Powder X-ray Diffraction Patterns Of Samples Research Articles

Optical and structural investigations of MLaAlO4:Eu3+ (M = Mg2 +, Ca2+, Sr2+, and Ba2+) nanophosphors for full-color displays

A series of Eu3+ -doped MLaAlO4 (M = Mg2+, Ca2+, Sr2+, and Ba2+) was synthesized via self-sustained solution combustion method. The samples were prepared at 600 °C, using large range of Eu3+ ion concentration (0.01–0.05 mol) to investigate the effect of concentration of dopant on the luminescence. The optimal dopant ion concentration obtained was 0.03 mol for the prepared aluminate lattice. Upon excitation at 393 nm, the samples showed the dominant photoluminescence emission bands in red region of the spectrum. The red emission of Eu3+ -activated phosphors corresponds to 5D0 → 7F2 (forced electric dipole) transition positioned at 606–611 nm. The samples were also calcined to a higher temperature to analyze the influence of temperature on the luminous efficacy. The structural determination was done via the combined efforts of Powder X-ray diffraction (PXRD) and transmission electron microscopy (TEM) analysis. PXRD patterns of samples contain sharp peaks in 10°–80° region. Diffraction Pattern of CaLaAlO4 material has been found in close agreement to JCPDS card no. 85-1071 confirming the tetragonal crystal structure with 14/mmm space group. The crystalline nature of materials increases with rise in temperature. TEM micrographs exhibited the spherical shape of particles in 13–30 nm size. FT-IR spectra of materials showed peaks in 400–1000 cm−1 corresponding to lanthanum–oxygen and aluminum–oxygen bond vibrations. Due to excellent photoluminescent and suitable CIE coordinates, the Eu3+ -doped MLaAlO4 could have brilliant applications in the development of effective red phosphor for modern display devices and white light-emitting diodes.

Processing, structure and magnetic properties correlation in co-precipitated Ca-ferrite

La-substituted hexagonal calcium ferrite, Ca1−XLaXFe12O19 (x varies from 0 to 0.6 with the step of 0.2), was synthesized by applying co-precipitation method, in which the molar ratio of Fe3+/(Ca2++La2+) was 11. The ferrite precursors were prepared from aqueous solution of calcium nitrate, ferric nitrate and lanthanum nitrate by co-precipitation of calcium, iron and lanthanum ions by using an aqueous base of sodium hydroxide (1.5M) at the pH of 14 and at room temperature. These precursors were calcinated with different amount of La at different temperature of 700, 1100 and 1200°C for constant calcination time of 1h in a static air atmosphere. Some tests such as simultaneous thermal analysis (STA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM) were carried out to investigate the thermal behavior, crystallographic properties, morphology and magnetic properties of the precursor powders which were calcinated at different temperatures. The powder XRD patterns of samples which consisted of La as dopant and were calcinated at 1200°C for 1h, indicates the formation of calcium hexaferrite and also α-Fe2O3 besides Magnetoplumbite-phase (M-phase). However, the results showed that CaFe4O7 and α-Fe2O3 phases were formed in the sample with the same condition but without using any dopant. The results of SEM showed that the calcium hexaferrite particle were regular hexagonal platelets with the size range of 1–2µm. The magnetic properties such as maximum magnetization (MMax), remanent magnetization (Mr) and coercivity (Hc) were measured from the hysteresis loops. Low values of coercive field (16.3kAm−1) and maximum magnetization (50.6Am2kg−1) were obtained from calcium hexaferrite particle in optimum amount of La (X=0.4) which calcinated at the temperature of 1200°C.

Improvement of structural and superconducting properties of Bi-2212 textured rods by substituting sodium

In this paper, the physical and superconducting properties of Bi2Sr2Ca1−xNaxCu2O8+δ with x=0.0, 0.05, 0.075, 0.1, and 0.20 textured superconducting fiber rods prepared by a laser floating zone (LFZ) technique were studied. The effects of Na+1 substitution for Ca2+ have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transport measurements, dc-magnetization, magnetic hysteresis and magnetic critical current density. The powder XRD patterns of samples have indicated that Bi-2212 phase is the major one, independently of Na content. The best critical temperature, TC, has been found as 93.3K from M–T data for the sample with 0.075Na substitution. The maximum magnetic JC value has been calculated as 1.35×105A/cm2 at 10K for the 0.10Na sample. The maximum transport critical current density has directly been measured as 1.3×103A/cm2 at 77K for the 0.05Na sample.