DC electrical resistivity studies and structure of Ni0.5Zn0.5CrxFe2-xO4 nanoferrites

2015 ◽  
Vol 29 (16) ◽  
pp. 1550101 ◽  
Author(s):  
M. Siva Ram Prasad ◽  
B. Rajesh Babu ◽  
K. V. Ramesh ◽  
K. Trinath
Keyword(s):  
Activation Energy ◽  
Thermal Analysis ◽  
Electrical Resistivity ◽  
Differential Thermal Analysis ◽  
Spinel Phase ◽  
Structural Defects ◽  
Scanning Electron Micrographs ◽  
Dc Electrical Resistivity ◽  
Dta Studies ◽  
Scanning Electron

Chromium substituted Ni – Zn nano ferrite samples with composition Ni 0.5 Zn 0.5 Cr x⋅ Fe 2-x O 4 (x = 0.00 to 0.25 in steps of 0.05) have been prepared by autocombustion method employing citric acid as an oxidant. Structural, morphological and microstructural characterizations were done on the sintered powders at 1000°C while the DC electrical resistivity studies have been performed on the pellets sintered at the same temperature. The thermogravimetric and differential thermal analysis (TG-DTA) studies indicated the presence of broad exotherm and valley centered about temperature of 400°C. The formation of single-spinel phase has been observed for all the samples. The ionic packing coefficient, vacancy parameter and fulfillment coefficient have all been obtained for each composition. The scanning electron micrographs showed the formation of fine grains with size very less than 1 μm in all samples with a little agglomeration. The observed variation in DC electrical resistivity and activation energy with Cr 3+ substitution are attributed to the modifications in microstructure, structural defects and the influence of Cr 3+ ions with support of hopping mechanism.

PENINGKATAN LAJU DISOLUSI ACYCLOVIR DENGAN METODE SISTEM DISPERSI PADAT MENGGUNAKAN POLOXAMER 188

2016 ◽  
Vol 5 (1) ◽  
pp. 6
Author(s):  
Budi Setiawan ◽  
Erizal Zaini ◽  
Salman Umar
Keyword(s):  
Electron Microscopy ◽  
Thermal Analysis ◽  
Scanning Electron Microscopy ◽  
Fourier Transform ◽  
Differential Thermal Analysis ◽  
Fourier Transform Infrared ◽  
X Ray Diffraction ◽  
Poloxamer 188 ◽  
X Ray ◽  
Scanning Electron

Sebuah penelitian tentang sistem dispersi padat dari asiklovir dengan poloxamer 188 telah dilakukan formulasi dengan pencampuran secara fisika dengan rasio 1 : 1, 1 : 3, 1 : 5 dan dispersi padat 1 : 1, 1 : 3, 1 : 5 dan penggilingan 1:1 sebagai pembanding. Dispersi padat dibuat menggunakan metode pencairan (fusi), yang digabung dengan poloxamer 188 pada hotplate kemudian asiklovir dimasukkan ke dalam hasil poloxamer 188 lalu di kocok hingga membentuk masa homogen. Semua formula yang terbentuk termasuk asiklovir poloxamer 188 murni dianalisis karakterisasinya dengan Differential Thermal Analysis (DTA), X-ray Diffraction, Scanning Electron Microscopy (SEM), dan Fourier Transform Infrared (FTIR), kemudian pengambilan dilakukan  (penentuan kadar) mengunakan spektrofotometer UV pada panjang gelombang 257,08 nm dan uji laju disolusi dengan aquadest bebas CO2 menggunakan metode dayung. Hasil pengambilan  (penentuan kadar) menunjukkan bahwa semua formula memenuhi persyaratan farmakope Amerika edisi 30 dan farmakope Indonesia edisi 4 yaitu 95-110%. Sedangkan hasil uji laju disolusi untuk campuran fisik 1: 1, dan dispersi padat 1: 1, dan penggilingan 1: 1 menunjukkan peningkatan yang nyata dibandingkan asiklovir murni. Hal ini juga dapat dilihat dari hasil perhitungan statistik  menggunakan analisis varian satu arah  SPSS 17.

The Roman Ceramics of Salobrena (Granada-Spain) and their Raw Materials

1992 ◽  
Vol 267 ◽  
Author(s):  
Ana M De Andres ◽  
Isabel MuÑOZ
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Raw Materials ◽  
Third Century ◽  
Western Coast ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Third ◽  
Good Number ◽  
Scanning Electron

ABSTRACTNineteen roman ceramic sherds found near Salobreña (Granada, Spain), in the western coast of the Mediterranean Sea, as well as different ceramic clays from the surroundingsare studied. Both clays and ceramic sherds are characterizad by X-ray diffraction and spectrometry, differential thermal analysis, and scanning electron and optical microscopies. A good number of the ceramic pieces, among which some “Terrae Sigillatae”, have a composition similar to that of the local clays and, thus, have been probably manufactured at Salobreña. Only a few of them have a foreign origin. For most of them, the firing temperature was about 800-850 °C, although some have been produced at 900-1000 °C, and some others at 1000-1100 °C. It is concluded that Salobreña appearsto have been an important settlement just in the third century of the Christian era.

Thermal Stability vs. Crystallization of the Lithiumsilicate Glasses with Addition Zirconium Dioxide and Titanium Dioxide

2008 ◽  
Vol 39-40 ◽  
pp. 399-401
Author(s):  
Viliam Pavlík ◽  
Eugen Jóna ◽  
Martina Sapietová ◽  
Soňa Šnircová
Keyword(s):  
Activation Energy ◽  
Thermal Stability ◽  
Thermal Analysis ◽  
Titanium Dioxide ◽  
Differential Thermal Analysis ◽  
Structural Analysis ◽  
Zirconium Dioxide ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Relationship

The glasses with composition of Li2O . 2 SiO2 . n ZrO2 . n TiO2 (where n = 0; 0.015; 0.031; 0.050; 0.075; 0.1; 0.15; 0.2) were prepared and the relationship between structural and selected parameters of thermal stability vs. crystallization has been studied by differential thermal analysis. Structural analysis was provided by X–ray diffraction. The order of thermal stability vs. crystallization representing of activation energy of studied glass systems which increase with higher addition both oxides. The same order was obtained from the values of XRD. On the comparison the glasses with zero addition titanium dioxide their activation energy was much higher.

About Thermostability of Fe-Ni-P Amorphous Alloys

2012 ◽  
Vol 188 ◽  
pp. 21-26
Author(s):  
Aurel Raduta ◽  
Mircea Nicoară ◽  
Cosmin Locovei
Keyword(s):  
Activation Energy ◽  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Amorphous Alloys ◽  
Structural Changes ◽  
P System ◽  
X Rays ◽  
Heating Rates ◽  
Planar Flow Casting ◽  
Activation Energy Of Crystallization

A research program has been completed in order to analyze structural changes during heating of amorphous alloys belonging to Fe-Ni-P system. Special attention has been given to thermodynamics and mechanism of crystallization, to determine some aspects of development for crystalline phases. Experimental material used to determine characteristics of crystallization consisted in long ribbons, 30 thick and 18 mm wide, fabricated by mean of “Planar Flow casting” as amorphous Fe42Ni38P16B4alloy. Differential Thermal Analysis (DTA) and X-rays diffraction have been used to determine crystallization temperature of this alloy. Curves of differential thermal analysis for heating rates ranging between 1°C/minute and 20 °C/minute have been used to determine activation energy of crystallization.

Crystal Growth in Amorphous Binary Alloys of Zr-Ni System

2007 ◽  
Vol 26-28 ◽  
pp. 675-678 ◽  
Author(s):  
Takeshi Fukami ◽  
I. Noda ◽  
M. Asada ◽  
D. Okai ◽  
T. Yamasaki
Keyword(s):  
Activation Energy ◽  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Crystal Growth ◽  
Crystallization Process ◽  
Isothermal Annealing ◽  
Binary Alloys ◽  
Isothermal Condition ◽  
Amorphous State ◽  
Dta Curves

A crystallization process in an amorphous state under isothermal condition is examined for binary alloys ZrNi and ZrNi2 by differential thermal analysis (DTA). Time dependence of DTA curves is measured at several constant temperatures just below crystallization temperature. The fraction of crystallized volume in amorphous state and its time evolution during isothermal annealing are measured. These data are analyzed by the Johnson-Mehl–Avrami formula. The Avrami exponent is 2.4±0.1 for ZrNi and 3~4 depending on the set temperature for ZrNi2. The activation energy for crystallization of amorphous ZrNi and ZrNi2 was estimated by plots of lnt1/2 vs. 1/T.

Research on the Composition and Property of Boron Mud

2013 ◽  
Vol 295-298 ◽  
pp. 1547-1549 ◽  
Author(s):  
Zhi Qiang Ning
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Infrared Spectroscopy ◽  
Electron Microscope ◽  
Decomposition Reaction ◽  
X Ray ◽  
Fourier Transformed Infrared Spectroscopy ◽  
Mineral Components ◽  
Boron Mud ◽  
Scanning Electron

The composition and property of the boron mud is investigated by X-ray diffractometry (XRD), scanning electron microscope (SEM), thermogravimetry (TG), differential thermal analysis (DTA) and fourier transformed infrared spectroscopy (FITR). The mineral components of the boron mud are magnesite (MgCO3)、forsterite (Mg2SiO4)、hematite (Fe2O3)、dolomite (CaMg(CO3)2) and a small amount of magnesium sulfate and lizardite((Mg,Al)3[(Si,Fe)2O5](OH)4)). The decomposition reaction of the boron mud can be carried on at 400~600°C, and silicate of the boron mud can reaction with NaOH with the increase of temperature to about 1000°C.

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