Influence of Gd-content on the electrical transport properties of La0.67−x Gd x Sr0.33MnO3 polycrystalline ceramics by sol–gel method

2017 ◽  
Vol 28 (22) ◽  
pp. 17026-17030
Author(s):  
Yalin Zhang ◽  
Qingming Chen ◽  
Hui Zhang ◽  
Xiaohui Chen ◽  
Fei Jin ◽  
...  
2011 ◽  
Vol 8 (s1) ◽  
pp. S189-S194 ◽  
Author(s):  
Yong-Qing Zhai ◽  
Jing Qiao ◽  
Zhang Zhang

With activated carbon for reducing agent, the sol-gel method was used to prepare the giant magnetoresistance materials Sr2FeMoO6, which is the double Perovskite oxide. The structure, morphology, magnetic and electrical transport properties were investigated respectively by x-ray diffraction, scanning electron microscopy and vibrating sample magnetometer. The as-synthesized sample is Sr2FeMoO6with tetragonal crystal structure and I4/mmm space group and unit cell parameter is a = 5.580Å, c = 7.882Å. The primary particles are spherical in shape and the grain size is below 100 nm. The curie temperature is above room temperature and the saturation magnetization is 13.321 A·m2/kg under 1.0 T at room temperature. The sample exhibit typical semiconductor behavior and the conductive mechanism can be described by small polaron variable range hopping model. The room temperature magnetoresistance of the sample under 1.0 T field is up to -10.02%. Moreover, it is found the dosage of citric acid and the amount of reducing agent has great effect on the phase structure and magnetic properties of the samples.


2010 ◽  
Vol 19 (02) ◽  
pp. 219-227
Author(s):  
DOAN THI THUY PHUONG ◽  
NGUYEN VAN MINH

We investigate effects of Co dopant concentration on the structure, as well as optical and electrical transport properties in SrTi 1-x Co x O 3 (x = 0.00, 0.10, 0.20, 0.30, 0.40, 0.50) nanoparticles prepared by sol–gel method with annealing temperature considerably lower than that employed conventionally. The dopant-induced changes are studied by XRD, Raman, Optical absorption and Impedance measurements. The results show an average particle size of about 30 nm, and decreasing lattice parameters. In the Raman spectra, a broad structure in the region 200–500 cm-1 is almost absent and the peaks in the region 600–800 cm-1 show different relative weights with respect to those from SrTiO 3, which is related to structural changes, decreasing gap with increasing dopant concentration in conjuction with increasing grain boundary contribution to the impedance. These results also demonstrate the feasibility of synthesizing the compound with low annealing temperature.


2015 ◽  
Vol 1107 ◽  
pp. 272-277 ◽  
Author(s):  
Siau Wei Ng ◽  
Kean Pah Lim ◽  
S.A. Halim ◽  
Hassan Jumiah ◽  
Albert H.M. Gan ◽  
...  

We have investigated the structural, microstructure and electrical transport properties of nanosized Pr0.85Na0.15MnO3 (PNMO) synthesized by sol-gel technique and sinter from 600°C to 1000°C. The grain size increases from 67 nm (S600) up to 284 nm (S1000) due to the grain growth during heat treatment. XRD showed that single phase orthorhombic crystal structure of PNMO is fully forms started at 600°C. The resistivity decreased with the increased of grain size and crystallite size due to the reduction of grain boundary effect (dead magnetic layer) which improved their grain conductivity.All samples showed semiconductor behavior where their metal insulator transition temperatures (TMIT) were estimated to be lower than 80K.


2017 ◽  
Vol 31 (17) ◽  
pp. 1750195
Author(s):  
Li Zhang ◽  
Yibao Li ◽  
Zhen Tang ◽  
Yan Deng ◽  
Hui Yuan ◽  
...  

Microstructures, electrical transport and magnetic properties of Sr[Formula: see text]Ti[Formula: see text]Co[Formula: see text]O[Formula: see text] ceramics are investigated. With Co doping, the Sr[Formula: see text]Ti[Formula: see text]Co[Formula: see text]O[Formula: see text] ceramics remain tetragonal structure while the grain size is decreased with doping. Magnetic moment is enhanced with Co doping and ferromagnetism is observed at low temperatures for Co-doped Sr[Formula: see text]TiO[Formula: see text]. The Sr[Formula: see text]Ti[Formula: see text]Co[Formula: see text]O[Formula: see text] and Sr[Formula: see text]Ti[Formula: see text]Co[Formula: see text]O[Formula: see text] show semiconductor-like transport properties, which can be well fitted by Mott variable range hopping model. The results will provide an effective route to synthesize Sr[Formula: see text]Ti[Formula: see text]Co[Formula: see text]O[Formula: see text] ceramics as well as to investigate the physical properties.


2013 ◽  
Vol 652-654 ◽  
pp. 576-580 ◽  
Author(s):  
Mya Theingi ◽  
Ji Ma ◽  
Hui Zhang ◽  
Xiang Gao ◽  
Jian Hong Yi ◽  
...  

Manganite perovskite La1-xCaxMnO3(x=0.33, 0.5 and 0.9) have been prepared by chemical co-precipitation method. Ammonium carbonate was used to coprecipitate lanthanum, calcium and manganese ions as carbonates under basic condition. This precursor on calcining at 900°C yields La-Ca-Mn-O perovskite phase. Follow by sintering at 1200°C after the powders were pressed into pellets gave La1-xCaxMnO3(LCMO) polycrystalline ceramics. The crystal phases of the resulting powders and ceramics were examined by X-ray diffraction (XRD) technique. The morphology of the powders was observed by scanning electron microscopy (SEM) and electrical transport properties of ceramics were measured by conventional four-point probe technique.


Sign in / Sign up

Export Citation Format

Share Document