Synthesis of Tantalum Hydride Using Mechanical Milling and Its Characterization by XRD, SEM, and TGA

José Luis Iturbe-García,Beatriz Eugenia López-Muñoz

doi:10.4236/anp.2014.34020

Abstract

In this paper, we report the results obtained from different phases of metal hydrides. The synthesis and characterization of tantalum hydrides were obtained “in situ” during mechanical milling. Elemental Ta with purity of 99.8% was used in this investigation to obtain the hydrides. A highenergy ball milling technique was utilized to prepare hydrogenated phases. Ta hydrides and oxides were formed as function of milling process time. Milling times of 5, 10 and 20 hours were programmed, and the ball-to-powder weight ratio was 10:1. The material was first characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Before and after hydrogenation process the material was also analyzed by TGA. X-ray diffraction analysis demonstrated that only tantalum hydrides (Ta2H and TaH0.5) were obtained after 20 h of milling. We will discuss the effect of the ball-milling process about formation “in situ” of nanometric tantalum hydrides with methanol as a hydrogen source.

Highlights

Diverse methods exist to prepare metallic alloys between them, the mechanical alloying technique is widely used [1]-[3]
The micrograph corresponds to Ta particles; according to the scanning electron microscopy (SEM) analysis, the scale reported indicated that the particle sizes were larger than 100 microns and possessed a heterogeneous morphology because we started from blades, which were roughly shaped with a lime before the mechanical milling process
Image B represents the material in detail, it can see a group of clusters formed by particles whose size is of nanometer order, and with the milling time used to reduce its size is supposed that the powders observed on the images corresponding to the tantalum hydrides, since according to X-ray diffraction (XRD) diffractograms only hydride phases were identified

Summary

Introduction

Diverse methods exist to prepare metallic alloys between them, the mechanical alloying technique is widely used [1]-[3]. Other studies related to Ta element is about the properties of surface layers formed by exposing samples to air and their disintegration as a function of temperature using thermal desorption spectroscopy of hydrogen in tantalum hydrides [23].The metal-hydrogen system has received considerable attention during the last decades because of their technological applications as well as scientific importance. It has been reported the preparation of monohydride-Ta by heating a mixture of CaH2 and Ta2O5 to temperature no exceeding 900 ̊C and studied different types of hydrides including their crystallography, thermodynamic properties and hysteresis in metal-hydrogen systems of the group V transition metals (Nb, V and Ta) [24]. The powders were analyzed by XRD, SEM and TGA for phases identification, morphology determination and hydrogen content respectively

Experimental

Results and Discussion

Conclusion