ISSN: 2456–5474 RNI No.  UPBIL/2016/68367 VOL.- VIII , ISSUE- IX October  - 2023
Innovation The Research Concept

Study of Pellet Density and Electrical Conductivity of Some Rare Earth and Titanium Metal Compounds as a Function of Pelletizing Pressure
Paper Id :  18181   Submission Date :  2023-10-15   Acceptance Date :  2023-10-22   Publication Date :  2023-10-25
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DOI:10.5281/zenodo.10148252
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Tushar Kant Srivastava
Associate Professor
Department Of Physics
Udai Pratap (Autonomous) College
Varanasi,Uttar Pradesh, India
Abstract

The variation of Pellet density and electrical conductivity as a function of Pelletizing pressure are presented in this paper. The various mixed rare earth and titanium metal compounds for which studies have been carried out are CeTiO3, TbTiO3, DyTiO3, HoTiO3, ErTiO3 and YbTiO3.Further the pellet density and electrical conductivity of several pellets of each studied compound made at different pelletizing pressure were measured.
Keywords Electrical Conductivity, Pellet Density, Pelletizing Pressure, Rare Earth Titaniummetal Compounds.
Introduction

For measuring Pellet density and electrical conductivity pressed pellets were used. In order to ensure that the measurements on these pellets represent the bulk behaviour of studied compounds, one has to meet various conditions particularly the nonexistence of grain boundaries and air pores. The first requirement in this direction is to make pellets of uniform density. This has been achieved by using a proper steel die and keeping (where t is the thickness and A the face area of pellet) ratio less than 0.4 fixed by the other Authors (Kumar 1971, Tripathi 1981 and Lal et. al 1982).
Objective of study
In this study we calculate pellet density and electrical conductivity of studied rare earth titanates compounds and correlate it with pelletizing pressure at constant temperature.
Review of Literature

Most of the work in this study has been done in the material science research lab in the department of Physics of TDPG College, Jaunpur, affiliated to VBS Purvanchal university, Jaunpur, metallurgical department, IIT, Kanpur and Ceramic department IIT, BHU, Varanasi.
Main Text

Measurement of pellet density (dp) and electrical conductivity (σp)of pellets:

The density of pellets of each studied compound well annealed at appropriate temperature have been obtainedfrom the measurement of its volume and mass. The mass of each compound is obtained by weighing the pellets on a sensitive balance. The thickness and area of the pellets are taken out and thereby the density of pellets is calculated. The density measurement has been done on each pellet of the compound made at a pressure ranging from 3.04X108  to 8.22X108Nm-2. The variation of pellet density (dp) with pelletizing pressure (P) is shown in figure-1 for different compounds.

It is seen from figure-1 that the pellet density (dp) depends upon the pelletizing pressure. It increases almost linearly with P upto pressure of 5.04X108Nm-2 and after that the increase becomes slow and when P exceeds 6.8X108Nm-2., the density of the pressed pellets, however, remains slightly less than the reported X-ray density (d0) of the materials. Thus, pores exist in the pressed pellets. The pore fraction (fp) for highest pressed pallet were determined by the relation

The values of d0, dp and fp for all the studied compounds are given in Table-1. The pore fraction is so small that the bulk value of any parameter can be obtained using suitable corrections.

Figure-1: Plots of pellet density (dp) against pelletizing pressure (P)







Table-1

The X-ray density (d0), pellet density (dp) of highest pressed pellet and pore fraction (fp) for studied compounds

Compounds

d0 x 10-3 (Kgm-3)

dp x 10-3  (Kgm-3)

fp

CeTiO3

4.71

4.49

0.047

TbTiO3,

5.15

4.75

0.078

DyTiO3,

5.15

4.91

0.047

HoTiO3,

5.21

4.80

0.079

ErTiO3

5.24

4.92

0.061

YbTiO3

5.21

5.03

0.035

The electrical conductivity (σp) of several pellets of each compound made at different pelletizing pressure (P) were measured using silver foil electrodes at a fixed temperature. The plots of logσp vs P for studied compounds are given in figure-2.

Figure-2: Plots of logarithm of electrical conductivity of pellets (logσp) against pelletizing pressure (P) at constant temperature (T= 715 K)
Conclusion

It is seen from figure-2 that logσp depends upon pressures. It increases with P and tends to become constant when P exceeds 6.20X108Nm-2. The relatively low conductivity observed at lower pressure is obviously due to presence of less conducting grain boundary regions. These and likewise effects decrease to some extent when pelletizing pressure is increased. This fact is strengthened further by observed constancy in the density of the pellets at higher pelletizing pressure dp of pellets made at same P having different dimensions are practically same. No effect of pellet shape and size has been observed on σp. It has been generally observed that both conductivity and density of the pellets attain their maximum value at the same pelletizing pressure.

Though the constancy observed in dp and σp ensures significant reduction of grain boundary effect, yet the density of the pellet lesser than X-ray density of the material indicates that σp may be significantly smaller than the crystalline value of electrical conductivity (σ).
References

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