La0.85−xSmxAg0.15MnO3 (x=0−0.2) ceramics were prepared using the conventional solid-state synthesis method to investigate the effect of Sm3+ substitution on magnetic and electrical transport ...properties. Magnetic susceptibility versus temperature measurements showed all samples exhibit ferromagnetic to paramagnetic transition with Curie temperature, Tc decreasing from 283K (x=0) to 164K (x=0.2) with increasing Sm3+. The observed slope in susceptibility, χ′ versus temperature curves below Tc indicates the possible presence of FM and AFM phases in the metallic region. In addition, a deviation from the Curie–Weiss law above Tc in 1/χ′ versus T curves indicates the existence of a Griffith's phase in the x=0.05−0.2 samples due to the Sm3+ ion substitution. The Griffith temperature, TG was found to decrease from 295K (x=0.05) to 229K (x=0.2). Electrical resistivity measurements of the samples in zero field showed transition from metallic behavior to insulating behavior as the temperature was increased. For x=0, two metal–insulator, MI transition peaks were observed at Tp1=282K and at Tp2=250K. Both peaks shifted to lower temperatures with the increase in Sm3+. The relative resistivity of the first peak to the second peak decreases with increasing Sm3+ for x>0.05 while at x=0.2 the Tp1 peak was strongly suppressed. Magnetoresistance, MR was observed to weaken with Sm3+ substitution. The metallic region of the ρ(T) curve of the x=0−0.15 samples was fitted to the model of electron–electron and electron–magnon scattering while the insulating region was fitted to the variable range hopping, VRH model. The resistivity behavior indicated that the substitution of Sm3+ weakened the double exchange process and enhanced the Jahn–Teller effect. Our results indicated that the Tp1 peak is strongly related to the double-exchange mechanism while the Tp2 peak is suggested to originate from magnetic inhomogeneity.
► Magnetic and electrical transport properties of La0.85−xSmxAg0.15MnO3 (x=0−0.2) were studied. ► Magnetic measurements indicated presence of Griffith's phase indicating Sm3+ substitution may induce minor ferromagnetic clusters in the paramagnetic region. ► Double resistivity peaks Tp1 and Tp2 were observed for all samples. ► The Tp1 was affected by external magnetic field and was accompanied by a magnetoresistance peak. ► The Tp2 peak increased with Sm3+ but changed weakly under magnetic field.
Purple urine bag syndrome (PUBS) occurs in catheterized patients with bacterial urinary infections that produce sulphatase/ phosphatase. The presence of indigo and indirubin pigments, which are ...tryptophan metabolites, causes the purple coloring. After antibiotic therapy, the purple colour reverts to normal. We present a case report of unusual phenomenon occurring in a 60-year-old woman with carcinoma cervix. She did not have fever, constipation or a history of medication administration. She presented with purple urine in her indwelling long term supra-pubic catheter bag and sought a consultation with an urologist because the urine in her urine bag had changed color to purple. Awareness about PUBS will prevent unnecessary investigation and over treatment.
Magnetic biologically active ceramics based on calcium phosphate with a content of M-type hexagonal ferrite (HF) particles varying from 10 to 50 wt % has been synthesized and characterized. It has ...been found that the ceramics synthesized consists of a biocompatible carbonated hydroxyapatite (CHA) with the matrix containing M-type HF particles, leading to the magnetic characteristics of the ceramics synthesized being significantly higher than those of iron-oxide-modified bioglass ceramics used in medicine.
The polycrystalline samples La
0.67
Ca
0.33
Mn
(1−x)
Fe
x
O
3
(x = 0.00, 0.01, 0.03, and 0.1) have been grown in single phase by solid state route. The analysis of the reaction has been done by ...thermogravimetry and differential thermal analysis measurements. DC electrical resistivity measurements have been carried out down to 15 K. The samples with x = 0.00, 0.01, and 0.03 exhibit metal-insulator (MI) transition at temperatures 221.5 K, 217 K, and 215 K respectively, whereas the sample with x = 0.1 is insulating in nature for entire temperature range. Interestingly, the electric transport properties of these samples are not consistent with their magnetic phase transitions and the samples show MI transition at a temperature, T
MI
, which is significantly lower than the paramagnetic to ferromagnetic transition temperature (T
c
). The resistivity data below T
MI
has been analyzed using the empirical relation ρ = ρ
0
+ ρ
1
T
n
and the data above this temperature has been analyzed using two existing models, Mott's variable range hopping model and spin polaronic conduction model.
A series of (1 − x)La
0.67
Ca
0.33
MnO
3
/(x)BaTiO
3
composites has been synthesized by the solid state route. Microstructural and transport studies on these samples show a complete immiscibility ...between metallic ferromagnet, La
0.67
Ca
0.33
MnO
3
(LCMO) and insulating ferroelectric, BaTiO
3
(BTO). Temperature dependent electrical transport studies show evidence of both intrinsic and extrinsic colossal magnetoresistance (CMR) effects. Inclusion of BTO in LCMO phase results in high resistive samples with a metal-insulator transition at temperature T
p
1
originating from intrinsic effect and another dominant metal-insulator transition at temperature T
p
2
caused because of extrinsic effect. T
p
2
decreases up to a certain percentage of BTO content above which this trend of variation is reversed.
We report here, the effect of γ-irradiation on low field AC susceptibility as a function of temperature on the grown polycrystalline Bi
1.2
Pb
0.33
Sr
1.54
Ca
2.06
Cu
3
O
10+δ
sample. The sample was ...irradiated with γ-ray dose of 100 MR and 300 MR. The temperature dependent AC susceptibility measurements have been carried out with varying AC field amplitude H
ac
(0.5 to 9.0 Oe) at frequency 131.1 Hz on both un-irradiated and irradiated samples. AC susceptibility measurements as a function of temperature at AC field amplitude H
ac
= 2.0 Oe have also been carried out with varying frequency (31.1 Hz to 1131.1 Hz). The temperature dependence of AC susceptibility with varying amplitude has been analyzed using well defined Bean's critical state model. The critical current density (J
c
) is calculated as a function of both AC field amplitude (H
ac
) and temperature. An increase in J
c
with the increase of γ-dose has been found.
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