رسائل ماجيستير
English
2016
Preparation of K 1-x Na x NbO 3 Ferroelectrics Composite for Solar Energy Harvesting Application
عامر عبدالله سلمان, عماد خضير الشكرجي
كلية العلوم-جامعة النهرين · العراق
In this study, K 1-x Na x NbO 3 were prepared with different substitutions (x), where x = (0, 0.5 and, 1) by conventional solid state reaction (SSR). The sample with (x=0) was prepared for different value of sintering temperature (900, 950, 1000 and 1050 II o C). while the samples with (x=0.5 and 1) with sintering temperature (1000 o C). The resulted powders have polycrystalline structure with a starting to produce a single crystal for the sample with (x=0) above sintering temperature (1000 o C). Also this appeared for (x=0.5 and 1). Crystal structure, space group, crystallite size, and grain size were determined from structural analysis (XRD and, SEM). Using special software for specifications and estimations the XRD, which help in calculations and to make a comparison with some international databases like ICDD, PDF2 database and, COD database. Physical properties represented by density, dielectric measurements, optical energy gap and the refractive index for K 1-x Na x NbO 3 system. The dielectric measurements were studied under two conditions, the first was by changing frequency at room temperature, the second was by changing temperature at fix frequency in role to measure the dielectric constant (ε r ) and loss tangent (D). Curie temperature (Tc) and dielectric constant were determined from dielectric measurements. From dielectric measurements for KNbO 3 , the maximum dielectric constant was appeared at the sample with sintering temperature (1000 C). While for all sample sintered at (1000 o C) the maximum dielectric constant was for (x=0.5). The Curie temperature was shifted to a lower temperature as the Na ratio increase in the system. The optical energy gap was calculated for the system and its value was in the range (4.23-4.27 eV). The refractive index also calculated from the reflectance spectrum and from the LCR- measurement. The maximum value of the refractive index from the reflectance pattern was in the range o (1.2, 1.8 and 1.24) for x = 0, 0.5 and 1 respectively. The refractive index also concluded form the LCR-measurement for the same frequency of its the maximum value the reflectance pattern calculation. It was (0.72, 0.96 and 0.67) for x = 0, 0.5 and 1 respectively. The total results showed that the ability of using this composition (K 1x Na x NbO 3 ) in the field of solar energy harvesting
