The results showed that the average size of nanoparticles was about 10-30 nm. Absorption edge of each sample depended on the content of substitution of Co, Ni. Besides, the content of ion substitution also had influence on the structure, Raman spectrum, structural diagram of energy area and state density of samples. | Communications in Physics, Vol. 23, No. 3 (2013), pp. 263-273 STRUCTURAL AND OPTICAL PROPERTIES OF SAMPLES SrTi1−x Mx O3 (M = Co, Ni) SYNTHESIZED BY SOL-GEL METHOD DOAN THI THUY PHUONG University of Transport and Communication, Lang Thuong, Dong Da, Hanoi NGUYEN VAN MINH National University of Education, 136 Xuan Thuy, Cau Giay, Hanoi CHU TIEN DUNG University of Transport and Communication, Lang Thuong, Dong Da, Hanoi Email: thuyphuongdp@ Received 25 June 2013; Accepted for publication 15 September 2013 Abstract. By sol-gel method, we synthesized SrTi1−x Mx O3 (M = Co, Ni; x = ; ; ; ; ; ) nano particles and investigated structure of Raman spectrum, absorption spectra, structural diagram of energy area and their density of states. The results showed that the average size of nanoparticles was about 10-30 nm. Absorption edge of each sample depended on the content of substitution of Co, Ni. Besides, the content of ion substitution also had influence on the structure, Raman spectrum, structural diagram of energy area and state density of samples. The results indicated that Co and Ni ions were substituted for position of Ti in the net cell, which changed structure of the material and reduced band gap of the synthesized materials and increases its conductivity. I. INTRODUCTION In recent years, strontium titanate SrTiO3 has been widely studied since the discovery of its ferroelectric properties. Due to the relatively high dielectric constant (ε = 300) and low loss, this material is appropriated for applications in the high-frequency components, short wave devices, especially in the low temperature conditions [14]. The researches on SrTiO3 often focused on doping and/or replacing Ti by transition metal ions that induced a distortion of cubic structure of the material and then led to the appearance of new physical phenomena. The SrTi1−x Mx O3 (M is the transition metal ions) has attracted the world-wide researchers [11, 15, 16, 18, 26]. The .
