Preparation of iridium metal films by spray chemical vapor deposition

Metal Ir films were prepared by spray chemical vapor deposition (CVD) in air from an Ir precursor, (1,3-cyclohexadiene)(ethylcyclopentadienyl)iridium, Ir(EtCp)(CHD). Film deposition was ascertained at 270–430°C on a SiO2/Si substrate and the deposition rate increased with the deposition temperature but was saturated above 330°C. The obtained films consisted of Ir metal without any iridium oxide impurity irrespective of the deposition temperature. Films tended to orient to (111) with increasing deposition temperature. Resistivity of these Ir films decreased with increasing film thickness and reached to values on the order of 10-6 Ω・cm, which was the same order of the values for bulk Ir metal. Good step coverage was observed for the Ir metal films deposited at 270°C and 330°C. This shows that the simple spray CVD process in air is a good candidate for depositing Ir metal films with good conductivity and step coverage.

RAPID SEPARATION AND DETERMINATION OF RIZATRIPTAN N-OXIDE IMPURITY IN RIZATRIPTAN BENZOATE IN A BULK DRUG SUBSTANCE BY REVERSE PHASE LIQUID CHROMATOGRAPHY

Objective: The objective is described to develop and validate a simple, reliable, precise, and specific analytical method for rapid separation and determination of N-oxide impurity in rizatriptan Benzoate active pharmaceutical ingredient bulk drug substances by reverse phase liquid chromatography as per the International Conference on Harmonization (ICH) guidelines.Methods: The methodology utilized as reverse phase liquid chromatography with gradient composition. The mobile phase proportion was compromised mobile A containing 0.25 mm potassium dihydrogen phosphate buffer pH 2.0 and methanol (95:5 v/v) and mobile B containing Acetonitrile. ODS 3V, 250 × 4.6 mm, 5 µm. column. The flow rate is 1.0 ml/minute using an LC system detector at wavelength 280 nm, and the column oven temperature is 40°C. The chromatographic separation performed in reverse phase by the gradient composer over run time was 35 minute. The resolution between N-oxide and rizatriptan was recorded on the chromatogram was more than six. The developed analytical method was validated according to the ICH guidelines.Results: Linearity was found in rizatriptan N-oxide over the concentration range of 450-11000 ng/ml, with the linear regression (Correlation coefficient R = 0.999) and proved to be robust. Limit of detection and limit of quantification of the rizatriptan N-oxide was found 150 and 450 ng/ml. The retention time of rizatriptan and rizatriptan N-oxide was recorded 22.6 and 24.7 minutes, respectively. The percentage recovery of N-oxide has been ranged from 96.0 to 102.0 in the bulk drug material sample. The proposed analytical method has been found suitable, precise, reliable, and accurate for the separation and quantitative determination.Conclusion: A specific, simple, accurate, reliable, and rapid reproducible analytical method has been developed and validated for reverse phase high- performance liquid chromatography to determine N-Oxide impurity in rizatriptan benzoate from bulk drugs material as per ICH guideline.Keywords: Rizatriptan benzoate, N-oxide impurity, High performance liquid chromatography, Reverse phase, ODS column and validation.

Effects of Particle Size on Densification Behavior of Si3N4 Ceramics

Silicon nitride (Si3N4) ceramics with Y2O3-Al2O3 as sintering additives were prepared by pressureless sintering technology using two kinds of Si3N4 powders as raw materials. The particle size of Si3N4 powders ball-milled with various times were characterized and the effects of particle size on the densification behavior of Si3N4 ceramics were investigated. The relative density and microstructure of the sintered bodies at different sintering temperatures were determined. The experimental results show that the powders with longer milling time have finer particle size and the samples with fine particle display higher shrinkage-rate at lower sintering temperature than the one with coarse particle. By extending milling time, the density gap between the sintered ceramics using different Si3N4 powder become narrower. The main factor resulting in the difference of sintering densification behavior is the particle size of Si3N4 powders rather than metallic oxide impurity of raw powders.

Effect of Yttrium Oxide Impurities on the Structure and Properties of Metallic Hafnium

The influence of yttrium oxide impurity content of 0 to 0.4 wt.% on the structure and microhardness metal hafniuminvestigated. It is shown that grain size decreases and the Microhardness of hafnium increases monotonically with increasing content of impurities, while increasing Y2O3 content more than 0.3 wt.% is cracking material.

The Centrifugation Casting of Nd:YAG Ceramics Melt by Combustion Synthesis

In this paper, Nd:YAG ceramic was prepared by combustion synthesis with centrifugation casting. Combustion temperature and pressure were calculated under adiabatic hypothesis, and measured experimentally by W/Re thermocouple and piezometer, respectively. The combustion temperature and pressure decreased with increase of the content of diluents (Y2O3and A12O3). The YAG could be obtained as the ratio between the Y2O3and A12O3reached 3:5. Phase composition and microstructures of the derived products were analyzed by XRD, SEM and EDS. The results show that the other reaction product TiN and a small quantity of gas and oxide impurity were not completely separated from YAG melt under centrifugal force so that transparent YAG ceramic was not obtained in this work.