by X-ray diffraction (XRD), Scanning electron microscopy (SEM) and differential thermal analysis (DTA). The study on the thermal stability of these compounds points to that the compoundY3(Fe,Cr)29is a high temperature phase and exists above 1100K. The alloys with single-phase of Y3(Fe,Cr)29was decomposed into Y2(Fe,Cr)17and Y(Fe,Cr)12annealed at high temperature 1100K.

scholarly journals Synthesis, Structure and Thermophysical Properties of Phosphates MNi0.5Zr1.5(PO4)3 (M = Mg, Ca, Sr)

2010 ◽  
Vol 12 (3,4) ◽  
pp. 241 ◽  
Author(s):  
M.V. Sukhanov ◽  
I.A. Schelokov ◽  
V.I. Pet'kov ◽  
E.R. Gobechiya ◽  
Yu.K. Kabalov ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Heat Capacity ◽  
Thermal Expansion ◽  
High Temperature ◽  
Single Phase ◽  
Rietveld Method ◽  
Type Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Expansion Behavior

<p>New phosphates MNi<sub>0.5</sub>Zr<sub>1.5</sub>(PO<sub>4</sub>)<sub>3</sub> (M = Mg, Ca, Sr) were prepared by the precipitating method.<strong><em> </em></strong>Phosphates were characterized using X-ray powder diffraction, IR-spectroscopy and electron microprobe analyses. The crystal structure of phosphates was refined by the Rietveld method. Phosphates CaNi<sub>0.5</sub>Zr<sub>1.5</sub>(PO<sub>4</sub>)<sub>3</sub> and SrNi<sub>0.5</sub>Zr<sub>1.5</sub>(PO<sub>4</sub>)<sub>3</sub> are shown to have been crystallized in the NaZr<sub>2</sub>(PO<sub>4</sub>)<sub>3</sub>-type structure and the phosphate MgNi<sub>0.5</sub>Zr<sub>1.5</sub>(PO<sub>4</sub>)<sub>3 </sub>was obtained as a single-phase with Sc<sub>2</sub>(WO<sub>4</sub>)<sub>3</sub>-type structure. Heat capacity of phosphate CaNi<sub>0.5</sub>Zr<sub>1.5</sub>(PO<sub>4</sub>)<sub>3</sub> was measured in the range 7 – 650 K and increased monotonically over the entire temperature range studied. Thermal expansion of phosphate CaNi<sub>0.5</sub>Zr<sub>1.5</sub>(PO<sub>4</sub>)<sub>3</sub> was studied in the interval 295-1073 K by the high temperature X-ray diffraction. This phosphate is similar to the best low-expansion ceramics, such as zircon, cordierite and silica glass in thermal expansion behavior.</p>

scholarly journals Effect of Fe Substitution on the Structural, Electrical and Dielectric Properties of La0.70Ca0.30MnO3 Cathode for SOFCs

2019 ◽  
Vol 9 (1) ◽  
pp. 324-328
Keyword(s):  
Dielectric Properties ◽  
Single Phase ◽  
Diffraction Method ◽  
X Ray Diffraction ◽  
Reaction Route ◽  
X Ray ◽  
Suitable Material ◽  
Density Values ◽  
Electrical And Dielectric Properties ◽  
Fe Substitution

Perovskite solid solutions (La0.70Ca0.30)(FexMn1-x)O3 where x = 0.01, 0.20, 0.30 and 0.40 ceramics were synthesized by solid state reaction route. The structural studies were carried by X-Ray diffraction method and the observed results have indicated that all the prepared samples were crystallized into single phase. The surface morphology was studied by Scanning Electron Microscopy and the images have revealed that grain size has increased with the increasing concentration of Fe. Archimedes principle was used to calculate the density of all the sintered samples and the density values were observed to be in increasing order. The impedance and dielectric properties have been characterized at different ranges of temperature and frequency. The value of electrical conductivity were found to be more than 100 S cm-1 , which indicate that the synthesized material is suitable material for cathode of Solid Oxide Fuel Cell.

Synthesis, Structural and Dielectric Studies on SrBi2-xGdxNb2O9 Lead Free Ceramics

2020 ◽  
Author(s):  
Nitchal Kiran Jaladi ◽  
K. Sambasiva Rao ◽  
Haileeyesus Workineh ◽  
J. Anindhya Kiran ◽  
S. Nagamani
Keyword(s):  
Dielectric Properties ◽  
Single Phase ◽  
Xrd Analysis ◽  
Sem Analysis ◽  
Ion Concentration ◽  
Layered Perovskite ◽  
Cell Parameters ◽  
Lead Free Ceramics ◽  
Layered Perovskite Structure ◽  
Diffuseness Parameter

Abstract In this manuscript, the structural and dielectric properties of Gadolinium (Gd3+) substituted at Bi-site of SrBi2-xGdxNb2O9 (x= 0.0, 0.4, 0.6 and 0.8) prepared by using solid state reaction are studied. XRD analysis revealed the formation of single phase with orthorhombic structure in SBN and Gadolinium modified SBN. It is found that cell parameters and volume were decreased with increase of Gd3+ ion concentration in SBN. SEM analysis revealed that the samples possess well defined needle shaped grains. The grain size of SBN was hindered by the presence of Gd3+ ion at Bi-site. The growth of single phase layered perovskite structure was confirmed from FTIR and Raman spectroscopy. The dielectric properties of Gd3+ ion doped SBN ceramics are studied as a function of frequency (50Hz-1MHz) from room temperature to 500ºC. It is observed that phase transition temperature (Tc) decreased from 430ºC to 330ºC with increase of frequency due to incorporation of Gd3+ ion in SBN. The broadness of peaks and decrease in Tc indicate the transition from a normal ferroelectric to ferroelectric-relaxor type. The study on variation of tanδ with temperature at different frequencies indicates that tanδ has larger values at higher temperatures. Further, the diffuseness parameter (γ) has been computed for all the compositions.

Preparation of Forsterite by Solid State Synthesis Process and its Dielectric Properties

2012 ◽  
Vol 534 ◽  
pp. 110-113 ◽  
Author(s):  
Fei Shi ◽  
Peng Cheng Du ◽  
Jing Xiao Liu ◽  
Ji Wei Wu ◽  
Chun Yuan Luo
Keyword(s):  
Dielectric Properties ◽  
Solid State ◽  
Single Phase ◽  
Raw Materials ◽  
Magnesium Carbonate ◽  
Solid State Synthesis ◽  
Molar Ratio ◽  
Synthesis Process ◽  
X Ray Diffraction ◽  
X Ray

Using basic magnesium carbonate (Mg(OH)2•4MgCO3•6H2O) and SiO2 as raw materials, forsterite (Mg2SiO4) was prepared by solid state synthesis process. The optimal process for synthesizing Mg2SiO4 was obtained by adjusting Mg/Si molar ratio and sintering temperature. The crystal phase of the obtained Mg2SiO4 powder was determined by X-ray diffraction (XRD). The results indicate that the single-phase Mg2SiO4 powder can be obtained when the mixtures with Mg/Si molar ratio of 2.05～2.01 were sintered at 1350°C for 3h in the air. The as-prepared Mg2SiO4 ceramic samples which were sintered at 1300～1360°C showed better dielectric properties with εr=7.4 and tanδ =7.5×10-4.

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