Preparation and Characterization of Materials

586 Pages·1981·28.741 MB·English

by  J. Honig (Eds.)

THE PROCEEDINGS OF THE
INDO-U.S. WORKSHOP
ON
THE PREPARATION AND CHARACTERIZATION OF MATERIALS
HELD
FEBRUARY 19-23, 1981
INDIAN INSTITUTE OF SCIENCE, BANGALORE, INDIA
This Workshop was supported by the
Department of Science and Technology
Government of India, New Delhi
National Science Foundation
Washington, D.C.
Indian Institute of Science
Bangalore, India
ORGANIZING COMMITTEE
INDIAN ORGANIZING N. S. Satyamurthy
COMMITTEE Bhabha Atomic Research Centre
Bombay 400 085
C. N. R. Rao (Chairman) A. P. B. Sinha
Indian Institute of Science National Chemical Laboratory
Bangalore 560 012 Poona 411 008
T. R. Anantharaman E. C. Subbarao
Banaras Hindu University Indian Institute of Technology
Varanasi 221 005 Kanpur 208 016
D. Chakravorty
U.S. ORGANIZING COMMITTEE
Indian Institute of Technology
Kanpur 208 016 J. M. Honig (Chairman)
Purdue University
J. Dhar
West Lafayette, Indiana 47907
Department of Science and Technology
New Delhi 110 029 Leroy Eyring
Arizona State University
G. C. Jain
Tempe, Arizona 85281
National Physical Laboratory
New Delhi 110 012 Rustum Roy
The Pennsylvania State University
S. Ramaseshan
University Park, Pennsylvania 16802
Indian Institute of Science
Bangalore 560 012 A. W. Sleight
DuPont de Nemours & Company
Wilmington, Delaware 19898
PREPARATION
AND CHARACTERIZATION
OF MATERIALS
Edited by
J. M. HONIG
Department of Chemistry and Materiah Sciences Council
Purdue University
West Lafayette, Indiana
C. N. R. RAO
Solid State and Structural Chemistry Unit
and Materials Research Laboratory
Indian Institute of Science
Bangalore, India
1981
®
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Library of Congress Cataloging in Publication Data
Main entry under title:
Preparation and characterization of materials.
Proceedings of the Indo-U.S. Workshop on the
Preparation and Characterization of Materials,
held Feb. 19-23, 1981, at the Indian Institute of
Science, Bangalore, India.
Includes index.
1. Materials—Congresses. I. Honig, Jürgen M.
II. Rao, C. N. R. (Chintamani Nagesa Ramachandra),
Date. III. Indo-U.S. Workshop on the Preparation
and Characterization of Materials (1981 : Indian
Institute of Science, Bangalore) IV. Indian
Institute of Science, Bangalore.
TM01.3.P73 620. l'l 81-20510
ISBN 0-12-355040-8 AACR2
PRINTED IN THE UNITED STATES OF AMERICA
81 82 83 84 9 8 7 6 5 4 3 2 1
CONTRIBUTORS
Numbers in parentheses indicate the pages on which the authors' contributions begin.
T. R. Anantharaman (477), Department of Metallurgical Engineering, Banaras
Hindu University, Varanasi-221005, India
C. A. Angell (449), Department of Chemistry, Purdue University, West
Lafayette, Indiana 47907
H. Bhat (315), Department of Materials Science and Engineering, State Univer-
sity of New York, Stony Brook, New York 11794
R. J. Bratton (565), Westinghouse Electric Corporation, Research and Devel-
opment Center, Pittsburgh, Pennsylvania 15235
R. W. Carpenter (133), Center for Solid State Science, and College of Engineer-
ing and Applied Science, Arizona State University, Tempe, Arizona 85281
R. Chakravarthy (105), Nuclear Physics Division, Bhabha Atomic Research
Centre, Bombay, India
D. Chakravorty (515), Advanced Centre of Materials Science, Indian Institute
of Technology, Kanpur, India
Abraham Clearfield (283), Department of Chemistry, Texas A&M University,
College Station, Texas 77843
L. E. Cross (249), Materials Research Laboratory, The Pennsylvania State Uni-
versity, University Park, Pennsylvania 16802
B. K. Das (75), Division of Materials, National Physical Laboratory, NewDelhi-
110012, India
B. A. Dasannacharya (105), Nuclear Physics Division, Bhabha Atomic
Research Centre, Bombay, India
R. C. DeVries (101), General Electric Research and Development Center, The
Knolls, Schenectady, New York 12301
C. D. George (417), Physical Chemistry Division, National Chemical Labora-
tory, Pune-411008, India
P. S. Gopalakrishnan (391), Materials Science Division, National Aeronautical
Laboratory, Bangalore-560017, India
M. S. Hegde (161), Solid State and Structural Chemistry Unit, Indian Institute
of Science, Bangalore-560012, India
ix
x CONTRIBUTORS
H. Herman (315), Department of Materials Science and Engineering, State Uni-
versity of New York, Stony Brook, New York 11794
J. M. Honig (339), Department of Chemistry, Purdue University, West
Lafayette, Indiana 47907
Harold S. Horowitz (29), Exxon Research and Engineering Company, Cor-
porate Research, Linden, New Jersey 07036
Animesh K. Jain (47), Nuclear Physics Division, Bhabha Atomic Research
Centre, Bombay, India
John M. Longo (29), Exxon Research and Engineering Company, Corporate
Research, Linden, New Jersey 07036
J. B. MacChesney (537), Bell Laboratories, Murray Hill, New Jersey 07971
A. Mitra (417), Physical Chemistry Division, National Chemical Laboratory,
Pune-411008, India
J. Mukerji (585), Central Glass and Ceramic Research Institute, Jadavpur,
Calcutta-32, India
Manu Multani (185), Materials Research Group, Tata Institute of Fundamental
Research, Bombay, India
R. E. Newnham (249), Materials Research Laboratory, The Pennsylvania State
University, University Park, Pennsylvania 16802
V. C. S. Prasad (217), Materials Development Centre, Bharat Electronics Ltd.,
Bangalore-560117, India
C. N. R. Rao (161), Solid State and Structural Chemistry Unit, Indian Insti-
tute of Science, Bangalore-560012, India
K. Veerabhadra Rao (217), Advanced Centre for Materials Science, Indian Insti-
tute of Technology, Kanpur, India
K. J. Rao (497), Solid State and Structural Chemistry Unit, Indian Institute of
Science, Bangalore-560012, India
Franz Rosenberger (3), Departments of Physics and Materials Science and
Engineering, University of Utah, Salt Lake City, Utah 84112
N. S. Satya Murthy (105), Nuclear Physics Division, Bhabha Atomic Research
Centre, Bombay, India
A. P. B. Sinha (417), Physical Chemistry Division, National Chemical Labora-
tory, Pune-411008, India
Sanjai Sinha (417), Physical Chemistry Division, National Chemical Labora-
tory, Pune-411008, India
D. K. Sood (47), Nuclear Physics Division, Bhabha Atomic Research Centre,
Bombay, India
E. C. Subbarao (217), Department of Metallurgical Engineering, Indian Insti-
tute of Technology, Kanpur, India
G. V. Subba Rao (269), Materials Science Research Centre, Indian Institute of
Technology, Madras-600036, India
S. V. Subramanyam (367), Department of Physics, Indian Institute of Science,
Bangalore-560012, India
C. S. Sunandana (269), Materials Science Research Centre, Indian Institute of
Technology, Madras-600036, India
PREFACE
The field of materials science is continually expanding; a very important first
step in any applications of this discipline is the proper preparation and
characterization of materials. Workers in this area are often faced with a rapidly
growing literature on this aspect of materials science.
It was therefore deemed appropriate to organize a workshop on the prepara-
tion and characterization of materials, which was convened at the Indian Insti-
tute of Science in Bangalore, India, during the period February 19-23,1981. The
meeting was sponsored jointly by the Department of Science and Technology of
the Government of India and by the U.S. National Science Foundation. Ten
United States delegates and fourteen Indian scientists presented invited talks,
virtually all of which are included in the present volume.
The workshop also included thirty-nine presentations at two poster sessions;
these papers are being published by the Indian Academy of Sciences as a special
issue of the Bulletin of Materials Science.
The main objectives of the workshop were to provide a forum for indepth
discussions of recent advances and developments in this area and to foster col-
laborative research efforts between scientists and engineers in the two countries
who are specialists in materials research.
The contributions to the present volume have been grouped into several
categories according to their subject matter: crystal growth and other prepara-
tion techniques, selected characterization techniques, ferroics, layered materials,
metal oxides and other electronic materials, amorphous materials including
glasses, and high temperature ceramics. Contributors were asked to provide
tutorial introductions to their areas of expertise, so that the subject matter might
be more generally accessible to nonspecialists. Authors were also encouraged to
bring readers up-to-date on certain aspects of their specialty. The editors hope
that these twin objectives have been met, so that the articles will be useful not
only to practicing materials scientists but also to interested teachers, students,
and researchers outside the field of materials research.
It is a pleasure to acknowledge the assistance of and to thank the following
xi
Xll PREFACE
individuals: Dr. Osman Shinaishin of the National Science Foundation for his
close liaison with respect to the funding aspect of the project; Mr. S. K. Dutt of
the U.S. Embassy in New Delhi, for assistance in travel and monetary arrange-
ments for the U.S. delegates; Dr. J. Gopalakrishnan and other members of the
Solid State and Structural Chemistry Unit, Indian Institute of Science, for local
organization; Professor M. G. K. Menon of the Department of Science and
Technology and Professor S. Dhawan of the Indian Institute of Science for their
kind encouragement; Mr. G. V. Srinivasa of the Raman Research Institute for
typing some of the manuscripts and Mr. D. D. Sarma for assistance in proof-
reading; Mrs. Srimathi Nagarajan for various forms of assistance in the
organization of the workshop; and Ms. Hali Myers, who generously contributed
her time and efforts both toward the organization of the workshop and to the
final processing of the manuscripts.
J. M. Honig
C. N. R. Rao
FLUID DYNAMIC EFFECTS IN VAPOR
CRYSTAL GROWTH AMPOULES*
Franz Rosenberger
Departments of Physics and
Materials Science and Engineering
University of Utah
Salt Lake City, Utah U.S.A.
I. INTRODUCTION
Crystallization from vapors has gained great importance in the prepara-
tion of solid state components and research samples. Vapor-to-solid
processes in open flow systems (Physical or Chemical Vapor Deposition) are
widely employed by the opto-electronic industry for the production of epi-
taxial and polycrystalline layers. Closed tube vapor transport processes
are mostly used in research laboratories for the growth of bulk samples.
If the vapor pressure of a not too congruently vaporizing material exceeds
-2
10 torr or so at convenient temperatures, it may efficiently be grown
by Physical Vapor Transport, PVT (sublimation-condensation), Fig. la. If
the vapor pressure is too low for practical PVT rates, one may utilize a
reversible chemical reaction, which yields only volatile products, for
Chemical Vapor Transport, CVT, Fig. lb.
The wide application of vapor growth is due to various advantages over,
say, crystallization from melts. Since the temperatures involved are
typically considerably lower, many materials that decompose before melting
or that exhibit high temperature solid-solid phase transitions can be
Supported by NSF Grant DMR79-13183 and NASA Grant NSG-1534.
PREPARATION AND CHARACTERIZATION Copyright ©1981 by Academic Press, Inc.
OF MATERIALS 3 All rights of reproduction in any form reserved.
ISBN 0-12-355040-8
4 FRANZ ROSENBERGER
(S SStfB>
wi2Lii
SOURCE CRYSTAL SOURCE CRYSTAL
PURE VAPOR OR
NON REACTIVE GAS MIXTURE REACTIVE
GAS MIXTURE
Figure 1. Closed ampoule methods for crystal growth from vapors.
(a) Physical Vapor Transport: sublimation and recrystallization of com-
ponent A in temperature gradient. (b) Chemical Vapor Transport: reaction
of solid A with vapor B to volatile product(s), here, C, and back-reaction
to solid A in a zone of different temperature; solid and dashed T(x) for
endothermomic and exothermic transport reaction respectively.
prepared with less difficulties from the vapor. Also, at lower tempera-
tures high purity conditions are attained more readily due to: a) reduced
diffusion of impurities from containers, b) reduced reaction rates with
containers, c) enhanced segregation of impurities at the growing interface
(1), and d) effective separation of particulate low-vapor-pressure impuri-
ties (carbon!) during transport. Furthermore, lower temperature gradients
and, hence, lower dislocation densities can be more readily obtained.
Lower growth temperatures result also in lower concentrations of thermally
created (Schottky, Frenkel) defects. Also, vapor-solid interfaces, due to
their low atomic roughness (2), exhibit considerably higher shape
stability against non-uniformities in heat and mass transfer. Due to the
low mass density of vapors, the nutrient flux to a growing interface is
readily controllable. This is particularly important for thin film
growth.
Low growth rates and parasitic nucleation are often referred to as
major drawbacks in vapor crystallization. Low growth rates may be a
consequence of interfacial kinetics limitations. Or they may simply
result from the large latent heat flux that must be dissipated at growing
VAPOR CRYSTAL GROWTH AMPOULES 5
solid-vapor interfaces. (Note that heats of vaporization are often up to
an order of magnitude larger than heats of melting.) But in many situa-
tions, low growth rates,as well as uncontrolled nucleation, reflect a lack
of macroscopic transport control, rather than intrinsic limitations.
Hence, a quantitative understanding of the transport conditions is most
desirable for practical purposes.
An even stronger need for such insight comes from a more fundamental
aspect. Most (technologically) interesting properties of solids are
extrinsic, i.e., are obtained through the introduction of impurities
("dopants, solutes") into the host lattice, typically during growth.
Thermodynamics governs the ratio of dopant concentration in the nutrient
at the interface to the concentration that is incorporated into the
solid (1). The actual local concentration that is offered to the inter-
face, however, is governed by the fluid dynamics that prevails in the
nutrient. Non-uniform interfacial dopant supply leads to a non-uniform
dopant distribution in a growing crystal. Particularly undesirable in-
homogeneities (striations) can result when the (interfacial) heat and mass
transport becomes time-dependent (oscillatory). Such striations, often
occurring with spacings that are commensurate with electronic component
dimensions in modern microcircuitry, can limit device performance
drastically.
Considerable progress has been made towards an understanding (and
consequent control) of the fluid dynamic origin of striations in melt
growth; see, e.g., (3,4). In vapor growth, progress has been slower. A
fundamental reason is that with the low mass densities of vapors, diffu-
sion velocities are often comparable to buoyancy-driven convective
velocities. Hence, the convection behavior of the nutrient cannot simply
be extrapolated from known solutions to fluid dynamically "similar" mono-
component (pure) systems — as can be successfully done for melt systems,