@conference{
author = "Grbović, Jasmina and Matović, Branko and Milovanović, S. and Andrić, V. and Umićević, Ana and Cekić, Božidar",
year = "2007",
abstract = "Despite its high cost, hafnium has been gaining wider acceptance in modern technologies. Owing to its refractory properties combined with high solubility and its positive effect on heat resistance, hafnium has been used as a component of a number of new construction materials containing d elements. Recently, the serial of intermetallic compounds formed between Hf M (M = V, Cr, Mn, Fe, Co, Ni, Cu) have been investigated as systems interesting for hydrogen storage [1,2], able to form hydrides in hydrogen-tometal atom ratios H/M 1 at rather low temperatures (T 3000 C) and pressures or as permanent magnets [3]. In this paper, we present a study on structural properties and compound formation in the CoHf systems. The microstructure of the powders was characterized by X-ray XRD with a Siemens KRISTALOFLEKX D-500, equipped with Cu-K Ni filtrated radiation. Morphological and microanalytical characterization was carried out by SEM with a Cambridge 250 MKIII and EDS microanalysis. EDXRF measurements were performed on the EDXRF spectrometer (Canberra) with a Si(Li) semiconductor detector and annular radioisotope excitation source 109Cd. All samples were measured for a period of 22500 s under the same experimental conditions on the sample holders made of Teflon rings and Mylar foil. To obtain HfCo, HfCo3 and HfCo6, the proper amount of constituent elements were arcmelting several times in purified argon atmosphere. Since there is no JSPDS data about HfCo3, size of the unit cell is deduced from the angular positions of the diffraction lines. An assumption is made on the basis of cubic crystal system. Pattern indexing was done by means of a slide rule and the correct Miller indices are assigned to each reflection. It was found that two phases are present with the same HfCo3 composition belonging to the different space groups (215 and 204) with the different lattice edges ao1 = 5.58 Å and ao2 = 4.17 Å, respectively. By EDXRF spectrometry it was observed that Hf:Co ratio in HfCo3 is 1:3 and in Hf:Co 1:1. SEM images also confirmed the XRD and EDXRF observations. One can see that samples a) HfCo3 and b) HfCo are homogenous, while in the sample c) on the porous HfCo6 phase (dark field), there are grains of HfCo phase (bright fields). Further investigation involving TDPAC and SQUID technique, regarding local measurements of hyperfine fields and their magnetic properties, as well as ab-initio calculations of the electronic structure are planed in order to give a dipper insight into structure and hydriding behavior of material.",
publisher = "Prague : Czechoslovak Microscopy Society",
journal = "8th Multinational congress on microscopy : Proceedings",
title = "Synthesis and Characterization of Hf-Co Intermetallic Compounds",
pages = "253-254",
url = "https://hdl.handle.net/21.15107/rcub_vinar_12515"
}
