A Study of Cordierite Ceramics Synthesis From domestic kaolin

This work aims to study the effect of chlorine ion on the formation of the cordierite phase (2MgO.2Al2O3.5SiO2) from domestic kaolin at various calcined temperatures.. The cordierite phase was synthesized by a solid-state reaction technique from the mixture of kaolin, aluminum nitrate nonahydrate (Al(NO3)3.9H2O), and magnesium chloride hexahydrate (MgCl2.6H2O) which was designed to the stoichiometric composition of cordierite in the absence and presence of chlorine ion (NH4Cl). The structure and formation of cordierite phase were characterized by X-ray diffraction (XRD) and thermogravimetric - differential thermal analysis (TG-DSC). Phase composition of samples calcined at various temperatures was calculated by using Match! (Version 3.7.0) software. It is noteworthy that the presence of chlorine ion in the mixture declined the formation temperature of cordierite by 50 °C. The cordierite phase was calculated to be 61.3 wt.% and 5.5 wt.% at 1150 °C for the present and absent chlorine ion, respectively. The presence of chlorine ion affected the cordierite formation rate and suppressed the temperature of formation. Cordierite phase could be obtained up to 89.6 wt.% at 1250 °C and 30 wt.% NH4Cl. This investigation found that cordierite ceramic could be synthesized from domestic kaolin at lower temperature by using NH4Cl additive.

Effect of Partial Substitution of Sr by Ba on the Structural Properties of Tl0.8Ni0.2Sr2-xBrxCa2Cu3O9-δ System

In this manuscript, the effect of substituting strontium with barium on the structural properties of Tl0.8Ni0.2Sr2-xBrxCa2Cu3O9-δ compound with x= 0, 0.2, 0.4, have been studied. Samples were prepared using solid state reaction technique, suitable oxides alternatives of Pb2O3, CaO, BaO and CuO with 99.99% purity as raw materials and then mixed. They were prepared in the form of discs with a diameter of 1.5 cm and a thickness of (0.2-0.3) cm under pressures 7 tons / cm2, and the samples were sintered at a constant temperature of 860 ° C. The structural properties were studied using X-ray diffraction for all samples, and the results showed that the samples have tetragonal structure and the change of the parameters structure with the change of the barium concentration. Full Width Half Maximum (FWHM) was calculated by Orange Pro using X-RAY data. The crystal size was calculated using Scherrer and Willeamson-Heall methods, where the results showed that the crystal size, compliance and degree of crystallinity changed with the change of barium concentration, and the highest average for the crystal size was 70.0271nm at x=0, and crystallization at 61.46% at x=0.6, and the strain decreased to 0.0037 when barium concentration equals 0.4.

THE SYNTHESIS IMPACT ON DIELECTRIC PROPERTIES OF La0.5Li0.5-xNaxTiO3

Using X-ray powder, diffraction the sequence of reactions occurring during the synthesis La0.5Li0.5-xNaxTiO3 by solid-state reaction technique has been determined. Using electron microscopy it has been shown that the grain size decreases with increasing x in La0.5Li0.5-xNaxTiO3 system. The influence of the grain size of ceramics on the dielectric characteristics has been indicated. The frequency dependences of permittivity and dielectric loss tangent have been investigated by ac impedance spectroscopy. It has been established that ceramic sample of La0.5Li0.4Na0.1TiO3 solid solution has the largest value of permittivity ɛ > 104 at wide frequency range (1–104 Hz) in La0.5Li0.5-xNaxTiO3 system.

Impedance and modulus studies of Na0.9Ba0.1Nb0.9(Sn0.5Ti0.5)0.1O3 ceramic

Polycrystalline Na[Formula: see text]Ba[Formula: see text]Nb[Formula: see text](Sn[Formula: see text]Ti[Formula: see text]O3is prepared by the solid-state reaction technique. The formation of single-phase material was confirmed by an X-ray diffraction study and it was found to be a tetragonal phase at room temperature. Nyquist plots ([Formula: see text]ˆ2 versus [Formula: see text] show that the conductivity behavior is accurately represented by an equivalent circuit model which consists of a parallel combination of bulk resistance and constant phase elements (CPE). The frequency dependence of the conductivity is interpreted in terms of Jonscher’s law. The conductivity [Formula: see text] follows the Arrhenius relation. The modulus plots can be characterized by the empirical Kohlrausch–Williams–Watts (KWW), [Formula: see text] = exp([Formula: see text]/[Formula: see text] function and the value of the stretched exponent ([Formula: see text] is found to be almost independent of temperature. The near value of activation energies obtained from the analyses of modulus and conductivity data confirms that the transport is through an ion hopping mechanism dominated by the motion of the (O[Formula: see text] ions in the structure of the investigated material.

Structural and transition tempreature of HgPb

solid state reaction technique (SSR) was used to prepare high-Tc phase in superconductors the effect of additional Pb to was investigated it has been found

Investigation of Dielectric and Ferroelectric Properties of Titanium Doped AgNbO3 Ceramic

The electrical properties of the titanium doped AgNbO3 system are defined in this paper. In the modified system, doping moderately replaced Nb5+ with Ti4+ ion where the ceramics are prepared using solid-state reaction technique. The dielectric characteristics were examined at frequencies ranging from 1 kHz to 100 kHz. The dielectric value of the modified systems increased substantially while the P-E curve emerged with a value of relatively increased spontaneous polarization.

The Influence of the Sintering Temperature on the Properties of the 0.98Pb(Zr1-xTix)O3 - 0.02La(Fe3+0.5, Nb5+0.5)O3 Ceramic Systems

The ferroelectric solid solutions described by a general formula 0.98Pb(Zr1-xTix)O3 – 0.02La(Fe3+0.5, Nb5+0.5)O3 have been obtained by solid state reaction technique, where x assumes the following values: 0.42, 0.48 and 0.58. The structure of these ferroelectric compositions has been investigated in detail using X-ray diffraction analysis (XRD) and Scanning Electron Microscopy (SEM). The results obtained by XRD have evidenced that all obtained samples have a perovskite structure. The influence of the sintering temperature on the degree of incorporation of the elements in the solid solution have been studied too. The dielectric and piezoelectric constants have been determined and the influence of temperature on obtained values are presented and discussed. The performed experimental results have pointed out that the materials are characterized by a high anisotropy. Furthermore, the obtained values of the electromechanical coupling factor (kp) is situated between 0.40÷0.65 depending on the composition and the sintering temperature too.

SYNTHESIS AND DIELECTRIC PROPERTIES OF La0.67LixTi1-xAlxO3 (0.15≤x≤0.3) CERAMICS

Solid solutions of Al-doped lithium lanthanum titanates La0.67LixTi1-xAlxO3 system (where 0.15 ≤ x ≤ 0.3) have been synthesized by solid-state reaction technique. Light optical microscopy has shown that the grain size of La0.67LixTi1-xAlxO3 ceramics insignificantly increases with an increase in lithium/aluminum concentration. The materials La0.67LixTi1-xAlxO3 show very high dielectric permittivity ε΄ 104 over a relatively wide frequency range (102 ≤ f ≤ 104 Hz) with no apparent dependence on the x. The impedance spectroscopy study indicates three semicircles on Cole-Cole diagram that can be attributed to electrically different areas of ceramic’s grain.

Effects of Sintering Temperature on Structural and Electrical Properties of Fe3+ Doping PZT Ceramics

The influence of the sintering temperature on the structure and on the hysteresis loops of Fe3+ doped Pb(ZrxTi1-x)O3 system has been investigated. Three compositions have been selected in the following mode: one in rhombohedral region, one in MPB region and one in tetragonal region have been obtained by solid state reaction technique. Sintering has been carried out at 12000C and 12500C respectively. The nature of the phases has been investigated in detail using X-ray diffraction analysis (XRD). All the sintered samples reveal a perovskite type structure. The surfaces have been lapped and metalized in order to obtaine the hysteresis loops at room temperature. The results showed a similar behaviour with “hard” PZT ceramics.

Facile modulation the sensitivity of Eu2+/Eu3+-coactivated Li2CaSiO4 phosphors through adjusting spatial mode and doping concentration

Series of Eu2+/Eu3+-coactivated Li2CaSiO4 phosphors were prepared by solid-state reaction technique. All the samples emitted the unique emissions of Eu2+ and Eu3+ ions when excited by 395 nm, while the strongest emission intensity was received when x = 0.03. On the basis of theoretical discussion, it is evident that crossover relaxation should be responsible for the thermal quenching mechanism which was further proved by the unchanged lifetime at elevated temperature. Besides, through analyzing the inconsistent responses of the emission intensities of the Eu2+ and Eu3+ ions to the temperature, the optical thermometric properties of the designed phosphors were studied. By selecting different emissions of Eu3+ ions and combining with that of the Eu2+ ions, adjustable sensitivities were realized in the resultant phosphors. Furthermore, the sensitivities of the studied compound were also found to be greatly affected by the doping concentration. The maximum absolute and relative sensitivities of the synthesized compounds were 0.0025 K−1 and 0.289% K−1, respectively. These achieved results implied that the Eu2+/Eu3+-coactivated Li2CaSiO4 phosphors were promising candidates for optical thermometry. Additionally, this work also provided promising methods to modulate the sensitivities of the luminescent compounds by adjusting spatial mode and doping concentration.