scholarly journals X-ray, IR and SEM studies on some Li-Cd ferrites

YMER Digital ◽  
2021 ◽  
Vol 20 (12) ◽  
pp. 333-340
Author(s):  
Sudhir Kulkarni ◽  
Keyword(s):  
Grain Size ◽  
Room Temperature ◽  
Single Phase ◽  
Lattice Parameter ◽  
Lithium Ferrite ◽  
Cadmium Content ◽  
X Ray Diffraction ◽  
Ceramic Method ◽  
X Ray ◽  
Single Phase Formation

Lithium-Cadmium ferrites with general formula Li0.5-x/2 Fe2.5-x/2 Cdx O4 (with x = 0,0.1,0.2....,0.7) were prepared by standard ceramic method. X-ray diffraction studies confirms single phase formation and lattice parameters were calculated. The crystal structure is cubic and lattice parameter increases with increasing Cd content. The infrared absorption (IR) spectra of all the samples were recorded in the range 200-800 cm-1 at room temperature in the KBr medium. Lithium ferrite shows four principal bands and some shoulders have been observed. The force constants Kt and Ko were calculated using Waldron's analysis. Scanning electron microscopy studies shows increase in grain size up to x = 0.1 and then the grain size decreases with increase in cadmium content.

Phase Formation and Grain Growth of BSCZT Ceramics Prepared by BST-BZT Seed Induced Method

2018 ◽  
Vol 766 ◽  
pp. 175-179
Author(s):  
Jiraporn Dangsak ◽  
Sukum Eitssayeam ◽  
Denis Russell Sweatman ◽  
Uraiwan Intatha
Keyword(s):  
Dielectric Constant ◽  
Grain Size ◽  
Phase Formation ◽  
Room Temperature ◽  
Single Phase ◽  
Seed Crystal ◽  
Lead Free ◽  
X Ray Diffraction ◽  
X Ray ◽  
Density Values

In this work, lead-free Ba0.4Sr0.4Ca0.2Zr0.05Ti0.95O3 ceramics were prepared by the seed induced method using (0.5Ba0.6Sr0.4TiO3–0.5BaZr0.05Ti0.95O3) (BST-BZT) seed. Seed crystals with concentrations of 0, 2.5, 5, 7.5, 10 mol% were mixed with BSCZT powder for 24 h and sintered at 1400 °C for 4 h. The phase formation and microstructure of BSCZT ceramic were characterized by X-ray diffraction technique (XRD) and the scanning electron microscopy (SEM). All samples showed a single phase perovskite structure without impurities and exhibited the existence of the tetragonal phase. The density values of the ceramics decreased from 4.90 to 4.75 g/cm3 with increasing seed crystal concentrations. The grain size of the sample without seed was 3.71 μm, whereas a grain size of 8.99 μm was observed for the sample with 10 mol% seed crystal. The dielectric constant at room temperature at 1 kHz was 1831 for the sample with 10 mol% seed crystal while the dielectric constant of the sample without seed was 1484. From the results in this work, BST-BZT seed can increase grain size and improve the dielectric constant at room temperature.

EFFECT OF PROCESSING CONDITIONS ON DIELECTRIC PROPERTIES OF CaCu3Ti4O12 CERAMICS

2011 ◽  
Vol 25 (08) ◽  
pp. 1049-1059 ◽  
Author(s):  
RAMAN KASHYAP ◽  
O. P. THAKUR ◽  
N. C. MEHRA ◽  
R. P. TANDON
Keyword(s):  
Dielectric Properties ◽  
Room Temperature ◽  
Single Phase ◽  
Solid State Reaction Method ◽  
Processing Conditions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sintering Time ◽  
Different Temperatures ◽  
Single Phase Formation

Samples of CaCu 3 Ti 4 O 12 (CCTO) ceramics were prepared by solid state reaction method. X-ray diffraction analysis confirmed single phase formation for the powder calcined at 1173 K. Sintering was done at different temperatures viz. 1348 K, 1373 K and 1398 K with a fixed heating rate of 3 K/min. Detailed study of dielectric properties was carried out for the CCTO samples sintered at 1373 K for different duration of holding times (2 h and 10 h). It is found that dielectric properties are sensitive to both sintering time and temperature. With increasing sintering time from 2 h to 10 h dielectric constant increases from ∼2.1 × 104 to ∼2.5 × 104 measured at 1 kHz at room temperature. Impedance spectroscopy has been used for separating out of grain and grain boundary contributions to the overall electrical properties.

scholarly journals Preparation of high-entropy carbides by different sintering techniques

2021 ◽  
Vol 56 (19) ◽  
pp. 11237-11247 ◽  
Author(s):  
Johannes Pötschke ◽  
Manisha Dahal ◽  
Mathias Herrmann ◽  
Anne Vornberger ◽  
Björn Matthey ◽  
...  
Keyword(s):  
Grain Size ◽  
Single Phase ◽  
X Ray Diffraction ◽  
Vacuum Sintering ◽  
X Ray ◽  
High Entropy ◽  
Mean Grain Size ◽  
The Mean ◽  
Gas Pressure Sintering ◽  
Hardness Values

AbstractDense (Hf, Ta, Nb, Ti, V)C- and (Ta, Nb, Ti, V, W)C-based high-entropy carbides (HEC) were produced by three different sintering techniques: gas pressure sintering/sinter–HIP at 1900 °C and 100 bar Ar, vacuum sintering at 2250 °C and 0.001 bar as well as SPS/FAST at 2000 °C and 60 MPa pressure. The relative density varied from 97.9 to 100%, with SPS producing 100% dense samples with both compositions. Grain size measurements showed that the substitution of Hf with W leads to an increase in the mean grain size of 5–10 times the size of the (Hf, Ta, Nb, Ti, V,)C samples. Vacuum-sintered samples showed uniform grain size distribution regardless of composition. EDS mapping revealed the formation of a solid solution with no intermetallic phases or element clustering. X-ray diffraction analysis showed the structure of mostly single-phase cubic high-entropy carbides. Hardness measurements revealed that (Hf, Ta, Nb, Ti, V)C samples possess higher hardness values than (Ta, Nb, Ti, V, W)C samples.

scholarly journals MOVPE Growth of Quaternary (Al,Ga,In)N for UV Optoelectronics

2000 ◽  
Vol 5 (S1) ◽  
pp. 412-424
Author(s):  
Jung Han ◽  
Jeffrey J. Figiel ◽  
Gary A. Petersen ◽  
Samuel M. Myers ◽  
Mary H. Crawford ◽  
...  
Keyword(s):  
Room Temperature ◽  
Rutherford Backscattering Spectrometry ◽  
Optoelectronic Devices ◽  
Lattice Parameter ◽  
X Ray Diffraction ◽  
X Ray ◽  
Peak Energy ◽  
Movpe Growth ◽  
Pl Emission

We report the growth and characterization of quaternary AlGaInN. A combination of photoluminescence (PL), high-resolution x-ray diffraction (XRD), and Rutherford backscattering spectrometry (RBS) characterizations enables us to explore the contours of constant- PL peak energy and lattice parameter as functions of the quaternary compositions. The observation of room temperature PL emission at 351nm (with 20% Al and 5% In) renders initial evidence that the quaternary could be used to provide confinement for GaInN (and possibly GaN). AlGaInN/GaInN MQW heterostructures have been grown; both XRD and PL measurements suggest the possibility of incorporating this quaternary into optoelectronic devices.

Impedance Spectroscopy Study of LiTaO3 Powder Synthesized via Sol-Gel Method

2012 ◽  
Vol 545 ◽  
pp. 275-278 ◽  
Author(s):  
Lili Widarti Zainuddin ◽  
Norlida Kamarulzaman
Keyword(s):  
Room Temperature ◽  
Single Phase ◽  
Sol Gel ◽  
Rhombohedral Structure ◽  
Spectroscopy Study ◽  
X Ray Diffraction ◽  
Gel Method ◽  
X Ray ◽  
Sol Gel Method ◽  
Impedance Spectroscopy Study

A ceramics sample of LiTaO3 was prepared using a sol-gel method. The sample is annealed at 750 °C for 48 hours. X-ray diffraction analysis indicate the formation of single phase, rhombohedral structure. An ac impedance study was used to analyse the conductivity of LiTaO3 at room temperature and at various temperatures.

INVESTIGATIONS ON Sm- AND Nb-SUBSTITUTED PZT CERAMICS

2006 ◽  
Vol 20 (29) ◽  
pp. 1879-1882 ◽  
Author(s):  
CHANDRA PRAKASH ◽  
J. K. JUNEJA
Keyword(s):  
Dielectric Constant ◽  
Single Phase ◽  
Xrd Analysis ◽  
Chemical Formula ◽  
X Ray Diffraction ◽  
Pzt Ceramics ◽  
Ceramic Method ◽  
X Ray ◽  
Niobium Doping ◽  
Constant Versus

In the present paper, we report the effect of Samarium substitution and Niobium doping on the properties of a PZT(52:48). The properties studied are: structural, dielectric and ferroelectric. The samples with chemical formula Pb 0.99 Sm 0.01 Zr 0.52 Ti 0.48 O 3 were prepared by solid-state dry ceramic method. Small amount (0.5 wt%) of Nb 2 O 5 was also added. X-ray diffraction (XRD) analysis showed formation of a single phase with tetragonal structure. Dielectric properties were studied as a function of temperature and frequency. Transition temperature, Tc, was determined from dielectric constant versus temperature plot. The material shows well-defined ferroelectric (PE) hysteresis loop.

Magnetic Properties of Sputtered Fe-O and Co-O Thin Films

1995 ◽  
Vol 403 ◽  
Author(s):  
D. V. Dimitrov ◽  
A. S. Murthy ◽  
G. C. Hadjipanayis ◽  
C. P. SWANN
Keyword(s):  
Grain Size ◽  
Low Temperatures ◽  
Room Temperature ◽  
Oxide Films ◽  
X Ray Diffraction ◽  
Dc Magnetron Sputtering ◽  
Large Shift ◽  
X Ray ◽  
Grain Size And Shape ◽  
Spherical Grains

AbstractFe-O and Co-O films were prepared by DC magnetron sputtering in a mixture of Ar and O2 gases. By varying the oxygen to argon ratio, oxide films with stoichiometry FeO, Fe3O4, α-Fe2O3, CoO and Co3O4 were produced. TEM studies showed that the Fe – oxide films were polycrystalline consisting of small almost spherical grains, about 10 nm in size. Co-O films had different microstructure with grain size and shape dependent on the amount of oxygen. X-ray diffraction studies showed that the grains in Fe-O films were randomly oriented in contrast to Co-O films in which a <111> texture was observed. Pure FeO and α-Fe2O3 films were found to be superparamagnetic at room temperature but strongly ferromagnetic at low temperatures in contrast to the antiferromagnetic nature of bulk samples. A very large shift in the hysteresis loop, about 3800 Oe, was observed in field cooled Co-CoO films indicating the presence of a large unidirectional exchange anisotropy.

scholarly journals Equimolar Yttria-Stabilized Zirconia and Samaria-Doped Ceria Solid Solutions

Ceramics ◽  
2018 ◽  
Vol 1 (2) ◽  
pp. 343-352 ◽  
Author(s):  
Reginaldo Muccillo ◽  
Daniel de Florio ◽  
Eliana Muccillo
Keyword(s):  
Tetragonal Phase ◽  
Room Temperature ◽  
Single Phase ◽  
Rietveld Analysis ◽  
X Ray Diffraction ◽  
Ceramic Powders ◽  
Stabilized Zirconia ◽  
X Ray ◽  
Ceria Solid Solutions ◽  
Attrition Milling

Compositions of (ZrO2)0.92(Y2O3)0.08 (zirconia: 8 mol % yttria—8YSZ) and (CeO2)0.8(Sm2O3)0.2 (ceria: 20 mol % samaria—SDC20) ceramic powders were prepared by attrition milling to form an equimolar powder mixture, followed by uniaxial and isostatic pressing. The pellets were quenched to room temperature from 1200 °C, 1300 °C, 1400 °C and 1500 °C to freeze the defects configuration attained at those temperatures. X-ray diffraction analyses, performed in all quenched pellets, show the evolution of the two (8YSZ and SDC20) cubic fluorite structural phases to a single phase at 1500 °C, identified by Rietveld analysis as a tetragonal phase. Impedance spectroscopy analyses were carried out in pellets either quenched or slowly cooled from 1500 °C. Heating the quenched pellets to 1000 °C decreases the electrical resistivity while it increases in the slowly cooled pellets; the decrease is ascribed to annealing of defects created by lattice micro-tensions during quenching while the increase to partial destabilization of the tetragonal phase.

scholarly journals Structure and electric properties of cerium substituted SrBi1.8Ce0.2Nb2O9 and SrBi1.8Ce0.2Ta2O9 ceramics

2016 ◽  
Vol 10 (3) ◽  
pp. 183-188 ◽  
Author(s):  
Mohamed Afqir ◽  
Amina Tachafine ◽  
Didier Fasquelle ◽  
Mohamed Elaatmani ◽  
Jean-Claude Carru ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Solid State ◽  
Room Temperature ◽  
Single Phase ◽  
Solid State Reaction Method ◽  
X Ray Diffraction ◽  
Reaction Method ◽  
X Ray ◽  
Lcr Meter ◽  
Curie Temperature Tc

SrBi1.8Ce0.2Nb2O9 (SBCN) and SrBi1.8Ce0.2Ta2O9 (SBCT) powders were prepared via solid-state reaction method. X-ray diffraction analysis reveals that the SBCN and SBCT powders have the single phase orthorhom-bic Aurivillius structure at room temperature. The contribution of Raman scattering and FTIR spectroscopy of these samples were relatively smooth and resemble each other. The calcined powders were uniaxially pressed and sintered at 1250?C for 8 h to obtaine dense ceramics. Dielectric constant, loss tangent and AC conductivity of the sintered Ce-doped SrBi2Nb2O9 and SrBi2Ta2O9 ceramics were measured by LCR meter. The Ce-doped SBN (SBCN) ceramics have a higher Curie temperature (TC) and dielectric constant at TC (380?C and ?? ~3510) compared to the Ce-doped SBT (SBCT) ceramics (330?C and ?? ~115) when measured at 100Hz. However, the Ce-doped SBT (SBCT) ceramics have lower conductivity and dielectric loss.

scholarly journals Ferromagnetic Order in the Intermetallic Alloys laNi5-xMgx

2012 ◽  
Vol 29 (1) ◽  
pp. 50
Author(s):  
D.N Ba ◽  
L.T Tai ◽  
N.T Trung ◽  
N.T Huy
Keyword(s):  
Magnetic Properties ◽  
Curie Temperature ◽  
Room Temperature ◽  
Single Phase ◽  
Chemical Doping ◽  
Intermetallic Alloys ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ferromagnetic Order ◽  
Diffraction Patterns

The influences of the substitution of Ni with Mg on crystallographic and magnetic properties of the intermetallic alloys LaNi5-xMgx (x ≤ 0.4) were investigated. The X-ray diffraction patterns showed that all samples were of single phase, and the lattice parameters, a and c, decreased slightly upon chemical doping. LaNi5 is well known as an exchange-enhanced Pauli paramagnet. Interestingly, in LaNi5-xMgx, the ferromagnetic order existed even with a small amount of dopants; the Curie temperature reached the value of room temperature for x = 0.2, and enhanced with increasing x.

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