In the east coast Peninsular Malaysia region, sediments are transported by several rivers from the east Malaysia into the South China Sea estuary. In the vicinity of the five river estuaries core sediments were collected in order to investigate rare earth elements (REEs) profile. Core sediments were divided into strata of between 2 to 4 cm intervals and prepared for analyzing by ICP-AES. REE concentrations of 54.3 μg/gr at 24-26 cm in EC4 increased to 114.1 μg/gr at 20-22 cm in EC5. The measured concentration of LREEs and Fe normalized enrichment factors indicated that sediments were not enriched with light rare earth elements derived from effluents of anthropogenic activities. Results of the total concentration were used to establish baseline data in environmental pollution assessment and to develop the correlations between the Ce/Ce* and Eu/Eu* anomalies and the distribution patterns of some light rare earth elements (LREEs) and the heavy rare earth elements (HREEs). The chondrite-normalized ratios of REEs showed LREEs enrichment and flat HREE depletion.

Polycrystalline samples of La0.67Ba0.33(Mn1-xRux)O3 with x = 0, 0.05, 0.1, 0.15 and 0.2 have been prepared using solid state reaction. The effects of doping of Ru at Mn site on La-Ba-Mn- O ceramics, the characteristics and magnetotransport properties of CMR materials are investigated. The magnetoresistance (MR) effect is measured using the four point probe technique. The magnetoresistance defined as MR% = (Ro – RH)/RH x 100% was measured at a magnetic field of H ≤ 1T at 90K, 100K, 150K, 200K, 250K, 270K and 300K for the sample of doping x = 0, 0.05, 0.1, 0.15 and 0.2. Overall, MR drops slowly when temperature rises. All doping concentration gives small variation range (~2.7% to ~26.78%). The electrical property has determined by using standard four-point probe resistivity measurement in a temperature range of 30 K to 300 K. Metalinsulator transition temperature (Tp) shifted to lower temperatures as Ru doping is increased. In this paper the structural pattern and microstructure property have investigated via XRD. XRD patterns show that these systems are in orthorhombic distorted perovskite structures.

Colossal magnetoresistance (CMR), as the name implies, is the phenomenon of dramatic changes in resistance attendant upon application of a magnetic field. The typical CMR material is derived from perovskite manganites with the chemical formula Ln1−xAxMnO3, where Ln is the rare earth (Ln = La, Pr, Nd, Sm) and A is the divalent metal (A = Ca, Ba, Sr). The objective of this paper is to study the effects of the doping Nd and Pr at La site on La-Ba-Mn-O ceramics using solid state reaction. The characteristics and magnetotransport properties of CMR materials are investigated. Polycrystalline (La1−xPrx)0.67Ba0.33MnO3 (x = 0, 1/6, 1/3, 1/2, 2/3, 5/6, 1) and (La1−xPrx)0.67Ba0.33MnO3 (x = 0, 1/6, 1/3, 1/2, 2/3, 5/6, 1), are doped with Pr and Nd site based manganites, calcined at 900°C for 12 hours, pelletized and sintered at 1300°C for 24 hours have been synthesized and investigated. The magnetoresistance (MR) effects are measured using the four point probe technique. The magnetoresistance defined as MR% = (Ro−RH)/RH × 100 was measured at a magnetic field of H ≤ 1T at room temperature. The MR values were increased from 7.9–12.7% and from 7.9–12.3% for doping with Nd (x = 0.17) and Pr (x = 0.33) respectively. The electrical property, Tp was determined by using standard four-point probe resistivity measurement in a temperature range of 20 K to 300 K. The result shows that Pr and Nd dopants shift the value of TP to a lower temperature. In this paper the structural pattern and microstructure property of bulk samples have been investigated via XRD, AFM and SEM. XRD patterns show that these systems are in single-phase with orthorhombic distorted perovskite structures. The rms roughness for the AFM images has obtained for undoped and doped samples. SEM micrographs have shown that undoped samples are observed to be more compact than the doped samples doped due to the existence of pores. The potential of this research is to produce magnetoresistive read head such as read/write heads in computer disc-drives, position sensor, magnetoresistive random access memory (MRAM), biomagnetic sensor and magnetic accelerometers.