مؤسسة الإزدواج والأسرة في ضوء الشريعة الاسلامية

Allah Almighty has created everything in pairs. It is a scientific fact that these pairs exist in all things, in vegetable kingdom, even in inorganic matters. There is no doubt that these elements do not exist by themselves. The Holy Quran has mentioned repeatedly this fact in different verses. Marriage in Islam is a divine bond between husband and wife to enjoy the social relationship with each other and is a basic unit of Islamic  family system. This article presents the structure of a Muslim Family in the light Islamic teachings.

The Effect of Various Substitutions on the Microstructure and Properties of Srtio 3 -Sr 2 Nb 2 O 7 Based Electroceramics for Microwave Applications

Sr 5 Nb 4 TiO 17 is known to exhibit low loss in comparison to other compounds in the SrTiO 3 –Sr 2 Nb 2 O 7 system; therefore, the aim of this work was to investigate the effect of various cation substitutions on the phase, microstructure and electrical properties of Sr 5 Nb 4 TiO 17 for possible microwave (MW) applications. All the compositions were prepared through a mixed oxide solid state sintering route. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used for phase and microstructural analysis, and LCR meter and a vector network analyzer for the measurement of electrical properties. Compositions in the Sr 5-x Ca x Nb 4 TiO 17 (x = 0-5) series formed single phase ceramics at ~1400°C; however, at temperatures ≥1500°C, secondary phases with general formula (Sr,Ca) 6 Nb 4 Ti 2 O 20 formed along with the parent Sr 5-x Ca x Nb 4 TiO 17 phases with x = 0 – 5. Optimum MW dielectric properties (e r ~54 t f ~6.5 ppm/°C, Q u ×f o ~1166 GHz) were achieved for the ~97% dense Sr 2 Ca 3 Nb 4 TiO 17 ceramics. Compositions in the Sr 5-x La x Nb 4-x Ti 1+x O 17 (x = 0-4) series also formed single phase ceramics at 1450°C to 1550°C. Optimum values for Q u ×f o (~ 9969 GHz), e r (~ 61) and t f (~ 117 ppm/°C) were achieved for the Sr 5-x La x Nb 4-x Ti 1+x O 17 composition with x = 4 (i.e. SrLa 4 Ti 5 O 17 ). In an attempt for further improvement in the electrical properties, compositions in the SrLa 4-x A x Ti 5 O 17 series (A = Nd or Sm, x = 0 ≤ x ≤ 4) were also investigated. An analysis of the properties vs. composition plots indicated that the optimum MW dielectric properties i.e. e r ~ 54, Q u ×f o ~ 6000 GHz and t f ~ 0 ppm/°C corresponded to the SrLa 4-x Nd x Ti 5 O 17 composition with x ~ 1.6. SrLa 4-x Sm x Ti 5 O 17 compositions formed single phase ceramics at x ≤ 3 and a mixture of Sm 2 Ti 2 O 7 and SrTiO 3 at x = 4. Here again, an analysis of the results indicated that the optimum properties i.e. e r = 53, t f ~ 0 ppm/ o C and Q u ×f o = 3200 GHz corresponded to the SrLa 4- x Sm x Ti 5 O 17 composition with x~1.4. Compounds in the Sr 1-x Ca x La 4 Ti 5 O 17 (x = 0 - 1) and SrLa 4 Ti 5-x Zr x O 17 (x = 0 – 0.1) composition series exhibited e r ~53.7, Q u ×f o ~11532 GHz and t f ~-1.4 ppm/°C, and e r ~ 57.3, t f ~ +71.5 ppm/°C and Q u ×f o ~9841 GHz for x = 0.6 (Ca 2+ ) and x = 0.1 (Zr 4+ ). Consistent with previous, the substitutions of smaller cations for larger ones led to the development of fine grained microstructures indicating improved density.